Merge remote-tracking branch 'remotes/origin/dev_native'

src/libslic3r/BoundingBox.cpp

@@ -0,0 +1,283 @@
+#include "BoundingBox.hpp"
+#include <algorithm>
+#include <assert.h>
+
+#include <Eigen/Dense>
+
+namespace Slic3r {
+
+template BoundingBoxBase<Point>::BoundingBoxBase(const std::vector<Point> &points);
+template BoundingBoxBase<Vec2d>::BoundingBoxBase(const std::vector<Vec2d> &points);
+
+template BoundingBox3Base<Vec3d>::BoundingBox3Base(const std::vector<Vec3d> &points);
+
+BoundingBox::BoundingBox(const Lines &lines)
+{
+    Points points;
+    points.reserve(lines.size());
+    for (const Line &line : lines) {
+        points.emplace_back(line.a);
+        points.emplace_back(line.b);
+    }
+    *this = BoundingBox(points);
+}
+
+void BoundingBox::polygon(Polygon* polygon) const
+{
+    polygon->points.clear();
+    polygon->points.resize(4);
+    polygon->points[0](0) = this->min(0);
+    polygon->points[0](1) = this->min(1);
+    polygon->points[1](0) = this->max(0);
+    polygon->points[1](1) = this->min(1);
+    polygon->points[2](0) = this->max(0);
+    polygon->points[2](1) = this->max(1);
+    polygon->points[3](0) = this->min(0);
+    polygon->points[3](1) = this->max(1);
+}
+
+Polygon BoundingBox::polygon() const
+{
+    Polygon p;
+    this->polygon(&p);
+    return p;
+}
+
+BoundingBox BoundingBox::rotated(double angle) const
+{
+    BoundingBox out;
+    out.merge(this->min.rotated(angle));
+    out.merge(this->max.rotated(angle));
+    out.merge(Point(this->min(0), this->max(1)).rotated(angle));
+    out.merge(Point(this->max(0), this->min(1)).rotated(angle));
+    return out;
+}
+
+BoundingBox BoundingBox::rotated(double angle, const Point &center) const
+{
+    BoundingBox out;
+    out.merge(this->min.rotated(angle, center));
+    out.merge(this->max.rotated(angle, center));
+    out.merge(Point(this->min(0), this->max(1)).rotated(angle, center));
+    out.merge(Point(this->max(0), this->min(1)).rotated(angle, center));
+    return out;
+}
+
+template <class PointClass> void
+BoundingBoxBase<PointClass>::scale(double factor)
+{
+    this->min *= factor;
+    this->max *= factor;
+}
+template void BoundingBoxBase<Point>::scale(double factor);
+template void BoundingBoxBase<Vec2d>::scale(double factor);
+template void BoundingBoxBase<Vec3d>::scale(double factor);
+
+template <class PointClass> void
+BoundingBoxBase<PointClass>::merge(const PointClass &point)
+{
+    if (this->defined) {
+        this->min = this->min.cwiseMin(point);
+        this->max = this->max.cwiseMax(point);
+    } else {
+        this->min = point;
+        this->max = point;
+        this->defined = true;
+    }
+}
+template void BoundingBoxBase<Point>::merge(const Point &point);
+template void BoundingBoxBase<Vec2d>::merge(const Vec2d &point);
+
+template <class PointClass> void
+BoundingBoxBase<PointClass>::merge(const std::vector<PointClass> &points)
+{
+    this->merge(BoundingBoxBase(points));
+}
+template void BoundingBoxBase<Point>::merge(const Points &points);
+template void BoundingBoxBase<Vec2d>::merge(const Pointfs &points);
+
+template <class PointClass> void
+BoundingBoxBase<PointClass>::merge(const BoundingBoxBase<PointClass> &bb)
+{
+    assert(bb.defined || bb.min(0) >= bb.max(0) || bb.min(1) >= bb.max(1));
+    if (bb.defined) {
+        if (this->defined) {
+            this->min = this->min.cwiseMin(bb.min);
+            this->max = this->max.cwiseMax(bb.max);
+        } else {
+            this->min = bb.min;
+            this->max = bb.max;
+            this->defined = true;
+        }
+    }
+}
+template void BoundingBoxBase<Point>::merge(const BoundingBoxBase<Point> &bb);
+template void BoundingBoxBase<Vec2d>::merge(const BoundingBoxBase<Vec2d> &bb);
+
+template <class PointClass> void
+BoundingBox3Base<PointClass>::merge(const PointClass &point)
+{
+    if (this->defined) {
+        this->min = this->min.cwiseMin(point);
+        this->max = this->max.cwiseMax(point);
+    } else {
+        this->min = point;
+        this->max = point;
+        this->defined = true;
+    }
+}
+template void BoundingBox3Base<Vec3d>::merge(const Vec3d &point);
+
+template <class PointClass> void
+BoundingBox3Base<PointClass>::merge(const std::vector<PointClass> &points)
+{
+    this->merge(BoundingBox3Base(points));
+}
+template void BoundingBox3Base<Vec3d>::merge(const Pointf3s &points);
+
+template <class PointClass> void
+BoundingBox3Base<PointClass>::merge(const BoundingBox3Base<PointClass> &bb)
+{
+    assert(bb.defined || bb.min(0) >= bb.max(0) || bb.min(1) >= bb.max(1) || bb.min(2) >= bb.max(2));
+    if (bb.defined) {
+        if (this->defined) {
+            this->min = this->min.cwiseMin(bb.min);
+            this->max = this->max.cwiseMax(bb.max);
+        } else {
+            this->min = bb.min;
+            this->max = bb.max;
+            this->defined = true;
+        }
+    }
+}
+template void BoundingBox3Base<Vec3d>::merge(const BoundingBox3Base<Vec3d> &bb);
+
+template <class PointClass> PointClass
+BoundingBoxBase<PointClass>::size() const
+{
+    return PointClass(this->max(0) - this->min(0), this->max(1) - this->min(1));
+}
+template Point BoundingBoxBase<Point>::size() const;
+template Vec2d BoundingBoxBase<Vec2d>::size() const;
+
+template <class PointClass> PointClass
+BoundingBox3Base<PointClass>::size() const
+{
+    return PointClass(this->max(0) - this->min(0), this->max(1) - this->min(1), this->max(2) - this->min(2));
+}
+template Vec3d BoundingBox3Base<Vec3d>::size() const;
+
+template <class PointClass> double BoundingBoxBase<PointClass>::radius() const
+{
+    assert(this->defined);
+    double x = this->max(0) - this->min(0);
+    double y = this->max(1) - this->min(1);
+    return 0.5 * sqrt(x*x+y*y);
+}
+template double BoundingBoxBase<Point>::radius() const;
+template double BoundingBoxBase<Vec2d>::radius() const;
+
+template <class PointClass> double BoundingBox3Base<PointClass>::radius() const
+{
+    double x = this->max(0) - this->min(0);
+    double y = this->max(1) - this->min(1);
+    double z = this->max(2) - this->min(2);
+    return 0.5 * sqrt(x*x+y*y+z*z);
+}
+template double BoundingBox3Base<Vec3d>::radius() const;
+
+template <class PointClass> void
+BoundingBoxBase<PointClass>::offset(coordf_t delta)
+{
+    PointClass v(delta, delta);
+    this->min -= v;
+    this->max += v;
+}
+template void BoundingBoxBase<Point>::offset(coordf_t delta);
+template void BoundingBoxBase<Vec2d>::offset(coordf_t delta);
+
+template <class PointClass> void
+BoundingBox3Base<PointClass>::offset(coordf_t delta)
+{
+    PointClass v(delta, delta, delta);
+    this->min -= v;
+    this->max += v;
+}
+template void BoundingBox3Base<Vec3d>::offset(coordf_t delta);
+
+template <class PointClass> PointClass
+BoundingBoxBase<PointClass>::center() const
+{
+    return (this->min + this->max) / 2;
+}
+template Point BoundingBoxBase<Point>::center() const;
+template Vec2d BoundingBoxBase<Vec2d>::center() const;
+
+template <class PointClass> PointClass
+BoundingBox3Base<PointClass>::center() const
+{
+    return (this->min + this->max) / 2;
+}
+template Vec3d BoundingBox3Base<Vec3d>::center() const;
+
+template <class PointClass> coordf_t
+BoundingBox3Base<PointClass>::max_size() const
+{
+    PointClass s = size();
+    return std::max(s(0), std::max(s(1), s(2)));
+}
+template coordf_t BoundingBox3Base<Vec3d>::max_size() const;
+
+// Align a coordinate to a grid. The coordinate may be negative,
+// the aligned value will never be bigger than the original one.
+static inline coord_t _align_to_grid(const coord_t coord, const coord_t spacing) {
+    // Current C++ standard defines the result of integer division to be rounded to zero,
+    // for both positive and negative numbers. Here we want to round down for negative
+    // numbers as well.
+    coord_t aligned = (coord < 0) ?
+            ((coord - spacing + 1) / spacing) * spacing :
+            (coord / spacing) * spacing;
+    assert(aligned <= coord);
+    return aligned;
+}
+
+void BoundingBox::align_to_grid(const coord_t cell_size)
+{
+    if (this->defined) {
+        min(0) = _align_to_grid(min(0), cell_size);
+        min(1) = _align_to_grid(min(1), cell_size);
+    }
+}
+
+BoundingBoxf3 BoundingBoxf3::transformed(const Transform3d& matrix) const
+{
+    typedef Eigen::Matrix<double, 3, 8, Eigen::DontAlign> Vertices;
+
+    Vertices src_vertices;
+    src_vertices(0, 0) = min(0); src_vertices(1, 0) = min(1); src_vertices(2, 0) = min(2);
+    src_vertices(0, 1) = max(0); src_vertices(1, 1) = min(1); src_vertices(2, 1) = min(2);
+    src_vertices(0, 2) = max(0); src_vertices(1, 2) = max(1); src_vertices(2, 2) = min(2);
+    src_vertices(0, 3) = min(0); src_vertices(1, 3) = max(1); src_vertices(2, 3) = min(2);
+    src_vertices(0, 4) = min(0); src_vertices(1, 4) = min(1); src_vertices(2, 4) = max(2);
+    src_vertices(0, 5) = max(0); src_vertices(1, 5) = min(1); src_vertices(2, 5) = max(2);
+    src_vertices(0, 6) = max(0); src_vertices(1, 6) = max(1); src_vertices(2, 6) = max(2);
+    src_vertices(0, 7) = min(0); src_vertices(1, 7) = max(1); src_vertices(2, 7) = max(2);
+
+    Vertices dst_vertices = matrix * src_vertices.colwise().homogeneous();
+
+    Vec3d v_min(dst_vertices(0, 0), dst_vertices(1, 0), dst_vertices(2, 0));
+    Vec3d v_max = v_min;
+
+    for (int i = 1; i < 8; ++i)
+    {
+        for (int j = 0; j < 3; ++j)
+        {
+            v_min(j) = std::min(v_min(j), dst_vertices(j, i));
+            v_max(j) = std::max(v_max(j), dst_vertices(j, i));
+        }
+    }
+
+    return BoundingBoxf3(v_min, v_max);
+}
+
+}

src/libslic3r/BoundingBox.hpp

@@ -0,0 +1,163 @@
+#ifndef slic3r_BoundingBox_hpp_
+#define slic3r_BoundingBox_hpp_
+
+#include "libslic3r.h"
+#include "Point.hpp"
+#include "Polygon.hpp"
+
+namespace Slic3r {
+
+template <class PointClass>
+class BoundingBoxBase
+{
+public:
+    PointClass min;
+    PointClass max;
+    bool defined;
+    
+    BoundingBoxBase() : defined(false), min(PointClass::Zero()), max(PointClass::Zero()) {}
+    BoundingBoxBase(const PointClass &pmin, const PointClass &pmax) : 
+        min(pmin), max(pmax), defined(pmin(0) < pmax(0) && pmin(1) < pmax(1)) {}
+    BoundingBoxBase(const std::vector<PointClass>& points) : min(PointClass::Zero()), max(PointClass::Zero())
+    {
+        if (points.empty())
+            throw std::invalid_argument("Empty point set supplied to BoundingBoxBase constructor");
+
+        typename std::vector<PointClass>::const_iterator it = points.begin();
+        this->min = *it;
+        this->max = *it;
+        for (++ it; it != points.end(); ++ it) {
+            this->min = this->min.cwiseMin(*it);
+            this->max = this->max.cwiseMax(*it);
+        }
+        this->defined = (this->min(0) < this->max(0)) && (this->min(1) < this->max(1));
+    }
+    void merge(const PointClass &point);
+    void merge(const std::vector<PointClass> &points);
+    void merge(const BoundingBoxBase<PointClass> &bb);
+    void scale(double factor);
+    PointClass size() const;
+    double radius() const;
+    void translate(coordf_t x, coordf_t y) { assert(this->defined); PointClass v(x, y); this->min += v; this->max += v; }
+    void translate(const Vec2d &v) { this->min += v; this->max += v; }
+    void offset(coordf_t delta);
+    PointClass center() const;
+    bool contains(const PointClass &point) const {
+        return point(0) >= this->min(0) && point(0) <= this->max(0)
+            && point(1) >= this->min(1) && point(1) <= this->max(1);
+    }
+    bool overlap(const BoundingBoxBase<PointClass> &other) const {
+        return ! (this->max(0) < other.min(0) || this->min(0) > other.max(0) ||
+                  this->max(1) < other.min(1) || this->min(1) > other.max(1));
+    }
+    bool operator==(const BoundingBoxBase<PointClass> &rhs) { return this->min == rhs.min && this->max == rhs.max; }
+    bool operator!=(const BoundingBoxBase<PointClass> &rhs) { return ! (*this == rhs); }
+};
+
+template <class PointClass>
+class BoundingBox3Base : public BoundingBoxBase<PointClass>
+{
+public:
+    BoundingBox3Base() : BoundingBoxBase<PointClass>() {};
+    BoundingBox3Base(const PointClass &pmin, const PointClass &pmax) : 
+        BoundingBoxBase<PointClass>(pmin, pmax) 
+        { if (pmin(2) >= pmax(2)) BoundingBoxBase<PointClass>::defined = false; }
+    BoundingBox3Base(const std::vector<PointClass>& points)
+    {
+        if (points.empty())
+            throw std::invalid_argument("Empty point set supplied to BoundingBox3Base constructor");
+        typename std::vector<PointClass>::const_iterator it = points.begin();
+        this->min = *it;
+        this->max = *it;
+        for (++ it; it != points.end(); ++ it) {
+            this->min = this->min.cwiseMin(*it);
+            this->max = this->max.cwiseMax(*it);
+        }
+        this->defined = (this->min(0) < this->max(0)) && (this->min(1) < this->max(1)) && (this->min(2) < this->max(2));
+    }
+    void merge(const PointClass &point);
+    void merge(const std::vector<PointClass> &points);
+    void merge(const BoundingBox3Base<PointClass> &bb);
+    PointClass size() const;
+    double radius() const;
+    void translate(coordf_t x, coordf_t y, coordf_t z) { assert(this->defined); PointClass v(x, y, z); this->min += v; this->max += v; }
+    void translate(const Vec3d &v) { this->min += v; this->max += v; }
+    void offset(coordf_t delta);
+    PointClass center() const;
+    coordf_t max_size() const;
+
+    bool contains(const PointClass &point) const {
+        return BoundingBoxBase<PointClass>::contains(point) && point(2) >= this->min(2) && point(2) <= this->max(2);
+    }
+
+    bool contains(const BoundingBox3Base<PointClass>& other) const {
+        return contains(other.min) && contains(other.max);
+    }
+
+    bool intersects(const BoundingBox3Base<PointClass>& other) const {
+        return (this->min(0) < other.max(0)) && (this->max(0) > other.min(0)) && (this->min(1) < other.max(1)) && (this->max(1) > other.min(1)) && (this->min(2) < other.max(2)) && (this->max(2) > other.min(2));
+    }
+};
+
+class BoundingBox : public BoundingBoxBase<Point>
+{
+public:
+    void polygon(Polygon* polygon) const;
+    Polygon polygon() const;
+    BoundingBox rotated(double angle) const;
+    BoundingBox rotated(double angle, const Point &center) const;
+    void rotate(double angle) { (*this) = this->rotated(angle); }
+    void rotate(double angle, const Point &center) { (*this) = this->rotated(angle, center); }
+    // Align the min corner to a grid of cell_size x cell_size cells,
+    // to encompass the original bounding box.
+    void align_to_grid(const coord_t cell_size);
+    
+    BoundingBox() : BoundingBoxBase<Point>() {};
+    BoundingBox(const Point &pmin, const Point &pmax) : BoundingBoxBase<Point>(pmin, pmax) {};
+    BoundingBox(const Points &points) : BoundingBoxBase<Point>(points) {};
+    BoundingBox(const Lines &lines);
+
+    friend BoundingBox get_extents_rotated(const Points &points, double angle);
+};
+
+class BoundingBox3  : public BoundingBox3Base<Vec3crd> 
+{
+public:
+    BoundingBox3() : BoundingBox3Base<Vec3crd>() {};
+    BoundingBox3(const Vec3crd &pmin, const Vec3crd &pmax) : BoundingBox3Base<Vec3crd>(pmin, pmax) {};
+    BoundingBox3(const Points3& points) : BoundingBox3Base<Vec3crd>(points) {};
+};
+
+class BoundingBoxf : public BoundingBoxBase<Vec2d> 
+{
+public:
+    BoundingBoxf() : BoundingBoxBase<Vec2d>() {};
+    BoundingBoxf(const Vec2d &pmin, const Vec2d &pmax) : BoundingBoxBase<Vec2d>(pmin, pmax) {};
+    BoundingBoxf(const std::vector<Vec2d> &points) : BoundingBoxBase<Vec2d>(points) {};
+};
+
+class BoundingBoxf3 : public BoundingBox3Base<Vec3d> 
+{
+public:
+    BoundingBoxf3() : BoundingBox3Base<Vec3d>() {};
+    BoundingBoxf3(const Vec3d &pmin, const Vec3d &pmax) : BoundingBox3Base<Vec3d>(pmin, pmax) {};
+    BoundingBoxf3(const std::vector<Vec3d> &points) : BoundingBox3Base<Vec3d>(points) {};
+
+    BoundingBoxf3 transformed(const Transform3d& matrix) const;
+};
+
+template<typename VT>
+inline bool empty(const BoundingBoxBase<VT> &bb)
+{
+    return ! bb.defined || bb.min(0) >= bb.max(0) || bb.min(1) >= bb.max(1);
+}
+
+template<typename VT>
+inline bool empty(const BoundingBox3Base<VT> &bb)
+{
+    return ! bb.defined || bb.min(0) >= bb.max(0) || bb.min(1) >= bb.max(1) || bb.min(2) >= bb.max(2);
+}
+
+} // namespace Slic3r
+
+#endif

src/libslic3r/BridgeDetector.cpp

@@ -0,0 +1,317 @@
+#include "BridgeDetector.hpp"
+#include "ClipperUtils.hpp"
+#include "Geometry.hpp"
+#include <algorithm>
+
+namespace Slic3r {
+
+BridgeDetector::BridgeDetector(
+    ExPolygon                   _expolygon,
+    const ExPolygonCollection  &_lower_slices, 
+    coord_t                     _spacing) :
+    // The original infill polygon, not inflated.
+    expolygons(expolygons_owned),
+    // All surfaces of the object supporting this region.
+    lower_slices(_lower_slices),
+    spacing(_spacing)
+{
+    this->expolygons_owned.push_back(std::move(_expolygon));
+    initialize();
+}
+
+BridgeDetector::BridgeDetector(
+    const ExPolygons           &_expolygons,
+    const ExPolygonCollection  &_lower_slices,
+    coord_t                     _spacing) : 
+    // The original infill polygon, not inflated.
+    expolygons(_expolygons),
+    // All surfaces of the object supporting this region.
+    lower_slices(_lower_slices),
+    spacing(_spacing)
+{
+    initialize();
+}
+
+void BridgeDetector::initialize()
+{
+    // 5 degrees stepping
+    this->resolution = PI/36.0; 
+    // output angle not known
+    this->angle = -1.;
+
+    // Outset our bridge by an arbitrary amout; we'll use this outer margin for detecting anchors.
+    Polygons grown = offset(to_polygons(this->expolygons), float(this->spacing));
+    
+    // Detect possible anchoring edges of this bridging region.
+    // Detect what edges lie on lower slices by turning bridge contour and holes
+    // into polylines and then clipping them with each lower slice's contour.
+    // Currently _edges are only used to set a candidate direction of the bridge (see bridge_direction_candidates()).
+    this->_edges = intersection_pl(to_polylines(grown), this->lower_slices.contours());
+    
+    #ifdef SLIC3R_DEBUG
+    printf("  bridge has " PRINTF_ZU " support(s)\n", this->_edges.size());
+    #endif
+    
+    // detect anchors as intersection between our bridge expolygon and the lower slices
+    // safety offset required to avoid Clipper from detecting empty intersection while Boost actually found some edges
+    this->_anchor_regions = intersection_ex(grown, to_polygons(this->lower_slices.expolygons), true);
+    
+    /*
+    if (0) {
+        require "Slic3r/SVG.pm";
+        Slic3r::SVG::output("bridge.svg",
+            expolygons      => [ $self->expolygon ],
+            red_expolygons  => $self->lower_slices,
+            polylines       => $self->_edges,
+        );
+    }
+    */
+}
+
+bool BridgeDetector::detect_angle(double bridge_direction_override)
+{
+    if (this->_edges.empty() || this->_anchor_regions.empty()) 
+        // The bridging region is completely in the air, there are no anchors available at the layer below.
+        return false;
+
+    std::vector<BridgeDirection> candidates;
+    if (bridge_direction_override == 0.) {
+        std::vector<double> angles = bridge_direction_candidates();
+        candidates.reserve(angles.size());
+        for (size_t i = 0; i < angles.size(); ++ i)
+            candidates.emplace_back(BridgeDirection(angles[i]));
+    } else
+        candidates.emplace_back(BridgeDirection(bridge_direction_override));
+    
+    /*  Outset the bridge expolygon by half the amount we used for detecting anchors;
+        we'll use this one to clip our test lines and be sure that their endpoints
+        are inside the anchors and not on their contours leading to false negatives. */
+    Polygons clip_area = offset(this->expolygons, 0.5f * float(this->spacing));
+    
+    /*  we'll now try several directions using a rudimentary visibility check:
+        bridge in several directions and then sum the length of lines having both
+        endpoints within anchors */
+        
+    bool have_coverage = false;
+    for (size_t i_angle = 0; i_angle < candidates.size(); ++ i_angle)
+    {
+        const double angle = candidates[i_angle].angle;
+
+        Lines lines;
+        {
+            // Get an oriented bounding box around _anchor_regions.
+            BoundingBox bbox = get_extents_rotated(this->_anchor_regions, - angle);
+            // Cover the region with line segments.
+            lines.reserve((bbox.max(1) - bbox.min(1) + this->spacing) / this->spacing);
+            double s = sin(angle);
+            double c = cos(angle);
+            //FIXME Vojtech: The lines shall be spaced half the line width from the edge, but then 
+            // some of the test cases fail. Need to adjust the test cases then?
+//            for (coord_t y = bbox.min(1) + this->spacing / 2; y <= bbox.max(1); y += this->spacing)
+            for (coord_t y = bbox.min(1); y <= bbox.max(1); y += this->spacing)
+                lines.push_back(Line(
+                    Point((coord_t)round(c * bbox.min(0) - s * y), (coord_t)round(c * y + s * bbox.min(0))),
+                    Point((coord_t)round(c * bbox.max(0) - s * y), (coord_t)round(c * y + s * bbox.max(0)))));
+        }
+
+        double total_length = 0;
+        double max_length = 0;
+        {
+            Lines clipped_lines = intersection_ln(lines, clip_area);
+            for (size_t i = 0; i < clipped_lines.size(); ++i) {
+                const Line &line = clipped_lines[i];
+                if (expolygons_contain(this->_anchor_regions, line.a) && expolygons_contain(this->_anchor_regions, line.b)) {
+                    // This line could be anchored.
+                    double len = line.length();
+                    total_length += len;
+                    max_length = std::max(max_length, len);
+                }
+            }        
+        }
+        if (total_length == 0.)
+            continue;
+
+        have_coverage = true;
+        // Sum length of bridged lines.
+        candidates[i_angle].coverage = total_length;
+        /*  The following produces more correct results in some cases and more broken in others.
+            TODO: investigate, as it looks more reliable than line clipping. */
+        // $directions_coverage{$angle} = sum(map $_->area, @{$self->coverage($angle)}) // 0;
+        // max length of bridged lines
+        candidates[i_angle].max_length = max_length;
+    }
+
+    // if no direction produced coverage, then there's no bridge direction
+    if (! have_coverage)
+        return false;
+    
+    // sort directions by coverage - most coverage first
+    std::sort(candidates.begin(), candidates.end());
+    
+    // if any other direction is within extrusion width of coverage, prefer it if shorter
+    // TODO: There are two options here - within width of the angle with most coverage, or within width of the currently perferred?
+    size_t i_best = 0;
+    for (size_t i = 1; i < candidates.size() && candidates[i_best].coverage - candidates[i].coverage < this->spacing; ++ i)
+        if (candidates[i].max_length < candidates[i_best].max_length)
+            i_best = i;
+
+    this->angle = candidates[i_best].angle;
+    if (this->angle >= PI)
+        this->angle -= PI;
+    
+    #ifdef SLIC3R_DEBUG
+    printf("  Optimal infill angle is %d degrees\n", (int)Slic3r::Geometry::rad2deg(this->angle));
+    #endif
+    
+    return true;
+}
+
+std::vector<double> BridgeDetector::bridge_direction_candidates() const
+{
+    // we test angles according to configured resolution
+    std::vector<double> angles;
+    for (int i = 0; i <= PI/this->resolution; ++i)
+        angles.push_back(i * this->resolution);
+    
+    // we also test angles of each bridge contour
+    {
+        Lines lines = to_lines(this->expolygons);
+        for (Lines::const_iterator line = lines.begin(); line != lines.end(); ++line)
+            angles.push_back(line->direction());
+    }
+    
+    /*  we also test angles of each open supporting edge
+        (this finds the optimal angle for C-shaped supports) */
+    for (const Polyline &edge : this->_edges)
+        if (edge.first_point() != edge.last_point())
+            angles.push_back(Line(edge.first_point(), edge.last_point()).direction());
+    
+    // remove duplicates
+    double min_resolution = PI/180.0;  // 1 degree
+    std::sort(angles.begin(), angles.end());
+    for (size_t i = 1; i < angles.size(); ++i) {
+        if (Slic3r::Geometry::directions_parallel(angles[i], angles[i-1], min_resolution)) {
+            angles.erase(angles.begin() + i);
+            --i;
+        }
+    }
+    /*  compare first value with last one and remove the greatest one (PI) 
+        in case they are parallel (PI, 0) */
+    if (Slic3r::Geometry::directions_parallel(angles.front(), angles.back(), min_resolution))
+        angles.pop_back();
+
+    return angles;
+}
+
+Polygons BridgeDetector::coverage(double angle) const
+{
+    if (angle == -1)
+        angle = this->angle;
+
+    Polygons covered;
+
+    if (angle != -1) {
+        // Get anchors, convert them to Polygons and rotate them.
+        Polygons anchors = to_polygons(this->_anchor_regions);
+        polygons_rotate(anchors, PI/2.0 - angle);
+        
+        for (ExPolygon expolygon : this->expolygons) {
+            // Clone our expolygon and rotate it so that we work with vertical lines.
+            expolygon.rotate(PI/2.0 - angle);            
+            // Outset the bridge expolygon by half the amount we used for detecting anchors;
+            // we'll use this one to generate our trapezoids and be sure that their vertices
+            // are inside the anchors and not on their contours leading to false negatives.
+            for (ExPolygon &expoly : offset_ex(expolygon, 0.5f * float(this->spacing))) {
+                // Compute trapezoids according to a vertical orientation
+                Polygons trapezoids;
+                expoly.get_trapezoids2(&trapezoids, PI/2.0);
+                for (const Polygon &trapezoid : trapezoids) {
+                    // not nice, we need a more robust non-numeric check
+                    size_t n_supported = 0;
+                    for (const Line &supported_line : intersection_ln(trapezoid.lines(), anchors))
+                        if (supported_line.length() >= this->spacing)
+                            ++ n_supported;
+                    if (n_supported >= 2) 
+                        covered.push_back(std::move(trapezoid));
+                }
+            }
+        }
+
+        // Unite the trapezoids before rotation, as the rotation creates tiny gaps and intersections between the trapezoids
+        // instead of exact overlaps.
+        covered = union_(covered);
+        // Intersect trapezoids with actual bridge area to remove extra margins and append it to result.
+        polygons_rotate(covered, -(PI/2.0 - angle));
+    	covered = intersection(covered, to_polygons(this->expolygons));
+#if 0
+        {
+            my @lines = map @{$_->lines}, @$trapezoids;
+            $_->rotate(-(PI/2 - $angle), [0,0]) for @lines;
+            
+            require "Slic3r/SVG.pm";
+            Slic3r::SVG::output(
+                "coverage_" . rad2deg($angle) . ".svg",
+                expolygons          => [$self->expolygon],
+                green_expolygons    => $self->_anchor_regions,
+                red_expolygons      => $coverage,
+                lines               => \@lines,
+            );
+        }
+#endif
+    }
+    return covered;
+}
+
+/*  This method returns the bridge edges (as polylines) that are not supported
+    but would allow the entire bridge area to be bridged with detected angle
+    if supported too */
+void
+BridgeDetector::unsupported_edges(double angle, Polylines* unsupported) const
+{
+    if (angle == -1) angle = this->angle;
+    if (angle == -1) return;
+
+    Polygons grown_lower = offset(this->lower_slices.expolygons, float(this->spacing));
+
+    for (ExPolygons::const_iterator it_expoly = this->expolygons.begin(); it_expoly != this->expolygons.end(); ++ it_expoly) {    
+        // get unsupported bridge edges (both contour and holes)
+        Lines unsupported_lines = to_lines(diff_pl(to_polylines(*it_expoly), grown_lower));
+        /*  Split into individual segments and filter out edges parallel to the bridging angle
+            TODO: angle tolerance should probably be based on segment length and flow width,
+            so that we build supports whenever there's a chance that at least one or two bridge
+            extrusions would be anchored within such length (i.e. a slightly non-parallel bridging
+            direction might still benefit from anchors if long enough)
+            double angle_tolerance = PI / 180.0 * 5.0; */
+        for (const Line &line : unsupported_lines)
+            if (! Slic3r::Geometry::directions_parallel(line.direction(), angle)) {
+                unsupported->emplace_back(Polyline());
+                unsupported->back().points.emplace_back(line.a);
+                unsupported->back().points.emplace_back(line.b);
+            }
+    }
+    
+    /*
+    if (0) {
+        require "Slic3r/SVG.pm";
+        Slic3r::SVG::output(
+            "unsupported_" . rad2deg($angle) . ".svg",
+            expolygons          => [$self->expolygon],
+            green_expolygons    => $self->_anchor_regions,
+            red_expolygons      => union_ex($grown_lower),
+            no_arrows           => 1,
+            polylines           => \@bridge_edges,
+            red_polylines       => $unsupported,
+        );
+    }
+    */
+}
+
+Polylines
+BridgeDetector::unsupported_edges(double angle) const
+{
+    Polylines pp;
+    this->unsupported_edges(angle, &pp);
+    return pp;
+}
+
+}

src/libslic3r/BridgeDetector.hpp

@@ -0,0 +1,69 @@
+#ifndef slic3r_BridgeDetector_hpp_
+#define slic3r_BridgeDetector_hpp_
+
+#include "libslic3r.h"
+#include "ExPolygon.hpp"
+#include "ExPolygonCollection.hpp"
+#include <string>
+
+namespace Slic3r {
+
+// The bridge detector optimizes a direction of bridges over a region or a set of regions.
+// A bridge direction is considered optimal, if the length of the lines strang over the region is maximal.
+// This is optimal if the bridge is supported in a single direction only, but
+// it may not likely be optimal, if the bridge region is supported from all sides. Then an optimal 
+// solution would find a direction with shortest bridges.
+// The bridge orientation is measured CCW from the X axis.
+class BridgeDetector {
+public:
+    // The non-grown holes.
+    const ExPolygons            &expolygons;
+    // In case the caller gaves us the input polygons by a value, make a copy.
+    ExPolygons                   expolygons_owned;
+    // Lower slices, all regions.
+    const ExPolygonCollection   &lower_slices;
+    // Scaled extrusion width of the infill.
+    coord_t                      spacing;
+    // Angle resolution for the brute force search of the best bridging angle.
+    double                       resolution;
+    // The final optimal angle.
+    double                       angle;
+    
+    BridgeDetector(ExPolygon _expolygon, const ExPolygonCollection &_lower_slices, coord_t _extrusion_width);
+    BridgeDetector(const ExPolygons &_expolygons, const ExPolygonCollection &_lower_slices, coord_t _extrusion_width);
+    // If bridge_direction_override != 0, then the angle is used instead of auto-detect.
+    bool detect_angle(double bridge_direction_override = 0.);
+    Polygons coverage(double angle = -1) const;
+    void unsupported_edges(double angle, Polylines* unsupported) const;
+    Polylines unsupported_edges(double angle = -1) const;
+    
+private:
+    // Suppress warning "assignment operator could not be generated"
+    BridgeDetector& operator=(const BridgeDetector &);
+
+    void initialize();
+
+    struct BridgeDirection {
+        BridgeDirection(double a = -1.) : angle(a), coverage(0.), max_length(0.) {}
+        // the best direction is the one causing most lines to be bridged (thus most coverage)
+        bool operator<(const BridgeDirection &other) const {
+            // Initial sort by coverage only - comparator must obey strict weak ordering
+            return this->coverage > other.coverage;
+        };
+        double angle;
+        double coverage;
+        double max_length;
+    };
+
+    // Get possible briging direction candidates.
+    std::vector<double> bridge_direction_candidates() const;
+
+    // Open lines representing the supporting edges.
+    Polylines _edges;
+    // Closed polygons representing the supporting areas.
+    ExPolygons _anchor_regions;
+};
+
+}
+
+#endif

src/libslic3r/CMakeLists.txt

@@ -0,0 +1,194 @@
+project(libslic3r)
+cmake_minimum_required(VERSION 2.6)
+
+include(PrecompiledHeader)
+
+configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libslic3r_version.h.in ${CMAKE_CURRENT_BINARY_DIR}/libslic3r_version.h @ONLY)
+
+add_library(libslic3r STATIC
+    pchheader.cpp
+    pchheader.hpp
+    BoundingBox.cpp
+    BoundingBox.hpp
+    BridgeDetector.cpp
+    BridgeDetector.hpp
+    ClipperUtils.cpp
+    ClipperUtils.hpp
+    Config.cpp
+    Config.hpp
+    EdgeGrid.cpp
+    EdgeGrid.hpp
+    ExPolygon.cpp
+    ExPolygon.hpp
+    ExPolygonCollection.cpp
+    ExPolygonCollection.hpp
+    Extruder.cpp
+    Extruder.hpp
+    ExtrusionEntity.cpp
+    ExtrusionEntity.hpp
+    ExtrusionEntityCollection.cpp
+    ExtrusionEntityCollection.hpp
+    ExtrusionSimulator.cpp
+    ExtrusionSimulator.hpp
+    FileParserError.hpp
+    Fill/Fill.cpp
+    Fill/Fill.hpp
+    Fill/Fill3DHoneycomb.cpp
+    Fill/Fill3DHoneycomb.hpp
+    Fill/FillBase.cpp
+    Fill/FillBase.hpp
+    Fill/FillConcentric.cpp
+    Fill/FillConcentric.hpp
+    Fill/FillHoneycomb.cpp
+    Fill/FillHoneycomb.hpp
+    Fill/FillGyroid.cpp
+    Fill/FillGyroid.hpp
+    Fill/FillPlanePath.cpp
+    Fill/FillPlanePath.hpp
+    Fill/FillRectilinear.cpp
+    Fill/FillRectilinear.hpp
+    Fill/FillRectilinear2.cpp
+    Fill/FillRectilinear2.hpp
+    Fill/FillRectilinear3.cpp
+    Fill/FillRectilinear3.hpp
+    Flow.cpp
+    Flow.hpp
+    Format/3mf.cpp
+    Format/3mf.hpp
+    Format/AMF.cpp
+    Format/AMF.hpp
+    Format/OBJ.cpp
+    Format/OBJ.hpp
+    Format/objparser.cpp
+    Format/objparser.hpp
+    Format/PRUS.cpp
+    Format/PRUS.hpp
+    Format/STL.cpp
+    Format/STL.hpp
+    GCode/Analyzer.cpp
+    GCode/Analyzer.hpp
+    GCode/CoolingBuffer.cpp
+    GCode/CoolingBuffer.hpp
+    GCode/PostProcessor.cpp
+    GCode/PostProcessor.hpp    
+    GCode/PressureEqualizer.cpp
+    GCode/PressureEqualizer.hpp
+    GCode/PreviewData.cpp
+    GCode/PreviewData.hpp
+    GCode/PrintExtents.cpp
+    GCode/PrintExtents.hpp
+    GCode/SpiralVase.cpp
+    GCode/SpiralVase.hpp
+    GCode/ToolOrdering.cpp
+    GCode/ToolOrdering.hpp
+    GCode/WipeTower.hpp
+    GCode/WipeTowerPrusaMM.cpp
+    GCode/WipeTowerPrusaMM.hpp
+    GCode.cpp
+    GCode.hpp
+    GCodeReader.cpp
+    GCodeReader.hpp
+    GCodeSender.cpp
+    GCodeSender.hpp
+    GCodeTimeEstimator.cpp
+    GCodeTimeEstimator.hpp
+    GCodeWriter.cpp
+    GCodeWriter.hpp
+    Geometry.cpp
+    Geometry.hpp
+    Int128.hpp
+#    KdTree.hpp
+    Layer.cpp
+    Layer.hpp
+    LayerRegion.cpp
+    libslic3r.h
+    "${CMAKE_CURRENT_BINARY_DIR}/libslic3r_version.h"
+    Line.cpp
+    Line.hpp
+    Model.cpp
+    Model.hpp
+    ModelArrange.hpp
+    ModelArrange.cpp
+    MotionPlanner.cpp
+    MotionPlanner.hpp
+    MultiPoint.cpp
+    MultiPoint.hpp
+    MutablePriorityQueue.hpp
+    PerimeterGenerator.cpp
+    PerimeterGenerator.hpp
+    PlaceholderParser.cpp
+    PlaceholderParser.hpp
+    Point.cpp
+    Point.hpp
+    Polygon.cpp
+    Polygon.hpp
+    Polyline.cpp
+    Polyline.hpp
+    PolylineCollection.cpp
+    PolylineCollection.hpp
+    Print.cpp
+    Print.hpp
+    PrintBase.cpp
+    PrintBase.hpp
+    PrintExport.hpp
+    PrintConfig.cpp
+    PrintConfig.hpp
+    PrintObject.cpp
+    PrintRegion.cpp
+    Rasterizer/Rasterizer.hpp
+    Rasterizer/Rasterizer.cpp
+    SLAPrint.cpp
+    SLAPrint.hpp
+    Slicing.cpp
+    Slicing.hpp
+    SlicingAdaptive.cpp
+    SlicingAdaptive.hpp
+    SupportMaterial.cpp
+    SupportMaterial.hpp
+    Surface.cpp
+    Surface.hpp
+    SurfaceCollection.cpp
+    SurfaceCollection.hpp
+    SVG.cpp
+    SVG.hpp
+    Technologies.hpp
+    TriangleMesh.cpp
+    TriangleMesh.hpp
+    utils.cpp
+    Utils.hpp
+    SLA/SLABoilerPlate.hpp
+    SLA/SLABasePool.hpp
+    SLA/SLABasePool.cpp
+    SLA/SLASupportTree.hpp
+    SLA/SLASupportTree.cpp
+    SLA/SLASupportTreeIGL.cpp
+    SLA/SLARotfinder.hpp
+    SLA/SLARotfinder.cpp
+    SLA/SLABoostAdapter.hpp
+    SLA/SLASpatIndex.hpp
+)
+
+add_precompiled_header(libslic3r pchheader.hpp FORCEINCLUDE)
+
+target_compile_definitions(libslic3r PUBLIC -DUSE_TBB ${PNG_DEFINITIONS})
+target_include_directories(libslic3r PUBLIC ${CMAKE_CURRENT_BINARY_DIR} ${LIBNEST2D_INCLUDES} ${PNG_INCLUDE_DIRS})
+target_link_libraries(libslic3r
+    libnest2d
+    admesh
+    miniz
+    ${Boost_LIBRARIES}
+    clipper
+    nowide
+    ${EXPAT_LIBRARIES}
+    ${GLEW_LIBRARIES}
+    ${PNG_LIBRARIES}
+    polypartition
+    poly2tri
+    qhull
+    semver
+    tbb
+    )
+
+if(SLIC3R_PROFILE)
+    target_link_libraries(slic3r Shiny)
+endif()

src/libslic3r/ClipperUtils.cpp

@@ -0,0 +1,798 @@
+#include "ClipperUtils.hpp"
+#include "Geometry.hpp"
+
+// #define CLIPPER_UTILS_DEBUG
+
+#ifdef CLIPPER_UTILS_DEBUG
+#include "SVG.hpp"
+#endif /* CLIPPER_UTILS_DEBUG */
+
+#include <Shiny/Shiny.h>
+
+#define CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR (0.005f)
+
+namespace Slic3r {
+
+#ifdef CLIPPER_UTILS_DEBUG
+bool clipper_export_enabled = false;
+// For debugging the Clipper library, for providing bug reports to the Clipper author.
+bool export_clipper_input_polygons_bin(const char *path, const ClipperLib::Paths &input_subject, const ClipperLib::Paths &input_clip)
+{
+    FILE *pfile = fopen(path, "wb");
+    if (pfile == NULL)
+        return false;
+
+    uint32_t sz = uint32_t(input_subject.size());
+    fwrite(&sz, 1, sizeof(sz), pfile);
+    for (size_t i = 0; i < input_subject.size(); ++i) {
+        const ClipperLib::Path &path = input_subject[i];
+        sz = uint32_t(path.size());
+        ::fwrite(&sz, 1, sizeof(sz), pfile);
+        ::fwrite(path.data(), sizeof(ClipperLib::IntPoint), sz, pfile);
+    }
+    sz = uint32_t(input_clip.size());
+    ::fwrite(&sz, 1, sizeof(sz), pfile);
+    for (size_t i = 0; i < input_clip.size(); ++i) {
+        const ClipperLib::Path &path = input_clip[i];
+        sz = uint32_t(path.size());
+        ::fwrite(&sz, 1, sizeof(sz), pfile);
+        ::fwrite(path.data(), sizeof(ClipperLib::IntPoint), sz, pfile);
+    }
+    ::fclose(pfile);
+    return true;
+
+err:
+    ::fclose(pfile);
+    return false;
+}
+#endif /* CLIPPER_UTILS_DEBUG */
+
+void scaleClipperPolygon(ClipperLib::Path &polygon)
+{
+    PROFILE_FUNC();
+    for (ClipperLib::Path::iterator pit = polygon.begin(); pit != polygon.end(); ++pit) {
+        pit->X <<= CLIPPER_OFFSET_POWER_OF_2;
+        pit->Y <<= CLIPPER_OFFSET_POWER_OF_2;
+    }
+}
+
+void scaleClipperPolygons(ClipperLib::Paths &polygons)
+{
+    PROFILE_FUNC();
+    for (ClipperLib::Paths::iterator it = polygons.begin(); it != polygons.end(); ++it)
+        for (ClipperLib::Path::iterator pit = (*it).begin(); pit != (*it).end(); ++pit) {
+            pit->X <<= CLIPPER_OFFSET_POWER_OF_2;
+            pit->Y <<= CLIPPER_OFFSET_POWER_OF_2;
+        }
+}
+
+void unscaleClipperPolygon(ClipperLib::Path &polygon)
+{
+    PROFILE_FUNC();
+    for (ClipperLib::Path::iterator pit = polygon.begin(); pit != polygon.end(); ++pit) {
+        pit->X += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+        pit->Y += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+        pit->X >>= CLIPPER_OFFSET_POWER_OF_2;
+        pit->Y >>= CLIPPER_OFFSET_POWER_OF_2;
+    }
+}
+
+void unscaleClipperPolygons(ClipperLib::Paths &polygons)
+{
+    PROFILE_FUNC();
+    for (ClipperLib::Paths::iterator it = polygons.begin(); it != polygons.end(); ++it)
+        for (ClipperLib::Path::iterator pit = (*it).begin(); pit != (*it).end(); ++pit) {
+            pit->X += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+            pit->Y += CLIPPER_OFFSET_SCALE_ROUNDING_DELTA;
+            pit->X >>= CLIPPER_OFFSET_POWER_OF_2;
+            pit->Y >>= CLIPPER_OFFSET_POWER_OF_2;
+        }
+}
+
+//-----------------------------------------------------------
+// legacy code from Clipper documentation
+void AddOuterPolyNodeToExPolygons(ClipperLib::PolyNode& polynode, ExPolygons* expolygons)
+{  
+  size_t cnt = expolygons->size();
+  expolygons->resize(cnt + 1);
+  (*expolygons)[cnt].contour = ClipperPath_to_Slic3rPolygon(polynode.Contour);
+  (*expolygons)[cnt].holes.resize(polynode.ChildCount());
+  for (int i = 0; i < polynode.ChildCount(); ++i)
+  {
+    (*expolygons)[cnt].holes[i] = ClipperPath_to_Slic3rPolygon(polynode.Childs[i]->Contour);
+    //Add outer polygons contained by (nested within) holes ...
+    for (int j = 0; j < polynode.Childs[i]->ChildCount(); ++j)
+      AddOuterPolyNodeToExPolygons(*polynode.Childs[i]->Childs[j], expolygons);
+  }
+}
+ 
+ExPolygons
+PolyTreeToExPolygons(ClipperLib::PolyTree& polytree)
+{
+    ExPolygons retval;
+    for (int i = 0; i < polytree.ChildCount(); ++i)
+        AddOuterPolyNodeToExPolygons(*polytree.Childs[i], &retval);
+    return retval;
+}
+//-----------------------------------------------------------
+
+Slic3r::Polygon ClipperPath_to_Slic3rPolygon(const ClipperLib::Path &input)
+{
+    Polygon retval;
+    for (ClipperLib::Path::const_iterator pit = input.begin(); pit != input.end(); ++pit)
+        retval.points.push_back(Point( (*pit).X, (*pit).Y ));
+    return retval;
+}
+
+Slic3r::Polyline ClipperPath_to_Slic3rPolyline(const ClipperLib::Path &input)
+{
+    Polyline retval;
+    for (ClipperLib::Path::const_iterator pit = input.begin(); pit != input.end(); ++pit)
+        retval.points.push_back(Point( (*pit).X, (*pit).Y ));
+    return retval;
+}
+
+Slic3r::Polygons ClipperPaths_to_Slic3rPolygons(const ClipperLib::Paths &input)
+{
+    Slic3r::Polygons retval;
+    retval.reserve(input.size());
+    for (ClipperLib::Paths::const_iterator it = input.begin(); it != input.end(); ++it)
+        retval.push_back(ClipperPath_to_Slic3rPolygon(*it));
+    return retval;
+}
+
+Slic3r::Polylines ClipperPaths_to_Slic3rPolylines(const ClipperLib::Paths &input)
+{
+    Slic3r::Polylines retval;
+    retval.reserve(input.size());
+    for (ClipperLib::Paths::const_iterator it = input.begin(); it != input.end(); ++it)
+        retval.push_back(ClipperPath_to_Slic3rPolyline(*it));
+    return retval;
+}
+
+ExPolygons
+ClipperPaths_to_Slic3rExPolygons(const ClipperLib::Paths &input)
+{
+    // init Clipper
+    ClipperLib::Clipper clipper;
+    clipper.Clear();
+    
+    // perform union
+    clipper.AddPaths(input, ClipperLib::ptSubject, true);
+    ClipperLib::PolyTree polytree;
+    clipper.Execute(ClipperLib::ctUnion, polytree, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd);  // offset results work with both EvenOdd and NonZero
+    
+    // write to ExPolygons object
+    return PolyTreeToExPolygons(polytree);
+}
+
+ClipperLib::Path
+Slic3rMultiPoint_to_ClipperPath(const MultiPoint &input)
+{
+    ClipperLib::Path retval;
+    for (Points::const_iterator pit = input.points.begin(); pit != input.points.end(); ++pit)
+        retval.push_back(ClipperLib::IntPoint( (*pit)(0), (*pit)(1) ));
+    return retval;
+}
+
+ClipperLib::Path
+Slic3rMultiPoint_to_ClipperPath_reversed(const Slic3r::MultiPoint &input)
+{
+    ClipperLib::Path output;
+    output.reserve(input.points.size());
+    for (Slic3r::Points::const_reverse_iterator pit = input.points.rbegin(); pit != input.points.rend(); ++pit)
+        output.push_back(ClipperLib::IntPoint( (*pit)(0), (*pit)(1) ));
+    return output;
+}
+
+ClipperLib::Paths Slic3rMultiPoints_to_ClipperPaths(const Polygons &input)
+{
+    ClipperLib::Paths retval;
+    for (Polygons::const_iterator it = input.begin(); it != input.end(); ++it)
+        retval.push_back(Slic3rMultiPoint_to_ClipperPath(*it));
+    return retval;
+}
+
+ClipperLib::Paths Slic3rMultiPoints_to_ClipperPaths(const Polylines &input)
+{
+    ClipperLib::Paths retval;
+    for (Polylines::const_iterator it = input.begin(); it != input.end(); ++it)
+        retval.push_back(Slic3rMultiPoint_to_ClipperPath(*it));
+    return retval;
+}
+
+ClipperLib::Paths _offset(ClipperLib::Paths &&input, ClipperLib::EndType endType, const float delta, ClipperLib::JoinType joinType, double miterLimit)
+{
+    // scale input
+    scaleClipperPolygons(input);
+    
+    // perform offset
+    ClipperLib::ClipperOffset co;
+    if (joinType == jtRound)
+        co.ArcTolerance = miterLimit;
+    else
+        co.MiterLimit = miterLimit;
+    float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
+    co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
+    co.AddPaths(input, joinType, endType);
+    ClipperLib::Paths retval;
+    co.Execute(retval, delta_scaled);
+    
+    // unscale output
+    unscaleClipperPolygons(retval);
+    return retval;
+}
+
+ClipperLib::Paths _offset(ClipperLib::Path &&input, ClipperLib::EndType endType, const float delta, ClipperLib::JoinType joinType, double miterLimit)
+{
+    ClipperLib::Paths paths;
+    paths.push_back(std::move(input));
+	return _offset(std::move(paths), endType, delta, joinType, miterLimit);
+}
+
+// This is a safe variant of the polygon offset, tailored for a single ExPolygon:
+// a single polygon with multiple non-overlapping holes.
+// Each contour and hole is offsetted separately, then the holes are subtracted from the outer contours.
+ClipperLib::Paths _offset(const Slic3r::ExPolygon &expolygon, const float delta,
+    ClipperLib::JoinType joinType, double miterLimit)
+{
+//    printf("new ExPolygon offset\n");
+    // 1) Offset the outer contour.
+    const float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
+    ClipperLib::Paths contours;
+    {
+        ClipperLib::Path input = Slic3rMultiPoint_to_ClipperPath(expolygon.contour);
+        scaleClipperPolygon(input);
+        ClipperLib::ClipperOffset co;
+        if (joinType == jtRound)
+            co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
+        else
+            co.MiterLimit = miterLimit;
+        co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
+        co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
+        co.Execute(contours, delta_scaled);
+    }
+
+    // 2) Offset the holes one by one, collect the results.
+    ClipperLib::Paths holes;
+    {
+        holes.reserve(expolygon.holes.size());
+        for (Polygons::const_iterator it_hole = expolygon.holes.begin(); it_hole != expolygon.holes.end(); ++ it_hole) {
+            ClipperLib::Path input = Slic3rMultiPoint_to_ClipperPath_reversed(*it_hole);
+            scaleClipperPolygon(input);
+            ClipperLib::ClipperOffset co;
+            if (joinType == jtRound)
+                co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
+            else
+                co.MiterLimit = miterLimit;
+            co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
+            co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
+            ClipperLib::Paths out;
+            co.Execute(out, - delta_scaled);
+            holes.insert(holes.end(), out.begin(), out.end());
+        }
+    }
+
+    // 3) Subtract holes from the contours.
+    ClipperLib::Paths output;
+    if (holes.empty()) {
+        output = std::move(contours);
+    } else {
+        ClipperLib::Clipper clipper;
+        clipper.Clear();
+        clipper.AddPaths(contours, ClipperLib::ptSubject, true);
+        clipper.AddPaths(holes, ClipperLib::ptClip, true);
+        clipper.Execute(ClipperLib::ctDifference, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
+    }
+    
+    // 4) Unscale the output.
+    unscaleClipperPolygons(output);
+    return output;
+}
+
+// This is a safe variant of the polygons offset, tailored for multiple ExPolygons.
+// It is required, that the input expolygons do not overlap and that the holes of each ExPolygon don't intersect with their respective outer contours.
+// Each ExPolygon is offsetted separately, then the offsetted ExPolygons are united.
+ClipperLib::Paths _offset(const Slic3r::ExPolygons &expolygons, const float delta,
+    ClipperLib::JoinType joinType, double miterLimit)
+{
+    const float delta_scaled = delta * float(CLIPPER_OFFSET_SCALE);
+    // Offsetted ExPolygons before they are united.
+    ClipperLib::Paths contours_cummulative;
+    contours_cummulative.reserve(expolygons.size());
+    // How many non-empty offsetted expolygons were actually collected into contours_cummulative?
+    // If only one, then there is no need to do a final union.
+    size_t expolygons_collected = 0;
+    for (Slic3r::ExPolygons::const_iterator it_expoly = expolygons.begin(); it_expoly != expolygons.end(); ++ it_expoly) {
+        // 1) Offset the outer contour.
+        ClipperLib::Paths contours;
+        {
+            ClipperLib::Path input = Slic3rMultiPoint_to_ClipperPath(it_expoly->contour);
+            scaleClipperPolygon(input);
+            ClipperLib::ClipperOffset co;
+            if (joinType == jtRound)
+                co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
+            else
+                co.MiterLimit = miterLimit;
+            co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
+            co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
+            co.Execute(contours, delta_scaled);
+        }
+        if (contours.empty())
+            // No need to try to offset the holes.
+            continue;
+
+        if (it_expoly->holes.empty()) {
+            // No need to subtract holes from the offsetted expolygon, we are done.
+            contours_cummulative.insert(contours_cummulative.end(), contours.begin(), contours.end());
+            ++ expolygons_collected;
+        } else {
+            // 2) Offset the holes one by one, collect the offsetted holes.
+            ClipperLib::Paths holes;
+            {
+                for (Polygons::const_iterator it_hole = it_expoly->holes.begin(); it_hole != it_expoly->holes.end(); ++ it_hole) {
+                    ClipperLib::Path input = Slic3rMultiPoint_to_ClipperPath_reversed(*it_hole);
+                    scaleClipperPolygon(input);
+                    ClipperLib::ClipperOffset co;
+                    if (joinType == jtRound)
+                        co.ArcTolerance = miterLimit * double(CLIPPER_OFFSET_SCALE);
+                    else
+                        co.MiterLimit = miterLimit;
+                    co.ShortestEdgeLength = double(std::abs(delta_scaled * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR));
+                    co.AddPath(input, joinType, ClipperLib::etClosedPolygon);
+                    ClipperLib::Paths out;
+                    co.Execute(out, - delta_scaled);
+                    holes.insert(holes.end(), out.begin(), out.end());
+                }
+            }
+
+            // 3) Subtract holes from the contours.
+            if (holes.empty()) {
+                // No hole remaining after an offset. Just copy the outer contour.
+                contours_cummulative.insert(contours_cummulative.end(), contours.begin(), contours.end());
+                ++ expolygons_collected;
+            } else if (delta < 0) {
+                // Negative offset. There is a chance, that the offsetted hole intersects the outer contour. 
+                // Subtract the offsetted holes from the offsetted contours.
+                ClipperLib::Clipper clipper;
+                clipper.Clear();
+                clipper.AddPaths(contours, ClipperLib::ptSubject, true);
+                clipper.AddPaths(holes, ClipperLib::ptClip, true);
+                ClipperLib::Paths output;
+                clipper.Execute(ClipperLib::ctDifference, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
+                if (! output.empty()) {
+                    contours_cummulative.insert(contours_cummulative.end(), output.begin(), output.end());
+                    ++ expolygons_collected;
+                } else {
+                    // The offsetted holes have eaten up the offsetted outer contour.
+                }
+            } else {
+                // Positive offset. As long as the Clipper offset does what one expects it to do, the offsetted hole will have a smaller
+                // area than the original hole or even disappear, therefore there will be no new intersections.
+                // Just collect the reversed holes.
+                contours_cummulative.reserve(contours.size() + holes.size());
+                contours_cummulative.insert(contours_cummulative.end(), contours.begin(), contours.end());
+                // Reverse the holes in place.
+                for (size_t i = 0; i < holes.size(); ++ i)
+                    std::reverse(holes[i].begin(), holes[i].end());
+                contours_cummulative.insert(contours_cummulative.end(), holes.begin(), holes.end());
+                ++ expolygons_collected;
+            }
+        }
+    }
+
+    // 4) Unite the offsetted expolygons.
+    ClipperLib::Paths output;
+    if (expolygons_collected > 1 && delta > 0) {
+        // There is a chance that the outwards offsetted expolygons may intersect. Perform a union.
+        ClipperLib::Clipper clipper;
+        clipper.Clear(); 
+        clipper.AddPaths(contours_cummulative, ClipperLib::ptSubject, true);
+        clipper.Execute(ClipperLib::ctUnion, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
+    } else {
+        // Negative offset. The shrunk expolygons shall not mutually intersect. Just copy the output.
+        output = std::move(contours_cummulative);
+    }
+    
+    // 4) Unscale the output.
+    unscaleClipperPolygons(output);
+    return output;
+}
+
+ClipperLib::Paths
+_offset2(const Polygons &polygons, const float delta1, const float delta2,
+    const ClipperLib::JoinType joinType, const double miterLimit)
+{
+    // read input
+    ClipperLib::Paths input = Slic3rMultiPoints_to_ClipperPaths(polygons);
+    
+    // scale input
+    scaleClipperPolygons(input);
+    
+    // prepare ClipperOffset object
+    ClipperLib::ClipperOffset co;
+    if (joinType == jtRound) {
+        co.ArcTolerance = miterLimit;
+    } else {
+        co.MiterLimit = miterLimit;
+    }
+    float delta_scaled1 = delta1 * float(CLIPPER_OFFSET_SCALE);
+    float delta_scaled2 = delta2 * float(CLIPPER_OFFSET_SCALE);
+    co.ShortestEdgeLength = double(std::max(std::abs(delta_scaled1), std::abs(delta_scaled2)) * CLIPPER_OFFSET_SHORTEST_EDGE_FACTOR);
+    
+    // perform first offset
+    ClipperLib::Paths output1;
+    co.AddPaths(input, joinType, ClipperLib::etClosedPolygon);
+    co.Execute(output1, delta_scaled1);
+    
+    // perform second offset
+    co.Clear();
+    co.AddPaths(output1, joinType, ClipperLib::etClosedPolygon);
+    ClipperLib::Paths retval;
+    co.Execute(retval, delta_scaled2);
+    
+    // unscale output
+    unscaleClipperPolygons(retval);
+    return retval;
+}
+
+Polygons
+offset2(const Polygons &polygons, const float delta1, const float delta2,
+    const ClipperLib::JoinType joinType, const double miterLimit)
+{
+    // perform offset
+    ClipperLib::Paths output = _offset2(polygons, delta1, delta2, joinType, miterLimit);
+    
+    // convert into ExPolygons
+    return ClipperPaths_to_Slic3rPolygons(output);
+}
+
+ExPolygons
+offset2_ex(const Polygons &polygons, const float delta1, const float delta2,
+    const ClipperLib::JoinType joinType, const double miterLimit)
+{
+    // perform offset
+    ClipperLib::Paths output = _offset2(polygons, delta1, delta2, joinType, miterLimit);
+    
+    // convert into ExPolygons
+    return ClipperPaths_to_Slic3rExPolygons(output);
+}
+
+//FIXME Vojtech: This functon may likely be optimized to avoid some of the Slic3r to Clipper 
+// conversions and unnecessary Clipper calls.
+ExPolygons offset2_ex(const ExPolygons &expolygons, const float delta1,
+    const float delta2, ClipperLib::JoinType joinType, double miterLimit)
+{
+    Polygons polys;
+    for (const ExPolygon &expoly : expolygons)
+        append(polys, 
+               offset(offset_ex(expoly, delta1, joinType, miterLimit), 
+                      delta2, joinType, miterLimit));
+    return union_ex(polys);
+}
+
+template <class T>
+T
+_clipper_do(const ClipperLib::ClipType clipType, const Polygons &subject, 
+    const Polygons &clip, const ClipperLib::PolyFillType fillType, const bool safety_offset_)
+{
+    // read input
+    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
+    ClipperLib::Paths input_clip    = Slic3rMultiPoints_to_ClipperPaths(clip);
+    
+    // perform safety offset
+    if (safety_offset_) {
+        if (clipType == ClipperLib::ctUnion) {
+            safety_offset(&input_subject);
+        } else {
+            safety_offset(&input_clip);
+        }
+    }
+    
+    // init Clipper
+    ClipperLib::Clipper clipper;
+    clipper.Clear();
+    
+    // add polygons
+    clipper.AddPaths(input_subject, ClipperLib::ptSubject, true);
+    clipper.AddPaths(input_clip,    ClipperLib::ptClip,    true);
+    
+    // perform operation
+    T retval;
+    clipper.Execute(clipType, retval, fillType, fillType);
+    return retval;
+}
+
+// Fix of #117: A large fractal pyramid takes ages to slice
+// The Clipper library has difficulties processing overlapping polygons.
+// Namely, the function Clipper::JoinCommonEdges() has potentially a terrible time complexity if the output
+// of the operation is of the PolyTree type.
+// This function implmenets a following workaround:
+// 1) Peform the Clipper operation with the output to Paths. This method handles overlaps in a reasonable time.
+// 2) Run Clipper Union once again to extract the PolyTree from the result of 1).
+inline ClipperLib::PolyTree _clipper_do_polytree2(const ClipperLib::ClipType clipType, const Polygons &subject, 
+    const Polygons &clip, const ClipperLib::PolyFillType fillType, const bool safety_offset_)
+{
+    // read input
+    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
+    ClipperLib::Paths input_clip    = Slic3rMultiPoints_to_ClipperPaths(clip);
+    
+    // perform safety offset
+    if (safety_offset_)
+        safety_offset((clipType == ClipperLib::ctUnion) ? &input_subject : &input_clip);
+    
+    ClipperLib::Clipper clipper;
+    clipper.AddPaths(input_subject, ClipperLib::ptSubject, true);
+    clipper.AddPaths(input_clip,    ClipperLib::ptClip,    true);
+    // Perform the operation with the output to input_subject.
+    // This pass does not generate a PolyTree, which is a very expensive operation with the current Clipper library
+    // if there are overapping edges.
+    clipper.Execute(clipType, input_subject, fillType, fillType);
+    // Perform an additional Union operation to generate the PolyTree ordering.
+    clipper.Clear();
+    clipper.AddPaths(input_subject, ClipperLib::ptSubject, true);
+    ClipperLib::PolyTree retval;
+    clipper.Execute(ClipperLib::ctUnion, retval, fillType, fillType);
+    return retval;
+}
+
+ClipperLib::PolyTree _clipper_do_pl(const ClipperLib::ClipType clipType, const Polylines &subject, 
+    const Polygons &clip, const ClipperLib::PolyFillType fillType,
+    const bool safety_offset_)
+{
+    // read input
+    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
+    ClipperLib::Paths input_clip    = Slic3rMultiPoints_to_ClipperPaths(clip);
+    
+    // perform safety offset
+    if (safety_offset_) safety_offset(&input_clip);
+    
+    // init Clipper
+    ClipperLib::Clipper clipper;
+    clipper.Clear();
+    
+    // add polygons
+    clipper.AddPaths(input_subject, ClipperLib::ptSubject, false);
+    clipper.AddPaths(input_clip,    ClipperLib::ptClip,    true);
+    
+    // perform operation
+    ClipperLib::PolyTree retval;
+    clipper.Execute(clipType, retval, fillType, fillType);
+    return retval;
+}
+
+Polygons _clipper(ClipperLib::ClipType clipType, const Polygons &subject, const Polygons &clip, bool safety_offset_)
+{
+    return ClipperPaths_to_Slic3rPolygons(_clipper_do<ClipperLib::Paths>(clipType, subject, clip, ClipperLib::pftNonZero, safety_offset_));
+}
+
+ExPolygons _clipper_ex(ClipperLib::ClipType clipType, const Polygons &subject, const Polygons &clip, bool safety_offset_)
+{
+    ClipperLib::PolyTree polytree = _clipper_do_polytree2(clipType, subject, clip, ClipperLib::pftNonZero, safety_offset_);
+    return PolyTreeToExPolygons(polytree);
+}
+
+Polylines _clipper_pl(ClipperLib::ClipType clipType, const Polylines &subject, const Polygons &clip, bool safety_offset_)
+{
+    ClipperLib::Paths output;
+    ClipperLib::PolyTreeToPaths(_clipper_do_pl(clipType, subject, clip, ClipperLib::pftNonZero, safety_offset_), output);
+    return ClipperPaths_to_Slic3rPolylines(output);
+}
+
+Polylines _clipper_pl(ClipperLib::ClipType clipType, const Polygons &subject, const Polygons &clip, bool safety_offset_)
+{
+    // transform input polygons into polylines
+    Polylines polylines;
+    polylines.reserve(subject.size());
+    for (Polygons::const_iterator polygon = subject.begin(); polygon != subject.end(); ++polygon)
+        polylines.push_back(*polygon);  // implicit call to split_at_first_point()
+    
+    // perform clipping
+    Polylines retval = _clipper_pl(clipType, polylines, clip, safety_offset_);
+    
+    /* If the split_at_first_point() call above happens to split the polygon inside the clipping area
+       we would get two consecutive polylines instead of a single one, so we go through them in order
+       to recombine continuous polylines. */
+    for (size_t i = 0; i < retval.size(); ++i) {
+        for (size_t j = i+1; j < retval.size(); ++j) {
+            if (retval[i].points.back() == retval[j].points.front()) {
+                /* If last point of i coincides with first point of j,
+                   append points of j to i and delete j */
+                retval[i].points.insert(retval[i].points.end(), retval[j].points.begin()+1, retval[j].points.end());
+                retval.erase(retval.begin() + j);
+                --j;
+            } else if (retval[i].points.front() == retval[j].points.back()) {
+                /* If first point of i coincides with last point of j,
+                   prepend points of j to i and delete j */
+                retval[i].points.insert(retval[i].points.begin(), retval[j].points.begin(), retval[j].points.end()-1);
+                retval.erase(retval.begin() + j);
+                --j;
+            } else if (retval[i].points.front() == retval[j].points.front()) {
+                /* Since Clipper does not preserve orientation of polylines, 
+                   also check the case when first point of i coincides with first point of j. */
+                retval[j].reverse();
+                retval[i].points.insert(retval[i].points.begin(), retval[j].points.begin(), retval[j].points.end()-1);
+                retval.erase(retval.begin() + j);
+                --j;
+            } else if (retval[i].points.back() == retval[j].points.back()) {
+                /* Since Clipper does not preserve orientation of polylines, 
+                   also check the case when last point of i coincides with last point of j. */
+                retval[j].reverse();
+                retval[i].points.insert(retval[i].points.end(), retval[j].points.begin()+1, retval[j].points.end());
+                retval.erase(retval.begin() + j);
+                --j;
+            }
+        }
+    }
+    return retval;
+}
+
+Lines
+_clipper_ln(ClipperLib::ClipType clipType, const Lines &subject, const Polygons &clip,
+    bool safety_offset_)
+{
+    // convert Lines to Polylines
+    Polylines polylines;
+    polylines.reserve(subject.size());
+    for (const Line &line : subject)
+        polylines.emplace_back(Polyline(line.a, line.b));
+    
+    // perform operation
+    polylines = _clipper_pl(clipType, polylines, clip, safety_offset_);
+    
+    // convert Polylines to Lines
+    Lines retval;
+    for (Polylines::const_iterator polyline = polylines.begin(); polyline != polylines.end(); ++polyline)
+        retval.push_back(*polyline);
+    return retval;
+}
+
+ClipperLib::PolyTree
+union_pt(const Polygons &subject, bool safety_offset_)
+{
+    return _clipper_do<ClipperLib::PolyTree>(ClipperLib::ctUnion, subject, Polygons(), ClipperLib::pftEvenOdd, safety_offset_);
+}
+
+Polygons
+union_pt_chained(const Polygons &subject, bool safety_offset_)
+{
+    ClipperLib::PolyTree polytree = union_pt(subject, safety_offset_);
+    
+    Polygons retval;
+    traverse_pt(polytree.Childs, &retval);
+    return retval;
+}
+
+void traverse_pt(ClipperLib::PolyNodes &nodes, Polygons* retval)
+{
+    /* use a nearest neighbor search to order these children
+       TODO: supply start_near to chained_path() too? */
+    
+    // collect ordering points
+    Points ordering_points;
+    ordering_points.reserve(nodes.size());
+    for (ClipperLib::PolyNodes::const_iterator it = nodes.begin(); it != nodes.end(); ++it) {
+        Point p((*it)->Contour.front().X, (*it)->Contour.front().Y);
+        ordering_points.push_back(p);
+    }
+    
+    // perform the ordering
+    ClipperLib::PolyNodes ordered_nodes;
+    Slic3r::Geometry::chained_path_items(ordering_points, nodes, ordered_nodes);
+    
+    // push results recursively
+    for (ClipperLib::PolyNodes::iterator it = ordered_nodes.begin(); it != ordered_nodes.end(); ++it) {
+        // traverse the next depth
+        traverse_pt((*it)->Childs, retval);
+        retval->push_back(ClipperPath_to_Slic3rPolygon((*it)->Contour));
+        if ((*it)->IsHole()) retval->back().reverse();  // ccw
+    }
+}
+
+Polygons simplify_polygons(const Polygons &subject, bool preserve_collinear)
+{
+    // convert into Clipper polygons
+    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
+    
+    ClipperLib::Paths output;
+    if (preserve_collinear) {
+        ClipperLib::Clipper c;
+        c.PreserveCollinear(true);
+        c.StrictlySimple(true);
+        c.AddPaths(input_subject, ClipperLib::ptSubject, true);
+        c.Execute(ClipperLib::ctUnion, output, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
+    } else {
+        ClipperLib::SimplifyPolygons(input_subject, output, ClipperLib::pftNonZero);
+    }
+    
+    // convert into Slic3r polygons
+    return ClipperPaths_to_Slic3rPolygons(output);
+}
+
+ExPolygons simplify_polygons_ex(const Polygons &subject, bool preserve_collinear)
+{
+    if (! preserve_collinear)
+        return union_ex(simplify_polygons(subject, false));
+
+    // convert into Clipper polygons
+    ClipperLib::Paths input_subject = Slic3rMultiPoints_to_ClipperPaths(subject);
+    
+    ClipperLib::PolyTree polytree;
+    
+    ClipperLib::Clipper c;
+    c.PreserveCollinear(true);
+    c.StrictlySimple(true);
+    c.AddPaths(input_subject, ClipperLib::ptSubject, true);
+    c.Execute(ClipperLib::ctUnion, polytree, ClipperLib::pftNonZero, ClipperLib::pftNonZero);
+    
+    // convert into ExPolygons
+    return PolyTreeToExPolygons(polytree);
+}
+
+void safety_offset(ClipperLib::Paths* paths)
+{
+    PROFILE_FUNC();
+
+    // scale input
+    scaleClipperPolygons(*paths);
+    
+    // perform offset (delta = scale 1e-05)
+    ClipperLib::ClipperOffset co;
+#ifdef CLIPPER_UTILS_DEBUG
+    if (clipper_export_enabled) {
+        static int iRun = 0;
+        export_clipper_input_polygons_bin(debug_out_path("safety_offset-polygons-%d", ++iRun).c_str(), *paths, ClipperLib::Paths());
+    }
+#endif /* CLIPPER_UTILS_DEBUG */
+    ClipperLib::Paths out;
+    for (size_t i = 0; i < paths->size(); ++ i) {
+        ClipperLib::Path &path = (*paths)[i];
+        co.Clear();
+        co.MiterLimit = 2;
+        bool ccw = ClipperLib::Orientation(path);
+        if (! ccw)
+            std::reverse(path.begin(), path.end());
+        {
+            PROFILE_BLOCK(safety_offset_AddPaths);
+            co.AddPath((*paths)[i], ClipperLib::jtMiter, ClipperLib::etClosedPolygon);
+        }
+        {
+            PROFILE_BLOCK(safety_offset_Execute);
+            // offset outside by 10um
+            ClipperLib::Paths out_this;
+            co.Execute(out_this, ccw ? 10.f * float(CLIPPER_OFFSET_SCALE) : -10.f * float(CLIPPER_OFFSET_SCALE));
+            if (! ccw) {
+                // Reverse the resulting contours once again.
+                for (ClipperLib::Paths::iterator it = out_this.begin(); it != out_this.end(); ++ it)
+                    std::reverse(it->begin(), it->end());
+            }
+            if (out.empty())
+                out = std::move(out_this);
+            else
+                std::move(std::begin(out_this), std::end(out_this), std::back_inserter(out));
+        }
+    }
+    *paths = std::move(out);
+    
+    // unscale output
+    unscaleClipperPolygons(*paths);
+}
+
+Polygons top_level_islands(const Slic3r::Polygons &polygons)
+{
+    // init Clipper
+    ClipperLib::Clipper clipper;
+    clipper.Clear();
+    // perform union
+    clipper.AddPaths(Slic3rMultiPoints_to_ClipperPaths(polygons), ClipperLib::ptSubject, true);
+    ClipperLib::PolyTree polytree;
+    clipper.Execute(ClipperLib::ctUnion, polytree, ClipperLib::pftEvenOdd, ClipperLib::pftEvenOdd); 
+    // Convert only the top level islands to the output.
+    Polygons out;
+    out.reserve(polytree.ChildCount());
+    for (int i = 0; i < polytree.ChildCount(); ++i)
+        out.push_back(ClipperPath_to_Slic3rPolygon(polytree.Childs[i]->Contour));
+    return out;
+}
+
+}

src/libslic3r/ClipperUtils.hpp

@@ -0,0 +1,231 @@
+#ifndef slic3r_ClipperUtils_hpp_
+#define slic3r_ClipperUtils_hpp_
+
+#include <libslic3r.h>
+#include "clipper.hpp"
+#include "ExPolygon.hpp"
+#include "Polygon.hpp"
+#include "Surface.hpp"
+
+// import these wherever we're included
+using ClipperLib::jtMiter;
+using ClipperLib::jtRound;
+using ClipperLib::jtSquare;
+
+// Factor to convert from coord_t (which is int32) to an int64 type used by the Clipper library
+// for general offsetting (the offset(), offset2(), offset_ex() functions) and for the safety offset,
+// which is optionally executed by other functions (union, intersection, diff).
+// This scaling (cca 130t) is applied over the usual SCALING_FACTOR.
+// By the way, is the scalling for offset needed at all?
+// The reason to apply this scaling may be to match the resolution of the double mantissa.
+#define CLIPPER_OFFSET_POWER_OF_2 17
+// 2^17=131072
+#define CLIPPER_OFFSET_SCALE (1 << CLIPPER_OFFSET_POWER_OF_2)
+#define CLIPPER_OFFSET_SCALE_ROUNDING_DELTA ((1 << (CLIPPER_OFFSET_POWER_OF_2 - 1)) - 1)
+#define CLIPPER_MAX_COORD_UNSCALED (ClipperLib::hiRange / CLIPPER_OFFSET_SCALE)
+
+namespace Slic3r {
+
+//-----------------------------------------------------------
+// legacy code from Clipper documentation
+void AddOuterPolyNodeToExPolygons(ClipperLib::PolyNode& polynode, Slic3r::ExPolygons& expolygons);
+void PolyTreeToExPolygons(ClipperLib::PolyTree& polytree, Slic3r::ExPolygons& expolygons);
+//-----------------------------------------------------------
+
+ClipperLib::Path   Slic3rMultiPoint_to_ClipperPath(const Slic3r::MultiPoint &input);
+ClipperLib::Paths  Slic3rMultiPoints_to_ClipperPaths(const Polygons &input);
+ClipperLib::Paths  Slic3rMultiPoints_to_ClipperPaths(const Polylines &input);
+Slic3r::Polygon    ClipperPath_to_Slic3rPolygon(const ClipperLib::Path &input);
+Slic3r::Polyline   ClipperPath_to_Slic3rPolyline(const ClipperLib::Path &input);
+Slic3r::Polygons   ClipperPaths_to_Slic3rPolygons(const ClipperLib::Paths &input);
+Slic3r::Polylines  ClipperPaths_to_Slic3rPolylines(const ClipperLib::Paths &input);
+Slic3r::ExPolygons ClipperPaths_to_Slic3rExPolygons(const ClipperLib::Paths &input);
+
+// offset Polygons
+ClipperLib::Paths _offset(ClipperLib::Path &&input, ClipperLib::EndType endType, const float delta, ClipperLib::JoinType joinType, double miterLimit);
+ClipperLib::Paths _offset(ClipperLib::Paths &&input, ClipperLib::EndType endType, const float delta, ClipperLib::JoinType joinType, double miterLimit);
+inline Slic3r::Polygons offset(const Slic3r::Polygon &polygon, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter,  double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rPolygons(_offset(Slic3rMultiPoint_to_ClipperPath(polygon), ClipperLib::etClosedPolygon, delta, joinType, miterLimit)); }
+inline Slic3r::Polygons offset(const Slic3r::Polygons &polygons, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rPolygons(_offset(Slic3rMultiPoints_to_ClipperPaths(polygons), ClipperLib::etClosedPolygon, delta, joinType, miterLimit)); }
+
+// offset Polylines
+inline Slic3r::Polygons offset(const Slic3r::Polyline &polyline, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtSquare, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rPolygons(_offset(Slic3rMultiPoint_to_ClipperPath(polyline), ClipperLib::etOpenButt, delta, joinType, miterLimit)); }
+inline Slic3r::Polygons offset(const Slic3r::Polylines &polylines, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtSquare, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rPolygons(_offset(Slic3rMultiPoints_to_ClipperPaths(polylines), ClipperLib::etOpenButt, delta, joinType, miterLimit)); }
+
+// offset expolygons and surfaces
+ClipperLib::Paths _offset(const Slic3r::ExPolygon &expolygon, const float delta, ClipperLib::JoinType joinType, double miterLimit);
+ClipperLib::Paths _offset(const Slic3r::ExPolygons &expolygons, const float delta, ClipperLib::JoinType joinType, double miterLimit);
+inline Slic3r::Polygons offset(const Slic3r::ExPolygon &expolygon, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rPolygons(_offset(expolygon, delta, joinType, miterLimit)); }
+inline Slic3r::Polygons offset(const Slic3r::ExPolygons &expolygons, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rPolygons(_offset(expolygons, delta, joinType, miterLimit)); }
+inline Slic3r::ExPolygons offset_ex(const Slic3r::Polygon &polygon, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rExPolygons(_offset(Slic3rMultiPoint_to_ClipperPath(polygon), ClipperLib::etClosedPolygon, delta, joinType, miterLimit)); }    
+inline Slic3r::ExPolygons offset_ex(const Slic3r::Polygons &polygons, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rExPolygons(_offset(Slic3rMultiPoints_to_ClipperPaths(polygons), ClipperLib::etClosedPolygon, delta, joinType, miterLimit)); }
+inline Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygon &expolygon, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rExPolygons(_offset(expolygon, delta, joinType, miterLimit)); }
+inline Slic3r::ExPolygons offset_ex(const Slic3r::ExPolygons &expolygons, const float delta, ClipperLib::JoinType joinType = ClipperLib::jtMiter, double miterLimit = 3)
+    { return ClipperPaths_to_Slic3rExPolygons(_offset(expolygons, delta, joinType, miterLimit)); }
+
+ClipperLib::Paths _offset2(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
+Slic3r::Polygons offset2(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
+Slic3r::ExPolygons offset2_ex(const Slic3r::Polygons &polygons, const float delta1,
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
+Slic3r::ExPolygons offset2_ex(const Slic3r::ExPolygons &expolygons, const float delta1,
+    const float delta2, ClipperLib::JoinType joinType = ClipperLib::jtMiter, 
+    double miterLimit = 3);
+
+Slic3r::Polygons _clipper(ClipperLib::ClipType clipType,
+    const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+Slic3r::ExPolygons _clipper_ex(ClipperLib::ClipType clipType,
+    const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+Slic3r::Polylines _clipper_pl(ClipperLib::ClipType clipType,
+    const Slic3r::Polylines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+Slic3r::Polylines _clipper_pl(ClipperLib::ClipType clipType,
+    const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+Slic3r::Lines _clipper_ln(ClipperLib::ClipType clipType,
+    const Slic3r::Lines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false);
+
+// diff
+inline Slic3r::Polygons
+diff(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper(ClipperLib::ctDifference, subject, clip, safety_offset_);
+}
+
+inline Slic3r::ExPolygons
+diff_ex(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctDifference, subject, clip, safety_offset_);
+}
+
+inline Slic3r::ExPolygons
+diff_ex(const Slic3r::ExPolygons &subject, const Slic3r::ExPolygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctDifference, to_polygons(subject), to_polygons(clip), safety_offset_);
+}
+
+inline Slic3r::Polygons
+diff(const Slic3r::ExPolygons &subject, const Slic3r::ExPolygons &clip, bool safety_offset_ = false)
+{
+    return _clipper(ClipperLib::ctDifference, to_polygons(subject), to_polygons(clip), safety_offset_);
+}
+
+inline Slic3r::Polylines
+diff_pl(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_pl(ClipperLib::ctDifference, subject, clip, safety_offset_);
+}
+
+inline Slic3r::Polylines
+diff_pl(const Slic3r::Polylines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_pl(ClipperLib::ctDifference, subject, clip, safety_offset_);
+}
+
+inline Slic3r::Lines
+diff_ln(const Slic3r::Lines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_ln(ClipperLib::ctDifference, subject, clip, safety_offset_);
+}
+
+// intersection
+inline Slic3r::Polygons
+intersection(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper(ClipperLib::ctIntersection, subject, clip, safety_offset_);
+}
+
+inline Slic3r::ExPolygons
+intersection_ex(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctIntersection, subject, clip, safety_offset_);
+}
+
+inline Slic3r::ExPolygons
+intersection_ex(const Slic3r::ExPolygons &subject, const Slic3r::ExPolygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctIntersection, to_polygons(subject), to_polygons(clip), safety_offset_);
+}
+
+inline Slic3r::Polygons
+intersection(const Slic3r::ExPolygons &subject, const Slic3r::ExPolygons &clip, bool safety_offset_ = false)
+{
+    return _clipper(ClipperLib::ctIntersection, to_polygons(subject), to_polygons(clip), safety_offset_);
+}
+
+inline Slic3r::Polylines
+intersection_pl(const Slic3r::Polygons &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_pl(ClipperLib::ctIntersection, subject, clip, safety_offset_);
+}
+
+inline Slic3r::Polylines
+intersection_pl(const Slic3r::Polylines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_pl(ClipperLib::ctIntersection, subject, clip, safety_offset_);
+}
+
+inline Slic3r::Lines intersection_ln(const Slic3r::Lines &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    return _clipper_ln(ClipperLib::ctIntersection, subject, clip, safety_offset_);
+}
+
+inline Slic3r::Lines intersection_ln(const Slic3r::Line &subject, const Slic3r::Polygons &clip, bool safety_offset_ = false)
+{
+    Slic3r::Lines lines;
+    lines.emplace_back(subject);
+    return _clipper_ln(ClipperLib::ctIntersection, lines, clip, safety_offset_);
+}
+
+// union
+inline Slic3r::Polygons union_(const Slic3r::Polygons &subject, bool safety_offset_ = false)
+{
+    return _clipper(ClipperLib::ctUnion, subject, Slic3r::Polygons(), safety_offset_);
+}
+
+inline Slic3r::Polygons union_(const Slic3r::Polygons &subject, const Slic3r::Polygons &subject2, bool safety_offset_ = false)
+{
+    return _clipper(ClipperLib::ctUnion, subject, subject2, safety_offset_);
+}
+
+inline Slic3r::ExPolygons union_ex(const Slic3r::Polygons &subject, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctUnion, subject, Slic3r::Polygons(), safety_offset_);
+}
+
+inline Slic3r::ExPolygons union_ex(const Slic3r::ExPolygons &subject, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctUnion, to_polygons(subject), Slic3r::Polygons(), safety_offset_);
+}
+
+inline Slic3r::ExPolygons union_ex(const Slic3r::Surfaces &subject, bool safety_offset_ = false)
+{
+    return _clipper_ex(ClipperLib::ctUnion, to_polygons(subject), Slic3r::Polygons(), safety_offset_);
+}
+
+
+ClipperLib::PolyTree union_pt(const Slic3r::Polygons &subject, bool safety_offset_ = false);
+Slic3r::Polygons union_pt_chained(const Slic3r::Polygons &subject, bool safety_offset_ = false);
+void traverse_pt(ClipperLib::PolyNodes &nodes, Slic3r::Polygons* retval);
+
+/* OTHER */
+Slic3r::Polygons simplify_polygons(const Slic3r::Polygons &subject, bool preserve_collinear = false);
+Slic3r::ExPolygons simplify_polygons_ex(const Slic3r::Polygons &subject, bool preserve_collinear = false);
+
+void safety_offset(ClipperLib::Paths* paths);
+
+Polygons top_level_islands(const Slic3r::Polygons &polygons);
+
+}
+
+#endif

src/libslic3r/Config.cpp

@@ -0,0 +1,699 @@
+#include "Config.hpp"
+#include "Utils.hpp"
+#include <assert.h>
+#include <fstream>
+#include <iostream>
+#include <exception> // std::runtime_error
+#include <boost/algorithm/string.hpp>
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/erase.hpp>
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/replace.hpp>
+#include <boost/algorithm/string/split.hpp>
+#include <boost/config.hpp>
+#include <boost/foreach.hpp>
+#include <boost/lexical_cast.hpp>
+#include <boost/nowide/cenv.hpp>
+#include <boost/nowide/fstream.hpp>
+#include <boost/property_tree/ini_parser.hpp>
+#include <boost/format.hpp>
+#include <string.h>
+
+namespace Slic3r {
+
+// Escape \n, \r and backslash
+std::string escape_string_cstyle(const std::string &str)
+{
+    // Allocate a buffer twice the input string length,
+    // so the output will fit even if all input characters get escaped.
+    std::vector<char> out(str.size() * 2, 0);
+    char *outptr = out.data();
+    for (size_t i = 0; i < str.size(); ++ i) {
+        char c = str[i];
+        if (c == '\r') {
+            (*outptr ++) = '\\';
+            (*outptr ++) = 'r';
+        } else if (c == '\n') {
+            (*outptr ++) = '\\';
+            (*outptr ++) = 'n';
+        } else if (c == '\\') {
+            (*outptr ++) = '\\';
+            (*outptr ++) = '\\';
+        } else
+            (*outptr ++) = c;
+    }
+    return std::string(out.data(), outptr - out.data());
+}
+
+std::string escape_strings_cstyle(const std::vector<std::string> &strs)
+{
+    // 1) Estimate the output buffer size to avoid buffer reallocation.
+    size_t outbuflen = 0;
+    for (size_t i = 0; i < strs.size(); ++ i)
+        // Reserve space for every character escaped + quotes + semicolon.
+        outbuflen += strs[i].size() * 2 + 3;
+    // 2) Fill in the buffer.
+    std::vector<char> out(outbuflen, 0);
+    char *outptr = out.data();
+    for (size_t j = 0; j < strs.size(); ++ j) {
+        if (j > 0)
+            // Separate the strings.
+            (*outptr ++) = ';';
+        const std::string &str = strs[j];
+        // Is the string simple or complex? Complex string contains spaces, tabs, new lines and other
+        // escapable characters. Empty string shall be quoted as well, if it is the only string in strs.
+        bool should_quote = strs.size() == 1 && str.empty();
+        for (size_t i = 0; i < str.size(); ++ i) {
+            char c = str[i];
+            if (c == ' ' || c == '\t' || c == '\\' || c == '"' || c == '\r' || c == '\n') {
+                should_quote = true;
+                break;
+            }
+        }
+        if (should_quote) {
+            (*outptr ++) = '"';
+            for (size_t i = 0; i < str.size(); ++ i) {
+                char c = str[i];
+                if (c == '\\' || c == '"') {
+                    (*outptr ++) = '\\';
+                    (*outptr ++) = c;
+                } else if (c == '\r') {
+                    (*outptr ++) = '\\';
+                    (*outptr ++) = 'r';
+                } else if (c == '\n') {
+                    (*outptr ++) = '\\';
+                    (*outptr ++) = 'n';
+                } else
+                    (*outptr ++) = c;
+            }
+            (*outptr ++) = '"';
+        } else {
+            memcpy(outptr, str.data(), str.size());
+            outptr += str.size();
+        }
+    }
+    return std::string(out.data(), outptr - out.data());
+}
+
+// Unescape \n, \r and backslash
+bool unescape_string_cstyle(const std::string &str, std::string &str_out)
+{
+    std::vector<char> out(str.size(), 0);
+    char *outptr = out.data();
+    for (size_t i = 0; i < str.size(); ++ i) {
+        char c = str[i];
+        if (c == '\\') {
+            if (++ i == str.size())
+                return false;
+            c = str[i];
+            if (c == 'r')
+                (*outptr ++) = '\r';
+            else if (c == 'n')
+                (*outptr ++) = '\n';
+            else
+                (*outptr ++) = c;
+        } else
+            (*outptr ++) = c;
+    }
+    str_out.assign(out.data(), outptr - out.data());
+    return true;
+}
+
+bool unescape_strings_cstyle(const std::string &str, std::vector<std::string> &out)
+{
+    if (str.empty())
+        return true;
+
+    size_t i = 0;
+    for (;;) {
+        // Skip white spaces.
+        char c = str[i];
+        while (c == ' ' || c == '\t') {
+            if (++ i == str.size())
+                return true;
+            c = str[i];
+        }
+        // Start of a word.
+        std::vector<char> buf;
+        buf.reserve(16);
+        // Is it enclosed in quotes?
+        c = str[i];
+        if (c == '"') {
+            // Complex case, string is enclosed in quotes.
+            for (++ i; i < str.size(); ++ i) {
+                c = str[i];
+                if (c == '"') {
+                    // End of string.
+                    break;
+                }
+                if (c == '\\') {
+                    if (++ i == str.size())
+                        return false;
+                    c = str[i];
+                    if (c == 'r')
+                        c = '\r';
+                    else if (c == 'n')
+                        c = '\n';
+                }
+                buf.push_back(c);
+            }
+            if (i == str.size())
+                return false;
+            ++ i;
+        } else {
+            for (; i < str.size(); ++ i) {
+                c = str[i];
+                if (c == ';')
+                    break;
+                buf.push_back(c);
+            }
+        }
+        // Store the string into the output vector.
+        out.push_back(std::string(buf.data(), buf.size()));
+        if (i == str.size())
+            return true;
+        // Skip white spaces.
+        c = str[i];
+        while (c == ' ' || c == '\t') {
+            if (++ i == str.size())
+                // End of string. This is correct.
+                return true;
+            c = str[i];
+        }
+        if (c != ';')
+            return false;
+        if (++ i == str.size()) {
+            // Emit one additional empty string.
+            out.push_back(std::string());
+            return true;
+        }
+    }
+}
+
+void ConfigBase::apply_only(const ConfigBase &other, const t_config_option_keys &keys, bool ignore_nonexistent)
+{
+    // loop through options and apply them
+    for (const t_config_option_key &opt_key : keys) {
+        // Create a new option with default value for the key.
+        // If the key is not in the parameter definition, or this ConfigBase is a static type and it does not support the parameter,
+        // an exception is thrown if not ignore_nonexistent.
+        ConfigOption *my_opt = this->option(opt_key, true);
+        if (my_opt == nullptr) {
+            // opt_key does not exist in this ConfigBase and it cannot be created, because it is not defined by this->def().
+            // This is only possible if other is of DynamicConfig type.
+            if (ignore_nonexistent)
+                continue;
+            throw UnknownOptionException(opt_key);
+        }
+		const ConfigOption *other_opt = other.option(opt_key);
+		if (other_opt == nullptr) {
+            // The key was not found in the source config, therefore it will not be initialized!
+//			printf("Not found, therefore not initialized: %s\n", opt_key.c_str());
+		} else
+            my_opt->set(other_opt);
+    }
+}
+
+// this will *ignore* options not present in both configs
+t_config_option_keys ConfigBase::diff(const ConfigBase &other) const
+{
+    t_config_option_keys diff;
+    for (const t_config_option_key &opt_key : this->keys()) {
+        const ConfigOption *this_opt  = this->option(opt_key);
+        const ConfigOption *other_opt = other.option(opt_key);
+        if (this_opt != nullptr && other_opt != nullptr && *this_opt != *other_opt)
+            diff.emplace_back(opt_key);
+    }
+    return diff;
+}
+
+template<class T>
+void add_correct_opts_to_diff(const std::string &opt_key, t_config_option_keys& vec, const ConfigBase &other, const ConfigBase *this_c)
+{
+	const T* opt_init = static_cast<const T*>(other.option(opt_key));
+	const T* opt_cur = static_cast<const T*>(this_c->option(opt_key));
+	int opt_init_max_id = opt_init->values.size() - 1;
+	for (int i = 0; i < opt_cur->values.size(); i++)
+	{
+		int init_id = i <= opt_init_max_id ? i : 0;
+		if (opt_cur->values[i] != opt_init->values[init_id])
+			vec.emplace_back(opt_key + "#" + std::to_string(i));
+	}
+}
+
+t_config_option_keys ConfigBase::deep_diff(const ConfigBase &other) const
+{
+    t_config_option_keys diff;
+    for (const t_config_option_key &opt_key : this->keys()) {
+        const ConfigOption *this_opt  = this->option(opt_key);
+        const ConfigOption *other_opt = other.option(opt_key);
+		if (this_opt != nullptr && other_opt != nullptr && *this_opt != *other_opt)
+		{
+			if (opt_key == "bed_shape"){ diff.emplace_back(opt_key);		continue; }
+			switch (other_opt->type())
+			{
+			case coInts:	add_correct_opts_to_diff<ConfigOptionInts		>(opt_key, diff, other, this);	break;
+			case coBools:	add_correct_opts_to_diff<ConfigOptionBools		>(opt_key, diff, other, this);	break;
+			case coFloats:	add_correct_opts_to_diff<ConfigOptionFloats		>(opt_key, diff, other, this);	break;
+			case coStrings:	add_correct_opts_to_diff<ConfigOptionStrings	>(opt_key, diff, other, this);	break;
+			case coPercents:add_correct_opts_to_diff<ConfigOptionPercents	>(opt_key, diff, other, this);	break;
+			case coPoints:	add_correct_opts_to_diff<ConfigOptionPoints		>(opt_key, diff, other, this);	break;
+			default:		diff.emplace_back(opt_key);		break;
+			}
+		}
+    }
+    return diff;
+}
+
+t_config_option_keys ConfigBase::equal(const ConfigBase &other) const
+{
+    t_config_option_keys equal;
+    for (const t_config_option_key &opt_key : this->keys()) {
+        const ConfigOption *this_opt  = this->option(opt_key);
+        const ConfigOption *other_opt = other.option(opt_key);
+        if (this_opt != nullptr && other_opt != nullptr && *this_opt == *other_opt)
+            equal.emplace_back(opt_key);
+    }
+    return equal;
+}
+
+std::string ConfigBase::serialize(const t_config_option_key &opt_key) const
+{
+    const ConfigOption* opt = this->option(opt_key);
+    assert(opt != nullptr);
+    return opt->serialize();
+}
+
+bool ConfigBase::set_deserialize(const t_config_option_key &opt_key_src, const std::string &value_src, bool append)
+{
+    t_config_option_key opt_key = opt_key_src;
+    std::string         value   = value_src;
+    // Both opt_key and value may be modified by _handle_legacy().
+    // If the opt_key is no more valid in this version of Slic3r, opt_key is cleared by _handle_legacy().
+    this->handle_legacy(opt_key, value);
+    if (opt_key.empty())
+        // Ignore the option.
+        return true;
+    return this->set_deserialize_raw(opt_key, value, append);
+}
+
+bool ConfigBase::set_deserialize_raw(const t_config_option_key &opt_key_src, const std::string &value, bool append)
+{
+    t_config_option_key opt_key = opt_key_src;
+    // Try to deserialize the option by its name.
+    const ConfigDef       *def    = this->def();
+    if (def == nullptr)
+        throw NoDefinitionException(opt_key);
+    const ConfigOptionDef *optdef = def->get(opt_key);
+    if (optdef == nullptr) {
+        // If we didn't find an option, look for any other option having this as an alias.
+        for (const auto &opt : def->options) {
+            for (const t_config_option_key &opt_key2 : opt.second.aliases) {
+                if (opt_key2 == opt_key) {
+                    opt_key = opt.first;
+                    optdef = &opt.second;
+                    break;
+                }
+            }
+            if (optdef != nullptr)
+                break;
+        }
+        if (optdef == nullptr)
+            throw UnknownOptionException(opt_key);
+    }
+    
+    if (! optdef->shortcut.empty()) {
+        // Aliasing for example "solid_layers" to "top_solid_layers" and "bottom_solid_layers".
+        for (const t_config_option_key &shortcut : optdef->shortcut)
+            // Recursive call.
+            if (! this->set_deserialize_raw(shortcut, value, append))
+                return false;
+        return true;
+    }
+    
+    ConfigOption *opt = this->option(opt_key, true);
+    assert(opt != nullptr);
+    return opt->deserialize(value, append);
+}
+
+// Return an absolute value of a possibly relative config variable.
+// For example, return absolute infill extrusion width, either from an absolute value, or relative to the layer height.
+double ConfigBase::get_abs_value(const t_config_option_key &opt_key) const
+{
+    // Get stored option value.
+    const ConfigOption *raw_opt = this->option(opt_key);
+    assert(raw_opt != nullptr);
+    if (raw_opt->type() == coFloat)
+        return static_cast<const ConfigOptionFloat*>(raw_opt)->value;
+    if (raw_opt->type() == coFloatOrPercent) {
+        // Get option definition.
+        const ConfigDef *def = this->def();
+        if (def == nullptr)
+            throw NoDefinitionException(opt_key);
+        const ConfigOptionDef *opt_def = def->get(opt_key);
+        assert(opt_def != nullptr);
+        // Compute absolute value over the absolute value of the base option.
+        //FIXME there are some ratio_over chains, which end with empty ratio_with.
+        // For example, XXX_extrusion_width parameters are not handled by get_abs_value correctly.
+        return opt_def->ratio_over.empty() ? 0. : 
+            static_cast<const ConfigOptionFloatOrPercent*>(raw_opt)->get_abs_value(this->get_abs_value(opt_def->ratio_over));
+    }
+    throw std::runtime_error("ConfigBase::get_abs_value(): Not a valid option type for get_abs_value()");
+}
+
+// Return an absolute value of a possibly relative config variable.
+// For example, return absolute infill extrusion width, either from an absolute value, or relative to a provided value.
+double ConfigBase::get_abs_value(const t_config_option_key &opt_key, double ratio_over) const 
+{
+    // Get stored option value.
+    const ConfigOption *raw_opt = this->option(opt_key);
+    assert(raw_opt != nullptr);
+    if (raw_opt->type() != coFloatOrPercent)
+        throw std::runtime_error("ConfigBase::get_abs_value(): opt_key is not of coFloatOrPercent");
+    // Compute absolute value.
+    return static_cast<const ConfigOptionFloatOrPercent*>(raw_opt)->get_abs_value(ratio_over);
+}
+
+void ConfigBase::setenv_()
+{
+    t_config_option_keys opt_keys = this->keys();
+    for (t_config_option_keys::const_iterator it = opt_keys.begin(); it != opt_keys.end(); ++it) {
+        // prepend the SLIC3R_ prefix
+        std::ostringstream ss;
+        ss << "SLIC3R_";
+        ss << *it;
+        std::string envname = ss.str();
+        
+        // capitalize environment variable name
+        for (size_t i = 0; i < envname.size(); ++i)
+            envname[i] = (envname[i] <= 'z' && envname[i] >= 'a') ? envname[i]-('a'-'A') : envname[i];
+        
+        boost::nowide::setenv(envname.c_str(), this->serialize(*it).c_str(), 1);
+    }
+}
+
+void ConfigBase::load(const std::string &file)
+{
+    if (boost::iends_with(file, ".gcode") || boost::iends_with(file, ".g"))
+        this->load_from_gcode_file(file);
+    else
+        this->load_from_ini(file);
+}
+
+void ConfigBase::load_from_ini(const std::string &file)
+{
+    boost::property_tree::ptree tree;
+    boost::nowide::ifstream ifs(file);
+    boost::property_tree::read_ini(ifs, tree);
+    this->load(tree);
+}
+
+void ConfigBase::load(const boost::property_tree::ptree &tree)
+{
+    for (const boost::property_tree::ptree::value_type &v : tree) {
+        try {
+            t_config_option_key opt_key = v.first;
+            this->set_deserialize(opt_key, v.second.get_value<std::string>());
+        } catch (UnknownOptionException & /* e */) {
+            // ignore
+        }
+    }
+}
+
+// Load the config keys from the tail of a G-code file.
+void ConfigBase::load_from_gcode_file(const std::string &file)
+{
+    // Read a 64k block from the end of the G-code.
+	boost::nowide::ifstream ifs(file);
+	{
+		const char slic3r_gcode_header[] = "; generated by Slic3r ";
+		std::string firstline;
+		std::getline(ifs, firstline);
+		if (strncmp(slic3r_gcode_header, firstline.c_str(), strlen(slic3r_gcode_header)) != 0)
+			throw std::runtime_error("Not a Slic3r generated g-code.");
+	}
+    ifs.seekg(0, ifs.end);
+	auto file_length = ifs.tellg();
+	auto data_length = std::min<std::fstream::streampos>(65535, file_length);
+	ifs.seekg(file_length - data_length, ifs.beg);
+    std::vector<char> data(size_t(data_length) + 1, 0);
+    ifs.read(data.data(), data_length);
+    ifs.close();
+
+    size_t key_value_pairs = load_from_gcode_string(data.data());
+    if (key_value_pairs < 80)
+        throw std::runtime_error((boost::format("Suspiciously low number of configuration values extracted from %1: %2") % file % key_value_pairs).str());
+}
+
+// Load the config keys from the given string.
+size_t ConfigBase::load_from_gcode_string(const char* str)
+{
+    if (str == nullptr)
+        return 0;
+
+    // Walk line by line in reverse until a non-configuration key appears.
+    char *data_start = const_cast<char*>(str);
+    // boost::nowide::ifstream seems to cook the text data somehow, so less then the 64k of characters may be retrieved.
+    char *end = data_start + strlen(str);
+    size_t num_key_value_pairs = 0;
+    for (;;) {
+        // Extract next line.
+        for (--end; end > data_start && (*end == '\r' || *end == '\n'); --end);
+        if (end == data_start)
+            break;
+        char *start = end;
+        *(++end) = 0;
+        for (; start > data_start && *start != '\r' && *start != '\n'; --start);
+        if (start == data_start)
+            break;
+        // Extracted a line from start to end. Extract the key = value pair.
+        if (end - (++start) < 10 || start[0] != ';' || start[1] != ' ')
+            break;
+        char *key = start + 2;
+        if (!(*key >= 'a' && *key <= 'z') || (*key >= 'A' && *key <= 'Z'))
+            // A key must start with a letter.
+            break;
+        char *sep = strchr(key, '=');
+        if (sep == nullptr || sep[-1] != ' ' || sep[1] != ' ')
+            break;
+        char *value = sep + 2;
+        if (value > end)
+            break;
+        char *key_end = sep - 1;
+        if (key_end - key < 3)
+            break;
+        *key_end = 0;
+        // The key may contain letters, digits and underscores.
+        for (char *c = key; c != key_end; ++c)
+            if (!((*c >= 'a' && *c <= 'z') || (*c >= 'A' && *c <= 'Z') || (*c >= '0' && *c <= '9') || *c == '_')) {
+                key = nullptr;
+                break;
+            }
+        if (key == nullptr)
+            break;
+        try {
+            this->set_deserialize(key, value);
+            ++num_key_value_pairs;
+        }
+        catch (UnknownOptionException & /* e */) {
+            // ignore
+        }
+        end = start;
+    }
+
+	return num_key_value_pairs;
+}
+
+void ConfigBase::save(const std::string &file) const
+{
+    boost::nowide::ofstream c;
+    c.open(file, std::ios::out | std::ios::trunc);
+    c << "# " << Slic3r::header_slic3r_generated() << std::endl;
+    for (const std::string &opt_key : this->keys())
+        c << opt_key << " = " << this->serialize(opt_key) << std::endl;
+    c.close();
+}
+
+bool DynamicConfig::operator==(const DynamicConfig &rhs) const
+{
+    t_options_map::const_iterator it1     = this->options.begin();
+    t_options_map::const_iterator it1_end = this->options.end();
+    t_options_map::const_iterator it2     = rhs.options.begin();
+    t_options_map::const_iterator it2_end = rhs.options.end();
+    for (; it1 != it1_end && it2 != it2_end; ++ it1, ++ it2)
+        if (*it1->second != *it2->second)
+            return false;
+    return it1 == it1_end && it2 == it2_end;
+}
+
+ConfigOption* DynamicConfig::optptr(const t_config_option_key &opt_key, bool create)
+{
+    t_options_map::iterator it = options.find(opt_key);
+    if (it != options.end())
+        // Option was found.
+        return it->second;
+    if (! create)
+        // Option was not found and a new option shall not be created.
+        return nullptr;
+    // Try to create a new ConfigOption.
+    const ConfigDef       *def    = this->def();
+    if (def == nullptr)
+        throw NoDefinitionException(opt_key);
+    const ConfigOptionDef *optdef = def->get(opt_key);
+    if (optdef == nullptr)
+//        throw std::runtime_error(std::string("Invalid option name: ") + opt_key);
+        // Let the parent decide what to do if the opt_key is not defined by this->def().
+        return nullptr;
+    ConfigOption *opt = nullptr;
+    switch (optdef->type) {
+    case coFloat:           opt = new ConfigOptionFloat();          break;
+    case coFloats:          opt = new ConfigOptionFloats();         break;
+    case coInt:             opt = new ConfigOptionInt();            break;
+    case coInts:            opt = new ConfigOptionInts();           break;
+    case coString:          opt = new ConfigOptionString();         break;
+    case coStrings:         opt = new ConfigOptionStrings();        break;
+    case coPercent:         opt = new ConfigOptionPercent();        break;
+    case coPercents:        opt = new ConfigOptionPercents();       break;
+    case coFloatOrPercent:  opt = new ConfigOptionFloatOrPercent(); break;
+    case coPoint:           opt = new ConfigOptionPoint();          break;
+    case coPoints:          opt = new ConfigOptionPoints();         break;
+    case coBool:            opt = new ConfigOptionBool();           break;
+    case coBools:           opt = new ConfigOptionBools();          break;
+    case coEnum:            opt = new ConfigOptionEnumGeneric(optdef->enum_keys_map); break;
+    default:                throw std::runtime_error(std::string("Unknown option type for option ") + opt_key);
+    }
+    this->options[opt_key] = opt;
+    return opt;
+}
+
+void DynamicConfig::read_cli(const std::vector<std::string> &tokens, t_config_option_keys* extra)
+{
+    std::vector<char*> args;    
+    // push a bogus executable name (argv[0])
+    args.emplace_back(const_cast<char*>(""));
+    for (size_t i = 0; i < tokens.size(); ++ i)
+        args.emplace_back(const_cast<char *>(tokens[i].c_str()));
+    this->read_cli(args.size(), &args[0], extra);
+}
+
+bool DynamicConfig::read_cli(int argc, char** argv, t_config_option_keys* extra)
+{
+    // cache the CLI option => opt_key mapping
+    std::map<std::string,std::string> opts;
+    for (const auto &oit : this->def()->options) {
+        std::string cli = oit.second.cli;
+        cli = cli.substr(0, cli.find("="));
+        boost::trim_right_if(cli, boost::is_any_of("!"));
+        std::vector<std::string> tokens;
+        boost::split(tokens, cli, boost::is_any_of("|"));
+        for (const std::string &t : tokens)
+            opts[t] = oit.first;
+    }
+    
+    bool parse_options = true;
+    for (int i = 1; i < argc; ++ i) {
+        std::string token = argv[i];
+        // Store non-option arguments in the provided vector.
+        if (! parse_options || ! boost::starts_with(token, "-")) {
+            extra->push_back(token);
+            continue;
+        }
+        // Stop parsing tokens as options when -- is supplied.
+        if (token == "--") {
+            parse_options = false;
+            continue;
+        }
+        // Remove leading dashes
+        boost::trim_left_if(token, boost::is_any_of("-"));
+        // Remove the "no-" prefix used to negate boolean options.
+        bool no = false;
+        if (boost::starts_with(token, "no-")) {
+            no = true;
+            boost::replace_first(token, "no-", "");
+        }
+        // Read value when supplied in the --key=value form.
+        std::string value;
+        {
+            size_t equals_pos = token.find("=");
+            if (equals_pos != std::string::npos) {
+                value = token.substr(equals_pos+1);
+                token.erase(equals_pos);
+            }
+        }
+        // Look for the cli -> option mapping.
+        const auto it = opts.find(token);
+        if (it == opts.end()) {
+            printf("Warning: unknown option --%s\n", token.c_str());
+            // instead of continuing, return false to caller
+            // to stop execution and print usage
+            return false;
+            //continue;
+        }
+        const t_config_option_key opt_key = it->second;
+        const ConfigOptionDef &optdef = this->def()->options.at(opt_key);
+        // If the option type expects a value and it was not already provided,
+        // look for it in the next token.
+        if (optdef.type != coBool && optdef.type != coBools && value.empty()) {
+            if (i == (argc-1)) {
+                printf("No value supplied for --%s\n", token.c_str());
+                continue;
+            }
+            value = argv[++ i];
+        }
+        // Store the option value.
+        const bool existing = this->has(opt_key);
+        if (ConfigOptionBool* opt = this->opt<ConfigOptionBool>(opt_key, true)) {
+            opt->value = !no;
+        } else if (ConfigOptionBools* opt = this->opt<ConfigOptionBools>(opt_key, true)) {
+            if (!existing) opt->values.clear(); // remove the default values
+            opt->values.push_back(!no);
+        } else if (ConfigOptionStrings* opt = this->opt<ConfigOptionStrings>(opt_key, true)) {
+            if (!existing) opt->values.clear(); // remove the default values
+            opt->deserialize(value, true);
+        } else if (ConfigOptionFloats* opt = this->opt<ConfigOptionFloats>(opt_key, true)) {
+            if (!existing) opt->values.clear(); // remove the default values
+            opt->deserialize(value, true);
+        } else if (ConfigOptionPoints* opt = this->opt<ConfigOptionPoints>(opt_key, true)) {
+            if (!existing) opt->values.clear(); // remove the default values
+            opt->deserialize(value, true);
+        } else {
+            this->set_deserialize(opt_key, value, true);
+        }
+    }
+    return true;
+}
+
+t_config_option_keys DynamicConfig::keys() const
+{
+    t_config_option_keys keys;
+    keys.reserve(this->options.size());
+    for (const auto &opt : this->options)
+        keys.emplace_back(opt.first);
+    return keys;
+}
+
+void StaticConfig::set_defaults()
+{
+    // use defaults from definition
+    auto *defs = this->def();
+    if (defs != nullptr) {
+        for (const std::string &key : this->keys()) {
+            const ConfigOptionDef   *def = defs->get(key);
+            ConfigOption            *opt = this->option(key);
+            if (def != nullptr && opt != nullptr && def->default_value != nullptr)
+                opt->set(def->default_value);
+        }
+    }
+}
+
+t_config_option_keys StaticConfig::keys() const 
+{
+    t_config_option_keys keys;
+    assert(this->def() != nullptr);
+    for (const auto &opt_def : this->def()->options)
+        if (this->option(opt_def.first) != nullptr) 
+            keys.push_back(opt_def.first);
+    return keys;
+}
+
+}

src/libslic3r/EdgeGrid.hpp

@@ -0,0 +1,130 @@
+#ifndef slic3r_EdgeGrid_hpp_
+#define slic3r_EdgeGrid_hpp_
+
+#include <stdint.h>
+#include <math.h>
+
+#include "Point.hpp"
+#include "BoundingBox.hpp"
+#include "ExPolygon.hpp"
+#include "ExPolygonCollection.hpp"
+
+namespace Slic3r {
+namespace EdgeGrid {
+
+class Grid
+{
+public:
+	Grid();
+	~Grid();
+
+	void set_bbox(const BoundingBox &bbox) { m_bbox = bbox; }
+
+	void create(const Polygons &polygons, coord_t resolution);
+	void create(const ExPolygon &expoly, coord_t resolution);
+	void create(const ExPolygons &expolygons, coord_t resolution);
+	void create(const ExPolygonCollection &expolygons, coord_t resolution);
+
+#if 0
+	// Test, whether the edges inside the grid intersect with the polygons provided.
+	bool intersect(const MultiPoint &polyline, bool closed);
+	bool intersect(const Polygon &polygon) { return intersect(static_cast<const MultiPoint&>(polygon), true); }
+	bool intersect(const Polygons &polygons) { for (size_t i = 0; i < polygons.size(); ++ i) if (intersect(polygons[i])) return true; return false; }
+	bool intersect(const ExPolygon &expoly) { if (intersect(expoly.contour)) return true; for (size_t i = 0; i < expoly.holes.size(); ++ i) if (intersect(expoly.holes[i])) return true; return false; }
+	bool intersect(const ExPolygons &expolygons) { for (size_t i = 0; i < expolygons.size(); ++ i) if (intersect(expolygons[i])) return true; return false; }
+	bool intersect(const ExPolygonCollection &expolygons) { return intersect(expolygons.expolygons); }
+
+	// Test, whether a point is inside a contour.
+	bool inside(const Point &pt);
+#endif
+
+	// Fill in a rough m_signed_distance_field from the edge grid.
+	// The rough SDF is used by signed_distance() for distances outside of the search_radius.
+	void calculate_sdf();
+
+	// Return an estimate of the signed distance based on m_signed_distance_field grid.
+	float signed_distance_bilinear(const Point &pt) const;
+
+	// Calculate a signed distance to the contours in search_radius from the point.
+	bool signed_distance_edges(const Point &pt, coord_t search_radius, coordf_t &result_min_dist, bool *pon_segment = NULL) const;
+
+	// Calculate a signed distance to the contours in search_radius from the point. If no edge is found in search_radius,
+	// return an interpolated value from m_signed_distance_field, if it exists.
+	bool signed_distance(const Point &pt, coord_t search_radius, coordf_t &result_min_dist) const;
+
+	const BoundingBox& 	bbox() const { return m_bbox; }
+	const coord_t 		resolution() const { return m_resolution; }
+	const size_t		rows() const { return m_rows; }
+	const size_t		cols() const { return m_cols; }
+
+	// For supports: Contours enclosing the rasterized edges.
+	Polygons 			contours_simplified(coord_t offset, bool fill_holes) const;
+
+	typedef std::pair<const Slic3r::Points*, size_t> ContourPoint;
+	typedef std::pair<const Slic3r::Points*, size_t> ContourEdge;
+	std::vector<std::pair<ContourEdge, ContourEdge>> intersecting_edges() const;
+	bool 											 has_intersecting_edges() const;
+
+protected:
+	struct Cell {
+		Cell() : begin(0), end(0) {}
+		size_t begin;
+		size_t end;
+	};
+
+	void create_from_m_contours(coord_t resolution);
+#if 0
+	bool line_cell_intersect(const Point &p1, const Point &p2, const Cell &cell);
+#endif
+	bool cell_inside_or_crossing(int r, int c) const
+	{
+		if (r < 0 || r >= m_rows ||
+			c < 0 || c >= m_cols)
+			// The cell is outside the domain. Hoping that the contours were correctly oriented, so
+			// there is a CCW outmost contour so the out of domain cells are outside.
+			return false;
+		const Cell &cell = m_cells[r * m_cols + c];
+		return 
+			(cell.begin < cell.end) || 
+			(! m_signed_distance_field.empty() && m_signed_distance_field[r * (m_cols + 1) + c] <= 0.f);
+	}
+
+	// Bounding box around the contours.
+	BoundingBox 								m_bbox;
+	// Grid dimensions.
+	coord_t										m_resolution;
+	size_t										m_rows;
+	size_t										m_cols;
+
+	// Referencing the source contours.
+	// This format allows one to work with any Slic3r fixed point contour format
+	// (Polygon, ExPolygon, ExPolygonCollection etc).
+	std::vector<const Slic3r::Points*>			m_contours;
+
+	// Referencing a contour and a line segment of m_contours.
+	std::vector<std::pair<size_t, size_t> >		m_cell_data;
+
+	// Full grid of cells.
+	std::vector<Cell> 							m_cells;
+
+	// Distance field derived from the edge grid, seed filled by the Danielsson chamfer metric.
+	// May be empty.
+	std::vector<float>							m_signed_distance_field;
+};
+
+#if 0
+// Debugging utility. Save the signed distance field.
+extern void save_png(const Grid &grid, const BoundingBox &bbox, coord_t resolution, const char *path);
+#endif /* SLIC3R_GUI */
+
+} // namespace EdgeGrid
+
+// Find all pairs of intersectiong edges from the set of polygons.
+extern std::vector<std::pair<EdgeGrid::Grid::ContourEdge, EdgeGrid::Grid::ContourEdge>> intersecting_edges(const Polygons &polygons);
+
+// Find all pairs of intersectiong edges from the set of polygons, highlight them in an SVG.
+extern void export_intersections_to_svg(const std::string &filename, const Polygons &polygons);
+
+} // namespace Slic3r
+
+#endif /* slic3r_EdgeGrid_hpp_ */

src/libslic3r/ExPolygon.cpp

@@ -0,0 +1,555 @@
+#include "BoundingBox.hpp"
+#include "ExPolygon.hpp"
+#include "Geometry.hpp"
+#include "Polygon.hpp"
+#include "Line.hpp"
+#include "ClipperUtils.hpp"
+#include "SVG.hpp"
+#include "polypartition.h"
+#include "poly2tri/poly2tri.h"
+#include <algorithm>
+#include <cassert>
+#include <list>
+
+namespace Slic3r {
+
+ExPolygon::operator Points() const
+{
+    Points points;
+    Polygons pp = *this;
+    for (Polygons::const_iterator poly = pp.begin(); poly != pp.end(); ++poly) {
+        for (Points::const_iterator point = poly->points.begin(); point != poly->points.end(); ++point)
+            points.push_back(*point);
+    }
+    return points;
+}
+
+ExPolygon::operator Polygons() const
+{
+    return to_polygons(*this);
+}
+
+ExPolygon::operator Polylines() const
+{
+    return to_polylines(*this);
+}
+
+void ExPolygon::scale(double factor)
+{
+    contour.scale(factor);
+    for (Polygon &hole : holes)
+        hole.scale(factor);
+}
+
+void ExPolygon::translate(double x, double y)
+{
+    contour.translate(x, y);
+    for (Polygon &hole : holes)
+        hole.translate(x, y);
+}
+
+void ExPolygon::rotate(double angle)
+{
+    contour.rotate(angle);
+    for (Polygon &hole : holes)
+        hole.rotate(angle);
+}
+
+void ExPolygon::rotate(double angle, const Point &center)
+{
+    contour.rotate(angle, center);
+    for (Polygon &hole : holes)
+        hole.rotate(angle, center);
+}
+
+double ExPolygon::area() const
+{
+    double a = this->contour.area();
+    for (const Polygon &hole : holes)
+        a -= - hole.area();  // holes have negative area
+    return a;
+}
+
+bool ExPolygon::is_valid() const
+{
+    if (!this->contour.is_valid() || !this->contour.is_counter_clockwise()) return false;
+    for (Polygons::const_iterator it = this->holes.begin(); it != this->holes.end(); ++it) {
+        if (!(*it).is_valid() || (*it).is_counter_clockwise()) return false;
+    }
+    return true;
+}
+
+bool ExPolygon::contains(const Line &line) const
+{
+    return this->contains(Polyline(line.a, line.b));
+}
+
+bool ExPolygon::contains(const Polyline &polyline) const
+{
+    return diff_pl((Polylines)polyline, *this).empty();
+}
+
+bool ExPolygon::contains(const Polylines &polylines) const
+{
+    #if 0
+    BoundingBox bbox = get_extents(polylines);
+    bbox.merge(get_extents(*this));
+    SVG svg(debug_out_path("ExPolygon_contains.svg"), bbox);
+    svg.draw(*this);
+    svg.draw_outline(*this);
+    svg.draw(polylines, "blue");
+    #endif
+    Polylines pl_out = diff_pl(polylines, *this);
+    #if 0
+    svg.draw(pl_out, "red");
+    #endif
+    return pl_out.empty();
+}
+
+bool ExPolygon::contains(const Point &point) const
+{
+    if (!this->contour.contains(point)) return false;
+    for (Polygons::const_iterator it = this->holes.begin(); it != this->holes.end(); ++it) {
+        if (it->contains(point)) return false;
+    }
+    return true;
+}
+
+// inclusive version of contains() that also checks whether point is on boundaries
+bool ExPolygon::contains_b(const Point &point) const
+{
+    return this->contains(point) || this->has_boundary_point(point);
+}
+
+bool
+ExPolygon::has_boundary_point(const Point &point) const
+{
+    if (this->contour.has_boundary_point(point)) return true;
+    for (Polygons::const_iterator h = this->holes.begin(); h != this->holes.end(); ++h) {
+        if (h->has_boundary_point(point)) return true;
+    }
+    return false;
+}
+
+bool
+ExPolygon::overlaps(const ExPolygon &other) const
+{
+    #if 0
+    BoundingBox bbox = get_extents(other);
+    bbox.merge(get_extents(*this));
+    static int iRun = 0;
+    SVG svg(debug_out_path("ExPolygon_overlaps-%d.svg", iRun ++), bbox);
+    svg.draw(*this);
+    svg.draw_outline(*this);
+    svg.draw_outline(other, "blue");
+    #endif
+    Polylines pl_out = intersection_pl((Polylines)other, *this);
+    #if 0
+    svg.draw(pl_out, "red");
+    #endif
+    if (! pl_out.empty())
+        return true; 
+    return ! other.contour.points.empty() && this->contains_b(other.contour.points.front());
+}
+
+void ExPolygon::simplify_p(double tolerance, Polygons* polygons) const
+{
+    Polygons pp = this->simplify_p(tolerance);
+    polygons->insert(polygons->end(), pp.begin(), pp.end());
+}
+
+Polygons ExPolygon::simplify_p(double tolerance) const
+{
+    Polygons pp;
+    pp.reserve(this->holes.size() + 1);
+    // contour
+    {
+        Polygon p = this->contour;
+        p.points.push_back(p.points.front());
+        p.points = MultiPoint::_douglas_peucker(p.points, tolerance);
+        p.points.pop_back();
+        pp.emplace_back(std::move(p));
+    }
+    // holes
+    for (Polygon p : this->holes) {
+        p.points.push_back(p.points.front());
+        p.points = MultiPoint::_douglas_peucker(p.points, tolerance);
+        p.points.pop_back();
+        pp.emplace_back(std::move(p));
+    }
+    return simplify_polygons(pp);
+}
+
+ExPolygons ExPolygon::simplify(double tolerance) const
+{
+    return union_ex(this->simplify_p(tolerance));
+}
+
+void ExPolygon::simplify(double tolerance, ExPolygons* expolygons) const
+{
+    append(*expolygons, this->simplify(tolerance));
+}
+
+void
+ExPolygon::medial_axis(double max_width, double min_width, ThickPolylines* polylines) const
+{
+    // init helper object
+    Slic3r::Geometry::MedialAxis ma(max_width, min_width, this);
+    ma.lines = this->lines();
+    
+    // compute the Voronoi diagram and extract medial axis polylines
+    ThickPolylines pp;
+    ma.build(&pp);
+    
+    /*
+    SVG svg("medial_axis.svg");
+    svg.draw(*this);
+    svg.draw(pp);
+    svg.Close();
+    */
+    
+    /* Find the maximum width returned; we're going to use this for validating and 
+       filtering the output segments. */
+    double max_w = 0;
+    for (ThickPolylines::const_iterator it = pp.begin(); it != pp.end(); ++it)
+        max_w = fmaxf(max_w, *std::max_element(it->width.begin(), it->width.end()));
+    
+    /* Loop through all returned polylines in order to extend their endpoints to the 
+       expolygon boundaries */
+    bool removed = false;
+    for (size_t i = 0; i < pp.size(); ++i) {
+        ThickPolyline& polyline = pp[i];
+        
+        // extend initial and final segments of each polyline if they're actual endpoints
+        /* We assign new endpoints to temporary variables because in case of a single-line
+           polyline, after we extend the start point it will be caught by the intersection()
+           call, so we keep the inner point until we perform the second intersection() as well */
+        Point new_front = polyline.points.front();
+        Point new_back  = polyline.points.back();
+        if (polyline.endpoints.first && !this->has_boundary_point(new_front)) {
+            Vec2d p1 = polyline.points.front().cast<double>();
+            Vec2d p2 = polyline.points[1].cast<double>();
+            // prevent the line from touching on the other side, otherwise intersection() might return that solution
+            if (polyline.points.size() == 2)
+                p2 = (p1 + p2) * 0.5;
+            // Extend the start of the segment.
+            p1 -= (p2 - p1).normalized() * max_width;
+            this->contour.intersection(Line(p1.cast<coord_t>(), p2.cast<coord_t>()), &new_front);
+        }
+        if (polyline.endpoints.second && !this->has_boundary_point(new_back)) {
+            Vec2d p1 = (polyline.points.end() - 2)->cast<double>();
+            Vec2d p2 = polyline.points.back().cast<double>();
+            // prevent the line from touching on the other side, otherwise intersection() might return that solution
+            if (polyline.points.size() == 2)
+                p1 = (p1 + p2) * 0.5;
+            // Extend the start of the segment.
+            p2 += (p2 - p1).normalized() * max_width;
+            this->contour.intersection(Line(p1.cast<coord_t>(), p2.cast<coord_t>()), &new_back);
+        }
+        polyline.points.front() = new_front;
+        polyline.points.back()  = new_back;
+        
+        /*  remove too short polylines
+            (we can't do this check before endpoints extension and clipping because we don't
+            know how long will the endpoints be extended since it depends on polygon thickness
+            which is variable - extension will be <= max_width/2 on each side)  */
+        if ((polyline.endpoints.first || polyline.endpoints.second)
+            && polyline.length() < max_w*2) {
+            pp.erase(pp.begin() + i);
+            --i;
+            removed = true;
+            continue;
+        }
+    }
+    
+    /*  If we removed any short polylines we now try to connect consecutive polylines
+        in order to allow loop detection. Note that this algorithm is greedier than 
+        MedialAxis::process_edge_neighbors() as it will connect random pairs of 
+        polylines even when more than two start from the same point. This has no 
+        drawbacks since we optimize later using nearest-neighbor which would do the 
+        same, but should we use a more sophisticated optimization algorithm we should
+        not connect polylines when more than two meet.  */
+    if (removed) {
+        for (size_t i = 0; i < pp.size(); ++i) {
+            ThickPolyline& polyline = pp[i];
+            if (polyline.endpoints.first && polyline.endpoints.second) continue; // optimization
+            
+            // find another polyline starting here
+            for (size_t j = i+1; j < pp.size(); ++j) {
+                ThickPolyline& other = pp[j];
+                if (polyline.last_point() == other.last_point()) {
+                    other.reverse();
+                } else if (polyline.first_point() == other.last_point()) {
+                    polyline.reverse();
+                    other.reverse();
+                } else if (polyline.first_point() == other.first_point()) {
+                    polyline.reverse();
+                } else if (polyline.last_point() != other.first_point()) {
+                    continue;
+                }
+                
+                polyline.points.insert(polyline.points.end(), other.points.begin() + 1, other.points.end());
+                polyline.width.insert(polyline.width.end(), other.width.begin(), other.width.end());
+                polyline.endpoints.second = other.endpoints.second;
+                assert(polyline.width.size() == polyline.points.size()*2 - 2);
+                
+                pp.erase(pp.begin() + j);
+                j = i;  // restart search from i+1
+            }
+        }
+    }
+    
+    polylines->insert(polylines->end(), pp.begin(), pp.end());
+}
+
+void
+ExPolygon::medial_axis(double max_width, double min_width, Polylines* polylines) const
+{
+    ThickPolylines tp;
+    this->medial_axis(max_width, min_width, &tp);
+    polylines->insert(polylines->end(), tp.begin(), tp.end());
+}
+
+void
+ExPolygon::get_trapezoids(Polygons* polygons) const
+{
+    ExPolygons expp;
+    expp.push_back(*this);
+    boost::polygon::get_trapezoids(*polygons, expp);
+}
+
+void
+ExPolygon::get_trapezoids(Polygons* polygons, double angle) const
+{
+    ExPolygon clone = *this;
+    clone.rotate(PI/2 - angle, Point(0,0));
+    clone.get_trapezoids(polygons);
+    for (Polygons::iterator polygon = polygons->begin(); polygon != polygons->end(); ++polygon)
+        polygon->rotate(-(PI/2 - angle), Point(0,0));
+}
+
+// This algorithm may return more trapezoids than necessary
+// (i.e. it may break a single trapezoid in several because
+// other parts of the object have x coordinates in the middle)
+void
+ExPolygon::get_trapezoids2(Polygons* polygons) const
+{
+    // get all points of this ExPolygon
+    Points pp = *this;
+    
+    // build our bounding box
+    BoundingBox bb(pp);
+    
+    // get all x coordinates
+    std::vector<coord_t> xx;
+    xx.reserve(pp.size());
+    for (Points::const_iterator p = pp.begin(); p != pp.end(); ++p)
+        xx.push_back(p->x());
+    std::sort(xx.begin(), xx.end());
+    
+    // find trapezoids by looping from first to next-to-last coordinate
+    for (std::vector<coord_t>::const_iterator x = xx.begin(); x != xx.end()-1; ++x) {
+        coord_t next_x = *(x + 1);
+        if (*x == next_x) continue;
+        
+        // build rectangle
+        Polygon poly;
+        poly.points.resize(4);
+        poly[0](0) = *x;
+        poly[0](1) = bb.min(1);
+        poly[1](0) = next_x;
+        poly[1](1) = bb.min(1);
+        poly[2](0) = next_x;
+        poly[2](1) = bb.max(1);
+        poly[3](0) = *x;
+        poly[3](1) = bb.max(1);
+        
+        // intersect with this expolygon
+        // append results to return value
+        polygons_append(*polygons, intersection(poly, to_polygons(*this)));
+    }
+}
+
+void
+ExPolygon::get_trapezoids2(Polygons* polygons, double angle) const
+{
+    ExPolygon clone = *this;
+    clone.rotate(PI/2 - angle, Point(0,0));
+    clone.get_trapezoids2(polygons);
+    for (Polygons::iterator polygon = polygons->begin(); polygon != polygons->end(); ++polygon)
+        polygon->rotate(-(PI/2 - angle), Point(0,0));
+}
+
+// While this triangulates successfully, it's NOT a constrained triangulation
+// as it will create more vertices on the boundaries than the ones supplied.
+void
+ExPolygon::triangulate(Polygons* polygons) const
+{
+    // first make trapezoids
+    Polygons trapezoids;
+    this->get_trapezoids2(&trapezoids);
+    
+    // then triangulate each trapezoid
+    for (Polygons::iterator polygon = trapezoids.begin(); polygon != trapezoids.end(); ++polygon)
+        polygon->triangulate_convex(polygons);
+}
+
+void
+ExPolygon::triangulate_pp(Polygons* polygons) const
+{
+    // convert polygons
+    std::list<TPPLPoly> input;
+    
+    ExPolygons expp = union_ex(simplify_polygons(to_polygons(*this), true));
+    
+    for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex) {
+        // contour
+        {
+            TPPLPoly p;
+            p.Init(int(ex->contour.points.size()));
+            //printf(PRINTF_ZU "\n0\n", ex->contour.points.size());
+            for (const Point &point : ex->contour.points) {
+                size_t i = &point - &ex->contour.points.front();
+                p[i].x = point(0);
+                p[i].y = point(1);
+                //printf("%ld %ld\n", point->x(), point->y());
+            }
+            p.SetHole(false);
+            input.push_back(p);
+        }
+    
+        // holes
+        for (Polygons::const_iterator hole = ex->holes.begin(); hole != ex->holes.end(); ++hole) {
+            TPPLPoly p;
+            p.Init(hole->points.size());
+            //printf(PRINTF_ZU "\n1\n", hole->points.size());
+            for (const Point &point : hole->points) {
+                size_t i = &point - &hole->points.front();
+                p[i].x = point(0);
+                p[i].y = point(1);
+                //printf("%ld %ld\n", point->x(), point->y());
+            }
+            p.SetHole(true);
+            input.push_back(p);
+        }
+    }
+    
+    // perform triangulation
+    std::list<TPPLPoly> output;
+    int res = TPPLPartition().Triangulate_MONO(&input, &output);
+    if (res != 1)
+        throw std::runtime_error("Triangulation failed");
+    
+    // convert output polygons
+    for (std::list<TPPLPoly>::iterator poly = output.begin(); poly != output.end(); ++poly) {
+        long num_points = poly->GetNumPoints();
+        Polygon p;
+        p.points.resize(num_points);
+        for (long i = 0; i < num_points; ++i) {
+            p.points[i](0) = coord_t((*poly)[i].x);
+            p.points[i](1) = coord_t((*poly)[i].y);
+        }
+        polygons->push_back(p);
+    }
+}
+
+void
+ExPolygon::triangulate_p2t(Polygons* polygons) const
+{
+    ExPolygons expp = simplify_polygons_ex(*this, true);
+    
+    for (ExPolygons::const_iterator ex = expp.begin(); ex != expp.end(); ++ex) {
+        // TODO: prevent duplicate points
+
+        // contour
+        std::vector<p2t::Point*> ContourPoints;
+        for (const Point &pt : ex->contour.points)
+            // We should delete each p2t::Point object
+            ContourPoints.push_back(new p2t::Point(pt(0), pt(1)));
+        p2t::CDT cdt(ContourPoints);
+
+        // holes
+        for (Polygons::const_iterator hole = ex->holes.begin(); hole != ex->holes.end(); ++hole) {
+            std::vector<p2t::Point*> points;
+            for (const Point &pt : hole->points)
+                // will be destructed in SweepContext::~SweepContext
+                points.push_back(new p2t::Point(pt(0), pt(1)));
+            cdt.AddHole(points);
+        }
+        
+        // perform triangulation
+        cdt.Triangulate();
+        std::vector<p2t::Triangle*> triangles = cdt.GetTriangles();
+        
+        for (std::vector<p2t::Triangle*>::const_iterator triangle = triangles.begin(); triangle != triangles.end(); ++triangle) {
+            Polygon p;
+            for (int i = 0; i <= 2; ++i) {
+                p2t::Point* point = (*triangle)->GetPoint(i);
+                p.points.push_back(Point(point->x, point->y));
+            }
+            polygons->push_back(p);
+        }
+
+        for (p2t::Point *ptr : ContourPoints)
+            delete ptr;
+    }
+}
+
+Lines
+ExPolygon::lines() const
+{
+    Lines lines = this->contour.lines();
+    for (Polygons::const_iterator h = this->holes.begin(); h != this->holes.end(); ++h) {
+        Lines hole_lines = h->lines();
+        lines.insert(lines.end(), hole_lines.begin(), hole_lines.end());
+    }
+    return lines;
+}
+
+BoundingBox get_extents(const ExPolygon &expolygon)
+{
+    return get_extents(expolygon.contour);
+}
+
+BoundingBox get_extents(const ExPolygons &expolygons)
+{
+    BoundingBox bbox;
+    if (! expolygons.empty()) {
+        for (size_t i = 0; i < expolygons.size(); ++ i)
+			if (! expolygons[i].contour.points.empty())
+				bbox.merge(get_extents(expolygons[i]));
+    }
+    return bbox;
+}
+
+BoundingBox get_extents_rotated(const ExPolygon &expolygon, double angle)
+{
+    return get_extents_rotated(expolygon.contour, angle);
+}
+
+BoundingBox get_extents_rotated(const ExPolygons &expolygons, double angle)
+{
+    BoundingBox bbox;
+    if (! expolygons.empty()) {
+        bbox = get_extents_rotated(expolygons.front().contour, angle);
+        for (size_t i = 1; i < expolygons.size(); ++ i)
+            bbox.merge(get_extents_rotated(expolygons[i].contour, angle));
+    }
+    return bbox;
+}
+
+extern std::vector<BoundingBox> get_extents_vector(const ExPolygons &polygons)
+{
+    std::vector<BoundingBox> out;
+    out.reserve(polygons.size());
+    for (ExPolygons::const_iterator it = polygons.begin(); it != polygons.end(); ++ it)
+        out.push_back(get_extents(*it));
+    return out;
+}
+
+bool remove_sticks(ExPolygon &poly)
+{
+    return remove_sticks(poly.contour) || remove_sticks(poly.holes);
+}
+
+} // namespace Slic3r

src/libslic3r/ExPolygon.hpp

@@ -0,0 +1,406 @@
+#ifndef slic3r_ExPolygon_hpp_
+#define slic3r_ExPolygon_hpp_
+
+#include "libslic3r.h"
+#include "Polygon.hpp"
+#include "Polyline.hpp"
+#include <vector>
+
+namespace Slic3r {
+
+class ExPolygon;
+typedef std::vector<ExPolygon> ExPolygons;
+
+class ExPolygon
+{
+public:
+    ExPolygon() {}
+    ExPolygon(const ExPolygon &other) : contour(other.contour), holes(other.holes) {}
+    ExPolygon(ExPolygon &&other) : contour(std::move(other.contour)), holes(std::move(other.holes)) {}
+
+    ExPolygon& operator=(const ExPolygon &other) { contour = other.contour; holes = other.holes; return *this; }
+    ExPolygon& operator=(ExPolygon &&other) { contour = std::move(other.contour); holes = std::move(other.holes); return *this; }
+
+    Polygon contour;
+    Polygons holes;
+
+    operator Points() const;
+    operator Polygons() const;
+    operator Polylines() const;
+    void clear() { contour.points.clear(); holes.clear(); }
+    void scale(double factor);
+    void translate(double x, double y);
+    void rotate(double angle);
+    void rotate(double angle, const Point &center);
+    double area() const;
+    bool empty() const { return contour.points.empty(); }
+    bool is_valid() const;
+
+    // Contains the line / polyline / polylines etc COMPLETELY.
+    bool contains(const Line &line) const;
+    bool contains(const Polyline &polyline) const;
+    bool contains(const Polylines &polylines) const;
+    bool contains(const Point &point) const;
+    bool contains_b(const Point &point) const;
+    bool has_boundary_point(const Point &point) const;
+
+    // Does this expolygon overlap another expolygon?
+    // Either the ExPolygons intersect, or one is fully inside the other,
+    // and it is not inside a hole of the other expolygon.
+    bool overlaps(const ExPolygon &other) const;
+
+    void simplify_p(double tolerance, Polygons* polygons) const;
+    Polygons simplify_p(double tolerance) const;
+    ExPolygons simplify(double tolerance) const;
+    void simplify(double tolerance, ExPolygons* expolygons) const;
+    void medial_axis(double max_width, double min_width, ThickPolylines* polylines) const;
+    void medial_axis(double max_width, double min_width, Polylines* polylines) const;
+    void get_trapezoids(Polygons* polygons) const;
+    void get_trapezoids(Polygons* polygons, double angle) const;
+    void get_trapezoids2(Polygons* polygons) const;
+    void get_trapezoids2(Polygons* polygons, double angle) const;
+    void triangulate(Polygons* polygons) const;
+    void triangulate_pp(Polygons* polygons) const;
+    void triangulate_p2t(Polygons* polygons) const;
+    Lines lines() const;
+};
+
+// Count a nuber of polygons stored inside the vector of expolygons.
+// Useful for allocating space for polygons when converting expolygons to polygons.
+inline size_t number_polygons(const ExPolygons &expolys)
+{
+    size_t n_polygons = 0;
+    for (ExPolygons::const_iterator it = expolys.begin(); it != expolys.end(); ++ it)
+        n_polygons += it->holes.size() + 1;
+    return n_polygons;
+}
+
+inline Lines to_lines(const ExPolygon &src) 
+{
+    size_t n_lines = src.contour.points.size();
+    for (size_t i = 0; i < src.holes.size(); ++ i)
+        n_lines += src.holes[i].points.size();
+    Lines lines;
+    lines.reserve(n_lines);
+    for (size_t i = 0; i <= src.holes.size(); ++ i) {
+        const Polygon &poly = (i == 0) ? src.contour : src.holes[i - 1];
+        for (Points::const_iterator it = poly.points.begin(); it != poly.points.end()-1; ++it)
+            lines.push_back(Line(*it, *(it + 1)));
+        lines.push_back(Line(poly.points.back(), poly.points.front()));
+    }
+    return lines;
+}
+
+inline Lines to_lines(const ExPolygons &src) 
+{
+    size_t n_lines = 0;
+    for (ExPolygons::const_iterator it_expoly = src.begin(); it_expoly != src.end(); ++ it_expoly) {
+        n_lines += it_expoly->contour.points.size();
+        for (size_t i = 0; i < it_expoly->holes.size(); ++ i)
+            n_lines += it_expoly->holes[i].points.size();
+    }
+    Lines lines;
+    lines.reserve(n_lines);
+    for (ExPolygons::const_iterator it_expoly = src.begin(); it_expoly != src.end(); ++ it_expoly) {
+        for (size_t i = 0; i <= it_expoly->holes.size(); ++ i) {
+            const Points &points = ((i == 0) ? it_expoly->contour : it_expoly->holes[i - 1]).points;
+            for (Points::const_iterator it = points.begin(); it != points.end()-1; ++it)
+                lines.push_back(Line(*it, *(it + 1)));
+            lines.push_back(Line(points.back(), points.front()));
+        }
+    }
+    return lines;
+}
+
+inline Polylines to_polylines(const ExPolygon &src)
+{
+    Polylines polylines;
+    polylines.assign(src.holes.size() + 1, Polyline());
+    size_t idx = 0;
+    Polyline &pl = polylines[idx ++];
+    pl.points = src.contour.points;
+    pl.points.push_back(pl.points.front());
+    for (Polygons::const_iterator ith = src.holes.begin(); ith != src.holes.end(); ++ith) {
+        Polyline &pl = polylines[idx ++];
+        pl.points = ith->points;
+        pl.points.push_back(ith->points.front());
+    }
+    assert(idx == polylines.size());
+    return polylines;
+}
+
+inline Polylines to_polylines(const ExPolygons &src)
+{
+    Polylines polylines;
+    polylines.assign(number_polygons(src), Polyline());
+    size_t idx = 0;
+    for (ExPolygons::const_iterator it = src.begin(); it != src.end(); ++it) {
+        Polyline &pl = polylines[idx ++];
+        pl.points = it->contour.points;
+        pl.points.push_back(pl.points.front());
+        for (Polygons::const_iterator ith = it->holes.begin(); ith != it->holes.end(); ++ith) {
+            Polyline &pl = polylines[idx ++];
+            pl.points = ith->points;
+            pl.points.push_back(ith->points.front());
+        }
+    }
+    assert(idx == polylines.size());
+    return polylines;
+}
+
+inline Polylines to_polylines(ExPolygon &&src)
+{
+    Polylines polylines;
+    polylines.assign(src.holes.size() + 1, Polyline());
+    size_t idx = 0;
+    Polyline &pl = polylines[idx ++];
+    pl.points = std::move(src.contour.points);
+    pl.points.push_back(pl.points.front());
+    for (Polygons::const_iterator ith = src.holes.begin(); ith != src.holes.end(); ++ith) {
+        Polyline &pl = polylines[idx ++];
+        pl.points = std::move(ith->points);
+        pl.points.push_back(ith->points.front());
+    }
+    assert(idx == polylines.size());
+    return polylines;
+}
+
+inline Polylines to_polylines(ExPolygons &&src)
+{
+    Polylines polylines;
+    polylines.assign(number_polygons(src), Polyline());
+    size_t idx = 0;
+    for (ExPolygons::const_iterator it = src.begin(); it != src.end(); ++it) {
+        Polyline &pl = polylines[idx ++];
+        pl.points = std::move(it->contour.points);
+        pl.points.push_back(pl.points.front());
+        for (Polygons::const_iterator ith = it->holes.begin(); ith != it->holes.end(); ++ith) {
+            Polyline &pl = polylines[idx ++];
+            pl.points = std::move(ith->points);
+            pl.points.push_back(ith->points.front());
+        }
+    }
+    assert(idx == polylines.size());
+    return polylines;
+}
+
+inline Polygons to_polygons(const ExPolygon &src)
+{
+    Polygons polygons;
+    polygons.reserve(src.holes.size() + 1);
+    polygons.push_back(src.contour);
+    polygons.insert(polygons.end(), src.holes.begin(), src.holes.end());
+    return polygons;
+}
+
+inline Polygons to_polygons(const ExPolygons &src)
+{
+    Polygons polygons;
+    polygons.reserve(number_polygons(src));
+    for (ExPolygons::const_iterator it = src.begin(); it != src.end(); ++it) {
+        polygons.push_back(it->contour);
+        polygons.insert(polygons.end(), it->holes.begin(), it->holes.end());
+    }
+    return polygons;
+}
+
+inline Polygons to_polygons(ExPolygon &&src)
+{
+    Polygons polygons;
+    polygons.reserve(src.holes.size() + 1);
+    polygons.push_back(std::move(src.contour));
+    std::move(std::begin(src.holes), std::end(src.holes), std::back_inserter(polygons));
+    src.holes.clear();
+    return polygons;
+}
+
+inline Polygons to_polygons(ExPolygons &&src)
+{
+    Polygons polygons;
+    polygons.reserve(number_polygons(src));
+    for (ExPolygons::iterator it = src.begin(); it != src.end(); ++it) {
+        polygons.push_back(std::move(it->contour));
+        std::move(std::begin(it->holes), std::end(it->holes), std::back_inserter(polygons));
+        it->holes.clear();
+    }
+    return polygons;
+}
+
+inline void polygons_append(Polygons &dst, const ExPolygon &src) 
+{ 
+    dst.reserve(dst.size() + src.holes.size() + 1);
+    dst.push_back(src.contour);
+    dst.insert(dst.end(), src.holes.begin(), src.holes.end());
+}
+
+inline void polygons_append(Polygons &dst, const ExPolygons &src) 
+{ 
+    dst.reserve(dst.size() + number_polygons(src));
+    for (ExPolygons::const_iterator it = src.begin(); it != src.end(); ++ it) {
+        dst.push_back(it->contour);
+        dst.insert(dst.end(), it->holes.begin(), it->holes.end());
+    }
+}
+
+inline void polygons_append(Polygons &dst, ExPolygon &&src)
+{ 
+    dst.reserve(dst.size() + src.holes.size() + 1);
+    dst.push_back(std::move(src.contour));
+    std::move(std::begin(src.holes), std::end(src.holes), std::back_inserter(dst));
+    src.holes.clear();
+}
+
+inline void polygons_append(Polygons &dst, ExPolygons &&src)
+{ 
+    dst.reserve(dst.size() + number_polygons(src));
+    for (ExPolygons::iterator it = src.begin(); it != src.end(); ++ it) {
+        dst.push_back(std::move(it->contour));
+        std::move(std::begin(it->holes), std::end(it->holes), std::back_inserter(dst));
+        it->holes.clear();
+    }
+}
+
+inline void expolygons_append(ExPolygons &dst, const ExPolygons &src) 
+{ 
+    dst.insert(dst.end(), src.begin(), src.end());
+}
+
+inline void expolygons_append(ExPolygons &dst, ExPolygons &&src)
+{ 
+    if (dst.empty()) {
+        dst = std::move(src);
+    } else {
+        std::move(std::begin(src), std::end(src), std::back_inserter(dst));
+        src.clear();
+    }
+}
+
+inline void expolygons_rotate(ExPolygons &expolys, double angle)
+{
+    for (ExPolygons::iterator p = expolys.begin(); p != expolys.end(); ++p)
+        p->rotate(angle);
+}
+
+inline bool expolygons_contain(ExPolygons &expolys, const Point &pt)
+{
+    for (ExPolygons::iterator p = expolys.begin(); p != expolys.end(); ++p)
+        if (p->contains(pt))
+            return true;
+    return false;
+}
+
+extern BoundingBox get_extents(const ExPolygon &expolygon);
+extern BoundingBox get_extents(const ExPolygons &expolygons);
+extern BoundingBox get_extents_rotated(const ExPolygon &poly, double angle);
+extern BoundingBox get_extents_rotated(const ExPolygons &polygons, double angle);
+extern std::vector<BoundingBox> get_extents_vector(const ExPolygons &polygons);
+
+extern bool        remove_sticks(ExPolygon &poly);
+
+} // namespace Slic3r
+
+// start Boost
+#include <boost/polygon/polygon.hpp>
+namespace boost { namespace polygon {
+    template <>
+        struct polygon_traits<Slic3r::ExPolygon> {
+        typedef coord_t coordinate_type;
+        typedef Slic3r::Points::const_iterator iterator_type;
+        typedef Slic3r::Point point_type;
+
+        // Get the begin iterator
+        static inline iterator_type begin_points(const Slic3r::ExPolygon& t) {
+            return t.contour.points.begin();
+        }
+
+        // Get the end iterator
+        static inline iterator_type end_points(const Slic3r::ExPolygon& t) {
+            return t.contour.points.end();
+        }
+
+        // Get the number of sides of the polygon
+        static inline std::size_t size(const Slic3r::ExPolygon& t) {
+            return t.contour.points.size();
+        }
+
+        // Get the winding direction of the polygon
+        static inline winding_direction winding(const Slic3r::ExPolygon& /* t */) {
+            return unknown_winding;
+        }
+    };
+
+    template <>
+    struct polygon_mutable_traits<Slic3r::ExPolygon> {
+        //expects stl style iterators
+        template <typename iT>
+        static inline Slic3r::ExPolygon& set_points(Slic3r::ExPolygon& expolygon, iT input_begin, iT input_end) {
+            expolygon.contour.points.assign(input_begin, input_end);
+            // skip last point since Boost will set last point = first point
+            expolygon.contour.points.pop_back();
+            return expolygon;
+        }
+    };
+    
+    
+    template <>
+    struct geometry_concept<Slic3r::ExPolygon> { typedef polygon_with_holes_concept type; };
+
+    template <>
+    struct polygon_with_holes_traits<Slic3r::ExPolygon> {
+        typedef Slic3r::Polygons::const_iterator iterator_holes_type;
+        typedef Slic3r::Polygon hole_type;
+        static inline iterator_holes_type begin_holes(const Slic3r::ExPolygon& t) {
+            return t.holes.begin();
+        }
+        static inline iterator_holes_type end_holes(const Slic3r::ExPolygon& t) {
+            return t.holes.end();
+        }
+        static inline unsigned int size_holes(const Slic3r::ExPolygon& t) {
+            return (int)t.holes.size();
+        }
+    };
+
+    template <>
+    struct polygon_with_holes_mutable_traits<Slic3r::ExPolygon> {
+         template <typename iT>
+         static inline Slic3r::ExPolygon& set_holes(Slic3r::ExPolygon& t, iT inputBegin, iT inputEnd) {
+              t.holes.assign(inputBegin, inputEnd);
+              return t;
+         }
+    };
+    
+    //first we register CPolygonSet as a polygon set
+    template <>
+    struct geometry_concept<Slic3r::ExPolygons> { typedef polygon_set_concept type; };
+
+    //next we map to the concept through traits
+    template <>
+    struct polygon_set_traits<Slic3r::ExPolygons> {
+        typedef coord_t coordinate_type;
+        typedef Slic3r::ExPolygons::const_iterator iterator_type;
+        typedef Slic3r::ExPolygons operator_arg_type;
+
+        static inline iterator_type begin(const Slic3r::ExPolygons& polygon_set) {
+            return polygon_set.begin();
+        }
+
+        static inline iterator_type end(const Slic3r::ExPolygons& polygon_set) {
+            return polygon_set.end();
+        }
+
+        //don't worry about these, just return false from them
+        static inline bool clean(const Slic3r::ExPolygons& /* polygon_set */) { return false; }
+        static inline bool sorted(const Slic3r::ExPolygons& /* polygon_set */) { return false; }
+    };
+
+    template <>
+    struct polygon_set_mutable_traits<Slic3r::ExPolygons> {
+        template <typename input_iterator_type>
+        static inline void set(Slic3r::ExPolygons& expolygons, input_iterator_type input_begin, input_iterator_type input_end) {
+            expolygons.assign(input_begin, input_end);
+        }
+    };
+} }
+// end Boost
+
+#endif

src/libslic3r/ExPolygonCollection.cpp

@@ -0,0 +1,135 @@
+#include "ExPolygonCollection.hpp"
+#include "Geometry.hpp"
+
+namespace Slic3r {
+
+ExPolygonCollection::ExPolygonCollection(const ExPolygon &expolygon)
+{
+    this->expolygons.push_back(expolygon);
+}
+
+ExPolygonCollection::operator Points() const
+{
+    Points points;
+    Polygons pp = *this;
+    for (Polygons::const_iterator poly = pp.begin(); poly != pp.end(); ++poly) {
+        for (Points::const_iterator point = poly->points.begin(); point != poly->points.end(); ++point)
+            points.push_back(*point);
+    }
+    return points;
+}
+
+ExPolygonCollection::operator Polygons() const
+{
+    Polygons polygons;
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it) {
+        polygons.push_back(it->contour);
+        for (Polygons::const_iterator ith = it->holes.begin(); ith != it->holes.end(); ++ith) {
+            polygons.push_back(*ith);
+        }
+    }
+    return polygons;
+}
+
+ExPolygonCollection::operator ExPolygons&()
+{
+    return this->expolygons;
+}
+
+void
+ExPolygonCollection::scale(double factor)
+{
+    for (ExPolygons::iterator it = expolygons.begin(); it != expolygons.end(); ++it) {
+        (*it).scale(factor);
+    }
+}
+
+void
+ExPolygonCollection::translate(double x, double y)
+{
+   for (ExPolygons::iterator it = expolygons.begin(); it != expolygons.end(); ++it) {
+        (*it).translate(x, y);
+    }
+}
+
+void
+ExPolygonCollection::rotate(double angle, const Point &center)
+{
+    for (ExPolygons::iterator it = expolygons.begin(); it != expolygons.end(); ++it) {
+        (*it).rotate(angle, center);
+    }
+}
+
+template <class T>
+bool ExPolygonCollection::contains(const T &item) const
+{
+    for (const ExPolygon &poly : this->expolygons)
+        if (poly.contains(item))
+            return true;
+    return false;
+}
+template bool ExPolygonCollection::contains<Point>(const Point &item) const;
+template bool ExPolygonCollection::contains<Line>(const Line &item) const;
+template bool ExPolygonCollection::contains<Polyline>(const Polyline &item) const;
+
+bool
+ExPolygonCollection::contains_b(const Point &point) const
+{
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it) {
+        if (it->contains_b(point)) return true;
+    }
+    return false;
+}
+
+void
+ExPolygonCollection::simplify(double tolerance)
+{
+    ExPolygons expp;
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it) {
+        it->simplify(tolerance, &expp);
+    }
+    this->expolygons = expp;
+}
+
+Polygon
+ExPolygonCollection::convex_hull() const
+{
+    Points pp;
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it)
+        pp.insert(pp.end(), it->contour.points.begin(), it->contour.points.end());
+    return Slic3r::Geometry::convex_hull(pp);
+}
+
+Lines
+ExPolygonCollection::lines() const
+{
+    Lines lines;
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it) {
+        Lines ex_lines = it->lines();
+        lines.insert(lines.end(), ex_lines.begin(), ex_lines.end());
+    }
+    return lines;
+}
+
+Polygons
+ExPolygonCollection::contours() const
+{
+    Polygons contours;
+    contours.reserve(this->expolygons.size());
+    for (ExPolygons::const_iterator it = this->expolygons.begin(); it != this->expolygons.end(); ++it)
+        contours.push_back(it->contour);
+    return contours;
+}
+
+void
+ExPolygonCollection::append(const ExPolygons &expp)
+{
+    this->expolygons.insert(this->expolygons.end(), expp.begin(), expp.end());
+}
+
+BoundingBox get_extents(const ExPolygonCollection &expolygon)
+{
+    return get_extents(expolygon.expolygons);
+}
+
+}

src/libslic3r/ExPolygonCollection.hpp

@@ -0,0 +1,41 @@
+#ifndef slic3r_ExPolygonCollection_hpp_
+#define slic3r_ExPolygonCollection_hpp_
+
+#include "libslic3r.h"
+#include "ExPolygon.hpp"
+#include "Line.hpp"
+#include "Polyline.hpp"
+
+namespace Slic3r {
+
+class ExPolygonCollection;
+typedef std::vector<ExPolygonCollection> ExPolygonCollections;
+
+class ExPolygonCollection
+{
+    public:
+    ExPolygons expolygons;
+    
+    ExPolygonCollection() {};
+    ExPolygonCollection(const ExPolygon &expolygon);
+    ExPolygonCollection(const ExPolygons &expolygons) : expolygons(expolygons) {};
+    operator Points() const;
+    operator Polygons() const;
+    operator ExPolygons&();
+    void scale(double factor);
+    void translate(double x, double y);
+    void rotate(double angle, const Point &center);
+    template <class T> bool contains(const T &item) const;
+    bool contains_b(const Point &point) const;
+    void simplify(double tolerance);
+    Polygon convex_hull() const;
+    Lines lines() const;
+    Polygons contours() const;
+    void append(const ExPolygons &expolygons);
+};
+
+extern BoundingBox get_extents(const ExPolygonCollection &expolygon);
+
+}
+
+#endif

src/libslic3r/Extruder.cpp

@@ -0,0 +1,138 @@
+#include "Extruder.hpp"
+
+namespace Slic3r {
+
+Extruder::Extruder(unsigned int id, GCodeConfig *config) :
+    m_id(id),
+    m_config(config)
+{
+    reset();
+    
+    // cache values that are going to be called often
+    m_e_per_mm3 = this->extrusion_multiplier();
+    if (! m_config->use_volumetric_e)
+        m_e_per_mm3 /= this->filament_crossection();
+}
+
+double Extruder::extrude(double dE)
+{
+    // in case of relative E distances we always reset to 0 before any output
+    if (m_config->use_relative_e_distances)
+        m_E = 0.;
+    m_E          += dE;
+    m_absolute_E += dE;
+    if (dE < 0.)
+        m_retracted -= dE;
+    return dE;
+}
+
+/* This method makes sure the extruder is retracted by the specified amount
+   of filament and returns the amount of filament retracted.
+   If the extruder is already retracted by the same or a greater amount, 
+   this method is a no-op.
+   The restart_extra argument sets the extra length to be used for
+   unretraction. If we're actually performing a retraction, any restart_extra
+   value supplied will overwrite the previous one if any. */
+double Extruder::retract(double length, double restart_extra)
+{
+    // in case of relative E distances we always reset to 0 before any output
+    if (m_config->use_relative_e_distances)
+        m_E = 0.;
+    double to_retract = std::max(0., length - m_retracted);
+    if (to_retract > 0.) {
+        m_E             -= to_retract;
+        m_absolute_E    -= to_retract;
+        m_retracted     += to_retract;
+        m_restart_extra = restart_extra;
+    }
+    return to_retract;
+}
+
+double Extruder::unretract()
+{
+    double dE = m_retracted + m_restart_extra;
+    this->extrude(dE);
+    m_retracted     = 0.;
+    m_restart_extra = 0.;
+    return dE;
+}
+
+// Used filament volume in mm^3.
+double Extruder::extruded_volume() const
+{
+    return m_config->use_volumetric_e ? 
+        m_absolute_E + m_retracted :
+        this->used_filament() * this->filament_crossection();
+}
+
+// Used filament length in mm.
+double Extruder::used_filament() const
+{
+    return m_config->use_volumetric_e ?
+        this->extruded_volume() / this->filament_crossection() :
+        m_absolute_E + m_retracted;
+}
+
+double Extruder::filament_diameter() const
+{
+    return m_config->filament_diameter.get_at(m_id);
+}
+
+double Extruder::filament_density() const
+{
+    return m_config->filament_density.get_at(m_id);
+}
+
+double Extruder::filament_cost() const
+{
+    return m_config->filament_cost.get_at(m_id);
+}
+
+double Extruder::extrusion_multiplier() const
+{
+    return m_config->extrusion_multiplier.get_at(m_id);
+}
+
+// Return a "retract_before_wipe" percentage as a factor clamped to <0, 1>
+double Extruder::retract_before_wipe() const
+{
+    return std::min(1., std::max(0., m_config->retract_before_wipe.get_at(m_id) * 0.01));
+}
+
+double Extruder::retract_length() const
+{
+    return m_config->retract_length.get_at(m_id);
+}
+
+double Extruder::retract_lift() const
+{
+    return m_config->retract_lift.get_at(m_id);
+}
+
+int Extruder::retract_speed() const
+{
+    return int(floor(m_config->retract_speed.get_at(m_id)+0.5));
+}
+
+int Extruder::deretract_speed() const
+{
+    int speed = int(floor(m_config->deretract_speed.get_at(m_id)+0.5));
+    return (speed > 0) ? speed : this->retract_speed();
+}
+
+double Extruder::retract_restart_extra() const
+{
+    return m_config->retract_restart_extra.get_at(m_id);
+}
+
+double Extruder::retract_length_toolchange() const
+{
+    return m_config->retract_length_toolchange.get_at(m_id);
+}
+
+double Extruder::retract_restart_extra_toolchange() const
+{
+    return m_config->retract_restart_extra_toolchange.get_at(m_id);
+}
+
+}

src/libslic3r/Extruder.hpp

@@ -0,0 +1,81 @@
+#ifndef slic3r_Extruder_hpp_
+#define slic3r_Extruder_hpp_
+
+#include "libslic3r.h"
+#include "Point.hpp"
+#include "PrintConfig.hpp"
+
+namespace Slic3r {
+
+class Extruder
+{
+public:
+    Extruder(unsigned int id, GCodeConfig *config);
+    virtual ~Extruder() {}
+
+    void   reset() {
+        m_E             = 0;
+        m_absolute_E    = 0;
+        m_retracted     = 0;
+        m_restart_extra = 0;
+    }
+
+    unsigned int id() const { return m_id; }
+
+    double extrude(double dE);
+    double retract(double length, double restart_extra);
+    double unretract();
+    double E() const { return m_E; }
+    void   reset_E() { m_E = 0.; }
+    double e_per_mm(double mm3_per_mm) const { return mm3_per_mm * m_e_per_mm3; }
+    double e_per_mm3() const { return m_e_per_mm3; }
+    // Used filament volume in mm^3.
+    double extruded_volume() const;
+    // Used filament length in mm.
+    double used_filament() const;
+    
+    double filament_diameter() const;
+    double filament_crossection() const { return this->filament_diameter() * this->filament_diameter() * 0.25 * PI; }
+    double filament_density() const;
+    double filament_cost() const;
+    double extrusion_multiplier() const;
+    double retract_before_wipe() const;
+    double retract_length() const;
+    double retract_lift() const;
+    int    retract_speed() const;
+    int    deretract_speed() const;
+    double retract_restart_extra() const;
+    double retract_length_toolchange() const;
+    double retract_restart_extra_toolchange() const;
+
+    // Constructor for a key object, to be used by the stdlib search functions.
+    static Extruder key(unsigned int id) { return Extruder(id); }
+
+private:
+    // Private constructor to create a key for a search in std::set.
+    Extruder(unsigned int id) : m_id(id) {}
+
+    // Reference to GCodeWriter instance owned by GCodeWriter.
+    GCodeConfig *m_config;
+    // Print-wide global ID of this extruder.
+    unsigned int m_id;
+    // Current state of the extruder axis, may be resetted if use_relative_e_distances.
+    double       m_E;
+    // Current state of the extruder tachometer, used to output the extruded_volume() and used_filament() statistics.
+    double       m_absolute_E;
+    // Current positive amount of retraction.
+    double       m_retracted;
+    // When retracted, this value stores the extra amount of priming on deretraction.
+    double       m_restart_extra;
+    double       m_e_per_mm3;
+};
+
+// Sort Extruder objects by the extruder id by default.
+inline bool operator==(const Extruder &e1, const Extruder &e2) { return e1.id() == e2.id(); }
+inline bool operator!=(const Extruder &e1, const Extruder &e2) { return e1.id() != e2.id(); }
+inline bool operator< (const Extruder &e1, const Extruder &e2) { return e1.id() < e2.id(); }
+inline bool operator> (const Extruder &e1, const Extruder &e2) { return e1.id() > e2.id(); }
+
+}
+
+#endif

src/libslic3r/ExtrusionEntity.cpp

@@ -0,0 +1,321 @@
+#include "ExtrusionEntity.hpp"
+#include "ExtrusionEntityCollection.hpp"
+#include "ExPolygonCollection.hpp"
+#include "ClipperUtils.hpp"
+#include "Extruder.hpp"
+#include "Flow.hpp"
+#include <cmath>
+#include <limits>
+#include <sstream>
+
+namespace Slic3r {
+    
+void
+ExtrusionPath::intersect_expolygons(const ExPolygonCollection &collection, ExtrusionEntityCollection* retval) const
+{
+    this->_inflate_collection(intersection_pl(this->polyline, collection), retval);
+}
+
+void
+ExtrusionPath::subtract_expolygons(const ExPolygonCollection &collection, ExtrusionEntityCollection* retval) const
+{
+    this->_inflate_collection(diff_pl(this->polyline, collection), retval);
+}
+
+void
+ExtrusionPath::clip_end(double distance)
+{
+    this->polyline.clip_end(distance);
+}
+
+void
+ExtrusionPath::simplify(double tolerance)
+{
+    this->polyline.simplify(tolerance);
+}
+
+double
+ExtrusionPath::length() const
+{
+    return this->polyline.length();
+}
+
+void
+ExtrusionPath::_inflate_collection(const Polylines &polylines, ExtrusionEntityCollection* collection) const
+{
+    for (Polylines::const_iterator it = polylines.begin(); it != polylines.end(); ++it) {
+        ExtrusionPath* path = this->clone();
+        path->polyline = *it;
+        collection->entities.push_back(path);
+    }
+}
+
+void ExtrusionPath::polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const
+{
+    polygons_append(out, offset(this->polyline, float(scale_(this->width/2)) + scaled_epsilon));
+}
+
+void ExtrusionPath::polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const
+{
+    // Instantiating the Flow class to get the line spacing.
+    // Don't know the nozzle diameter, setting to zero. It shall not matter it shall be optimized out by the compiler.
+    Flow flow(this->width, this->height, 0.f, is_bridge(this->role()));
+    polygons_append(out, offset(this->polyline, 0.5f * float(flow.scaled_spacing()) + scaled_epsilon));
+}
+
+void ExtrusionMultiPath::reverse()
+{
+    for (ExtrusionPaths::iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        path->reverse();
+    std::reverse(this->paths.begin(), this->paths.end());
+}
+
+double ExtrusionMultiPath::length() const
+{
+    double len = 0;
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        len += path->polyline.length();
+    return len;
+}
+
+void ExtrusionMultiPath::polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const
+{
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        path->polygons_covered_by_width(out, scaled_epsilon);
+}
+
+void ExtrusionMultiPath::polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const
+{
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        path->polygons_covered_by_spacing(out, scaled_epsilon);
+}
+
+double ExtrusionMultiPath::min_mm3_per_mm() const
+{
+    double min_mm3_per_mm = std::numeric_limits<double>::max();
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        min_mm3_per_mm = std::min(min_mm3_per_mm, path->mm3_per_mm);
+    return min_mm3_per_mm;
+}
+
+Polyline ExtrusionMultiPath::as_polyline() const
+{
+    Polyline out;
+    if (! paths.empty()) {
+        size_t len = 0;
+        for (size_t i_path = 0; i_path < paths.size(); ++ i_path) {
+            assert(! paths[i_path].polyline.points.empty());
+            assert(i_path == 0 || paths[i_path - 1].polyline.points.back() == paths[i_path].polyline.points.front());
+            len += paths[i_path].polyline.points.size();
+        }
+        // The connecting points between the segments are equal.
+        len -= paths.size() - 1;
+        assert(len > 0);
+        out.points.reserve(len);
+        out.points.push_back(paths.front().polyline.points.front());
+        for (size_t i_path = 0; i_path < paths.size(); ++ i_path)
+            out.points.insert(out.points.end(), paths[i_path].polyline.points.begin() + 1, paths[i_path].polyline.points.end());
+    }
+    return out;
+}
+
+bool
+ExtrusionLoop::make_clockwise()
+{
+    bool was_ccw = this->polygon().is_counter_clockwise();
+    if (was_ccw) this->reverse();
+    return was_ccw;
+}
+
+bool
+ExtrusionLoop::make_counter_clockwise()
+{
+    bool was_cw = this->polygon().is_clockwise();
+    if (was_cw) this->reverse();
+    return was_cw;
+}
+
+void
+ExtrusionLoop::reverse()
+{
+    for (ExtrusionPaths::iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        path->reverse();
+    std::reverse(this->paths.begin(), this->paths.end());
+}
+
+Polygon
+ExtrusionLoop::polygon() const
+{
+    Polygon polygon;
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path) {
+        // for each polyline, append all points except the last one (because it coincides with the first one of the next polyline)
+        polygon.points.insert(polygon.points.end(), path->polyline.points.begin(), path->polyline.points.end()-1);
+    }
+    return polygon;
+}
+
+double
+ExtrusionLoop::length() const
+{
+    double len = 0;
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        len += path->polyline.length();
+    return len;
+}
+
+bool
+ExtrusionLoop::split_at_vertex(const Point &point)
+{
+    for (ExtrusionPaths::iterator path = this->paths.begin(); path != this->paths.end(); ++path) {
+        int idx = path->polyline.find_point(point);
+        if (idx != -1) {
+            if (this->paths.size() == 1) {
+                // just change the order of points
+                path->polyline.points.insert(path->polyline.points.end(), path->polyline.points.begin() + 1, path->polyline.points.begin() + idx + 1);
+                path->polyline.points.erase(path->polyline.points.begin(), path->polyline.points.begin() + idx);
+            } else {
+                // new paths list starts with the second half of current path
+                ExtrusionPaths new_paths;
+                new_paths.reserve(this->paths.size() + 1);
+                {
+                    ExtrusionPath p = *path;
+                    p.polyline.points.erase(p.polyline.points.begin(), p.polyline.points.begin() + idx);
+                    if (p.polyline.is_valid()) new_paths.push_back(p);
+                }
+            
+                // then we add all paths until the end of current path list
+                new_paths.insert(new_paths.end(), path+1, this->paths.end());  // not including this path
+            
+                // then we add all paths since the beginning of current list up to the previous one
+                new_paths.insert(new_paths.end(), this->paths.begin(), path);  // not including this path
+            
+                // finally we add the first half of current path
+                {
+                    ExtrusionPath p = *path;
+                    p.polyline.points.erase(p.polyline.points.begin() + idx + 1, p.polyline.points.end());
+                    if (p.polyline.is_valid()) new_paths.push_back(p);
+                }
+                // we can now override the old path list with the new one and stop looping
+                std::swap(this->paths, new_paths);
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
+// Splitting an extrusion loop, possibly made of multiple segments, some of the segments may be bridging.
+void ExtrusionLoop::split_at(const Point &point, bool prefer_non_overhang)
+{
+    if (this->paths.empty())
+        return;
+    
+    // Find the closest path and closest point belonging to that path. Avoid overhangs, if asked for.
+    size_t path_idx = 0;
+    Point  p;
+    {
+        double min = std::numeric_limits<double>::max();
+        Point  p_non_overhang;
+        size_t path_idx_non_overhang = 0;
+        double min_non_overhang = std::numeric_limits<double>::max();
+        for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path) {
+            Point p_tmp = point.projection_onto(path->polyline);
+            double dist = (p_tmp - point).cast<double>().norm();
+            if (dist < min) {
+                p = p_tmp;
+                min = dist;
+                path_idx = path - this->paths.begin();
+            } 
+            if (prefer_non_overhang && ! is_bridge(path->role()) && dist < min_non_overhang) {
+                p_non_overhang = p_tmp;
+                min_non_overhang = dist;
+                path_idx_non_overhang = path - this->paths.begin();
+            }
+        }
+        if (prefer_non_overhang && min_non_overhang != std::numeric_limits<double>::max()) {
+            // Only apply the non-overhang point if there is one.
+            path_idx = path_idx_non_overhang;
+            p        = p_non_overhang;
+        }
+    }
+    
+    // now split path_idx in two parts
+    const ExtrusionPath &path = this->paths[path_idx];
+    ExtrusionPath p1(path.role(), path.mm3_per_mm, path.width, path.height);
+    ExtrusionPath p2(path.role(), path.mm3_per_mm, path.width, path.height);
+    path.polyline.split_at(p, &p1.polyline, &p2.polyline);
+    
+    if (this->paths.size() == 1) {
+        if (! p1.polyline.is_valid())
+            std::swap(this->paths.front().polyline.points, p2.polyline.points);
+        else if (! p2.polyline.is_valid())
+            std::swap(this->paths.front().polyline.points, p1.polyline.points);
+        else {
+            p2.polyline.points.insert(p2.polyline.points.end(), p1.polyline.points.begin() + 1, p1.polyline.points.end());
+            std::swap(this->paths.front().polyline.points, p2.polyline.points);
+        }
+    } else {
+        // install the two paths
+        this->paths.erase(this->paths.begin() + path_idx);
+        if (p2.polyline.is_valid()) this->paths.insert(this->paths.begin() + path_idx, p2);
+        if (p1.polyline.is_valid()) this->paths.insert(this->paths.begin() + path_idx, p1);
+    }
+    
+    // split at the new vertex
+    this->split_at_vertex(p);
+}
+
+void
+ExtrusionLoop::clip_end(double distance, ExtrusionPaths* paths) const
+{
+    *paths = this->paths;
+    
+    while (distance > 0 && !paths->empty()) {
+        ExtrusionPath &last = paths->back();
+        double len = last.length();
+        if (len <= distance) {
+            paths->pop_back();
+            distance -= len;
+        } else {
+            last.polyline.clip_end(distance);
+            break;
+        }
+    }
+}
+
+bool
+ExtrusionLoop::has_overhang_point(const Point &point) const
+{
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path) {
+        int pos = path->polyline.find_point(point);
+        if (pos != -1) {
+            // point belongs to this path
+            // we consider it overhang only if it's not an endpoint
+            return (is_bridge(path->role()) && pos > 0 && pos != (int)(path->polyline.points.size())-1);
+        }
+    }
+    return false;
+}
+
+void ExtrusionLoop::polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const
+{
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        path->polygons_covered_by_width(out, scaled_epsilon);
+}
+
+void ExtrusionLoop::polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const
+{
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        path->polygons_covered_by_spacing(out, scaled_epsilon);
+}
+
+double
+ExtrusionLoop::min_mm3_per_mm() const
+{
+    double min_mm3_per_mm = std::numeric_limits<double>::max();
+    for (ExtrusionPaths::const_iterator path = this->paths.begin(); path != this->paths.end(); ++path)
+        min_mm3_per_mm = std::min(min_mm3_per_mm, path->mm3_per_mm);
+    return min_mm3_per_mm;
+}
+
+}

src/libslic3r/ExtrusionEntity.hpp

@@ -0,0 +1,321 @@
+#ifndef slic3r_ExtrusionEntity_hpp_
+#define slic3r_ExtrusionEntity_hpp_
+
+#include "libslic3r.h"
+#include "Polygon.hpp"
+#include "Polyline.hpp"
+
+namespace Slic3r {
+
+class ExPolygonCollection;
+class ExtrusionEntityCollection;
+class Extruder;
+
+/* Each ExtrusionRole value identifies a distinct set of { extruder, speed } */
+enum ExtrusionRole {
+    erNone,
+    erPerimeter,
+    erExternalPerimeter,
+    erOverhangPerimeter,
+    erInternalInfill,
+    erSolidInfill,
+    erTopSolidInfill,
+    erBridgeInfill,
+    erGapFill,
+    erSkirt,
+    erSupportMaterial,
+    erSupportMaterialInterface,
+    erWipeTower,
+    erCustom,
+    // Extrusion role for a collection with multiple extrusion roles.
+    erMixed,
+};
+
+inline bool is_perimeter(ExtrusionRole role)
+{
+    return role == erPerimeter
+        || role == erExternalPerimeter
+        || role == erOverhangPerimeter;
+}
+
+inline bool is_infill(ExtrusionRole role)
+{
+    return role == erBridgeInfill
+        || role == erInternalInfill
+        || role == erSolidInfill
+        || role == erTopSolidInfill;
+}
+
+inline bool is_solid_infill(ExtrusionRole role)
+{
+    return role == erBridgeInfill
+        || role == erSolidInfill
+        || role == erTopSolidInfill;
+}
+
+inline bool is_bridge(ExtrusionRole role) {
+    return role == erBridgeInfill
+        || role == erOverhangPerimeter;
+}
+
+/* Special flags describing loop */
+enum ExtrusionLoopRole {
+    elrDefault,
+    elrContourInternalPerimeter,
+    elrSkirt,
+};
+
+class ExtrusionEntity
+{
+public:
+    virtual ExtrusionRole role() const = 0;
+    virtual bool is_collection() const { return false; }
+    virtual bool is_loop() const { return false; }
+    virtual bool can_reverse() const { return true; }
+    virtual ExtrusionEntity* clone() const = 0;
+    virtual ~ExtrusionEntity() {};
+    virtual void reverse() = 0;
+    virtual Point first_point() const = 0;
+    virtual Point last_point() const = 0;
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion width.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    virtual void polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const = 0;
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion spacing.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    // Useful to calculate area of an infill, which has been really filled in by a 100% rectilinear infill.
+    virtual void polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const = 0;
+    Polygons polygons_covered_by_width(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_width(out, scaled_epsilon); return out; }
+    Polygons polygons_covered_by_spacing(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_spacing(out, scaled_epsilon); return out; }
+    // Minimum volumetric velocity of this extrusion entity. Used by the constant nozzle pressure algorithm.
+    virtual double min_mm3_per_mm() const = 0;
+    virtual Polyline as_polyline() const = 0;
+    virtual void   collect_polylines(Polylines &dst) const = 0;
+    virtual Polylines as_polylines() const { Polylines dst; this->collect_polylines(dst); return dst; }
+    virtual double length() const = 0;
+    virtual double total_volume() const = 0;
+};
+
+typedef std::vector<ExtrusionEntity*> ExtrusionEntitiesPtr;
+
+class ExtrusionPath : public ExtrusionEntity
+{
+public:
+    Polyline polyline;
+    // Volumetric velocity. mm^3 of plastic per mm of linear head motion. Used by the G-code generator.
+    double mm3_per_mm;
+    // Width of the extrusion, used for visualization purposes.
+    float width;
+    // Height of the extrusion, used for visualization purposed.
+    float height;
+    // Feedrate of the extrusion, used for visualization purposed.
+    float feedrate;
+    // Id of the extruder, used for visualization purposed.
+    unsigned int extruder_id;
+
+    ExtrusionPath(ExtrusionRole role) : mm3_per_mm(-1), width(-1), height(-1), feedrate(0.0f), extruder_id(0), m_role(role) {};
+    ExtrusionPath(ExtrusionRole role, double mm3_per_mm, float width, float height) : mm3_per_mm(mm3_per_mm), width(width), height(height), feedrate(0.0f), extruder_id(0), m_role(role) {};
+    ExtrusionPath(const ExtrusionPath &rhs) : polyline(rhs.polyline), mm3_per_mm(rhs.mm3_per_mm), width(rhs.width), height(rhs.height), feedrate(rhs.feedrate), extruder_id(rhs.extruder_id), m_role(rhs.m_role) {}
+    ExtrusionPath(ExtrusionPath &&rhs) : polyline(std::move(rhs.polyline)), mm3_per_mm(rhs.mm3_per_mm), width(rhs.width), height(rhs.height), feedrate(rhs.feedrate), extruder_id(rhs.extruder_id), m_role(rhs.m_role) {}
+//    ExtrusionPath(ExtrusionRole role, const Flow &flow) : m_role(role), mm3_per_mm(flow.mm3_per_mm()), width(flow.width), height(flow.height), feedrate(0.0f), extruder_id(0) {};
+
+    ExtrusionPath& operator=(const ExtrusionPath &rhs) { m_role = rhs.m_role; this->mm3_per_mm = rhs.mm3_per_mm; this->width = rhs.width; this->height = rhs.height; this->feedrate = rhs.feedrate, this->extruder_id = rhs.extruder_id, this->polyline = rhs.polyline; return *this; }
+    ExtrusionPath& operator=(ExtrusionPath &&rhs) { m_role = rhs.m_role; this->mm3_per_mm = rhs.mm3_per_mm; this->width = rhs.width; this->height = rhs.height; this->feedrate = rhs.feedrate, this->extruder_id = rhs.extruder_id, this->polyline = std::move(rhs.polyline); return *this; }
+
+    ExtrusionPath* clone() const { return new ExtrusionPath (*this); }
+    void reverse() { this->polyline.reverse(); }
+    Point first_point() const override { return this->polyline.points.front(); }
+    Point last_point() const override { return this->polyline.points.back(); }
+    size_t size() const { return this->polyline.size(); }
+    bool empty() const { return this->polyline.empty(); }
+    bool is_closed() const { return ! this->empty() && this->polyline.points.front() == this->polyline.points.back(); }
+    // Produce a list of extrusion paths into retval by clipping this path by ExPolygonCollection.
+    // Currently not used.
+    void intersect_expolygons(const ExPolygonCollection &collection, ExtrusionEntityCollection* retval) const;
+    // Produce a list of extrusion paths into retval by removing parts of this path by ExPolygonCollection.
+    // Currently not used.
+    void subtract_expolygons(const ExPolygonCollection &collection, ExtrusionEntityCollection* retval) const;
+    void clip_end(double distance);
+    void simplify(double tolerance);
+    double length() const override;
+    ExtrusionRole role() const override { return m_role; }
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion width.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    void polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const;
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion spacing.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    // Useful to calculate area of an infill, which has been really filled in by a 100% rectilinear infill.
+    void polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const;
+    Polygons polygons_covered_by_width(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_width(out, scaled_epsilon); return out; }
+    Polygons polygons_covered_by_spacing(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_spacing(out, scaled_epsilon); return out; }
+    // Minimum volumetric velocity of this extrusion entity. Used by the constant nozzle pressure algorithm.
+    double min_mm3_per_mm() const { return this->mm3_per_mm; }
+    Polyline as_polyline() const { return this->polyline; }
+    void   collect_polylines(Polylines &dst) const override { if (! this->polyline.empty()) dst.emplace_back(this->polyline); }
+    double total_volume() const override { return mm3_per_mm * unscale<double>(length()); }
+
+private:
+    void _inflate_collection(const Polylines &polylines, ExtrusionEntityCollection* collection) const;
+
+    ExtrusionRole m_role;
+};
+
+typedef std::vector<ExtrusionPath> ExtrusionPaths;
+
+// Single continuous extrusion path, possibly with varying extrusion thickness, extrusion height or bridging / non bridging.
+class ExtrusionMultiPath : public ExtrusionEntity
+{
+public:
+    ExtrusionPaths paths;
+    
+    ExtrusionMultiPath() {};
+    ExtrusionMultiPath(const ExtrusionMultiPath &rhs) : paths(rhs.paths) {}
+    ExtrusionMultiPath(ExtrusionMultiPath &&rhs) : paths(std::move(rhs.paths)) {}
+    ExtrusionMultiPath(const ExtrusionPaths &paths) : paths(paths) {};
+    ExtrusionMultiPath(const ExtrusionPath &path) { this->paths.push_back(path); }
+
+    ExtrusionMultiPath& operator=(const ExtrusionMultiPath &rhs) { this->paths = rhs.paths; return *this; }
+    ExtrusionMultiPath& operator=(ExtrusionMultiPath &&rhs) { this->paths = std::move(rhs.paths); return *this; }
+
+    bool is_loop() const { return false; }
+    bool can_reverse() const { return true; }
+    ExtrusionMultiPath* clone() const { return new ExtrusionMultiPath(*this); }
+    void reverse();
+    Point first_point() const override { return this->paths.front().polyline.points.front(); }
+    Point last_point() const override { return this->paths.back().polyline.points.back(); }
+    double length() const override;
+    ExtrusionRole role() const override { return this->paths.empty() ? erNone : this->paths.front().role(); }
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion width.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    void polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const;
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion spacing.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    // Useful to calculate area of an infill, which has been really filled in by a 100% rectilinear infill.
+    void polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const;
+    Polygons polygons_covered_by_width(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_width(out, scaled_epsilon); return out; }
+    Polygons polygons_covered_by_spacing(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_spacing(out, scaled_epsilon); return out; }
+    // Minimum volumetric velocity of this extrusion entity. Used by the constant nozzle pressure algorithm.
+    double min_mm3_per_mm() const;
+    Polyline as_polyline() const;
+    void   collect_polylines(Polylines &dst) const override { Polyline pl = this->as_polyline(); if (! pl.empty()) dst.emplace_back(std::move(pl)); }
+    double total_volume() const override { double volume =0.; for (const auto& path : paths) volume += path.total_volume(); return volume; }
+};
+
+// Single continuous extrusion loop, possibly with varying extrusion thickness, extrusion height or bridging / non bridging.
+class ExtrusionLoop : public ExtrusionEntity
+{
+public:
+    ExtrusionPaths paths;
+    
+    ExtrusionLoop(ExtrusionLoopRole role = elrDefault) : m_loop_role(role) {};
+    ExtrusionLoop(const ExtrusionPaths &paths, ExtrusionLoopRole role = elrDefault) : paths(paths), m_loop_role(role) {};
+    ExtrusionLoop(ExtrusionPaths &&paths, ExtrusionLoopRole role = elrDefault) : paths(std::move(paths)), m_loop_role(role) {};
+    ExtrusionLoop(const ExtrusionPath &path, ExtrusionLoopRole role = elrDefault) : m_loop_role(role) 
+        { this->paths.push_back(path); };
+    ExtrusionLoop(const ExtrusionPath &&path, ExtrusionLoopRole role = elrDefault) : m_loop_role(role)
+        { this->paths.emplace_back(std::move(path)); };
+    bool is_loop() const { return true; }
+    bool can_reverse() const { return false; }
+    ExtrusionLoop* clone() const { return new ExtrusionLoop (*this); }
+    bool make_clockwise();
+    bool make_counter_clockwise();
+    void reverse();
+    Point first_point() const override { return this->paths.front().polyline.points.front(); }
+    Point last_point() const override { assert(first_point() == this->paths.back().polyline.points.back()); return first_point(); }
+    Polygon polygon() const;
+    double length() const override;
+    bool split_at_vertex(const Point &point);
+    void split_at(const Point &point, bool prefer_non_overhang);
+    void clip_end(double distance, ExtrusionPaths* paths) const;
+    // Test, whether the point is extruded by a bridging flow.
+    // This used to be used to avoid placing seams on overhangs, but now the EdgeGrid is used instead.
+    bool has_overhang_point(const Point &point) const;
+    ExtrusionRole role() const override { return this->paths.empty() ? erNone : this->paths.front().role(); }
+    ExtrusionLoopRole loop_role() const { return m_loop_role; }
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion width.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    void polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const;
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion spacing.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    // Useful to calculate area of an infill, which has been really filled in by a 100% rectilinear infill.
+    void polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const;
+    Polygons polygons_covered_by_width(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_width(out, scaled_epsilon); return out; }
+    Polygons polygons_covered_by_spacing(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_spacing(out, scaled_epsilon); return out; }
+    // Minimum volumetric velocity of this extrusion entity. Used by the constant nozzle pressure algorithm.
+    double min_mm3_per_mm() const;
+    Polyline as_polyline() const { return this->polygon().split_at_first_point(); }
+    void   collect_polylines(Polylines &dst) const override { Polyline pl = this->as_polyline(); if (! pl.empty()) dst.emplace_back(std::move(pl)); }
+    double total_volume() const override { double volume =0.; for (const auto& path : paths) volume += path.total_volume(); return volume; }
+
+private:
+    ExtrusionLoopRole m_loop_role;
+};
+
+inline void extrusion_paths_append(ExtrusionPaths &dst, Polylines &polylines, ExtrusionRole role, double mm3_per_mm, float width, float height)
+{
+    dst.reserve(dst.size() + polylines.size());
+    for (Polyline &polyline : polylines)
+        if (polyline.is_valid()) {
+            dst.push_back(ExtrusionPath(role, mm3_per_mm, width, height));
+            dst.back().polyline = polyline;
+        }
+}
+
+inline void extrusion_paths_append(ExtrusionPaths &dst, Polylines &&polylines, ExtrusionRole role, double mm3_per_mm, float width, float height)
+{
+    dst.reserve(dst.size() + polylines.size());
+    for (Polyline &polyline : polylines)
+        if (polyline.is_valid()) {
+            dst.push_back(ExtrusionPath(role, mm3_per_mm, width, height));
+            dst.back().polyline = std::move(polyline);
+        }
+    polylines.clear();
+}
+
+inline void extrusion_entities_append_paths(ExtrusionEntitiesPtr &dst, Polylines &polylines, ExtrusionRole role, double mm3_per_mm, float width, float height)
+{
+    dst.reserve(dst.size() + polylines.size());
+    for (Polyline &polyline : polylines)
+        if (polyline.is_valid()) {
+            ExtrusionPath *extrusion_path = new ExtrusionPath(role, mm3_per_mm, width, height);
+            dst.push_back(extrusion_path);
+            extrusion_path->polyline = polyline;
+        }
+}
+
+inline void extrusion_entities_append_paths(ExtrusionEntitiesPtr &dst, Polylines &&polylines, ExtrusionRole role, double mm3_per_mm, float width, float height)
+{
+    dst.reserve(dst.size() + polylines.size());
+    for (Polyline &polyline : polylines)
+        if (polyline.is_valid()) {
+            ExtrusionPath *extrusion_path = new ExtrusionPath(role, mm3_per_mm, width, height);
+            dst.push_back(extrusion_path);
+            extrusion_path->polyline = std::move(polyline);
+        }
+    polylines.clear();
+}
+
+inline void extrusion_entities_append_loops(ExtrusionEntitiesPtr &dst, Polygons &&loops, ExtrusionRole role, double mm3_per_mm, float width, float height)
+{
+    dst.reserve(dst.size() + loops.size());
+    for (Polygon &poly : loops) {
+        if (poly.is_valid()) {
+            ExtrusionPath path(role, mm3_per_mm, width, height);
+            path.polyline.points = std::move(poly.points);
+            path.polyline.points.push_back(path.polyline.points.front());
+            dst.emplace_back(new ExtrusionLoop(std::move(path)));
+        }
+    }
+    loops.clear();
+}
+
+}
+
+#endif

src/libslic3r/ExtrusionEntityCollection.cpp

@@ -0,0 +1,220 @@
+#include "ExtrusionEntityCollection.hpp"
+#include <algorithm>
+#include <cmath>
+#include <map>
+
+namespace Slic3r {
+
+ExtrusionEntityCollection::ExtrusionEntityCollection(const ExtrusionPaths &paths)
+    : no_sort(false)
+{
+    this->append(paths);
+}
+
+ExtrusionEntityCollection& ExtrusionEntityCollection::operator= (const ExtrusionEntityCollection &other)
+{
+    this->entities      = other.entities;
+    for (size_t i = 0; i < this->entities.size(); ++i)
+        this->entities[i] = this->entities[i]->clone();
+    this->orig_indices  = other.orig_indices;
+    this->no_sort       = other.no_sort;
+    return *this;
+}
+
+void
+ExtrusionEntityCollection::swap(ExtrusionEntityCollection &c)
+{
+    std::swap(this->entities, c.entities);
+    std::swap(this->orig_indices, c.orig_indices);
+    std::swap(this->no_sort, c.no_sort);
+}
+
+void ExtrusionEntityCollection::clear()
+{
+	for (size_t i = 0; i < this->entities.size(); ++i)
+		delete this->entities[i];
+    this->entities.clear();
+}
+
+ExtrusionEntityCollection::operator ExtrusionPaths() const
+{
+    ExtrusionPaths paths;
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
+        if (const ExtrusionPath* path = dynamic_cast<const ExtrusionPath*>(*it))
+            paths.push_back(*path);
+    }
+    return paths;
+}
+
+ExtrusionEntityCollection*
+ExtrusionEntityCollection::clone() const
+{
+    ExtrusionEntityCollection* coll = new ExtrusionEntityCollection(*this);
+    for (size_t i = 0; i < coll->entities.size(); ++i)
+        coll->entities[i] = this->entities[i]->clone();
+    return coll;
+}
+
+void
+ExtrusionEntityCollection::reverse()
+{
+    for (ExtrusionEntitiesPtr::iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
+        // Don't reverse it if it's a loop, as it doesn't change anything in terms of elements ordering
+        // and caller might rely on winding order
+        if (!(*it)->is_loop()) (*it)->reverse();
+    }
+    std::reverse(this->entities.begin(), this->entities.end());
+}
+
+void
+ExtrusionEntityCollection::replace(size_t i, const ExtrusionEntity &entity)
+{
+    delete this->entities[i];
+    this->entities[i] = entity.clone();
+}
+
+void
+ExtrusionEntityCollection::remove(size_t i)
+{
+    delete this->entities[i];
+    this->entities.erase(this->entities.begin() + i);
+}
+
+ExtrusionEntityCollection
+ExtrusionEntityCollection::chained_path(bool no_reverse, ExtrusionRole role) const
+{
+    ExtrusionEntityCollection coll;
+    this->chained_path(&coll, no_reverse, role);
+    return coll;
+}
+
+void
+ExtrusionEntityCollection::chained_path(ExtrusionEntityCollection* retval, bool no_reverse, ExtrusionRole role, std::vector<size_t>* orig_indices) const
+{
+    if (this->entities.empty()) return;
+    this->chained_path_from(this->entities.front()->first_point(), retval, no_reverse, role, orig_indices);
+}
+
+ExtrusionEntityCollection ExtrusionEntityCollection::chained_path_from(Point start_near, bool no_reverse, ExtrusionRole role) const
+{
+    ExtrusionEntityCollection coll;
+    this->chained_path_from(start_near, &coll, no_reverse, role);
+    return coll;
+}
+
+void ExtrusionEntityCollection::chained_path_from(Point start_near, ExtrusionEntityCollection* retval, bool no_reverse, ExtrusionRole role, std::vector<size_t>* orig_indices) const
+{
+    if (this->no_sort) {
+        *retval = *this;
+        return;
+    }
+    retval->entities.reserve(this->entities.size());
+    retval->orig_indices.reserve(this->entities.size());
+    
+    // if we're asked to return the original indices, build a map
+    std::map<ExtrusionEntity*,size_t> indices_map;
+    
+    ExtrusionEntitiesPtr my_paths;
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
+        if (role != erMixed) {
+            // The caller wants only paths with a specific extrusion role.
+            auto role2 = (*it)->role();
+            if (role != role2) {
+                // This extrusion entity does not match the role asked.
+                assert(role2 != erMixed);
+                continue;
+            }
+        }
+
+        ExtrusionEntity* entity = (*it)->clone();
+        my_paths.push_back(entity);
+        if (orig_indices != NULL) indices_map[entity] = it - this->entities.begin();
+    }
+    
+    Points endpoints;
+    for (ExtrusionEntitiesPtr::iterator it = my_paths.begin(); it != my_paths.end(); ++it) {
+        endpoints.push_back((*it)->first_point());
+        if (no_reverse || !(*it)->can_reverse()) {
+            endpoints.push_back((*it)->first_point());
+        } else {
+            endpoints.push_back((*it)->last_point());
+        }
+    }
+    
+    while (!my_paths.empty()) {
+        // find nearest point
+        int start_index = start_near.nearest_point_index(endpoints);
+        int path_index = start_index/2;
+        ExtrusionEntity* entity = my_paths.at(path_index);
+        // never reverse loops, since it's pointless for chained path and callers might depend on orientation
+        if (start_index % 2 && !no_reverse && entity->can_reverse()) {
+            entity->reverse();
+        }
+        retval->entities.push_back(my_paths.at(path_index));
+        if (orig_indices != NULL) orig_indices->push_back(indices_map[entity]);
+        my_paths.erase(my_paths.begin() + path_index);
+        endpoints.erase(endpoints.begin() + 2*path_index, endpoints.begin() + 2*path_index + 2);
+        start_near = retval->entities.back()->last_point();
+    }
+}
+
+void ExtrusionEntityCollection::polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const
+{
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it)
+        (*it)->polygons_covered_by_width(out, scaled_epsilon);
+}
+
+void ExtrusionEntityCollection::polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const
+{
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it)
+        (*it)->polygons_covered_by_spacing(out, scaled_epsilon);
+}
+
+/* Recursively count paths and loops contained in this collection */
+size_t
+ExtrusionEntityCollection::items_count() const
+{
+    size_t count = 0;
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
+        if ((*it)->is_collection()) {
+            ExtrusionEntityCollection* collection = dynamic_cast<ExtrusionEntityCollection*>(*it);
+            count += collection->items_count();
+        } else {
+            ++count;
+        }
+    }
+    return count;
+}
+
+/* Returns a single vector of pointers to all non-collection items contained in this one */
+void
+ExtrusionEntityCollection::flatten(ExtrusionEntityCollection* retval) const
+{
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it) {
+        if ((*it)->is_collection()) {
+            ExtrusionEntityCollection* collection = dynamic_cast<ExtrusionEntityCollection*>(*it);
+            retval->append(collection->flatten().entities);
+        } else {
+            retval->append(**it);
+        }
+    }
+}
+
+ExtrusionEntityCollection
+ExtrusionEntityCollection::flatten() const
+{
+    ExtrusionEntityCollection coll;
+    this->flatten(&coll);
+    return coll;
+}
+
+double
+ExtrusionEntityCollection::min_mm3_per_mm() const
+{
+    double min_mm3_per_mm = std::numeric_limits<double>::max();
+    for (ExtrusionEntitiesPtr::const_iterator it = this->entities.begin(); it != this->entities.end(); ++it)
+        min_mm3_per_mm = std::min(min_mm3_per_mm, (*it)->min_mm3_per_mm());
+    return min_mm3_per_mm;
+}
+
+}

src/libslic3r/ExtrusionEntityCollection.hpp

@@ -0,0 +1,108 @@
+#ifndef slic3r_ExtrusionEntityCollection_hpp_
+#define slic3r_ExtrusionEntityCollection_hpp_
+
+#include "libslic3r.h"
+#include "ExtrusionEntity.hpp"
+
+namespace Slic3r {
+
+class ExtrusionEntityCollection : public ExtrusionEntity
+{
+public:
+    ExtrusionEntityCollection* clone() const;
+    ExtrusionEntitiesPtr entities;     // we own these entities
+    std::vector<size_t> orig_indices;  // handy for XS
+    bool no_sort;
+    ExtrusionEntityCollection(): no_sort(false) {};
+    ExtrusionEntityCollection(const ExtrusionEntityCollection &other) : orig_indices(other.orig_indices), no_sort(other.no_sort) { this->append(other.entities); }
+    ExtrusionEntityCollection(ExtrusionEntityCollection &&other) : entities(std::move(other.entities)), orig_indices(std::move(other.orig_indices)), no_sort(other.no_sort) {}
+    explicit ExtrusionEntityCollection(const ExtrusionPaths &paths);
+    ExtrusionEntityCollection& operator=(const ExtrusionEntityCollection &other);
+    ExtrusionEntityCollection& operator=(ExtrusionEntityCollection &&other) 
+        { this->entities = std::move(other.entities); this->orig_indices = std::move(other.orig_indices); this->no_sort = other.no_sort; return *this; }
+    ~ExtrusionEntityCollection() { clear(); }
+    explicit operator ExtrusionPaths() const;
+    
+    bool is_collection() const { return true; };
+    ExtrusionRole role() const override {
+        ExtrusionRole out = erNone;
+        for (const ExtrusionEntity *ee : entities) {
+            ExtrusionRole er = ee->role();
+            out = (out == erNone || out == er) ? er : erMixed;
+        }
+        return out;
+    }
+    bool can_reverse() const { return !this->no_sort; };
+    bool empty() const { return this->entities.empty(); };
+    void clear();
+    void swap (ExtrusionEntityCollection &c);
+    void append(const ExtrusionEntity &entity) { this->entities.push_back(entity.clone()); }
+    void append(const ExtrusionEntitiesPtr &entities) { 
+        this->entities.reserve(this->entities.size() + entities.size());
+        for (ExtrusionEntitiesPtr::const_iterator ptr = entities.begin(); ptr != entities.end(); ++ptr)
+            this->entities.push_back((*ptr)->clone());
+    }
+    void append(ExtrusionEntitiesPtr &&src) {
+        if (entities.empty())
+            entities = std::move(src);
+        else {
+            std::move(std::begin(src), std::end(src), std::back_inserter(entities));
+            src.clear();
+        }
+    }
+    void append(const ExtrusionPaths &paths) {
+        this->entities.reserve(this->entities.size() + paths.size());
+        for (const ExtrusionPath &path : paths)
+            this->entities.emplace_back(path.clone());
+    }
+    void append(ExtrusionPaths &&paths) {
+        this->entities.reserve(this->entities.size() + paths.size());
+        for (ExtrusionPath &path : paths)
+            this->entities.emplace_back(new ExtrusionPath(std::move(path)));
+    }
+    void replace(size_t i, const ExtrusionEntity &entity);
+    void remove(size_t i);
+    ExtrusionEntityCollection chained_path(bool no_reverse = false, ExtrusionRole role = erMixed) const;
+    void chained_path(ExtrusionEntityCollection* retval, bool no_reverse = false, ExtrusionRole role = erMixed, std::vector<size_t>* orig_indices = nullptr) const;
+    ExtrusionEntityCollection chained_path_from(Point start_near, bool no_reverse = false, ExtrusionRole role = erMixed) const;
+    void chained_path_from(Point start_near, ExtrusionEntityCollection* retval, bool no_reverse = false, ExtrusionRole role = erMixed, std::vector<size_t>* orig_indices = nullptr) const;
+    void reverse();
+    Point first_point() const { return this->entities.front()->first_point(); }
+    Point last_point() const { return this->entities.back()->last_point(); }
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion width.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    void polygons_covered_by_width(Polygons &out, const float scaled_epsilon) const override;
+    // Produce a list of 2D polygons covered by the extruded paths, offsetted by the extrusion spacing.
+    // Increase the offset by scaled_epsilon to achieve an overlap, so a union will produce no gaps.
+    // Useful to calculate area of an infill, which has been really filled in by a 100% rectilinear infill.
+    void polygons_covered_by_spacing(Polygons &out, const float scaled_epsilon) const override;
+    Polygons polygons_covered_by_width(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_width(out, scaled_epsilon); return out; }
+    Polygons polygons_covered_by_spacing(const float scaled_epsilon = 0.f) const
+        { Polygons out; this->polygons_covered_by_spacing(out, scaled_epsilon); return out; }
+    size_t items_count() const;
+    void flatten(ExtrusionEntityCollection* retval) const;
+    ExtrusionEntityCollection flatten() const;
+    double min_mm3_per_mm() const;
+    double total_volume() const override { double volume=0.; for (const auto& ent : entities) volume+=ent->total_volume(); return volume; }
+
+    // Following methods shall never be called on an ExtrusionEntityCollection.
+    Polyline as_polyline() const {
+        throw std::runtime_error("Calling as_polyline() on a ExtrusionEntityCollection");
+        return Polyline();
+    };
+
+    void collect_polylines(Polylines &dst) const override {
+        for (ExtrusionEntity* extrusion_entity : this->entities)
+            extrusion_entity->collect_polylines(dst);
+    }
+
+    double length() const override {
+        throw std::runtime_error("Calling length() on a ExtrusionEntityCollection");
+        return 0.;        
+    }
+};
+
+}
+
+#endif

src/libslic3r/ExtrusionSimulator.hpp

@@ -0,0 +1,59 @@
+#ifndef slic3r_ExtrusionSimulator_hpp_
+#define slic3r_ExtrusionSimulator_hpp_
+
+#include "libslic3r.h"
+#include "ExtrusionEntity.hpp"
+#include "BoundingBox.hpp"
+
+namespace Slic3r {
+
+enum ExtrusionSimulationType
+{
+    ExtrusionSimulationSimple,
+    ExtrusionSimulationDontSpread,
+    ExtrisopmSimulationSpreadNotOverfilled,
+    ExtrusionSimulationSpreadFull,
+    ExtrusionSimulationSpreadExcess
+};
+
+// An opaque class, to keep the boost stuff away from the header.
+class ExtrusionSimulatorImpl;
+
+class ExtrusionSimulator
+{
+public:
+    ExtrusionSimulator();
+    ~ExtrusionSimulator();
+
+    // Size of the image, that will be returned by image_ptr().
+    // The image may be bigger than the viewport as many graphics drivers 
+    // expect the size of a texture to be rounded to a power of two.
+    void  		set_image_size(const Point &image_size);
+    // Which part of the image shall be rendered to?
+    void  		set_viewport(const BoundingBox &viewport);
+    // Shift and scale of the rendered extrusion paths into the viewport.
+    void		set_bounding_box(const BoundingBox &bbox);
+
+    // Reset the extrusion accumulator to zero for all buckets.
+    void		reset_accumulator();
+    // Paint a thick path into an extrusion buffer.
+    // A simple implementation is provided now, splatting a rectangular extrusion for each linear segment.
+    // In the future, spreading and suqashing of a material will be simulated.
+    void		extrude_to_accumulator(const ExtrusionPath &path, const Point &shift, ExtrusionSimulationType simulationType);
+    // Evaluate the content of the accumulator and paint it into the viewport.
+    // After this call the image_ptr() call will return a valid image.
+    void		evaluate_accumulator(ExtrusionSimulationType simulationType);
+    // An RGBA image of image_size, to be loaded into a GPU texture.
+    const void* image_ptr() const;
+
+private:
+	Point					    	image_size;
+	BoundingBox				    	viewport;
+	BoundingBox 					bbox;
+
+	ExtrusionSimulatorImpl		   *pimpl;
+};
+
+}
+
+#endif /* slic3r_ExtrusionSimulator_hpp_ */

src/libslic3r/FileParserError.hpp

@@ -0,0 +1,52 @@
+#ifndef slic3r_FileParserError_hpp_
+#define slic3r_FileParserError_hpp_
+
+#include "libslic3r.h"
+
+#include <string>
+#include <boost/filesystem/path.hpp>
+#include <stdexcept>
+
+namespace Slic3r {
+
+// Generic file parser error, mostly copied from boost::property_tree::file_parser_error
+class file_parser_error: public std::runtime_error
+{
+public:
+    file_parser_error(const std::string &msg, const std::string &file, unsigned long line = 0) :
+        std::runtime_error(format_what(msg, file, line)),
+        m_message(msg), m_filename(file), m_line(line) {}
+    file_parser_error(const std::string &msg, const boost::filesystem::path &file, unsigned long line = 0) :
+        std::runtime_error(format_what(msg, file.string(), line)),
+        m_message(msg), m_filename(file.string()), m_line(line) {}
+    // gcc 3.4.2 complains about lack of throw specifier on compiler
+    // generated dtor
+    ~file_parser_error() throw() {}
+
+    // Get error message (without line and file - use what() to get full message)
+    std::string message() const { return m_message; }
+    // Get error filename
+    std::string filename() const { return m_filename; }
+    // Get error line number
+    unsigned long line() const { return m_line; }
+
+private:
+    std::string     m_message;
+    std::string     m_filename;
+    unsigned long   m_line;
+
+    // Format error message to be returned by std::runtime_error::what()
+    static std::string format_what(const std::string &msg, const std::string &file, unsigned long l)
+    {
+        std::stringstream stream;
+        stream << (file.empty() ? "<unspecified file>" : file.c_str());
+        if (l > 0)
+            stream << '(' << l << ')';
+        stream << ": " << msg;
+        return stream.str();
+    }
+};
+
+}; // Slic3r
+
+#endif // slic3r_FileParserError_hpp_

src/libslic3r/Fill/Fill.cpp

@@ -0,0 +1,271 @@
+#include <assert.h>
+#include <stdio.h>
+#include <memory>
+
+#include "../ClipperUtils.hpp"
+#include "../Geometry.hpp"
+#include "../Layer.hpp"
+#include "../Print.hpp"
+#include "../PrintConfig.hpp"
+#include "../Surface.hpp"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+struct SurfaceGroupAttrib
+{
+    SurfaceGroupAttrib() : is_solid(false), flow_width(0.f), pattern(-1) {}
+    bool operator==(const SurfaceGroupAttrib &other) const
+        { return is_solid == other.is_solid && flow_width == other.flow_width && pattern == other.pattern; }
+    bool    is_solid;
+    float   flow_width;
+    // pattern is of type InfillPattern, -1 for an unset pattern.
+    int     pattern;
+};
+
+// Generate infills for Slic3r::Layer::Region.
+// The Slic3r::Layer::Region at this point of time may contain
+// surfaces of various types (internal/bridge/top/bottom/solid).
+// The infills are generated on the groups of surfaces with a compatible type. 
+// Returns an array of Slic3r::ExtrusionPath::Collection objects containing the infills generaed now
+// and the thin fills generated by generate_perimeters().
+void make_fill(LayerRegion &layerm, ExtrusionEntityCollection &out)
+{    
+//    Slic3r::debugf "Filling layer %d:\n", $layerm->layer->id;
+    
+    double  fill_density           = layerm.region()->config().fill_density;
+    Flow    infill_flow            = layerm.flow(frInfill);
+    Flow    solid_infill_flow      = layerm.flow(frSolidInfill);
+    Flow    top_solid_infill_flow  = layerm.flow(frTopSolidInfill);
+
+    Surfaces surfaces;
+    
+    // merge adjacent surfaces
+    // in case of bridge surfaces, the ones with defined angle will be attached to the ones
+    // without any angle (shouldn't this logic be moved to process_external_surfaces()?)
+    {
+        Polygons polygons_bridged;
+        polygons_bridged.reserve(layerm.fill_surfaces.surfaces.size());
+        for (Surfaces::iterator it = layerm.fill_surfaces.surfaces.begin(); it != layerm.fill_surfaces.surfaces.end(); ++ it)
+            if (it->bridge_angle >= 0)
+                polygons_append(polygons_bridged, *it);
+        
+        // group surfaces by distinct properties (equal surface_type, thickness, thickness_layers, bridge_angle)
+        // group is of type Slic3r::SurfaceCollection
+        //FIXME: Use some smart heuristics to merge similar surfaces to eliminate tiny regions.
+        std::vector<SurfacesPtr> groups;
+        layerm.fill_surfaces.group(&groups);
+        
+        // merge compatible groups (we can generate continuous infill for them)
+        {
+            // cache flow widths and patterns used for all solid groups
+            // (we'll use them for comparing compatible groups)
+            std::vector<SurfaceGroupAttrib> group_attrib(groups.size());
+            for (size_t i = 0; i < groups.size(); ++ i) {
+                // we can only merge solid non-bridge surfaces, so discard
+                // non-solid surfaces
+                const Surface &surface = *groups[i].front();
+                if (surface.is_solid() && (!surface.is_bridge() || layerm.layer()->id() == 0)) {
+                    group_attrib[i].is_solid = true;
+                    group_attrib[i].flow_width = (surface.surface_type == stTop) ? top_solid_infill_flow.width : solid_infill_flow.width;
+                    group_attrib[i].pattern = surface.is_external() ? layerm.region()->config().external_fill_pattern.value : ipRectilinear;
+                }
+            }
+            // Loop through solid groups, find compatible groups and append them to this one.
+            for (size_t i = 0; i < groups.size(); ++ i) {
+                if (! group_attrib[i].is_solid)
+                    continue;
+                for (size_t j = i + 1; j < groups.size();) {
+                    if (group_attrib[i] == group_attrib[j]) {
+                        // groups are compatible, merge them
+                        groups[i].insert(groups[i].end(), groups[j].begin(), groups[j].end());
+                        groups.erase(groups.begin() + j);
+                        group_attrib.erase(group_attrib.begin() + j);
+                    } else
+                         ++ j;
+                }
+            }
+        }
+        
+        // Give priority to bridges. Process the bridges in the first round, the rest of the surfaces in the 2nd round.
+        for (size_t round = 0; round < 2; ++ round) {
+            for (std::vector<SurfacesPtr>::iterator it_group = groups.begin(); it_group != groups.end(); ++ it_group) {
+                const SurfacesPtr &group = *it_group;
+                bool is_bridge = group.front()->bridge_angle >= 0;
+                if (is_bridge != (round == 0))
+                    continue;
+                // Make a union of polygons defining the infiill regions of a group, use a safety offset.
+                Polygons union_p = union_(to_polygons(*it_group), true);
+                // Subtract surfaces having a defined bridge_angle from any other, use a safety offset.
+                if (! polygons_bridged.empty() && ! is_bridge)
+                    union_p = diff(union_p, polygons_bridged, true);
+                // subtract any other surface already processed
+                //FIXME Vojtech: Because the bridge surfaces came first, they are subtracted twice!
+                // Using group.front() as a template.
+                surfaces_append(surfaces, diff_ex(union_p, to_polygons(surfaces), true), *group.front());
+            }
+        }
+    }
+    
+    // we need to detect any narrow surfaces that might collapse
+    // when adding spacing below
+    // such narrow surfaces are often generated in sloping walls
+    // by bridge_over_infill() and combine_infill() as a result of the
+    // subtraction of the combinable area from the layer infill area,
+    // which leaves small areas near the perimeters
+    // we are going to grow such regions by overlapping them with the void (if any)
+    // TODO: detect and investigate whether there could be narrow regions without
+    // any void neighbors
+    {
+        coord_t distance_between_surfaces = std::max(
+            std::max(infill_flow.scaled_spacing(), solid_infill_flow.scaled_spacing()),
+            top_solid_infill_flow.scaled_spacing());
+        Polygons surfaces_polygons = to_polygons(surfaces);
+        Polygons collapsed = diff(
+            surfaces_polygons,
+            offset2(surfaces_polygons, -distance_between_surfaces/2, +distance_between_surfaces/2),
+            true);
+        Polygons to_subtract;
+        to_subtract.reserve(collapsed.size() + number_polygons(surfaces));
+        for (Surfaces::const_iterator it_surface = surfaces.begin(); it_surface != surfaces.end(); ++ it_surface)
+            if (it_surface->surface_type == stInternalVoid)
+                polygons_append(to_subtract, *it_surface);
+        polygons_append(to_subtract, collapsed);
+        surfaces_append(
+            surfaces,
+            intersection_ex(
+                offset(collapsed, distance_between_surfaces),
+                to_subtract,
+                true),
+            stInternalSolid);
+    }
+
+    if (0) {
+//        require "Slic3r/SVG.pm";
+//        Slic3r::SVG::output("fill_" . $layerm->print_z . ".svg",
+//            expolygons      => [ map $_->expolygon, grep !$_->is_solid, @surfaces ],
+//            red_expolygons  => [ map $_->expolygon, grep  $_->is_solid, @surfaces ],
+//        );
+    }
+
+    for (const Surface &surface : surfaces) {
+        if (surface.surface_type == stInternalVoid)
+            continue;
+        InfillPattern  fill_pattern = layerm.region()->config().fill_pattern.value;
+        double         density      = fill_density;
+        FlowRole role = (surface.surface_type == stTop) ? frTopSolidInfill :
+            (surface.is_solid() ? frSolidInfill : frInfill);
+        bool is_bridge = layerm.layer()->id() > 0 && surface.is_bridge();
+        
+        if (surface.is_solid()) {
+            density = 100.;
+            fill_pattern = (surface.is_external() && ! is_bridge) ? 
+                layerm.region()->config().external_fill_pattern.value :
+                ipRectilinear;
+        } else if (density <= 0)
+            continue;
+        
+        // get filler object
+        std::unique_ptr<Fill> f = std::unique_ptr<Fill>(Fill::new_from_type(fill_pattern));
+        f->set_bounding_box(layerm.layer()->object()->bounding_box());
+        
+        // calculate the actual flow we'll be using for this infill
+        coordf_t h = (surface.thickness == -1) ? layerm.layer()->height : surface.thickness;
+        Flow flow = layerm.region()->flow(
+            role,
+            h,
+            is_bridge || f->use_bridge_flow(),  // bridge flow?
+            layerm.layer()->id() == 0,          // first layer?
+            -1,                                 // auto width
+            *layerm.layer()->object()
+        );
+        
+        // calculate flow spacing for infill pattern generation
+        bool using_internal_flow = false;
+        if (! surface.is_solid() && ! is_bridge) {
+            // it's internal infill, so we can calculate a generic flow spacing 
+            // for all layers, for avoiding the ugly effect of
+            // misaligned infill on first layer because of different extrusion width and
+            // layer height
+            Flow internal_flow = layerm.region()->flow(
+                frInfill,
+                layerm.layer()->object()->config().layer_height.value,  // TODO: handle infill_every_layers?
+                false,  // no bridge
+                false,  // no first layer
+                -1,     // auto width
+                *layerm.layer()->object()
+            );
+            f->spacing = internal_flow.spacing();
+            using_internal_flow = true;
+        } else {
+            f->spacing = flow.spacing();
+        }
+
+        double link_max_length = 0.;
+        if (! is_bridge) {
+#if 0
+            link_max_length = layerm.region()->config().get_abs_value(surface.is_external() ? "external_fill_link_max_length" : "fill_link_max_length", flow.spacing());
+//            printf("flow spacing: %f,  is_external: %d, link_max_length: %lf\n", flow.spacing(), int(surface.is_external()), link_max_length);
+#else
+            if (density > 80.) // 80%
+                link_max_length = 3. * f->spacing;
+#endif
+        }
+
+        f->layer_id = layerm.layer()->id();
+        f->z = layerm.layer()->print_z;
+        f->angle = float(Geometry::deg2rad(layerm.region()->config().fill_angle.value));
+        // Maximum length of the perimeter segment linking two infill lines.
+        f->link_max_length = scale_(link_max_length);
+        // Used by the concentric infill pattern to clip the loops to create extrusion paths.
+        f->loop_clipping = scale_(flow.nozzle_diameter) * LOOP_CLIPPING_LENGTH_OVER_NOZZLE_DIAMETER;
+//        f->layer_height = h;
+
+        // apply half spacing using this flow's own spacing and generate infill
+        FillParams params;
+        params.density = 0.01 * density;
+//        params.dont_adjust = true;
+        params.dont_adjust = false;
+        Polylines polylines = f->fill_surface(&surface, params);
+        if (polylines.empty())
+            continue;
+
+        // calculate actual flow from spacing (which might have been adjusted by the infill
+        // pattern generator)
+        if (using_internal_flow) {
+            // if we used the internal flow we're not doing a solid infill
+            // so we can safely ignore the slight variation that might have
+            // been applied to $f->flow_spacing
+        } else {
+            flow = Flow::new_from_spacing(f->spacing, flow.nozzle_diameter, h, is_bridge || f->use_bridge_flow());
+        }
+
+        // Save into layer.
+        auto *eec = new ExtrusionEntityCollection();
+        out.entities.push_back(eec);
+        // Only concentric fills are not sorted.
+        eec->no_sort = f->no_sort();
+        extrusion_entities_append_paths(
+            eec->entities, std::move(polylines),
+            is_bridge ?
+                erBridgeInfill :
+                (surface.is_solid() ?
+                    ((surface.surface_type == stTop) ? erTopSolidInfill : erSolidInfill) :
+                    erInternalInfill),
+            flow.mm3_per_mm(), flow.width, flow.height);
+    }
+
+    // add thin fill regions
+    // thin_fills are of C++ Slic3r::ExtrusionEntityCollection, perl type Slic3r::ExtrusionPath::Collection
+    // Unpacks the collection, creates multiple collections per path.
+    // The path type could be ExtrusionPath, ExtrusionLoop or ExtrusionEntityCollection.
+    // Why the paths are unpacked?
+    for (const ExtrusionEntity *thin_fill : layerm.thin_fills.entities) {
+        ExtrusionEntityCollection &collection = *(new ExtrusionEntityCollection());
+        out.entities.push_back(&collection);
+        collection.entities.push_back(thin_fill->clone());
+    }
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/Fill.hpp

@@ -0,0 +1,36 @@
+#ifndef slic3r_Fill_hpp_
+#define slic3r_Fill_hpp_
+
+#include <memory.h>
+#include <float.h>
+#include <stdint.h>
+
+#include "../libslic3r.h"
+#include "../BoundingBox.hpp"
+#include "../PrintConfig.hpp"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class ExtrusionEntityCollection;
+class LayerRegion;
+
+// An interface class to Perl, aggregating an instance of a Fill and a FillData.
+class Filler
+{
+public:
+    Filler() : fill(NULL) {}
+    ~Filler() { 
+        delete fill; 
+        fill = NULL;
+    }
+    Fill        *fill;
+    FillParams   params;
+};
+
+void make_fill(LayerRegion &layerm, ExtrusionEntityCollection &out);
+
+} // namespace Slic3r
+
+#endif // slic3r_Fill_hpp_

src/libslic3r/Fill/Fill3DHoneycomb.cpp

@@ -0,0 +1,204 @@
+#include "../ClipperUtils.hpp"
+#include "../PolylineCollection.hpp"
+#include "../Surface.hpp"
+
+#include "Fill3DHoneycomb.hpp"
+
+namespace Slic3r {
+
+/*
+Creates a contiguous sequence of points at a specified height that make
+up a horizontal slice of the edges of a space filling truncated
+octahedron tesselation. The octahedrons are oriented so that the
+square faces are in the horizontal plane with edges parallel to the X
+and Y axes.
+
+Credits: David Eccles (gringer).
+*/
+
+// Generate an array of points that are in the same direction as the
+// basic printing line (i.e. Y points for columns, X points for rows)
+// Note: a negative offset only causes a change in the perpendicular
+// direction
+static std::vector<coordf_t> colinearPoints(const coordf_t offset, const size_t baseLocation, size_t gridLength)
+{
+    const coordf_t offset2 = std::abs(offset / coordf_t(2.));
+    std::vector<coordf_t> points;
+    points.push_back(baseLocation - offset2);
+    for (size_t i = 0; i < gridLength; ++i) {
+        points.push_back(baseLocation + i + offset2);
+        points.push_back(baseLocation + i + 1 - offset2);
+    }
+    points.push_back(baseLocation + gridLength + offset2);
+    return points;
+}
+
+// Generate an array of points for the dimension that is perpendicular to
+// the basic printing line (i.e. X points for columns, Y points for rows)
+static std::vector<coordf_t> perpendPoints(const coordf_t offset, const size_t baseLocation, size_t gridLength)
+{
+    coordf_t offset2 = offset / coordf_t(2.);
+    coord_t  side    = 2 * (baseLocation & 1) - 1;
+    std::vector<coordf_t> points;
+    points.push_back(baseLocation - offset2 * side);
+    for (size_t i = 0; i < gridLength; ++i) {
+        side = 2*((i+baseLocation) & 1) - 1;
+        points.push_back(baseLocation + offset2 * side);
+        points.push_back(baseLocation + offset2 * side);
+    }
+    points.push_back(baseLocation - offset2 * side);
+    return points;
+}
+
+// Trims an array of points to specified rectangular limits. Point
+// components that are outside these limits are set to the limits.
+static inline void trim(Pointfs &pts, coordf_t minX, coordf_t minY, coordf_t maxX, coordf_t maxY)
+{
+    for (Vec2d &pt : pts) {
+        pt(0) = clamp(minX, maxX, pt(0));
+        pt(1) = clamp(minY, maxY, pt(1));
+    }
+}
+
+static inline Pointfs zip(const std::vector<coordf_t> &x, const std::vector<coordf_t> &y)
+{
+    assert(x.size() == y.size());
+    Pointfs out;
+    out.reserve(x.size());
+    for (size_t i = 0; i < x.size(); ++ i)
+        out.push_back(Vec2d(x[i], y[i]));
+    return out;
+}
+
+// Generate a set of curves (array of array of 2d points) that describe a
+// horizontal slice of a truncated regular octahedron with edge length 1.
+// curveType specifies which lines to print, 1 for vertical lines
+// (columns), 2 for horizontal lines (rows), and 3 for both.
+static std::vector<Pointfs> makeNormalisedGrid(coordf_t z, size_t gridWidth, size_t gridHeight, size_t curveType)
+{
+    // offset required to create a regular octagram
+    coordf_t octagramGap = coordf_t(0.5);
+    
+    // sawtooth wave function for range f($z) = [-$octagramGap .. $octagramGap]
+    coordf_t a = std::sqrt(coordf_t(2.));  // period
+    coordf_t wave = fabs(fmod(z, a) - a/2.)/a*4. - 1.;
+    coordf_t offset = wave * octagramGap;
+    
+    std::vector<Pointfs> points;
+    if ((curveType & 1) != 0) {
+        for (size_t x = 0; x <= gridWidth; ++x) {
+            points.push_back(Pointfs());
+            Pointfs &newPoints = points.back();
+            newPoints = zip(
+                perpendPoints(offset, x, gridHeight), 
+                colinearPoints(offset, 0, gridHeight));
+            // trim points to grid edges
+            trim(newPoints, coordf_t(0.), coordf_t(0.), coordf_t(gridWidth), coordf_t(gridHeight));
+            if (x & 1)
+                std::reverse(newPoints.begin(), newPoints.end());
+        }
+    }
+    if ((curveType & 2) != 0) {
+        for (size_t y = 0; y <= gridHeight; ++y) {
+            points.push_back(Pointfs());
+            Pointfs &newPoints = points.back();
+            newPoints = zip(
+                colinearPoints(offset, 0, gridWidth),
+                perpendPoints(offset, y, gridWidth));
+            // trim points to grid edges
+            trim(newPoints, coordf_t(0.), coordf_t(0.), coordf_t(gridWidth), coordf_t(gridHeight));
+            if (y & 1)
+                std::reverse(newPoints.begin(), newPoints.end());
+        }
+    }
+    return points;
+}
+
+// Generate a set of curves (array of array of 2d points) that describe a
+// horizontal slice of a truncated regular octahedron with a specified
+// grid square size.
+static Polylines makeGrid(coord_t z, coord_t gridSize, size_t gridWidth, size_t gridHeight, size_t curveType)
+{
+    coord_t  scaleFactor = gridSize;
+    coordf_t normalisedZ = coordf_t(z) / coordf_t(scaleFactor);
+    std::vector<Pointfs> polylines = makeNormalisedGrid(normalisedZ, gridWidth, gridHeight, curveType);
+    Polylines result;
+    result.reserve(polylines.size());
+    for (std::vector<Pointfs>::const_iterator it_polylines = polylines.begin(); it_polylines != polylines.end(); ++ it_polylines) {
+        result.push_back(Polyline());
+        Polyline &polyline = result.back();
+        for (Pointfs::const_iterator it = it_polylines->begin(); it != it_polylines->end(); ++ it)
+            polyline.points.push_back(Point(coord_t((*it)(0) * scaleFactor), coord_t((*it)(1) * scaleFactor)));
+    }
+    return result;
+}
+
+void Fill3DHoneycomb::_fill_surface_single(
+    const FillParams                &params, 
+    unsigned int                     thickness_layers,
+    const std::pair<float, Point>   &direction, 
+    ExPolygon                       &expolygon, 
+    Polylines                       &polylines_out)
+{
+    // no rotation is supported for this infill pattern
+    BoundingBox bb = expolygon.contour.bounding_box();
+    coord_t     distance = coord_t(scale_(this->spacing) / params.density);
+
+    // align bounding box to a multiple of our honeycomb grid module
+    // (a module is 2*$distance since one $distance half-module is 
+    // growing while the other $distance half-module is shrinking)
+    bb.merge(_align_to_grid(bb.min, Point(2*distance, 2*distance)));
+    
+    // generate pattern
+    Polylines   polylines = makeGrid(
+        scale_(this->z),
+        distance,
+        ceil(bb.size()(0) / distance) + 1,
+        ceil(bb.size()(1) / distance) + 1,
+        ((this->layer_id/thickness_layers) % 2) + 1);
+    
+    // move pattern in place
+    for (Polylines::iterator it = polylines.begin(); it != polylines.end(); ++ it)
+        it->translate(bb.min(0), bb.min(1));
+
+    // clip pattern to boundaries
+    polylines = intersection_pl(polylines, (Polygons)expolygon);
+
+    // connect lines
+    if (! params.dont_connect && ! polylines.empty()) { // prevent calling leftmost_point() on empty collections
+        ExPolygon expolygon_off;
+        {
+            ExPolygons expolygons_off = offset_ex(expolygon, SCALED_EPSILON);
+            if (! expolygons_off.empty()) {
+                // When expanding a polygon, the number of islands could only shrink. Therefore the offset_ex shall generate exactly one expanded island for one input island.
+                assert(expolygons_off.size() == 1);
+                std::swap(expolygon_off, expolygons_off.front());
+            }
+        }
+        Polylines chained = PolylineCollection::chained_path_from(
+            std::move(polylines), 
+            PolylineCollection::leftmost_point(polylines), false); // reverse allowed
+        bool first = true;
+        for (Polylines::iterator it_polyline = chained.begin(); it_polyline != chained.end(); ++ it_polyline) {
+            if (! first) {
+                // Try to connect the lines.
+                Points &pts_end = polylines_out.back().points;
+                const Point &first_point = it_polyline->points.front();
+                const Point &last_point = pts_end.back();
+                // TODO: we should also check that both points are on a fill_boundary to avoid 
+                // connecting paths on the boundaries of internal regions
+                if ((last_point - first_point).cast<double>().norm() <= 1.5 * distance && 
+                    expolygon_off.contains(Line(last_point, first_point))) {
+                    // Append the polyline.
+                    pts_end.insert(pts_end.end(), it_polyline->points.begin(), it_polyline->points.end());
+                    continue;
+                }
+            }
+            // The lines cannot be connected.
+            polylines_out.emplace_back(std::move(*it_polyline));
+            first = false;
+        }
+    }
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/Fill3DHoneycomb.hpp

@@ -0,0 +1,32 @@
+#ifndef slic3r_Fill3DHoneycomb_hpp_
+#define slic3r_Fill3DHoneycomb_hpp_
+
+#include <map>
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class Fill3DHoneycomb : public Fill
+{
+public:
+    virtual Fill* clone() const { return new Fill3DHoneycomb(*this); };
+    virtual ~Fill3DHoneycomb() {}
+
+	// require bridge flow since most of this pattern hangs in air
+    virtual bool use_bridge_flow() const { return true; }
+
+protected:
+	virtual void _fill_surface_single(
+	    const FillParams                &params, 
+	    unsigned int                     thickness_layers,
+	    const std::pair<float, Point>   &direction, 
+	    ExPolygon                       &expolygon, 
+	    Polylines                       &polylines_out);
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_Fill3DHoneycomb_hpp_

src/libslic3r/Fill/FillBase.cpp

@@ -0,0 +1,133 @@
+#include <stdio.h>
+
+#include "../ClipperUtils.hpp"
+#include "../Surface.hpp"
+#include "../PrintConfig.hpp"
+
+#include "FillBase.hpp"
+#include "FillConcentric.hpp"
+#include "FillHoneycomb.hpp"
+#include "Fill3DHoneycomb.hpp"
+#include "FillGyroid.hpp"
+#include "FillPlanePath.hpp"
+#include "FillRectilinear.hpp"
+#include "FillRectilinear2.hpp"
+#include "FillRectilinear3.hpp"
+
+namespace Slic3r {
+
+Fill* Fill::new_from_type(const InfillPattern type)
+{
+    switch (type) {
+    case ipConcentric:          return new FillConcentric();
+    case ipHoneycomb:           return new FillHoneycomb();
+    case ip3DHoneycomb:         return new Fill3DHoneycomb();
+    case ipGyroid:              return new FillGyroid();
+    case ipRectilinear:         return new FillRectilinear2();
+//  case ipRectilinear:         return new FillRectilinear();
+    case ipLine:                return new FillLine();
+    case ipGrid:                return new FillGrid2();
+    case ipTriangles:           return new FillTriangles();
+    case ipStars:               return new FillStars();
+    case ipCubic:               return new FillCubic();
+//  case ipGrid:                return new FillGrid();
+    case ipArchimedeanChords:   return new FillArchimedeanChords();
+    case ipHilbertCurve:        return new FillHilbertCurve();
+    case ipOctagramSpiral:      return new FillOctagramSpiral();
+    default: throw std::invalid_argument("unknown type");;
+    }
+}
+
+Fill* Fill::new_from_type(const std::string &type)
+{
+    const t_config_enum_values &enum_keys_map = ConfigOptionEnum<InfillPattern>::get_enum_values();
+    t_config_enum_values::const_iterator it = enum_keys_map.find(type);
+    return (it == enum_keys_map.end()) ? nullptr : new_from_type(InfillPattern(it->second));
+}
+
+Polylines Fill::fill_surface(const Surface *surface, const FillParams &params)
+{
+    // Perform offset.
+    Slic3r::ExPolygons expp = offset_ex(surface->expolygon, float(scale_(this->overlap - 0.5 * this->spacing)));
+    // Create the infills for each of the regions.
+    Polylines polylines_out;
+    for (size_t i = 0; i < expp.size(); ++ i)
+        _fill_surface_single(
+            params,
+            surface->thickness_layers,
+            _infill_direction(surface),
+            expp[i],
+            polylines_out);
+    return polylines_out;
+}
+
+// Calculate a new spacing to fill width with possibly integer number of lines,
+// the first and last line being centered at the interval ends.
+// This function possibly increases the spacing, never decreases, 
+// and for a narrow width the increase in spacing may become severe,
+// therefore the adjustment is limited to 20% increase.
+coord_t Fill::_adjust_solid_spacing(const coord_t width, const coord_t distance)
+{
+    assert(width >= 0);
+    assert(distance > 0);
+    // floor(width / distance)
+    coord_t number_of_intervals = (width - EPSILON) / distance;
+    coord_t distance_new = (number_of_intervals == 0) ? 
+        distance : 
+        ((width - EPSILON) / number_of_intervals);
+    const coordf_t factor = coordf_t(distance_new) / coordf_t(distance);
+    assert(factor > 1. - 1e-5);
+    // How much could the extrusion width be increased? By 20%.
+    const coordf_t factor_max = 1.2;
+    if (factor > factor_max)
+        distance_new = coord_t(floor((coordf_t(distance) * factor_max + 0.5)));
+    return distance_new;
+}
+
+// Returns orientation of the infill and the reference point of the infill pattern.
+// For a normal print, the reference point is the center of a bounding box of the STL.
+std::pair<float, Point> Fill::_infill_direction(const Surface *surface) const
+{
+    // set infill angle
+    float out_angle = this->angle;
+
+	if (out_angle == FLT_MAX) {
+		//FIXME Vojtech: Add a warning?
+        printf("Using undefined infill angle\n");
+        out_angle = 0.f;
+    }
+
+    // Bounding box is the bounding box of a perl object Slic3r::Print::Object (c++ object Slic3r::PrintObject)
+    // The bounding box is only undefined in unit tests.
+    Point out_shift = empty(this->bounding_box) ? 
+    	surface->expolygon.contour.bounding_box().center() : 
+        this->bounding_box.center();
+
+#if 0
+    if (empty(this->bounding_box)) {
+        printf("Fill::_infill_direction: empty bounding box!");
+    } else {
+        printf("Fill::_infill_direction: reference point %d, %d\n", out_shift.x, out_shift.y);
+    }
+#endif
+
+    if (surface->bridge_angle >= 0) {
+	    // use bridge angle
+		//FIXME Vojtech: Add a debugf?
+        // Slic3r::debugf "Filling bridge with angle %d\n", rad2deg($surface->bridge_angle);
+#ifdef SLIC3R_DEBUG
+        printf("Filling bridge with angle %f\n", surface->bridge_angle);
+#endif /* SLIC3R_DEBUG */
+        out_angle = surface->bridge_angle;
+    } else if (this->layer_id != size_t(-1)) {
+        // alternate fill direction
+        out_angle += this->_layer_angle(this->layer_id / surface->thickness_layers);
+    } else {
+//    	printf("Layer_ID undefined!\n");
+    }
+
+    out_angle += float(M_PI/2.);
+    return std::pair<float, Point>(out_angle, out_shift);
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/FillBase.hpp

@@ -0,0 +1,133 @@
+#ifndef slic3r_FillBase_hpp_
+#define slic3r_FillBase_hpp_
+
+#include <assert.h>
+#include <memory.h>
+#include <float.h>
+#include <stdint.h>
+
+#include "../libslic3r.h"
+#include "../BoundingBox.hpp"
+#include "../PrintConfig.hpp"
+
+namespace Slic3r {
+
+class Surface;
+
+struct FillParams
+{
+    FillParams() { 
+        memset(this, 0, sizeof(FillParams));
+        // Adjustment does not work.
+        dont_adjust = true;
+    }
+
+    bool        full_infill() const { return density > 0.9999f; }
+
+    // Fill density, fraction in <0, 1>
+    float       density;
+
+    // Don't connect the fill lines around the inner perimeter.
+    bool        dont_connect;
+
+    // Don't adjust spacing to fill the space evenly.
+    bool        dont_adjust;
+
+    // For Honeycomb.
+    // we were requested to complete each loop;
+    // in this case we don't try to make more continuous paths
+    bool        complete;
+};
+
+class Fill
+{
+public:
+    // Index of the layer.
+    size_t      layer_id;
+    // Z coordinate of the top print surface, in unscaled coordinates
+    coordf_t    z;
+    // in unscaled coordinates
+    coordf_t    spacing;
+    // infill / perimeter overlap, in unscaled coordinates
+    coordf_t    overlap;
+    // in radians, ccw, 0 = East
+    float       angle;
+    // In scaled coordinates. Maximum lenght of a perimeter segment connecting two infill lines.
+    // Used by the FillRectilinear2, FillGrid2, FillTriangles, FillStars and FillCubic.
+    // If left to zero, the links will not be limited.
+    coord_t     link_max_length;
+    // In scaled coordinates. Used by the concentric infill pattern to clip the loops to create extrusion paths.
+    coord_t     loop_clipping;
+    // In scaled coordinates. Bounding box of the 2D projection of the object.
+    BoundingBox bounding_box;
+
+public:
+    virtual ~Fill() {}
+
+    static Fill* new_from_type(const InfillPattern type);
+    static Fill* new_from_type(const std::string &type);
+
+    void         set_bounding_box(const Slic3r::BoundingBox &bbox) { bounding_box = bbox; }
+
+    // Use bridge flow for the fill?
+    virtual bool use_bridge_flow() const { return false; }
+
+    // Do not sort the fill lines to optimize the print head path?
+    virtual bool no_sort() const { return false; }
+
+    // Perform the fill.
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+    Fill() :
+        layer_id(size_t(-1)),
+        z(0.),
+        spacing(0.),
+        // Infill / perimeter overlap.
+        overlap(0.),
+        // Initial angle is undefined.
+        angle(FLT_MAX),
+        link_max_length(0),
+        loop_clipping(0),
+        // The initial bounding box is empty, therefore undefined.
+        bounding_box(Point(0, 0), Point(-1, -1))
+        {}
+
+    // The expolygon may be modified by the method to avoid a copy.
+    virtual void    _fill_surface_single(
+        const FillParams                & /* params */, 
+        unsigned int                      /* thickness_layers */,
+        const std::pair<float, Point>   & /* direction */, 
+        ExPolygon                       & /* expolygon */, 
+        Polylines                       & /* polylines_out */) {};
+
+    virtual float _layer_angle(size_t idx) const { return (idx & 1) ? float(M_PI/2.) : 0; }
+
+    virtual std::pair<float, Point> _infill_direction(const Surface *surface) const;
+
+public:
+    static coord_t  _adjust_solid_spacing(const coord_t width, const coord_t distance);
+
+    // Align a coordinate to a grid. The coordinate may be negative,
+    // the aligned value will never be bigger than the original one.
+    static coord_t _align_to_grid(const coord_t coord, const coord_t spacing) {
+        // Current C++ standard defines the result of integer division to be rounded to zero,
+        // for both positive and negative numbers. Here we want to round down for negative
+        // numbers as well.
+        coord_t aligned = (coord < 0) ?
+        		((coord - spacing + 1) / spacing) * spacing :
+        		(coord / spacing) * spacing;
+        assert(aligned <= coord);
+        return aligned;
+    }
+    static Point   _align_to_grid(Point   coord, Point   spacing) 
+        { return Point(_align_to_grid(coord(0), spacing(0)), _align_to_grid(coord(1), spacing(1))); }
+    static coord_t _align_to_grid(coord_t coord, coord_t spacing, coord_t base) 
+        { return base + _align_to_grid(coord - base, spacing); }
+    static Point   _align_to_grid(Point   coord, Point   spacing, Point   base)
+        { return Point(_align_to_grid(coord(0), spacing(0), base(0)), _align_to_grid(coord(1), spacing(1), base(1))); }
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FillBase_hpp_

src/libslic3r/Fill/FillConcentric.cpp

@@ -0,0 +1,64 @@
+#include "../ClipperUtils.hpp"
+#include "../ExPolygon.hpp"
+#include "../Surface.hpp"
+
+#include "FillConcentric.hpp"
+
+namespace Slic3r {
+
+void FillConcentric::_fill_surface_single(
+    const FillParams                &params, 
+    unsigned int                     thickness_layers,
+    const std::pair<float, Point>   &direction, 
+    ExPolygon                       &expolygon, 
+    Polylines                       &polylines_out)
+{
+    // no rotation is supported for this infill pattern
+    BoundingBox bounding_box = expolygon.contour.bounding_box();
+    
+    coord_t min_spacing = scale_(this->spacing);
+    coord_t distance = coord_t(min_spacing / params.density);
+    
+    if (params.density > 0.9999f && !params.dont_adjust) {
+        distance = this->_adjust_solid_spacing(bounding_box.size()(0), distance);
+        this->spacing = unscale<double>(distance);
+    }
+
+    Polygons loops = (Polygons)expolygon;
+    Polygons last  = loops;
+    while (! last.empty()) {
+        last = offset2(last, -(distance + min_spacing/2), +min_spacing/2);
+        loops.insert(loops.end(), last.begin(), last.end());
+    }
+
+    // generate paths from the outermost to the innermost, to avoid
+    // adhesion problems of the first central tiny loops
+    loops = union_pt_chained(loops, false);
+    
+    // split paths using a nearest neighbor search
+    size_t iPathFirst = polylines_out.size();
+    Point last_pos(0, 0);
+    for (const Polygon &loop : loops) {
+        polylines_out.push_back(loop.split_at_index(last_pos.nearest_point_index(loop)));
+        last_pos = polylines_out.back().last_point();
+    }
+
+    // clip the paths to prevent the extruder from getting exactly on the first point of the loop
+    // Keep valid paths only.
+    size_t j = iPathFirst;
+    for (size_t i = iPathFirst; i < polylines_out.size(); ++ i) {
+        polylines_out[i].clip_end(this->loop_clipping);
+        if (polylines_out[i].is_valid()) {
+            if (j < i)
+                polylines_out[j] = std::move(polylines_out[i]);
+            ++ j;
+        }
+    }
+    if (j < polylines_out.size())
+        polylines_out.erase(polylines_out.begin() + j, polylines_out.end());
+    //TODO: return ExtrusionLoop objects to get better chained paths,
+    // otherwise the outermost loop starts at the closest point to (0, 0).
+    // We want the loops to be split inside the G-code generator to get optimum path planning.
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/FillConcentric.hpp

@@ -0,0 +1,27 @@
+#ifndef slic3r_FillConcentric_hpp_
+#define slic3r_FillConcentric_hpp_
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class FillConcentric : public Fill
+{
+public:
+    virtual ~FillConcentric() {}
+
+protected:
+    virtual Fill* clone() const { return new FillConcentric(*this); };
+	virtual void _fill_surface_single(
+	    const FillParams                &params, 
+	    unsigned int                     thickness_layers,
+	    const std::pair<float, Point>   &direction, 
+	    ExPolygon                       &expolygon, 
+	    Polylines                       &polylines_out);
+
+	virtual bool no_sort() const { return true; }
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FillConcentric_hpp_

src/libslic3r/Fill/FillGyroid.cpp

@@ -0,0 +1,196 @@
+#include "../ClipperUtils.hpp"
+#include "../PolylineCollection.hpp"
+#include "../Surface.hpp"
+#include <cmath>
+#include <algorithm>
+#include <iostream>
+
+#include "FillGyroid.hpp"
+
+namespace Slic3r {
+
+static inline double f(double x, double z_sin, double z_cos, bool vertical, bool flip)
+{
+    if (vertical) {
+        double phase_offset = (z_cos < 0 ? M_PI : 0) + M_PI;
+        double a   = sin(x + phase_offset);
+        double b   = - z_cos;
+        double res = z_sin * cos(x + phase_offset + (flip ? M_PI : 0.));
+        double r   = sqrt(sqr(a) + sqr(b));
+        return asin(a/r) + asin(res/r) + M_PI;
+    }
+    else {
+        double phase_offset = z_sin < 0 ? M_PI : 0.;
+        double a   = cos(x + phase_offset);
+        double b   = - z_sin;
+        double res = z_cos * sin(x + phase_offset + (flip ? 0 : M_PI));
+        double r   = sqrt(sqr(a) + sqr(b));
+        return (asin(a/r) + asin(res/r) + 0.5 * M_PI);
+    }
+}
+
+static inline Polyline make_wave(
+    const std::vector<Vec2d>& one_period, double width, double height, double offset, double scaleFactor,
+    double z_cos, double z_sin, bool vertical)
+{
+    std::vector<Vec2d> points = one_period;
+    double period = points.back()(0);
+    points.pop_back();
+    int n = points.size();
+    do {
+        points.emplace_back(Vec2d(points[points.size()-n](0) + period, points[points.size()-n](1)));
+    } while (points.back()(0) < width);
+    points.back()(0) = width;
+
+    // and construct the final polyline to return:
+    Polyline polyline;
+    for (auto& point : points) {
+        point(1) += offset;
+        point(1) = clamp(0., height, double(point(1)));
+        if (vertical)
+            std::swap(point(0), point(1));
+        polyline.points.emplace_back((point * scaleFactor).cast<coord_t>());
+    }
+
+    return polyline;
+}
+
+static std::vector<Vec2d> make_one_period(double width, double scaleFactor, double z_cos, double z_sin, bool vertical, bool flip)
+{
+    std::vector<Vec2d> points;
+    double dx = M_PI_4; // very coarse spacing to begin with
+    double limit = std::min(2*M_PI, width);
+    for (double x = 0.; x < limit + EPSILON; x += dx) {  // so the last point is there too
+        x = std::min(x, limit);
+        points.emplace_back(Vec2d(x,f(x, z_sin,z_cos, vertical, flip)));
+    }
+
+    // now we will check all internal points and in case some are too far from the line connecting its neighbours,
+    // we will add one more point on each side:
+    const double tolerance = .1;
+    for (unsigned int i=1;i<points.size()-1;++i) {
+        auto& lp = points[i-1]; // left point
+        auto& tp = points[i];   // this point
+        Vec2d lrv = tp - lp;
+        auto& rp = points[i+1]; // right point
+        // calculate distance of the point to the line:
+        double dist_mm = unscale<double>(scaleFactor) * std::abs(cross2(rp, lp) - cross2(rp - lp, tp)) / lrv.norm();
+        if (dist_mm > tolerance) {                               // if the difference from straight line is more than this
+            double x = 0.5f * (points[i-1](0) + points[i](0));
+            points.emplace_back(Vec2d(x, f(x, z_sin, z_cos, vertical, flip)));
+            x = 0.5f * (points[i+1](0) + points[i](0));
+            points.emplace_back(Vec2d(x, f(x, z_sin, z_cos, vertical, flip)));
+            // we added the points to the end, but need them all in order
+            std::sort(points.begin(), points.end(), [](const Vec2d &lhs, const Vec2d &rhs){ return lhs < rhs; });
+            // decrement i so we also check the first newly added point
+            --i;
+        }
+    }
+    return points;
+}
+
+static Polylines make_gyroid_waves(double gridZ, double density_adjusted, double line_spacing, double width, double height)
+{
+    const double scaleFactor = scale_(line_spacing) / density_adjusted;
+ //scale factor for 5% : 8 712 388
+ // 1z = 10^-6 mm ?
+    const double z     = gridZ / scaleFactor;
+    const double z_sin = sin(z);
+    const double z_cos = cos(z);
+
+    bool vertical = (std::abs(z_sin) <= std::abs(z_cos));
+    double lower_bound = 0.;
+    double upper_bound = height;
+    bool flip = true;
+    if (vertical) {
+        flip = false;
+        lower_bound = -M_PI;
+        upper_bound = width - M_PI_2;
+        std::swap(width,height);
+    }
+
+    std::vector<Vec2d> one_period = make_one_period(width, scaleFactor, z_cos, z_sin, vertical, flip); // creates one period of the waves, so it doesn't have to be recalculated all the time
+    Polylines result;
+
+    for (double y0 = lower_bound; y0 < upper_bound+EPSILON; y0 += 2*M_PI)           // creates odd polylines
+            result.emplace_back(make_wave(one_period, width, height, y0, scaleFactor, z_cos, z_sin, vertical));
+
+    flip = !flip;                                                                   // even polylines are a bit shifted
+    one_period = make_one_period(width, scaleFactor, z_cos, z_sin, vertical, flip); // updates the one period sample
+    for (double y0 = lower_bound + M_PI; y0 < upper_bound+EPSILON; y0 += 2*M_PI)    // creates even polylines
+            result.emplace_back(make_wave(one_period, width, height, y0, scaleFactor, z_cos, z_sin, vertical));
+
+    return result;
+}
+
+void FillGyroid::_fill_surface_single(
+    const FillParams                &params, 
+    unsigned int                     thickness_layers,
+    const std::pair<float, Point>   &direction, 
+    ExPolygon                       &expolygon, 
+    Polylines                       &polylines_out)
+{
+    // no rotation is supported for this infill pattern (yet)
+    BoundingBox bb = expolygon.contour.bounding_box();
+    // Density adjusted to have a good %of weight.
+    double      density_adjusted = std::max(0., params.density * 2.);
+    // Distance between the gyroid waves in scaled coordinates.
+    coord_t     distance = coord_t(scale_(this->spacing) / density_adjusted);
+
+    // align bounding box to a multiple of our grid module
+    bb.merge(_align_to_grid(bb.min, Point(2.*M_PI*distance, 2.*M_PI*distance)));
+
+    // generate pattern
+    Polylines   polylines = make_gyroid_waves(
+        scale_(this->z),
+        density_adjusted,
+        this->spacing,
+        ceil(bb.size()(0) / distance) + 1.,
+        ceil(bb.size()(1) / distance) + 1.);
+    
+    // move pattern in place
+    for (Polyline &polyline : polylines)
+        polyline.translate(bb.min(0), bb.min(1));
+
+    // clip pattern to boundaries
+    polylines = intersection_pl(polylines, (Polygons)expolygon);
+
+    // connect lines
+    if (! params.dont_connect && ! polylines.empty()) { // prevent calling leftmost_point() on empty collections
+        ExPolygon expolygon_off;
+        {
+            ExPolygons expolygons_off = offset_ex(expolygon, (float)SCALED_EPSILON);
+            if (! expolygons_off.empty()) {
+                // When expanding a polygon, the number of islands could only shrink. Therefore the offset_ex shall generate exactly one expanded island for one input island.
+                assert(expolygons_off.size() == 1);
+                std::swap(expolygon_off, expolygons_off.front());
+            }
+        }
+        Polylines chained = PolylineCollection::chained_path_from(
+            std::move(polylines), 
+            PolylineCollection::leftmost_point(polylines), false); // reverse allowed
+        bool first = true;
+        for (Polyline &polyline : chained) {
+            if (! first) {
+                // Try to connect the lines.
+                Points &pts_end = polylines_out.back().points;
+                const Point &first_point = polyline.points.front();
+                const Point &last_point = pts_end.back();
+                // TODO: we should also check that both points are on a fill_boundary to avoid 
+                // connecting paths on the boundaries of internal regions
+                // TODO: avoid crossing current infill path
+                if ((last_point - first_point).cast<double>().norm() <= 5 * distance && 
+                    expolygon_off.contains(Line(last_point, first_point))) {
+                    // Append the polyline.
+                    pts_end.insert(pts_end.end(), polyline.points.begin(), polyline.points.end());
+                    continue;
+                }
+            }
+            // The lines cannot be connected.
+            polylines_out.emplace_back(std::move(polyline));
+            first = false;
+        }
+    }
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/FillGyroid.hpp

@@ -0,0 +1,30 @@
+#ifndef slic3r_FillGyroid_hpp_
+#define slic3r_FillGyroid_hpp_
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class FillGyroid : public Fill
+{
+public:
+    FillGyroid() {}
+    virtual Fill* clone() const { return new FillGyroid(*this); }
+
+    // require bridge flow since most of this pattern hangs in air
+    virtual bool use_bridge_flow() const { return false; }
+
+protected:
+    virtual void _fill_surface_single(
+        const FillParams                &params, 
+        unsigned int                     thickness_layers,
+        const std::pair<float, Point>   &direction, 
+        ExPolygon                       &expolygon, 
+        Polylines                       &polylines_out);
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FillGyroid_hpp_

src/libslic3r/Fill/FillHoneycomb.cpp

@@ -0,0 +1,125 @@
+#include "../ClipperUtils.hpp"
+#include "../PolylineCollection.hpp"
+#include "../Surface.hpp"
+
+#include "FillHoneycomb.hpp"
+
+namespace Slic3r {
+
+void FillHoneycomb::_fill_surface_single(
+    const FillParams                &params, 
+    unsigned int                     thickness_layers,
+    const std::pair<float, Point>   &direction, 
+    ExPolygon                       &expolygon, 
+    Polylines                       &polylines_out)
+{
+    // cache hexagons math
+    CacheID cache_id(params.density, this->spacing);
+    Cache::iterator it_m = this->cache.find(cache_id);
+    if (it_m == this->cache.end()) {
+        it_m = this->cache.insert(it_m, std::pair<CacheID, CacheData>(cache_id, CacheData()));
+        CacheData &m = it_m->second;
+        coord_t min_spacing = scale_(this->spacing);
+        m.distance = min_spacing / params.density;
+        m.hex_side = m.distance / (sqrt(3)/2);
+        m.hex_width = m.distance * 2; // $m->{hex_width} == $m->{hex_side} * sqrt(3);
+        coord_t hex_height = m.hex_side * 2;
+        m.pattern_height = hex_height + m.hex_side;
+        m.y_short = m.distance * sqrt(3)/3;
+        m.x_offset = min_spacing / 2;
+        m.y_offset = m.x_offset * sqrt(3)/3;
+        m.hex_center = Point(m.hex_width/2, m.hex_side);
+    }
+    CacheData &m = it_m->second;
+
+    Polygons polygons;
+    {
+        // adjust actual bounding box to the nearest multiple of our hex pattern
+        // and align it so that it matches across layers
+        
+        BoundingBox bounding_box = expolygon.contour.bounding_box();
+        {
+            // rotate bounding box according to infill direction
+            Polygon bb_polygon = bounding_box.polygon();
+            bb_polygon.rotate(direction.first, m.hex_center);
+            bounding_box = bb_polygon.bounding_box();
+            
+            // extend bounding box so that our pattern will be aligned with other layers
+            // $bounding_box->[X1] and [Y1] represent the displacement between new bounding box offset and old one
+            // The infill is not aligned to the object bounding box, but to a world coordinate system. Supposedly good enough.
+            bounding_box.merge(_align_to_grid(bounding_box.min, Point(m.hex_width, m.pattern_height)));
+        }
+
+        coord_t x = bounding_box.min(0);
+        while (x <= bounding_box.max(0)) {
+            Polygon p;
+            coord_t ax[2] = { x + m.x_offset, x + m.distance - m.x_offset };
+            for (size_t i = 0; i < 2; ++ i) {
+                std::reverse(p.points.begin(), p.points.end()); // turn first half upside down
+                for (coord_t y = bounding_box.min(1); y <= bounding_box.max(1); y += m.y_short + m.hex_side + m.y_short + m.hex_side) {
+                    p.points.push_back(Point(ax[1], y + m.y_offset));
+                    p.points.push_back(Point(ax[0], y + m.y_short - m.y_offset));
+                    p.points.push_back(Point(ax[0], y + m.y_short + m.hex_side + m.y_offset));
+                    p.points.push_back(Point(ax[1], y + m.y_short + m.hex_side + m.y_short - m.y_offset));
+                    p.points.push_back(Point(ax[1], y + m.y_short + m.hex_side + m.y_short + m.hex_side + m.y_offset));
+                }
+                ax[0] = ax[0] + m.distance;
+                ax[1] = ax[1] + m.distance;
+                std::swap(ax[0], ax[1]); // draw symmetrical pattern
+                x += m.distance;
+            }
+            p.rotate(-direction.first, m.hex_center);
+            polygons.push_back(p);
+        }
+    }
+    
+    if (params.complete || true) {
+        // we were requested to complete each loop;
+        // in this case we don't try to make more continuous paths
+        Polygons polygons_trimmed = intersection((Polygons)expolygon, polygons);
+        for (Polygons::iterator it = polygons_trimmed.begin(); it != polygons_trimmed.end(); ++ it)
+            polylines_out.push_back(it->split_at_first_point());
+    } else {
+        // consider polygons as polylines without re-appending the initial point:
+        // this cuts the last segment on purpose, so that the jump to the next 
+        // path is more straight
+        Polylines paths;
+        {
+            Polylines p;
+            for (Polygon &poly : polygons)
+                p.emplace_back(poly.points);
+            paths = intersection_pl(p, to_polygons(expolygon));
+        }
+
+        // connect paths
+        if (! paths.empty()) { // prevent calling leftmost_point() on empty collections
+            Polylines chained = PolylineCollection::chained_path_from(
+                std::move(paths), 
+                PolylineCollection::leftmost_point(paths), false);
+            assert(paths.empty());
+            paths.clear();
+            for (Polylines::iterator it_path = chained.begin(); it_path != chained.end(); ++ it_path) {
+                if (! paths.empty()) {
+                    // distance between first point of this path and last point of last path
+                    double distance = (it_path->first_point() - paths.back().last_point()).cast<double>().norm();
+                    if (distance <= m.hex_width) {
+                        paths.back().points.insert(paths.back().points.end(), it_path->points.begin(), it_path->points.end());
+                        continue;
+                    }
+                }
+                // Don't connect the paths.
+                paths.push_back(*it_path);
+            }
+        }
+        
+        // clip paths again to prevent connection segments from crossing the expolygon boundaries
+        paths = intersection_pl(paths, to_polygons(offset_ex(expolygon, SCALED_EPSILON)));
+        // Move the polylines to the output, avoid a deep copy.
+        size_t j = polylines_out.size();
+        polylines_out.resize(j + paths.size(), Polyline());
+        for (size_t i = 0; i < paths.size(); ++ i)
+            std::swap(polylines_out[j ++], paths[i]);
+    }
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/FillHoneycomb.hpp

@@ -0,0 +1,57 @@
+#ifndef slic3r_FillHoneycomb_hpp_
+#define slic3r_FillHoneycomb_hpp_
+
+#include <map>
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class FillHoneycomb : public Fill
+{
+public:
+    virtual ~FillHoneycomb() {}
+
+protected:
+    virtual Fill* clone() const { return new FillHoneycomb(*this); };
+	virtual void _fill_surface_single(
+	    const FillParams                &params, 
+	    unsigned int                     thickness_layers,
+	    const std::pair<float, Point>   &direction, 
+	    ExPolygon                       &expolygon, 
+	    Polylines                       &polylines_out);
+
+	// Caching the 
+	struct CacheID 
+	{
+		CacheID(float adensity, coordf_t aspacing) : 
+			density(adensity), spacing(aspacing) {}
+		float		density;
+		coordf_t	spacing;
+		bool operator<(const CacheID &other) const 
+			{ return (density < other.density) || (density == other.density && spacing < other.spacing); }
+		bool operator==(const CacheID &other) const 
+			{ return density == other.density && spacing == other.spacing; }
+	};
+	struct CacheData
+	{
+		coord_t	distance;
+        coord_t hex_side;
+        coord_t hex_width;
+        coord_t	pattern_height;
+        coord_t y_short;
+        coord_t x_offset;
+        coord_t	y_offset;
+        Point	hex_center;
+    };
+    typedef std::map<CacheID, CacheData> Cache;
+	Cache cache;
+
+    virtual float _layer_angle(size_t idx) const { return float(M_PI/3.) * (idx % 3); }
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FillHoneycomb_hpp_

src/libslic3r/Fill/FillPlanePath.cpp

@@ -0,0 +1,203 @@
+#include "../ClipperUtils.hpp"
+#include "../PolylineCollection.hpp"
+#include "../Surface.hpp"
+
+#include "FillPlanePath.hpp"
+
+namespace Slic3r {
+
+void FillPlanePath::_fill_surface_single(
+    const FillParams                &params, 
+    unsigned int                     thickness_layers,
+    const std::pair<float, Point>   &direction, 
+    ExPolygon                       &expolygon, 
+    Polylines                       &polylines_out)
+{
+    expolygon.rotate(- direction.first);
+
+    coord_t distance_between_lines = scale_(this->spacing) / params.density;
+    
+    // align infill across layers using the object's bounding box
+    // Rotated bounding box of the whole object.
+    BoundingBox bounding_box = this->bounding_box.rotated(- direction.first);
+    
+    Point shift = this->_centered() ? 
+        bounding_box.center() :
+        bounding_box.min;
+    expolygon.translate(-shift(0), -shift(1));
+    bounding_box.translate(-shift(0), -shift(1));
+
+    Pointfs pts = _generate(
+        coord_t(ceil(coordf_t(bounding_box.min(0)) / distance_between_lines)),
+        coord_t(ceil(coordf_t(bounding_box.min(1)) / distance_between_lines)),
+        coord_t(ceil(coordf_t(bounding_box.max(0)) / distance_between_lines)),
+        coord_t(ceil(coordf_t(bounding_box.max(1)) / distance_between_lines)));
+
+    Polylines polylines;
+    if (pts.size() >= 2) {
+        // Convert points to a polyline, upscale.
+        polylines.push_back(Polyline());
+        Polyline &polyline = polylines.back();
+        polyline.points.reserve(pts.size());
+        for (Pointfs::iterator it = pts.begin(); it != pts.end(); ++ it)
+            polyline.points.push_back(Point(
+                coord_t(floor((*it)(0) * distance_between_lines + 0.5)), 
+                coord_t(floor((*it)(1) * distance_between_lines + 0.5))));
+//      intersection(polylines_src, offset((Polygons)expolygon, scale_(0.02)), &polylines);
+        polylines = intersection_pl(polylines, to_polygons(expolygon));
+
+/*        
+        if (1) {
+            require "Slic3r/SVG.pm";
+            print "Writing fill.svg\n";
+            Slic3r::SVG::output("fill.svg",
+                no_arrows       => 1,
+                polygons        => \@$expolygon,
+                green_polygons  => [ $bounding_box->polygon ],
+                polylines       => [ $polyline ],
+                red_polylines   => \@paths,
+            );
+        }
+*/
+        
+        // paths must be repositioned and rotated back
+        for (Polylines::iterator it = polylines.begin(); it != polylines.end(); ++ it) {
+            it->translate(shift(0), shift(1));
+            it->rotate(direction.first);
+        }
+    }
+
+    // Move the polylines to the output, avoid a deep copy.
+    size_t j = polylines_out.size();
+    polylines_out.resize(j + polylines.size(), Polyline());
+    for (size_t i = 0; i < polylines.size(); ++ i)
+        std::swap(polylines_out[j ++], polylines[i]);
+}
+
+// Follow an Archimedean spiral, in polar coordinates: r=a+b\theta
+Pointfs FillArchimedeanChords::_generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y)
+{
+    // Radius to achieve.
+    coordf_t rmax = std::sqrt(coordf_t(max_x)*coordf_t(max_x)+coordf_t(max_y)*coordf_t(max_y)) * std::sqrt(2.) + 1.5;
+    // Now unwind the spiral.
+    coordf_t a = 1.;
+    coordf_t b = 1./(2.*M_PI);
+    coordf_t theta = 0.;
+    coordf_t r = 1;
+    Pointfs out;
+    //FIXME Vojtech: If used as a solid infill, there is a gap left at the center.
+    out.push_back(Vec2d(0, 0));
+    out.push_back(Vec2d(1, 0));
+    while (r < rmax) {
+        theta += 1. / r;
+        r = a + b * theta;
+        out.push_back(Vec2d(r * cos(theta), r * sin(theta)));
+    }
+    return out;
+}
+
+// Adapted from 
+// http://cpansearch.perl.org/src/KRYDE/Math-PlanePath-122/lib/Math/PlanePath/HilbertCurve.pm
+//
+// state=0    3--2   plain
+//               |
+//            0--1
+//
+// state=4    1--2  transpose
+//            |  |
+//            0  3
+//
+// state=8
+//
+// state=12   3  0  rot180 + transpose
+//            |  |
+//            2--1
+//
+static inline Point hilbert_n_to_xy(const size_t n)
+{
+    static const int next_state[16] = { 4,0,0,12, 0,4,4,8, 12,8,8,4, 8,12,12,0 };
+    static const int digit_to_x[16] = { 0,1,1,0, 0,0,1,1, 1,0,0,1, 1,1,0,0 };
+    static const int digit_to_y[16] = { 0,0,1,1, 0,1,1,0, 1,1,0,0, 1,0,0,1 };
+
+    // Number of 2 bit digits.
+    size_t ndigits = 0;
+    {
+        size_t nc = n;
+        while(nc > 0) {
+            nc >>= 2;
+            ++ ndigits;
+        }
+    }
+    int state    = (ndigits & 1) ? 4 : 0;
+    int dirstate = (ndigits & 1) ? 0 : 4;
+    coord_t x = 0;
+    coord_t y = 0;
+    for (int i = (int)ndigits - 1; i >= 0; -- i) {
+        int digit = (n >> (i * 2)) & 3;
+        state += digit;
+        if (digit != 3)
+            dirstate = state; // lowest non-3 digit
+        x |= digit_to_x[state] << i;
+        y |= digit_to_y[state] << i;
+        state = next_state[state];
+    }
+    return Point(x, y);
+}
+
+Pointfs FillHilbertCurve::_generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y)
+{
+    // Minimum power of two square to fit the domain.
+    size_t sz = 2;
+    size_t pw = 1;
+    {
+        size_t sz0 = std::max(max_x + 1 - min_x, max_y + 1 - min_y);
+        while (sz < sz0) {
+            sz = sz << 1;
+            ++ pw;
+        }
+    }
+
+    size_t sz2 = sz * sz;
+    Pointfs line;
+    line.reserve(sz2);
+    for (size_t i = 0; i < sz2; ++ i) {
+        Point p = hilbert_n_to_xy(i);
+        line.push_back(Vec2d(p(0) + min_x, p(1) + min_y));
+    }
+    return line;
+}
+
+Pointfs FillOctagramSpiral::_generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y)
+{
+    // Radius to achieve.
+    coordf_t rmax = std::sqrt(coordf_t(max_x)*coordf_t(max_x)+coordf_t(max_y)*coordf_t(max_y)) * std::sqrt(2.) + 1.5;
+    // Now unwind the spiral.
+    coordf_t r = 0;
+    coordf_t r_inc = sqrt(2.);
+    Pointfs out;
+    out.push_back(Vec2d(0, 0));
+    while (r < rmax) {
+        r += r_inc;
+        coordf_t rx = r / sqrt(2.);
+        coordf_t r2 = r + rx;
+        out.push_back(Vec2d( r,  0.));
+        out.push_back(Vec2d( r2, rx));
+        out.push_back(Vec2d( rx, rx));
+        out.push_back(Vec2d( rx, r2));
+        out.push_back(Vec2d(0.,  r));
+        out.push_back(Vec2d(-rx, r2));
+        out.push_back(Vec2d(-rx, rx));
+        out.push_back(Vec2d(-r2, rx));
+        out.push_back(Vec2d(-r,  0.));
+        out.push_back(Vec2d(-r2, -rx));
+        out.push_back(Vec2d(-rx, -rx));
+        out.push_back(Vec2d(-rx, -r2));
+        out.push_back(Vec2d(0., -r));
+        out.push_back(Vec2d( rx, -r2));
+        out.push_back(Vec2d( rx, -rx));
+        out.push_back(Vec2d( r2+r_inc, -rx));
+    }
+    return out;
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/FillPlanePath.hpp

@@ -0,0 +1,69 @@
+#ifndef slic3r_FillPlanePath_hpp_
+#define slic3r_FillPlanePath_hpp_
+
+#include <map>
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+// The original Perl code used path generators from Math::PlanePath library:
+// http://user42.tuxfamily.org/math-planepath/
+// http://user42.tuxfamily.org/math-planepath/gallery.html
+
+class FillPlanePath : public Fill
+{
+public:
+    virtual ~FillPlanePath() {}
+
+protected:
+    virtual void _fill_surface_single(
+        const FillParams                &params, 
+        unsigned int                     thickness_layers,
+        const std::pair<float, Point>   &direction, 
+        ExPolygon                       &expolygon, 
+        Polylines                       &polylines_out);
+
+    virtual float _layer_angle(size_t idx) const { return 0.f; }
+    virtual bool  _centered() const = 0;
+    virtual Pointfs _generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y) = 0;
+};
+
+class FillArchimedeanChords : public FillPlanePath
+{
+public:
+    virtual Fill* clone() const { return new FillArchimedeanChords(*this); };
+    virtual ~FillArchimedeanChords() {}
+
+protected:
+    virtual bool  _centered() const { return true; }
+    virtual Pointfs _generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y);
+};
+
+class FillHilbertCurve : public FillPlanePath
+{
+public:
+    virtual Fill* clone() const { return new FillHilbertCurve(*this); };
+    virtual ~FillHilbertCurve() {}
+
+protected:
+    virtual bool  _centered() const { return false; }
+    virtual Pointfs _generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y);
+};
+
+class FillOctagramSpiral : public FillPlanePath
+{
+public:
+    virtual Fill* clone() const { return new FillOctagramSpiral(*this); };
+    virtual ~FillOctagramSpiral() {}
+
+protected:
+    virtual bool  _centered() const { return true; }
+    virtual Pointfs _generate(coord_t min_x, coord_t min_y, coord_t max_x, coord_t max_y);
+};
+
+} // namespace Slic3r
+
+#endif // slic3r_FillPlanePath_hpp_

src/libslic3r/Fill/FillRectilinear.cpp

@@ -0,0 +1,130 @@
+#include "../ClipperUtils.hpp"
+#include "../ExPolygon.hpp"
+#include "../PolylineCollection.hpp"
+#include "../Surface.hpp"
+
+#include "FillRectilinear.hpp"
+
+namespace Slic3r {
+
+void FillRectilinear::_fill_surface_single(
+    const FillParams                &params,
+    unsigned int                     thickness_layers,
+    const std::pair<float, Point>   &direction,
+    ExPolygon                       &expolygon,
+    Polylines                       &polylines_out)
+{
+    // rotate polygons so that we can work with vertical lines here
+    expolygon.rotate(- direction.first);
+
+    this->_min_spacing = scale_(this->spacing);
+    assert(params.density > 0.0001f && params.density <= 1.f);
+    this->_line_spacing = coord_t(coordf_t(this->_min_spacing) / params.density);
+    this->_diagonal_distance = this->_line_spacing * 2;
+    this->_line_oscillation = this->_line_spacing - this->_min_spacing; // only for Line infill
+    BoundingBox bounding_box = expolygon.contour.bounding_box();
+    
+    // define flow spacing according to requested density
+    if (params.density > 0.9999f && !params.dont_adjust) {
+        this->_line_spacing = this->_adjust_solid_spacing(bounding_box.size()(0), this->_line_spacing);
+        this->spacing = unscale<double>(this->_line_spacing);
+    } else {
+        // extend bounding box so that our pattern will be aligned with other layers
+        // Transform the reference point to the rotated coordinate system.
+        bounding_box.merge(_align_to_grid(
+            bounding_box.min, 
+            Point(this->_line_spacing, this->_line_spacing), 
+            direction.second.rotated(- direction.first)));
+    }
+
+    // generate the basic pattern
+    coord_t x_max = bounding_box.max(0) + SCALED_EPSILON;
+    Lines lines;
+    for (coord_t x = bounding_box.min(0); x <= x_max; x += this->_line_spacing)
+        lines.push_back(this->_line(lines.size(), x, bounding_box.min(1), bounding_box.max(1)));
+    if (this->_horizontal_lines()) {
+        coord_t y_max = bounding_box.max(1) + SCALED_EPSILON;
+        for (coord_t y = bounding_box.min(1); y <= y_max; y += this->_line_spacing)
+            lines.push_back(Line(Point(bounding_box.min(0), y), Point(bounding_box.max(0), y)));
+    }
+
+    // clip paths against a slightly larger expolygon, so that the first and last paths
+    // are kept even if the expolygon has vertical sides
+    // the minimum offset for preventing edge lines from being clipped is SCALED_EPSILON;
+    // however we use a larger offset to support expolygons with slightly skewed sides and 
+    // not perfectly straight
+    //FIXME Vojtech: Update the intersecton function to work directly with lines.
+    Polylines polylines_src;
+    polylines_src.reserve(lines.size());
+    for (Lines::const_iterator it = lines.begin(); it != lines.end(); ++ it) {
+        polylines_src.push_back(Polyline());
+        Points &pts = polylines_src.back().points;
+        pts.reserve(2);
+        pts.push_back(it->a);
+        pts.push_back(it->b);
+    }
+    Polylines polylines = intersection_pl(polylines_src, offset(to_polygons(expolygon), scale_(0.02)), false);
+
+    // FIXME Vojtech: This is only performed for horizontal lines, not for the vertical lines!
+    const float INFILL_OVERLAP_OVER_SPACING = 0.3f;
+    // How much to extend an infill path from expolygon outside?
+    coord_t extra = coord_t(floor(this->_min_spacing * INFILL_OVERLAP_OVER_SPACING + 0.5f));
+    for (Polylines::iterator it_polyline = polylines.begin(); it_polyline != polylines.end(); ++ it_polyline) {
+        Point *first_point = &it_polyline->points.front();
+        Point *last_point  = &it_polyline->points.back();
+        if (first_point->y() > last_point->y())
+            std::swap(first_point, last_point);
+        first_point->y() -= extra;
+        last_point->y() += extra;
+    }
+
+    size_t n_polylines_out_old = polylines_out.size();
+
+    // connect lines
+    if (! params.dont_connect && ! polylines.empty()) { // prevent calling leftmost_point() on empty collections
+        // offset the expolygon by max(min_spacing/2, extra)
+        ExPolygon expolygon_off;
+        {
+            ExPolygons expolygons_off = offset_ex(expolygon, this->_min_spacing/2);
+            if (! expolygons_off.empty()) {
+                // When expanding a polygon, the number of islands could only shrink. Therefore the offset_ex shall generate exactly one expanded island for one input island.
+                assert(expolygons_off.size() == 1);
+                std::swap(expolygon_off, expolygons_off.front());
+            }
+        }
+        Polylines chained = PolylineCollection::chained_path_from(
+            std::move(polylines), 
+            PolylineCollection::leftmost_point(polylines), false); // reverse allowed
+        bool first = true;
+        for (Polylines::iterator it_polyline = chained.begin(); it_polyline != chained.end(); ++ it_polyline) {
+            if (! first) {
+                // Try to connect the lines.
+                Points &pts_end = polylines_out.back().points;
+                const Point &first_point = it_polyline->points.front();
+                const Point &last_point = pts_end.back();
+                // Distance in X, Y.
+                const Vector distance = last_point - first_point;
+                // TODO: we should also check that both points are on a fill_boundary to avoid 
+                // connecting paths on the boundaries of internal regions
+                if (this->_can_connect(std::abs(distance(0)), std::abs(distance(1))) && 
+                    expolygon_off.contains(Line(last_point, first_point))) {
+                    // Append the polyline.
+                    pts_end.insert(pts_end.end(), it_polyline->points.begin(), it_polyline->points.end());
+                    continue;
+                }
+            }
+            // The lines cannot be connected.
+            polylines_out.emplace_back(std::move(*it_polyline));
+            first = false;
+        }
+    }
+
+    // paths must be rotated back
+    for (Polylines::iterator it = polylines_out.begin() + n_polylines_out_old; it != polylines_out.end(); ++ it) {
+        // No need to translate, the absolute position is irrelevant.
+        // it->translate(- direction.second(0), - direction.second(1));
+        it->rotate(direction.first);
+    }
+}
+
+} // namespace Slic3r

src/libslic3r/Fill/FillRectilinear.hpp

@@ -0,0 +1,79 @@
+#ifndef slic3r_FillRectilinear_hpp_
+#define slic3r_FillRectilinear_hpp_
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class Surface;
+
+class FillRectilinear : public Fill
+{
+public:
+    virtual Fill* clone() const { return new FillRectilinear(*this); };
+    virtual ~FillRectilinear() {}
+
+protected:
+	virtual void _fill_surface_single(
+	    const FillParams                &params, 
+	    unsigned int                     thickness_layers,
+	    const std::pair<float, Point>   &direction, 
+	    ExPolygon                       &expolygon, 
+	    Polylines                       &polylines_out);
+
+	coord_t _min_spacing;
+	coord_t _line_spacing;
+	// distance threshold for allowing the horizontal infill lines to be connected into a continuous path
+	coord_t _diagonal_distance;
+	// only for line infill
+	coord_t _line_oscillation;
+
+	// Enabled for the grid infill, disabled for the rectilinear and line infill.
+	virtual bool _horizontal_lines() const { return false; }
+
+	virtual Line _line(int i, coord_t x, coord_t y_min, coord_t y_max) const 
+		{ return Line(Point(x, y_min), Point(x, y_max)); }
+	
+	virtual bool _can_connect(coord_t dist_X, coord_t dist_Y) {
+	    return dist_X <= this->_diagonal_distance
+	        && dist_Y <= this->_diagonal_distance;
+    }
+};
+
+class FillLine : public FillRectilinear
+{
+public:
+    virtual ~FillLine() {}
+
+protected:
+	virtual Line _line(int i, coord_t x, coord_t y_min, coord_t y_max) const {
+		coord_t osc = (i & 1) ? this->_line_oscillation : 0;
+		return Line(Point(x - osc, y_min), Point(x + osc, y_max));
+	}
+
+	virtual bool _can_connect(coord_t dist_X, coord_t dist_Y)
+	{
+	    coord_t TOLERANCE = 10 * SCALED_EPSILON;
+    	return (dist_X >= (this->_line_spacing - this->_line_oscillation) - TOLERANCE)
+        	&& (dist_X <= (this->_line_spacing + this->_line_oscillation) + TOLERANCE)
+        	&& (dist_Y <= this->_diagonal_distance);
+    }
+};
+
+class FillGrid : public FillRectilinear
+{
+public:
+    virtual ~FillGrid() {}
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t idx) const { return 0.f; }
+	// Flag for Slic3r::Fill::Rectilinear to fill both directions.
+	virtual bool _horizontal_lines() const { return true; }
+};
+
+}; // namespace Slic3r
+
+#endif // slic3r_FillRectilinear_hpp_

src/libslic3r/Fill/FillRectilinear2.hpp

@@ -0,0 +1,74 @@
+#ifndef slic3r_FillRectilinear2_hpp_
+#define slic3r_FillRectilinear2_hpp_
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class Surface;
+
+class FillRectilinear2 : public Fill
+{
+public:
+    virtual Fill* clone() const { return new FillRectilinear2(*this); };
+    virtual ~FillRectilinear2() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	bool fill_surface_by_lines(const Surface *surface, const FillParams &params, float angleBase, float pattern_shift, Polylines &polylines_out);
+};
+
+class FillGrid2 : public FillRectilinear2
+{
+public:
+    virtual Fill* clone() const { return new FillGrid2(*this); };
+    virtual ~FillGrid2() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t idx) const { return 0.f; }
+};
+
+class FillTriangles : public FillRectilinear2
+{
+public:
+    virtual Fill* clone() const { return new FillTriangles(*this); };
+    virtual ~FillTriangles() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t idx) const { return 0.f; }
+};
+
+class FillStars : public FillRectilinear2
+{
+public:
+    virtual Fill* clone() const { return new FillStars(*this); };
+    virtual ~FillStars() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+    // The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t idx) const { return 0.f; }
+};
+
+class FillCubic : public FillRectilinear2
+{
+public:
+    virtual Fill* clone() const { return new FillCubic(*this); };
+    virtual ~FillCubic() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t idx) const { return 0.f; }
+};
+
+
+}; // namespace Slic3r
+
+#endif // slic3r_FillRectilinear2_hpp_

src/libslic3r/Fill/FillRectilinear3.hpp

@@ -0,0 +1,83 @@
+#ifndef slic3r_FillRectilinear3_hpp_
+#define slic3r_FillRectilinear3_hpp_
+
+#include "../libslic3r.h"
+
+#include "FillBase.hpp"
+
+namespace Slic3r {
+
+class Surface;
+
+class FillRectilinear3 : public Fill
+{
+public:
+    virtual Fill* clone() const { return new FillRectilinear3(*this); };
+    virtual ~FillRectilinear3() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+    struct FillDirParams
+    {
+        FillDirParams(coordf_t spacing, double angle, coordf_t pattern_shift = 0.f) : 
+            spacing(spacing), angle(angle), pattern_shift(pattern_shift) {}
+        coordf_t    spacing;
+        double      angle;
+        coordf_t    pattern_shift;
+    };
+
+protected:
+	bool fill_surface_by_lines(const Surface *surface, const FillParams &params, std::vector<FillDirParams> &fill_dir_params, Polylines &polylines_out);
+};
+
+class FillGrid3 : public FillRectilinear3
+{
+public:
+    virtual Fill* clone() const { return new FillGrid3(*this); };
+    virtual ~FillGrid3() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t /* idx */) const { return 0.f; }
+};
+
+class FillTriangles3 : public FillRectilinear3
+{
+public:
+    virtual Fill* clone() const { return new FillTriangles3(*this); };
+    virtual ~FillTriangles3() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t /* idx */) const { return 0.f; }
+};
+
+class FillStars3 : public FillRectilinear3
+{
+public:
+    virtual Fill* clone() const { return new FillStars3(*this); };
+    virtual ~FillStars3() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+    // The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t /* idx */) const { return 0.f; }
+};
+
+class FillCubic3 : public FillRectilinear3
+{
+public:
+    virtual Fill* clone() const { return new FillCubic3(*this); };
+    virtual ~FillCubic3() {}
+    virtual Polylines fill_surface(const Surface *surface, const FillParams &params);
+
+protected:
+	// The grid fill will keep the angle constant between the layers, see the implementation of Slic3r::Fill.
+    virtual float _layer_angle(size_t /* idx */) const { return 0.f; }
+};
+
+
+}; // namespace Slic3r
+
+#endif // slic3r_FillRectilinear3_hpp_

src/libslic3r/Flow.cpp

@@ -0,0 +1,148 @@
+#include "Flow.hpp"
+#include "Print.hpp"
+#include <cmath>
+#include <assert.h>
+
+namespace Slic3r {
+
+// This static method returns a sane extrusion width default.
+static inline float auto_extrusion_width(FlowRole role, float nozzle_diameter, float height)
+{
+    switch (role) {
+    case frSupportMaterial:
+    case frSupportMaterialInterface:
+    case frTopSolidInfill:
+        return nozzle_diameter;
+    default:
+    case frExternalPerimeter:
+    case frPerimeter:
+    case frSolidInfill:
+    case frInfill:
+        return 1.125f * nozzle_diameter;
+    }
+}
+
+// This constructor builds a Flow object from an extrusion width config setting
+// and other context properties.
+Flow Flow::new_from_config_width(FlowRole role, const ConfigOptionFloatOrPercent &width, float nozzle_diameter, float height, float bridge_flow_ratio)
+{
+    // we need layer height unless it's a bridge
+    if (height <= 0 && bridge_flow_ratio == 0) 
+        throw std::invalid_argument("Invalid flow height supplied to new_from_config_width()");
+
+    float w;
+    if (bridge_flow_ratio > 0) {
+        // If bridge flow was requested, calculate the bridge width.
+        height = w = (bridge_flow_ratio == 1.) ?
+            // optimization to avoid sqrt()
+            nozzle_diameter :
+            sqrt(bridge_flow_ratio) * nozzle_diameter;
+    } else if (! width.percent && width.value == 0.) {
+        // If user left option to 0, calculate a sane default width.
+        w = auto_extrusion_width(role, nozzle_diameter, height);
+    } else {
+        // If user set a manual value, use it.
+        w = float(width.get_abs_value(height));
+    }
+    
+    return Flow(w, height, nozzle_diameter, bridge_flow_ratio > 0);
+}
+
+// This constructor builds a Flow object from a given centerline spacing.
+Flow Flow::new_from_spacing(float spacing, float nozzle_diameter, float height, bool bridge) 
+{
+    // we need layer height unless it's a bridge
+    if (height <= 0 && !bridge) 
+        throw std::invalid_argument("Invalid flow height supplied to new_from_spacing()");
+    // Calculate width from spacing.
+    // For normal extrusons, extrusion width is wider than the spacing due to the rounding and squishing of the extrusions.
+    // For bridge extrusions, the extrusions are placed with a tiny BRIDGE_EXTRA_SPACING gaps between the threads.
+    float width = float(bridge ?
+        (spacing - BRIDGE_EXTRA_SPACING) : 
+#ifdef HAS_PERIMETER_LINE_OVERLAP
+        (spacing + PERIMETER_LINE_OVERLAP_FACTOR * height * (1. - 0.25 * PI));
+#else
+        (spacing + height * (1. - 0.25 * PI)));
+#endif
+    return Flow(width, bridge ? width : height, nozzle_diameter, bridge);
+}
+
+// This method returns the centerline spacing between two adjacent extrusions 
+// having the same extrusion width (and other properties).
+float Flow::spacing() const 
+{
+#ifdef HAS_PERIMETER_LINE_OVERLAP
+    if (this->bridge)
+        return this->width + BRIDGE_EXTRA_SPACING;
+    // rectangle with semicircles at the ends
+    float min_flow_spacing = this->width - this->height * (1. - 0.25 * PI);
+    return this->width - PERIMETER_LINE_OVERLAP_FACTOR * (this->width - min_flow_spacing);
+#else
+    return float(this->bridge ? (this->width + BRIDGE_EXTRA_SPACING) : (this->width - this->height * (1. - 0.25 * PI)));
+#endif
+}
+
+// This method returns the centerline spacing between an extrusion using this
+// flow and another one using another flow.
+// this->spacing(other) shall return the same value as other.spacing(*this)
+float Flow::spacing(const Flow &other) const
+{
+    assert(this->height == other.height);
+    assert(this->bridge == other.bridge);
+    return float(this->bridge ? 
+        0.5 * this->width + 0.5 * other.width + BRIDGE_EXTRA_SPACING :
+        0.5 * this->spacing() + 0.5 * other.spacing());
+}
+
+// This method returns extrusion volume per head move unit.
+double Flow::mm3_per_mm() const 
+{
+    double res = this->bridge ?
+        // Area of a circle with dmr of this->width.
+        (this->width * this->width) * 0.25 * PI :
+        // Rectangle with semicircles at the ends. ~ h (w - 0.215 h)
+        this->height * (this->width - this->height * (1. - 0.25 * PI));
+    assert(res > 0.);
+    return res;
+}
+
+Flow support_material_flow(const PrintObject *object, float layer_height)
+{
+    return Flow::new_from_config_width(
+        frSupportMaterial,
+        // The width parameter accepted by new_from_config_width is of type ConfigOptionFloatOrPercent, the Flow class takes care of the percent to value substitution.
+        (object->config().support_material_extrusion_width.value > 0) ? object->config().support_material_extrusion_width : object->config().extrusion_width,
+        // if object->config().support_material_extruder == 0 (which means to not trigger tool change, but use the current extruder instead), get_at will return the 0th component.
+        float(object->print()->config().nozzle_diameter.get_at(object->config().support_material_extruder-1)),
+        (layer_height > 0.f) ? layer_height : float(object->config().layer_height.value),
+        // bridge_flow_ratio
+        0.f);
+}
+
+Flow support_material_1st_layer_flow(const PrintObject *object, float layer_height)
+{
+    const auto &width = (object->print()->config().first_layer_extrusion_width.value > 0) ? object->print()->config().first_layer_extrusion_width : object->config().support_material_extrusion_width;
+    return Flow::new_from_config_width(
+        frSupportMaterial,
+        // The width parameter accepted by new_from_config_width is of type ConfigOptionFloatOrPercent, the Flow class takes care of the percent to value substitution.
+        (width.value > 0) ? width : object->config().extrusion_width,
+        float(object->print()->config().nozzle_diameter.get_at(object->config().support_material_extruder-1)),
+        (layer_height > 0.f) ? layer_height : float(object->config().first_layer_height.get_abs_value(object->config().layer_height.value)),
+        // bridge_flow_ratio
+        0.f);
+}
+
+Flow support_material_interface_flow(const PrintObject *object, float layer_height)
+{
+    return Flow::new_from_config_width(
+        frSupportMaterialInterface,
+        // The width parameter accepted by new_from_config_width is of type ConfigOptionFloatOrPercent, the Flow class takes care of the percent to value substitution.
+        (object->config().support_material_extrusion_width > 0) ? object->config().support_material_extrusion_width : object->config().extrusion_width,
+        // if object->config().support_material_interface_extruder == 0 (which means to not trigger tool change, but use the current extruder instead), get_at will return the 0th component.
+        float(object->print()->config().nozzle_diameter.get_at(object->config().support_material_interface_extruder-1)),
+        (layer_height > 0.f) ? layer_height : float(object->config().layer_height.value),
+        // bridge_flow_ratio
+        0.f);
+}
+
+}

src/libslic3r/Flow.hpp

@@ -0,0 +1,67 @@
+#ifndef slic3r_Flow_hpp_
+#define slic3r_Flow_hpp_
+
+#include "libslic3r.h"
+#include "Config.hpp"
+#include "ExtrusionEntity.hpp"
+
+namespace Slic3r {
+
+class PrintObject;
+
+// Extra spacing of bridge threads, in mm.
+#define BRIDGE_EXTRA_SPACING 0.05
+
+// Overlap factor of perimeter lines. Currently no overlap.
+#ifdef HAS_PERIMETER_LINE_OVERLAP
+    #define PERIMETER_LINE_OVERLAP_FACTOR 1.0
+#endif
+
+enum FlowRole {
+    frExternalPerimeter,
+    frPerimeter,
+    frInfill,
+    frSolidInfill,
+    frTopSolidInfill,
+    frSupportMaterial,
+    frSupportMaterialInterface,
+};
+
+class Flow
+{
+public:
+    // Non bridging flow: Maximum width of an extrusion with semicircles at the ends.
+    // Bridging flow: Bridge thread diameter.
+    float width;
+    // Non bridging flow: Layer height.
+    // Bridging flow: Bridge thread diameter = layer height.
+    float height;
+    // Nozzle diameter. 
+    float nozzle_diameter;
+    // Is it a bridge?
+    bool  bridge;
+    
+    Flow(float _w, float _h, float _nd, bool _bridge = false) :
+        width(_w), height(_h), nozzle_diameter(_nd), bridge(_bridge) {};
+
+    float   spacing() const;
+    float   spacing(const Flow &other) const;
+    double  mm3_per_mm() const;
+    coord_t scaled_width() const { return coord_t(scale_(this->width)); };
+    coord_t scaled_spacing() const { return coord_t(scale_(this->spacing())); };
+    coord_t scaled_spacing(const Flow &other) const { return coord_t(scale_(this->spacing(other))); };
+    
+    static Flow new_from_config_width(FlowRole role, const ConfigOptionFloatOrPercent &width, float nozzle_diameter, float height, float bridge_flow_ratio);
+    // Create a flow from the spacing of extrusion lines.
+    // This method is used exclusively to calculate new flow of 100% infill, where the extrusion width was allowed to scale
+    // to fit a region with integer number of lines.
+    static Flow new_from_spacing(float spacing, float nozzle_diameter, float height, bool bridge);
+};
+
+extern Flow support_material_flow(const PrintObject *object, float layer_height = 0.f);
+extern Flow support_material_1st_layer_flow(const PrintObject *object, float layer_height = 0.f);
+extern Flow support_material_interface_flow(const PrintObject *object, float layer_height = 0.f);
+
+}
+
+#endif

src/libslic3r/Format/3mf.hpp

@@ -0,0 +1,18 @@
+#ifndef slic3r_Format_3mf_hpp_
+#define slic3r_Format_3mf_hpp_
+
+namespace Slic3r {
+
+    class Model;
+    class DynamicPrintConfig;
+
+    // Load the content of a 3mf file into the given model and preset bundle.
+    extern bool load_3mf(const char* path, DynamicPrintConfig* config, Model* model);
+
+    // Save the given model and the config data contained in the given Print into a 3mf file.
+    // The model could be modified during the export process if meshes are not repaired or have no shared vertices
+    extern bool store_3mf(const char* path, Model* model, const DynamicPrintConfig* config);
+
+}; // namespace Slic3r
+
+#endif /* slic3r_Format_3mf_hpp_ */

src/libslic3r/Format/AMF.hpp

@@ -0,0 +1,18 @@
+#ifndef slic3r_Format_AMF_hpp_
+#define slic3r_Format_AMF_hpp_
+
+namespace Slic3r {
+
+class Model;
+class DynamicPrintConfig;
+
+// Load the content of an amf file into the given model and configuration.
+extern bool load_amf(const char *path, DynamicPrintConfig *config, Model *model);
+
+// Save the given model and the config data into an amf file.
+// The model could be modified during the export process if meshes are not repaired or have no shared vertices
+extern bool store_amf(const char *path, Model *model, const DynamicPrintConfig *config);
+
+}; // namespace Slic3r
+
+#endif /* slic3r_Format_AMF_hpp_ */

src/libslic3r/Format/OBJ.cpp

@@ -0,0 +1,118 @@
+#include "../libslic3r.h"
+#include "../Model.hpp"
+#include "../TriangleMesh.hpp"
+
+#include "OBJ.hpp"
+#include "objparser.hpp"
+
+#include <string>
+
+#ifdef _WIN32
+#define DIR_SEPARATOR '\\'
+#else
+#define DIR_SEPARATOR '/'
+#endif
+
+namespace Slic3r {
+
+bool load_obj(const char *path, Model *model, const char *object_name_in)
+{
+    // Parse the OBJ file.
+    ObjParser::ObjData data;
+    if (! ObjParser::objparse(path, data)) {
+//    die "Failed to parse $file\n" if !-e $path;
+        return false;
+    }
+
+    // Count the faces and verify, that all faces are triangular.
+    size_t num_faces = 0;
+	size_t num_quads = 0;
+    for (size_t i = 0; i < data.vertices.size(); ) {
+        size_t j = i;
+        for (; j < data.vertices.size() && data.vertices[j].coordIdx != -1; ++ j) ;
+        if (i == j)
+            continue;
+		size_t face_vertices = j - i;
+		if (face_vertices != 3 && face_vertices != 4) {
+            // Non-triangular and non-quad faces are not supported as of now.
+            return false;
+        }
+		if (face_vertices == 4)
+			++ num_quads;
+		++ num_faces;
+        i = j + 1;
+    }
+
+    // Convert ObjData into STL.
+    TriangleMesh mesh;
+    stl_file &stl = mesh.stl;
+    stl.stats.type = inmemory;
+    stl.stats.number_of_facets = int(num_faces + num_quads);
+    stl.stats.original_num_facets = int(num_faces + num_quads);
+    // stl_allocate clears all the allocated data to zero, all normals are set to zeros as well.
+    stl_allocate(&stl);
+    size_t i_face = 0;
+    for (size_t i = 0; i < data.vertices.size(); ++ i) {
+        if (data.vertices[i].coordIdx == -1)
+            continue;
+        stl_facet &facet = stl.facet_start[i_face ++];
+        size_t     num_normals = 0;
+        stl_normal normal(stl_normal::Zero());
+        for (unsigned int v = 0; v < 3; ++ v) {
+            const ObjParser::ObjVertex &vertex = data.vertices[i++];
+            memcpy(facet.vertex[v].data(), &data.coordinates[vertex.coordIdx*4], 3 * sizeof(float));
+            if (vertex.normalIdx != -1) {
+                normal(0) += data.normals[vertex.normalIdx*3];
+                normal(1) += data.normals[vertex.normalIdx*3+1];
+                normal(2) += data.normals[vertex.normalIdx*3+2];
+                ++ num_normals;
+            }
+        }
+		if (data.vertices[i].coordIdx != -1) {
+			// This is a quad. Produce the other triangle.
+			stl_facet &facet2 = stl.facet_start[i_face++];
+            facet2.vertex[0] = facet.vertex[0];
+            facet2.vertex[1] = facet.vertex[2];
+			const ObjParser::ObjVertex &vertex = data.vertices[i++];
+			memcpy(facet2.vertex[2].data(), &data.coordinates[vertex.coordIdx * 4], 3 * sizeof(float));
+			if (vertex.normalIdx != -1) {
+                normal(0) += data.normals[vertex.normalIdx*3];
+                normal(1) += data.normals[vertex.normalIdx*3+1];
+                normal(2) += data.normals[vertex.normalIdx*3+2];
+                ++ num_normals;
+            }
+            if (num_normals == 4) {
+                // Normalize an average normal of a quad.
+                float len = facet.normal.norm();
+                if (len > EPSILON) {
+                    normal /= len;
+                    facet.normal = normal;
+                    facet2.normal = normal;
+                }
+            }
+        } else if (num_normals == 3) {
+            // Normalize an average normal of a triangle.
+            float len = facet.normal.norm();
+            if (len > EPSILON)
+                facet.normal = normal / len;
+        }
+	}
+    stl_get_size(&stl);
+    mesh.repair();
+    if (mesh.facets_count() == 0) {
+        // die "This STL file couldn't be read because it's empty.\n"
+        return false;
+    }
+
+    std::string  object_name;
+    if (object_name_in == nullptr) {
+        const char *last_slash = strrchr(path, DIR_SEPARATOR);
+        object_name.assign((last_slash == nullptr) ? path : last_slash + 1);
+    } else
+       object_name.assign(object_name_in);
+
+    model->add_object(object_name.c_str(), path, std::move(mesh));
+    return true;
+}
+
+}; // namespace Slic3r

src/libslic3r/Format/OBJ.hpp

@@ -0,0 +1,14 @@
+#ifndef slic3r_Format_OBJ_hpp_
+#define slic3r_Format_OBJ_hpp_
+
+namespace Slic3r {
+
+class TriangleMesh;
+class Model;
+
+// Load an OBJ file into a provided model.
+extern bool load_obj(const char *path, Model *model, const char *object_name = nullptr);
+
+}; // namespace Slic3r
+
+#endif /* slic3r_Format_OBJ_hpp_ */

src/libslic3r/Format/PRUS.cpp

@@ -0,0 +1,354 @@
+#include <string.h>
+#include <exception>
+
+#include <boost/algorithm/string.hpp>
+#include <boost/nowide/convert.hpp>
+
+#include <miniz/miniz_zip.h>
+
+#include <Eigen/Geometry>
+
+#include "../libslic3r.h"
+#include "../Model.hpp"
+
+#include "PRUS.hpp"
+
+#if 0
+// Enable debugging and assert in this file.
+#define DEBUG
+#define _DEBUG
+#undef NDEBUG
+#endif
+
+#include <assert.h>
+
+namespace Slic3r
+{
+
+struct StlHeader
+{
+    char        comment[80];
+    uint32_t    nTriangles;
+};
+
+static_assert(sizeof(StlHeader) == 84, "StlHeader size not correct");
+
+// Buffered line reader to a string buffer.
+class LineReader
+{
+public:
+    LineReader(std::vector<char> &data) : m_buffer(data), m_pos(0), m_len((int)data.size()) {}
+
+    const char* next_line() {
+        // Skip empty lines.
+        while (m_pos < m_len && (m_buffer[m_pos] == '\r' || m_buffer[m_pos] == '\n'))
+            ++ m_pos;
+        if (m_pos == m_len) {
+            // End of file.
+            return nullptr;
+        }
+        // The buffer is nonempty and it does not start with end of lines. Find the first end of line.
+        int end = m_pos + 1;
+        while (end < m_len && m_buffer[end] != '\r' && m_buffer[end] != '\n')
+            ++ end;
+        char *ptr_out = m_buffer.data() + m_pos;
+        m_pos = end + 1;
+        m_buffer[end] = 0;
+        return ptr_out;
+    }
+
+    int next_line_scanf(const char *format, ...)
+    {
+        const char *line = next_line();
+        if (line == nullptr)
+            return -1;
+        int result;
+        va_list arglist;
+        va_start(arglist, format);
+        result = vsscanf(line, format, arglist);
+        va_end(arglist);
+        return result;
+    }
+
+private:
+    std::vector<char>  &m_buffer;
+    int                 m_pos;
+    int                 m_len;
+};
+
+static void extract_model_from_archive(
+    // name of the model file
+    const char              *name,
+    // path to the archive
+    const char              *path,
+    // content of scene.xml
+    const std::vector<char> &scene_xml_data,
+    // loaded data of this STL
+    std::vector<char>       &data,
+    // Model, to which the newly loaded objects will be added
+    Model                   *model,
+    // To map multiple STLs into a single model object for multi-material prints.
+    std::map<int, ModelObject*> &group_to_model_object)
+{
+    // Find the model entry in the XML data.
+    char model_name_tag[1024];
+    sprintf(model_name_tag, "<model name=\"%s\">", name);
+    const char *model_xml = strstr(scene_xml_data.data(), model_name_tag);
+    const char *zero_tag  = "<zero>";
+    const char *zero_xml  = strstr(scene_xml_data.data(), zero_tag);
+    float  trafo[3][4] = { 0 };
+    Vec3d instance_rotation = Vec3d::Zero();
+    Vec3d instance_scaling_factor = Vec3d::Ones();
+    Vec3d instance_offset = Vec3d::Zero();
+    bool         trafo_set    = false;
+    unsigned int group_id     = (unsigned int)-1;
+    unsigned int extruder_id  = (unsigned int)-1;
+    ModelObject *model_object = nullptr;
+    if (model_xml != nullptr) {
+        model_xml += strlen(model_name_tag);
+        const char *position_tag = "<position>";
+        const char *position_xml = strstr(model_xml, position_tag);
+        const char *rotation_tag = "<rotation>";
+        const char *rotation_xml = strstr(model_xml, rotation_tag);
+        const char *scale_tag    = "<scale>";
+        const char *scale_xml    = strstr(model_xml, scale_tag);
+        float position[3], rotation[3], scale[3], zero[3];
+        if (position_xml != nullptr && rotation_xml != nullptr && scale_xml != nullptr && zero_xml != nullptr &&
+            sscanf(position_xml+strlen(position_tag), 
+                "[%f, %f, %f]", position, position+1, position+2) == 3 &&
+            sscanf(rotation_xml+strlen(rotation_tag), 
+                "[%f, %f, %f]", rotation, rotation+1, rotation+2) == 3 &&
+            sscanf(scale_xml+strlen(scale_tag),
+                "[%f, %f, %f]", scale, scale+1, scale+2) == 3 &&
+            sscanf(zero_xml+strlen(zero_tag), 
+                "[%f, %f, %f]", zero, zero+1, zero+2) == 3) {
+            instance_scaling_factor = Vec3d((double)scale[0], (double)scale[1], (double)scale[2]);
+            instance_rotation = Vec3d(-(double)rotation[0], -(double)rotation[1], -(double)rotation[2]);
+            Eigen::Matrix3f mat_rot, mat_scale, mat_trafo;
+            mat_rot = Eigen::AngleAxisf(-rotation[2], Eigen::Vector3f::UnitZ()) * 
+                      Eigen::AngleAxisf(-rotation[1], Eigen::Vector3f::UnitY()) *
+                      Eigen::AngleAxisf(-rotation[0], Eigen::Vector3f::UnitX());
+            mat_scale = Eigen::Scaling(scale[0], scale[1], scale[2]);
+            mat_trafo = mat_rot * mat_scale;
+            for (size_t r = 0; r < 3; ++ r) {
+                for (size_t c = 0; c < 3; ++ c)
+                    trafo[r][c] += mat_trafo(r, c);
+            }
+            instance_offset = Vec3d((double)(position[0] - zero[0]), (double)(position[1] - zero[1]), (double)(position[2] - zero[2]));
+            // CHECK_ME -> Is the following correct ?
+            trafo[2][3] = position[2] / (float)instance_scaling_factor(2);
+            trafo_set = true;
+        }
+        const char *group_tag    = "<group>";
+        const char *group_xml    = strstr(model_xml, group_tag);
+        const char *extruder_tag = "<extruder>";
+        const char *extruder_xml = strstr(model_xml, extruder_tag);
+        if (group_xml != nullptr) {
+            int group = atoi(group_xml + strlen(group_tag));
+            if (group > 0) {
+                group_id = group;
+                auto it = group_to_model_object.find(group_id);
+                if (it != group_to_model_object.end())
+                    model_object = it->second;
+            }
+        }
+        if (extruder_xml != nullptr) {
+            int e = atoi(extruder_xml + strlen(extruder_tag));
+            if (e > 0)
+            extruder_id = e;
+        }
+    }
+    if (! trafo_set)
+        throw std::runtime_error(std::string("Archive ") + path + " does not contain a valid entry in scene.xml for " + name);
+
+    // Extract the STL.
+    StlHeader header;
+    TriangleMesh mesh;
+    bool mesh_valid = false;
+    bool stl_ascii  = false;
+    if (data.size() > sizeof(StlHeader)) {
+        memcpy((char*)&header, data.data(), sizeof(StlHeader));
+        if (strncmp(header.comment, "solid ", 6) == 0)
+            stl_ascii = true;
+        else {
+            // Header has been extracted. Now read the faces.
+            stl_file &stl = mesh.stl;
+            stl.error = 0;
+            stl.stats.type = inmemory;
+            stl.stats.number_of_facets = header.nTriangles;
+            stl.stats.original_num_facets = header.nTriangles;
+            stl_allocate(&stl);
+            if (header.nTriangles > 0 && data.size() == 50 * header.nTriangles + sizeof(StlHeader)) {
+                memcpy((char*)stl.facet_start, data.data() + sizeof(StlHeader), 50 * header.nTriangles);
+                if (sizeof(stl_facet) > SIZEOF_STL_FACET) {
+                    // The stl.facet_start is not packed tightly. Unpack the array of stl_facets.
+                    unsigned char *data = (unsigned char*)stl.facet_start;
+                    for (size_t i = header.nTriangles - 1; i > 0; -- i)
+                        memmove(data + i * sizeof(stl_facet), data + i * SIZEOF_STL_FACET, SIZEOF_STL_FACET);
+                }
+                // All the faces have been read.
+                stl_get_size(&stl);
+                mesh.repair();
+                // Transform the model.
+                stl_transform(&stl, &trafo[0][0]);
+                if (std::abs(stl.stats.min(2)) < EPSILON)
+                    stl.stats.min(2) = 0.;
+                // Add a mesh to a model.
+                if (mesh.facets_count() > 0)
+                    mesh_valid = true;
+            }
+        }
+    } else
+        stl_ascii = true;
+
+    if (stl_ascii) {
+        // Try to parse ASCII STL.
+        char                    normal_buf[3][32];
+        stl_facet               facet;
+        std::vector<stl_facet>  facets;
+        LineReader              line_reader(data);
+        std::string             solid_name;
+        facet.extra[0] = facet.extra[1] = 0;
+        for (;;) {
+            const char *line = line_reader.next_line();
+            if (line == nullptr)
+                // End of file.
+                break;
+            if (strncmp(line, "solid", 5) == 0) {
+                // Opening the "solid" block.
+                if (! solid_name.empty()) {
+                    // Error, solid block is already open.
+                    facets.clear();
+                    break;
+                }
+                solid_name = line + 5;
+                if (solid_name.empty())
+                    solid_name = "unknown";
+                continue;
+            }
+            if (strncmp(line, "endsolid", 8) == 0) {
+                // Closing the "solid" block.
+                if (solid_name.empty()) {
+                    // Error, no solid block is open.
+                    facets.clear();
+                    break;
+                }
+                solid_name.clear();
+                continue;
+            }
+            // Line has to start with the word solid.
+            int res_normal      = sscanf(line, " facet normal %31s %31s %31s", normal_buf[0], normal_buf[1], normal_buf[2]);
+            assert(res_normal == 3);
+            int res_outer_loop  = line_reader.next_line_scanf(" outer loop");
+            assert(res_outer_loop == 0);
+            int res_vertex1 = line_reader.next_line_scanf(" vertex %f %f %f", &facet.vertex[0](0), &facet.vertex[0](1), &facet.vertex[0](2));
+            assert(res_vertex1 == 3);
+            int res_vertex2 = line_reader.next_line_scanf(" vertex %f %f %f", &facet.vertex[1](0), &facet.vertex[1](1), &facet.vertex[1](2));
+            assert(res_vertex2 == 3);
+            int res_vertex3 = line_reader.next_line_scanf(" vertex %f %f %f", &facet.vertex[2](0), &facet.vertex[2](1), &facet.vertex[2](2));
+            assert(res_vertex3 == 3);
+            int res_endloop = line_reader.next_line_scanf(" endloop");
+            assert(res_endloop == 0);
+            int res_endfacet = line_reader.next_line_scanf(" endfacet");
+            if (res_normal != 3 || res_outer_loop != 0 || res_vertex1 != 3 || res_vertex2 != 3 || res_vertex3 != 3 || res_endloop != 0 || res_endfacet != 0) {
+                // perror("Something is syntactically very wrong with this ASCII STL!");
+                facets.clear();
+                break;
+            }
+            // The facet normal has been parsed as a single string as to workaround for not a numbers in the normal definition.
+            if (sscanf(normal_buf[0], "%f", &facet.normal(0)) != 1 ||
+                sscanf(normal_buf[1], "%f", &facet.normal(1)) != 1 ||
+                sscanf(normal_buf[2], "%f", &facet.normal(2)) != 1) {
+                // Normal was mangled. Maybe denormals or "not a number" were stored?
+                // Just reset the normal and silently ignore it.
+                memset(&facet.normal, 0, sizeof(facet.normal));
+            }
+            facets.emplace_back(facet);
+        }
+        if (! facets.empty() && solid_name.empty()) {
+            stl_file &stl = mesh.stl;
+            stl.stats.type = inmemory;
+            stl.stats.number_of_facets = (uint32_t)facets.size();
+            stl.stats.original_num_facets = (int)facets.size();
+            stl_allocate(&stl);
+            memcpy((void*)stl.facet_start, facets.data(), facets.size() * 50);
+            stl_get_size(&stl);
+            mesh.repair();
+            // Transform the model.
+            stl_transform(&stl, &trafo[0][0]);
+            // Add a mesh to a model.
+            if (mesh.facets_count() > 0)
+                mesh_valid = true;
+        }
+    }
+
+    if (! mesh_valid)
+        throw std::runtime_error(std::string("Archive ") + path + " does not contain a valid mesh for " + name);
+
+    // Add this mesh to the model.
+    ModelVolume *volume = nullptr;
+    if (model_object == nullptr) {
+        // This is a first mesh of a group. Create a new object & volume.
+        model_object = model->add_object(name, path, std::move(mesh));
+        volume = model_object->volumes.front();
+        ModelInstance *instance  = model_object->add_instance();
+        instance->set_rotation(instance_rotation);
+        instance->set_scaling_factor(instance_scaling_factor);
+        instance->set_offset(instance_offset);
+        if (group_id != (size_t)-1)
+            group_to_model_object[group_id] = model_object;
+    } else {
+        // This is not the 1st mesh of a group. Add it to the ModelObject.
+        volume = model_object->add_volume(std::move(mesh));
+        volume->name = name;
+    }
+    // Set the extruder to the volume.
+    if (extruder_id != (unsigned int)-1) {
+        char str_extruder[64];
+        sprintf(str_extruder, "%ud", extruder_id);
+        volume->config.set_deserialize("extruder", str_extruder);
+    }
+}
+
+// Load a PrusaControl project file into a provided model.
+bool load_prus(const char *path, Model *model)
+{
+    mz_zip_archive archive;
+    mz_zip_zero_struct(&archive);
+    mz_bool res = mz_zip_reader_init_file(&archive, path, 0);
+    size_t  n_models_initial = model->objects.size();
+    try {
+        if (res == MZ_FALSE)
+            throw std::runtime_error(std::string("Unable to init zip reader for ") + path);
+        std::vector<char>           scene_xml_data;
+        // For grouping multiple STLs into a single ModelObject for multi-material prints.
+        std::map<int, ModelObject*> group_to_model_object;
+        mz_uint                     num_entries = mz_zip_reader_get_num_files(&archive);
+        for (mz_uint i = 0; i < num_entries; ++ i) {
+            mz_zip_archive_file_stat stat;
+            if (! mz_zip_reader_file_stat(&archive, i, &stat))
+                continue;
+            std::vector<char> buffer;
+            buffer.assign((size_t)stat.m_uncomp_size + 1, 0);
+            res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, (char*)buffer.data(), (size_t)stat.m_uncomp_size, 0);
+            if (res == MZ_FALSE)
+                std::runtime_error(std::string("Error while extracting a file from ") + path);
+            if (strcmp(stat.m_filename, "scene.xml") == 0) {
+                if (! scene_xml_data.empty())
+                    throw std::runtime_error(std::string("Multiple scene.xml were found in the archive.") + path);
+                scene_xml_data = std::move(buffer);
+            } else if (boost::iends_with(stat.m_filename, ".stl")) {
+                // May throw std::exception
+                extract_model_from_archive(stat.m_filename, path, scene_xml_data, buffer, model, group_to_model_object);
+            }
+        }
+    } catch (std::exception &ex) {
+        mz_zip_reader_end(&archive);
+        throw ex;
+    }
+
+    mz_zip_reader_end(&archive);
+    return model->objects.size() > n_models_initial;
+}
+
+}; // namespace Slic3r

src/libslic3r/Format/PRUS.hpp

@@ -0,0 +1,11 @@
+#define slic3r_Format_PRUS_hpp_
+
+namespace Slic3r {
+
+class TriangleMesh;
+class Model;
+
+// Load a PrusaControl project file into a provided model.
+extern bool load_prus(const char *path, Model *model);
+
+}; // namespace Slic3r

src/libslic3r/Format/STL.cpp

@@ -0,0 +1,58 @@
+#include "../libslic3r.h"
+#include "../Model.hpp"
+#include "../TriangleMesh.hpp"
+
+#include "STL.hpp"
+
+#include <string>
+
+#ifdef _WIN32
+#define DIR_SEPARATOR '\\'
+#else
+#define DIR_SEPARATOR '/'
+#endif
+
+namespace Slic3r {
+
+bool load_stl(const char *path, Model *model, const char *object_name_in)
+{
+    TriangleMesh mesh;
+    mesh.ReadSTLFile(path);
+    if (mesh.stl.error) {
+//    die "Failed to open $file\n" if !-e $path;
+        return false;
+    }
+    mesh.repair();
+    if (mesh.facets_count() == 0) {
+        // die "This STL file couldn't be read because it's empty.\n"
+        return false;
+    }
+
+    std::string object_name;
+    if (object_name_in == nullptr) {
+        const char *last_slash = strrchr(path, DIR_SEPARATOR);
+        object_name.assign((last_slash == nullptr) ? path : last_slash + 1);
+    } else
+       object_name.assign(object_name_in);
+
+    model->add_object(object_name.c_str(), path, std::move(mesh));
+    return true;
+}
+
+bool store_stl(const char *path, TriangleMesh *mesh, bool binary)
+{
+    if (binary)
+        mesh->write_binary(path);
+    else
+        mesh->write_ascii(path);
+    //FIXME returning false even if write failed.
+    return true;
+}
+
+bool store_stl(const char *path, ModelObject *model_object, bool binary)
+{
+    TriangleMesh mesh = model_object->mesh();
+    return store_stl(path, &mesh, binary);
+}
+
+}; // namespace Slic3r

src/libslic3r/Format/STL.hpp

@@ -0,0 +1,17 @@
+#ifndef slic3r_Format_STL_hpp_
+#define slic3r_Format_STL_hpp_
+
+namespace Slic3r {
+
+class TriangleMesh;
+class ModelObject;
+
+// Load an STL file into a provided model.
+extern bool load_stl(const char *path, Model *model, const char *object_name = nullptr);
+
+extern bool store_stl(const char *path, TriangleMesh *mesh, bool binary);
+extern bool store_stl(const char *path, ModelObject *model_object, bool binary);
+
+}; // namespace Slic3r
+
+#endif /* slic3r_Format_STL_hpp_ */

src/libslic3r/Format/objparser.cpp

@@ -0,0 +1,540 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include <boost/nowide/cstdio.hpp>
+
+#include "objparser.hpp"
+
+namespace ObjParser {
+
+static bool obj_parseline(const char *line, ObjData &data)
+{
+#define EATWS() while (*line == ' ' || *line == '\t') ++ line
+
+	if (*line == 0)
+		return true;
+
+	// Ignore whitespaces at the beginning of the line.
+	//FIXME is this a good idea?
+	EATWS();
+
+	char c1 = *line ++;
+	switch (c1) {
+	case '#':
+		// Comment, ignore the rest of the line.
+		break;
+	case 'v':
+	{
+		// Parse vertex geometry (position, normal, texture coordinates)
+		char c2 = *line ++;
+		switch (c2) {
+		case 't':
+		{
+			// vt - vertex texture parameter
+			// u v [w], w == 0 (or w == 1)
+			char c2 = *line ++;
+			if (c2 != ' ' && c2 != '\t')
+				return false;
+			EATWS();
+			char *endptr = 0;
+			double u = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t'))
+				return false;
+			line = endptr;
+			EATWS();
+			double v = 0;
+			if (*line != 0) {
+				v = strtod(line, &endptr);
+				if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+					return false;
+				line = endptr;
+				EATWS();
+			}
+			double w = 0;
+			if (*line != 0) {
+				w = strtod(line, &endptr);
+				if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+					return false;
+				line = endptr;
+				EATWS();
+			}
+			if (*line != 0)
+				return false;
+			data.textureCoordinates.push_back((float)u);
+			data.textureCoordinates.push_back((float)v);
+			data.textureCoordinates.push_back((float)w);
+			break;
+		}
+		case 'n':
+		{
+			// vn - vertex normal
+			// x y z
+			char c2 = *line ++;
+			if (c2 != ' ' && c2 != '\t')
+				return false;
+			EATWS();
+			char *endptr = 0;
+			double x = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t'))
+				return false;
+			line = endptr;
+			EATWS();
+			double y = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t'))
+				return false;
+			line = endptr;
+			EATWS();
+			double z = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+				return false;
+			line = endptr;
+			EATWS();
+			if (*line != 0)
+				return false;
+			data.normals.push_back((float)x);
+			data.normals.push_back((float)y);
+			data.normals.push_back((float)z);
+			break;
+		}
+		case 'p':
+		{
+			// vp - vertex parameter
+			char c2 = *line ++;
+			if (c2 != ' ' && c2 != '\t')
+				return false;
+			EATWS();
+			char *endptr = 0;
+			double u = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+				return false;
+			line = endptr;
+			EATWS();
+			double v = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+				return false;
+			line = endptr;
+			EATWS();
+			double w = 0;
+			if (*line != 0) {
+				w = strtod(line, &endptr);
+				if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+					return false;
+				line = endptr;
+				EATWS();
+			}
+			if (*line != 0)
+				return false;
+			data.parameters.push_back((float)u);
+			data.parameters.push_back((float)v);
+			data.parameters.push_back((float)w);
+			break;
+		}
+		default:
+		{
+			// v - vertex geometry
+			if (c2 != ' ' && c2 != '\t')
+				return false;
+			EATWS();
+			char *endptr = 0;
+			double x = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t'))
+				return false;
+			line = endptr;
+			EATWS();
+			double y = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t'))
+				return false;
+			line = endptr;
+			EATWS();
+			double z = strtod(line, &endptr);
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+				return false;
+			line = endptr;
+			EATWS();
+			double w = 1.0;
+			if (*line != 0) {
+				w = strtod(line, &endptr);
+				if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+					return false;
+				line = endptr;
+				EATWS();
+			}
+			if (*line != 0)
+				return false;
+			data.coordinates.push_back((float)x);
+			data.coordinates.push_back((float)y);
+			data.coordinates.push_back((float)z);
+			data.coordinates.push_back((float)w);
+			break;
+		}
+		}
+		break;
+	}
+	case 'f':
+	{
+		// face
+		EATWS();
+		if (*line == 0)
+			return false;
+		// number of vertices of this face
+		int n = 0;
+		// current vertex to be parsed
+		ObjVertex vertex;
+		char *endptr = 0;
+		while (*line != 0) {
+			// Parse a single vertex reference.
+			vertex.coordIdx			= 0;
+			vertex.normalIdx		= 0;
+			vertex.textureCoordIdx	= 0;
+			vertex.coordIdx = strtol(line, &endptr, 10);
+			// Coordinate has to be defined
+			if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != '/' && *endptr != 0))
+				return false;
+			line = endptr;
+			if (*line == '/') {
+				++ line;
+				// Texture coordinate index may be missing after a 1st slash, but then the normal index has to be present.
+				if (*line != '/') {
+					// Parse the texture coordinate index.
+					vertex.textureCoordIdx = strtol(line, &endptr, 10);
+					if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != '/' && *endptr != 0))
+						return false;
+					line = endptr;
+				}
+				if (*line == '/') {
+					// Parse normal index.
+					++ line;
+					vertex.normalIdx = strtol(line, &endptr, 10);
+					if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+						return false;
+					line = endptr;
+				}
+			}
+			if (vertex.coordIdx < 0)
+				vertex.coordIdx += data.coordinates.size() / 4;
+			else
+				-- vertex.coordIdx;
+			if (vertex.normalIdx < 0)
+				vertex.normalIdx += data.normals.size() / 3;
+			else
+				-- vertex.normalIdx;
+			if (vertex.textureCoordIdx < 0)
+				vertex.textureCoordIdx += data.textureCoordinates.size() / 3;
+			else
+				-- vertex.textureCoordIdx;
+			data.vertices.push_back(vertex);
+			EATWS();
+		}
+		vertex.coordIdx			= -1;
+		vertex.normalIdx		= -1;
+		vertex.textureCoordIdx	= -1;
+		data.vertices.push_back(vertex);
+		break;
+	}
+	case 'm':
+	{
+		if (*(line ++) != 't' ||
+			*(line ++) != 'l' ||
+			*(line ++) != 'l' ||
+			*(line ++) != 'i' ||
+			*(line ++) != 'b')
+			return false;
+		// mtllib [external .mtl file name]
+		// printf("mtllib %s\r\n", line);
+		EATWS();
+		data.mtllibs.push_back(std::string(line));
+		break;
+	}
+	case 'u':
+	{
+		if (*(line ++) != 's' ||
+			*(line ++) != 'e' ||
+			*(line ++) != 'm' ||
+			*(line ++) != 't' ||
+			*(line ++) != 'l')
+			return false;
+		// usemtl [material name]
+		// printf("usemtl %s\r\n", line);
+		EATWS();
+		ObjUseMtl usemtl;
+		usemtl.vertexIdxFirst = data.vertices.size();
+		usemtl.name = line;
+		data.usemtls.push_back(usemtl);
+		break;
+	}
+	case 'o':
+	{
+		// o [object name]
+		EATWS();
+		const char *name = line;
+		while (*line != ' ' && *line != '\t' && *line != 0)
+			++ line;
+		// copy name to line.
+		EATWS();
+		if (*line != 0)
+			return false;
+		ObjObject object;
+		object.vertexIdxFirst = data.vertices.size();
+		object.name = line;
+		data.objects.push_back(object);
+		break;
+	}
+	case 'g':
+	{
+		// g [group name]
+		// printf("group %s\r\n", line);
+		ObjGroup group;
+		group.vertexIdxFirst = data.vertices.size();
+		group.name = line;
+		data.groups.push_back(group);
+		break;
+	}
+	case 's':
+	{
+		// s 1 / off
+		char c2 = *line ++;
+		if (c2 != ' ' && c2 != '\t')
+			return false;
+		EATWS();
+		char *endptr = 0;
+		long g = strtol(line, &endptr, 10);
+		if (endptr == 0 || (*endptr != ' ' && *endptr != '\t' && *endptr != 0))
+			return false;
+		line = endptr;
+		EATWS();
+		if (*line != 0)
+			return false;
+		ObjSmoothingGroup group;
+		group.vertexIdxFirst   = data.vertices.size();
+		group.smoothingGroupID = g;
+		data.smoothingGroups.push_back(group);
+		break;
+	}
+	default:
+		printf("ObjParser: Unknown command: %c\r\n", c1);
+		break;
+	}
+
+	return true;
+}
+
+bool objparse(const char *path, ObjData &data)
+{
+	FILE *pFile = boost::nowide::fopen(path, "rt");
+	if (pFile == 0)
+		return false;
+
+	try {
+		char buf[65536 * 2];
+		size_t len = 0;
+		size_t lenPrev = 0;
+		while ((len = ::fread(buf + lenPrev, 1, 65536, pFile)) != 0) {
+			len += lenPrev;
+			size_t lastLine = 0;
+			for (size_t i = 0; i < len; ++ i)
+				if (buf[i] == '\r' || buf[i] == '\n') {
+					buf[i] = 0;
+					char *c = buf + lastLine;
+					while (*c == ' ' || *c == '\t')
+						++ c;
+					obj_parseline(c, data);
+					lastLine = i + 1;
+				}
+			lenPrev = len - lastLine;
+			memmove(buf, buf + lastLine, lenPrev);
+		}
+	} catch (std::bad_alloc &ex) {
+		printf("Out of memory\r\n");
+	}
+	::fclose(pFile);
+
+	// printf("vertices: %d\r\n", data.vertices.size() / 4);
+	// printf("coords: %d\r\n", data.coordinates.size());
+	return true;
+}
+
+template<typename T> 
+bool savevector(FILE *pFile, const std::vector<T> &v)
+{
+	size_t cnt = v.size();
+	::fwrite(&cnt, 1, sizeof(cnt), pFile);
+	//FIXME sizeof(T) works for data types leaving no gaps in the allocated vector because of alignment of the T type.
+	if (! v.empty())
+		::fwrite(&v.front(), 1, sizeof(T) * cnt, pFile);
+	return true;
+}
+
+bool savevector(FILE *pFile, const std::vector<std::string> &v)
+{
+	size_t cnt = v.size();
+	::fwrite(&cnt, 1, sizeof(cnt), pFile);
+	for (size_t i = 0; i < cnt; ++ i) {
+		size_t len = v[i].size();
+		::fwrite(&len, 1, sizeof(cnt), pFile);
+		::fwrite(v[i].c_str(), 1, len, pFile);
+	}
+	return true;
+}
+
+template<typename T>
+bool savevectornameidx(FILE *pFile, const std::vector<T> &v)
+{
+	size_t cnt = v.size();
+	::fwrite(&cnt, 1, sizeof(cnt), pFile);
+	for (size_t i = 0; i < cnt; ++ i) {
+		::fwrite(&v[i].vertexIdxFirst, 1, sizeof(int), pFile);
+		size_t len = v[i].name.size();
+		::fwrite(&len, 1, sizeof(cnt), pFile);
+		::fwrite(v[i].name.c_str(), 1, len, pFile);
+	}
+	return true;
+}
+
+template<typename T> 
+bool loadvector(FILE *pFile, std::vector<T> &v)
+{
+	v.clear();
+	size_t cnt = 0;
+	if (::fread(&cnt, sizeof(cnt), 1, pFile) != 1)
+		return false;
+	//FIXME sizeof(T) works for data types leaving no gaps in the allocated vector because of alignment of the T type.
+	if (cnt != 0) {
+		v.assign(cnt, T());
+		if (::fread(&v.front(), sizeof(T), cnt, pFile) != cnt)
+			return false;
+	}
+	return true;
+}
+
+bool loadvector(FILE *pFile, std::vector<std::string> &v)
+{
+	v.clear();
+	size_t cnt = 0;
+	if (::fread(&cnt, sizeof(cnt), 1, pFile) != 1)
+		return false;
+	v.reserve(cnt);
+	for (size_t i = 0; i < cnt; ++ i) {
+		size_t len = 0;
+		if (::fread(&len, sizeof(len), 1, pFile) != 1)
+			return false;
+		std::string s(" ", len);
+		if (::fread(const_cast<char*>(s.c_str()), 1, len, pFile) != len)
+			return false;
+		v.push_back(std::move(s));
+	}
+	return true;
+}
+
+template<typename T>
+bool loadvectornameidx(FILE *pFile, std::vector<T> &v)
+{
+	v.clear();
+	size_t cnt = 0;
+	if (::fread(&cnt, sizeof(cnt), 1, pFile) != 1)
+		return false;
+	v.assign(cnt, T());
+	for (size_t i = 0; i < cnt; ++ i) {
+		if (::fread(&v[i].vertexIdxFirst, sizeof(int), 1, pFile) != 1)
+			return false;
+		size_t len = 0;
+		if (::fread(&len, sizeof(len), 1, pFile) != 1)
+			return false;
+		v[i].name.assign(" ", len);
+		if (::fread(const_cast<char*>(v[i].name.c_str()), 1, len, pFile) != len)
+			return false;
+	}
+	return true;
+}
+
+bool objbinsave(const char *path, const ObjData &data)
+{
+	FILE *pFile = boost::nowide::fopen(path, "wb");
+	if (pFile == 0)
+		return false;
+
+	size_t version = 1;
+	::fwrite(&version, 1, sizeof(version), pFile);
+
+	bool result =
+		savevector(pFile, data.coordinates)			&&
+		savevector(pFile, data.textureCoordinates)	&&
+		savevector(pFile, data.normals)				&&
+		savevector(pFile, data.parameters)			&&
+		savevector(pFile, data.mtllibs)				&&
+		savevectornameidx(pFile, data.usemtls)		&&
+		savevectornameidx(pFile, data.objects)		&&
+		savevectornameidx(pFile, data.groups)		&&
+		savevector(pFile, data.smoothingGroups)		&&
+		savevector(pFile, data.vertices);
+
+	::fclose(pFile);
+	return result;
+}
+
+bool objbinload(const char *path, ObjData &data)
+{
+	FILE *pFile = boost::nowide::fopen(path, "rb");
+	if (pFile == 0)
+		return false;
+
+	data.version = 0;
+	if (::fread(&data.version, sizeof(data.version), 1, pFile) != 1)
+		return false;
+	if (data.version != 1)
+		return false;
+
+	bool result =
+		loadvector(pFile, data.coordinates)			&&
+		loadvector(pFile, data.textureCoordinates)	&&
+		loadvector(pFile, data.normals)				&&
+		loadvector(pFile, data.parameters)			&&
+		loadvector(pFile, data.mtllibs)				&&
+		loadvectornameidx(pFile, data.usemtls)		&&
+		loadvectornameidx(pFile, data.objects)		&&
+		loadvectornameidx(pFile, data.groups)		&&
+		loadvector(pFile, data.smoothingGroups)		&&
+		loadvector(pFile, data.vertices);
+
+	::fclose(pFile);
+	return result;
+}
+
+template<typename T>
+bool vectorequal(const std::vector<T> &v1, const std::vector<T> &v2)
+{
+	if (v1.size() != v2.size())
+		return false;
+	for (size_t i = 0; i < v1.size(); ++ i)
+		if (! (v1[i] == v2[i]))
+			return false;
+	return true;
+}
+
+bool vectorequal(const std::vector<std::string> &v1, const std::vector<std::string> &v2)
+{
+	if (v1.size() != v2.size())
+		return false;
+	for (size_t i = 0; i < v1.size(); ++ i)
+		if (v1[i].compare(v2[i]) != 0)
+			return false;
+	return true;
+}
+
+extern bool objequal(const ObjData &data1, const ObjData &data2)
+{
+	//FIXME ignore version number
+	// version;
+
+	return 
+		vectorequal(data1.coordinates,			data2.coordinates)			&&
+		vectorequal(data1.textureCoordinates,	data2.textureCoordinates)	&&
+		vectorequal(data1.normals,				data2.normals)				&&
+		vectorequal(data1.parameters,			data2.parameters)			&&
+		vectorequal(data1.mtllibs,				data2.mtllibs)				&&
+		vectorequal(data1.usemtls,				data2.usemtls)				&&
+		vectorequal(data1.objects,				data2.objects)				&&
+		vectorequal(data1.groups,				data2.groups)				&&
+		vectorequal(data1.vertices,				data2.vertices);
+}
+
+} // namespace ObjParser

src/libslic3r/Format/objparser.hpp

@@ -0,0 +1,109 @@
+#ifndef slic3r_Format_objparser_hpp_
+#define slic3r_Format_objparser_hpp_
+
+#include <string>
+#include <vector>
+
+namespace ObjParser {
+
+struct ObjVertex
+{
+	int coordIdx;
+	int textureCoordIdx;
+	int normalIdx;
+};
+
+inline bool operator==(const ObjVertex &v1, const ObjVertex &v2)
+{
+	return 
+		v1.coordIdx			== v2.coordIdx			&& 
+		v1.textureCoordIdx	== v2.textureCoordIdx	&& 
+		v1.normalIdx		== v2.normalIdx;
+}
+
+struct ObjUseMtl
+{
+	int			vertexIdxFirst;
+	std::string name;
+};
+
+inline bool operator==(const ObjUseMtl &v1, const ObjUseMtl &v2)
+{
+	return 
+		v1.vertexIdxFirst	== v2.vertexIdxFirst	&& 
+		v1.name.compare(v2.name) == 0;
+}
+
+struct ObjObject
+{
+	int			vertexIdxFirst;
+	std::string name;
+};
+
+inline bool operator==(const ObjObject &v1, const ObjObject &v2)
+{
+	return 
+		v1.vertexIdxFirst	== v2.vertexIdxFirst	&& 
+		v1.name.compare(v2.name) == 0;
+}
+
+struct ObjGroup
+{
+	int			vertexIdxFirst;
+	std::string name;
+};
+
+inline bool operator==(const ObjGroup &v1, const ObjGroup &v2)
+{
+	return 
+		v1.vertexIdxFirst	== v2.vertexIdxFirst	&& 
+		v1.name.compare(v2.name) == 0;
+}
+
+struct ObjSmoothingGroup
+{
+	int			vertexIdxFirst;
+	int			smoothingGroupID;
+};
+
+inline bool operator==(const ObjSmoothingGroup &v1, const ObjSmoothingGroup &v2)
+{
+	return 
+		v1.vertexIdxFirst	== v2.vertexIdxFirst	&& 
+		v1.smoothingGroupID == v2.smoothingGroupID;
+}
+
+struct ObjData {
+	// Version of the data structure for load / store in the private binary format.
+	int								version;
+
+	// x, y, z, w
+	std::vector<float>				coordinates;
+	// u, v, w
+	std::vector<float>				textureCoordinates;
+	// x, y, z
+	std::vector<float>				normals;
+	// u, v, w
+	std::vector<float>				parameters;
+
+	std::vector<std::string>		mtllibs;
+	std::vector<ObjUseMtl>			usemtls;
+	std::vector<ObjObject>			objects;
+	std::vector<ObjGroup>			groups;
+	std::vector<ObjSmoothingGroup>	smoothingGroups;
+
+	// List of faces, delimited by an ObjVertex with all members set to -1.
+	std::vector<ObjVertex>			vertices;
+};
+
+extern bool objparse(const char *path, ObjData &data);
+
+extern bool objbinsave(const char *path, const ObjData &data);
+
+extern bool objbinload(const char *path, ObjData &data);
+
+extern bool objequal(const ObjData &data1, const ObjData &data2);
+
+} // namespace ObjParser
+
+#endif /* slic3r_Format_objparser_hpp_ */

src/libslic3r/GCode.hpp

@@ -0,0 +1,368 @@
+#ifndef slic3r_GCode_hpp_
+#define slic3r_GCode_hpp_
+
+#include "libslic3r.h"
+#include "ExPolygon.hpp"
+#include "GCodeWriter.hpp"
+#include "Layer.hpp"
+#include "MotionPlanner.hpp"
+#include "Point.hpp"
+#include "PlaceholderParser.hpp"
+#include "Print.hpp"
+#include "PrintConfig.hpp"
+#include "GCode/CoolingBuffer.hpp"
+#include "GCode/PressureEqualizer.hpp"
+#include "GCode/SpiralVase.hpp"
+#include "GCode/ToolOrdering.hpp"
+#include "GCode/WipeTower.hpp"
+#include "GCodeTimeEstimator.hpp"
+#include "EdgeGrid.hpp"
+#include "GCode/Analyzer.hpp"
+
+#include <memory>
+#include <string>
+
+namespace Slic3r {
+
+// Forward declarations.
+class GCode;
+class GCodePreviewData;
+
+class AvoidCrossingPerimeters {
+public:
+    
+    // this flag triggers the use of the external configuration space
+    bool use_external_mp;
+    bool use_external_mp_once;  // just for the next travel move
+    
+    // this flag disables avoid_crossing_perimeters just for the next travel move
+    // we enable it by default for the first travel move in print
+    bool disable_once;
+    
+    AvoidCrossingPerimeters() : use_external_mp(false), use_external_mp_once(false), disable_once(true) {}
+    ~AvoidCrossingPerimeters() {}
+
+    void init_external_mp(const ExPolygons &islands) { m_external_mp = Slic3r::make_unique<MotionPlanner>(islands); }
+    void init_layer_mp(const ExPolygons &islands) { m_layer_mp = Slic3r::make_unique<MotionPlanner>(islands); }
+
+    Polyline travel_to(const GCode &gcodegen, const Point &point);
+
+private:
+    std::unique_ptr<MotionPlanner> m_external_mp;
+    std::unique_ptr<MotionPlanner> m_layer_mp;
+};
+
+class OozePrevention {
+public:
+    bool enable;
+    Points standby_points;
+    
+    OozePrevention() : enable(false) {}
+    std::string pre_toolchange(GCode &gcodegen);
+    std::string post_toolchange(GCode &gcodegen);
+    
+private:
+    int _get_temp(GCode &gcodegen);
+};
+
+class Wipe {
+public:
+    bool enable;
+    Polyline path;
+    
+    Wipe() : enable(false) {}
+    bool has_path() const { return !this->path.points.empty(); }
+    void reset_path() { this->path = Polyline(); }
+    std::string wipe(GCode &gcodegen, bool toolchange = false);
+};
+
+class WipeTowerIntegration {
+public:
+    WipeTowerIntegration(
+        const PrintConfig                                           &print_config,
+        const WipeTower::ToolChangeResult                           &priming,
+        const std::vector<std::vector<WipeTower::ToolChangeResult>> &tool_changes,
+        const WipeTower::ToolChangeResult                           &final_purge) :
+        m_left(/*float(print_config.wipe_tower_x.value)*/ 0.f),
+        m_right(float(/*print_config.wipe_tower_x.value +*/ print_config.wipe_tower_width.value)),
+        m_wipe_tower_pos(float(print_config.wipe_tower_x.value), float(print_config.wipe_tower_y.value)),
+        m_wipe_tower_rotation(float(print_config.wipe_tower_rotation_angle)),
+        m_priming(priming),
+        m_tool_changes(tool_changes),
+        m_final_purge(final_purge),
+        m_layer_idx(-1),
+        m_tool_change_idx(0),
+        m_brim_done(false) {}
+
+    std::string prime(GCode &gcodegen);
+    void next_layer() { ++ m_layer_idx; m_tool_change_idx = 0; }
+    std::string tool_change(GCode &gcodegen, int extruder_id, bool finish_layer);
+    std::string finalize(GCode &gcodegen);
+    std::vector<float> used_filament_length() const;
+
+private:
+    WipeTowerIntegration& operator=(const WipeTowerIntegration&);
+    std::string append_tcr(GCode &gcodegen, const WipeTower::ToolChangeResult &tcr, int new_extruder_id) const;
+
+    // Postprocesses gcode: rotates and moves all G1 extrusions and returns result
+    std::string rotate_wipe_tower_moves(const std::string& gcode_original, const WipeTower::xy& start_pos, const WipeTower::xy& translation, float angle) const;
+
+    // Left / right edges of the wipe tower, for the planning of wipe moves.
+    const float                                                  m_left;
+    const float                                                  m_right;
+    const WipeTower::xy                                          m_wipe_tower_pos;
+    const float                                                  m_wipe_tower_rotation;
+    // Reference to cached values at the Printer class.
+    const WipeTower::ToolChangeResult                           &m_priming;
+    const std::vector<std::vector<WipeTower::ToolChangeResult>> &m_tool_changes;
+    const WipeTower::ToolChangeResult                           &m_final_purge;
+    // Current layer index.
+    int                                                          m_layer_idx;
+    int                                                          m_tool_change_idx;
+    bool                                                         m_brim_done;
+    bool                                                         i_have_brim = false;
+};
+
+class GCode {
+public:        
+    GCode() : 
+    	m_origin(Vec2d::Zero()),
+        m_enable_loop_clipping(true), 
+        m_enable_cooling_markers(false), 
+        m_enable_extrusion_role_markers(false), 
+        m_enable_analyzer(false),
+        m_last_analyzer_extrusion_role(erNone),
+        m_layer_count(0),
+        m_layer_index(-1), 
+        m_layer(nullptr), 
+        m_volumetric_speed(0),
+        m_last_pos_defined(false),
+        m_last_extrusion_role(erNone),
+        m_last_mm3_per_mm(GCodeAnalyzer::Default_mm3_per_mm),
+        m_last_width(GCodeAnalyzer::Default_Width),
+        m_last_height(GCodeAnalyzer::Default_Height),
+        m_brim_done(false),
+        m_second_layer_things_done(false),
+        m_normal_time_estimator(GCodeTimeEstimator::Normal),
+        m_silent_time_estimator(GCodeTimeEstimator::Silent),
+        m_silent_time_estimator_enabled(false),
+        m_last_obj_copy(nullptr, Point(std::numeric_limits<coord_t>::max(), std::numeric_limits<coord_t>::max()))
+        {}
+    ~GCode() {}
+
+    // throws std::runtime_exception on error,
+    // throws CanceledException through print->throw_if_canceled().
+    void            do_export(Print *print, const char *path, GCodePreviewData *preview_data = nullptr);
+
+    // Exported for the helper classes (OozePrevention, Wipe) and for the Perl binding for unit tests.
+    const Vec2d&   origin() const { return m_origin; }
+    void            set_origin(const Vec2d &pointf);
+    void            set_origin(const coordf_t x, const coordf_t y) { this->set_origin(Vec2d(x, y)); }
+    const Point&    last_pos() const { return m_last_pos; }
+    Vec2d          point_to_gcode(const Point &point) const;
+    Point           gcode_to_point(const Vec2d &point) const;
+    const FullPrintConfig &config() const { return m_config; }
+    const Layer*    layer() const { return m_layer; }
+    GCodeWriter&    writer() { return m_writer; }
+    PlaceholderParser& placeholder_parser() { return m_placeholder_parser; }
+    const PlaceholderParser& placeholder_parser() const { return m_placeholder_parser; }
+    // Process a template through the placeholder parser, collect error messages to be reported
+    // inside the generated string and after the G-code export finishes.
+    std::string     placeholder_parser_process(const std::string &name, const std::string &templ, unsigned int current_extruder_id, const DynamicConfig *config_override = nullptr);
+    bool            enable_cooling_markers() const { return m_enable_cooling_markers; }
+
+    // For Perl bindings, to be used exclusively by unit tests.
+    unsigned int    layer_count() const { return m_layer_count; }
+    void            set_layer_count(unsigned int value) { m_layer_count = value; }
+    void            apply_print_config(const PrintConfig &print_config);
+
+    // append full config to the given string
+    static void append_full_config(const Print& print, std::string& str);
+
+protected:
+    void            _do_export(Print &print, FILE *file, GCodePreviewData *preview_data);
+
+    // Object and support extrusions of the same PrintObject at the same print_z.
+    struct LayerToPrint
+    {
+        LayerToPrint() : object_layer(nullptr), support_layer(nullptr) {}
+        const Layer          *object_layer;
+        const SupportLayer   *support_layer;
+        const Layer*          layer() const { return (object_layer != nullptr) ? object_layer : support_layer; }
+        const PrintObject*    object() const { return (this->layer() != nullptr) ? this->layer()->object() : nullptr; }
+        coordf_t              print_z() const { return (object_layer != nullptr && support_layer != nullptr) ? 0.5 * (object_layer->print_z + support_layer->print_z) : this->layer()->print_z; }
+    };
+    static std::vector<GCode::LayerToPrint>                            collect_layers_to_print(const PrintObject &object);
+    static std::vector<std::pair<coordf_t, std::vector<LayerToPrint>>> collect_layers_to_print(const Print &print);
+    void            process_layer(
+        // Write into the output file.
+        FILE                            *file,
+        const Print                     &print,
+        // Set of object & print layers of the same PrintObject and with the same print_z.
+        const std::vector<LayerToPrint> &layers,
+        const LayerTools  &layer_tools,
+        // If set to size_t(-1), then print all copies of all objects.
+        // Otherwise print a single copy of a single object.
+        const size_t                     single_object_idx = size_t(-1));
+
+    void            set_last_pos(const Point &pos) { m_last_pos = pos; m_last_pos_defined = true; }
+    bool            last_pos_defined() const { return m_last_pos_defined; }
+    void            set_extruders(const std::vector<unsigned int> &extruder_ids);
+    std::string     preamble();
+    std::string     change_layer(coordf_t print_z);
+    std::string     extrude_entity(const ExtrusionEntity &entity, std::string description = "", double speed = -1., std::unique_ptr<EdgeGrid::Grid> *lower_layer_edge_grid = nullptr);
+    std::string     extrude_loop(ExtrusionLoop loop, std::string description, double speed = -1., std::unique_ptr<EdgeGrid::Grid> *lower_layer_edge_grid = nullptr);
+    std::string     extrude_multi_path(ExtrusionMultiPath multipath, std::string description = "", double speed = -1.);
+    std::string     extrude_path(ExtrusionPath path, std::string description = "", double speed = -1.);
+
+    typedef std::vector<int> ExtruderPerCopy;
+    // Extruding multiple objects with soluble / non-soluble / combined supports
+    // on a multi-material printer, trying to minimize tool switches.
+    // Following structures sort extrusions by the extruder ID, by an order of objects and object islands.
+    struct ObjectByExtruder
+    {
+        ObjectByExtruder() : support(nullptr), support_extrusion_role(erNone) {}
+        const ExtrusionEntityCollection  *support;
+        // erSupportMaterial / erSupportMaterialInterface or erMixed.
+        ExtrusionRole                     support_extrusion_role;
+
+        struct Island
+        {
+            struct Region {
+                ExtrusionEntityCollection perimeters;
+                ExtrusionEntityCollection infills;
+
+                std::vector<const ExtruderPerCopy*> infills_overrides;
+                std::vector<const ExtruderPerCopy*> perimeters_overrides;
+
+                // Appends perimeter/infill entities and writes don't indices of those that are not to be extruder as part of perimeter/infill wiping
+                void append(const std::string& type, const ExtrusionEntityCollection* eec, const ExtruderPerCopy* copy_extruders, unsigned int object_copies_num);
+            };
+
+            std::vector<Region> by_region;                                    // all extrusions for this island, grouped by regions
+            const std::vector<Region>& by_region_per_copy(unsigned int copy, int extruder, bool wiping_entities = false); // returns reference to subvector of by_region
+
+        private:
+            std::vector<Region> by_region_per_copy_cache;   // caches vector generated by function above to avoid copying and recalculating
+        };
+        std::vector<Island>         islands;
+    };
+
+
+    std::string     extrude_perimeters(const Print &print, const std::vector<ObjectByExtruder::Island::Region> &by_region, std::unique_ptr<EdgeGrid::Grid> &lower_layer_edge_grid);
+    std::string     extrude_infill(const Print &print, const std::vector<ObjectByExtruder::Island::Region> &by_region);
+    std::string     extrude_support(const ExtrusionEntityCollection &support_fills);
+
+    std::string     travel_to(const Point &point, ExtrusionRole role, std::string comment);
+    bool            needs_retraction(const Polyline &travel, ExtrusionRole role = erNone);
+    std::string     retract(bool toolchange = false);
+    std::string     unretract() { return m_writer.unlift() + m_writer.unretract(); }
+    std::string     set_extruder(unsigned int extruder_id);
+
+    /* Origin of print coordinates expressed in unscaled G-code coordinates.
+       This affects the input arguments supplied to the extrude*() and travel_to()
+       methods. */
+    Vec2d                              m_origin;
+    FullPrintConfig                     m_config;
+    GCodeWriter                         m_writer;
+    PlaceholderParser                   m_placeholder_parser;
+    // Collection of templates, on which the placeholder substitution failed.
+    std::set<std::string>               m_placeholder_parser_failed_templates;
+    OozePrevention                      m_ooze_prevention;
+    Wipe                                m_wipe;
+    AvoidCrossingPerimeters             m_avoid_crossing_perimeters;
+    bool                                m_enable_loop_clipping;
+    // If enabled, the G-code generator will put following comments at the ends
+    // of the G-code lines: _EXTRUDE_SET_SPEED, _WIPE, _BRIDGE_FAN_START, _BRIDGE_FAN_END
+    // Those comments are received and consumed (removed from the G-code) by the CoolingBuffer.pm Perl module.
+    bool                                m_enable_cooling_markers;
+    // Markers for the Pressure Equalizer to recognize the extrusion type.
+    // The Pressure Equalizer removes the markers from the final G-code.
+    bool                                m_enable_extrusion_role_markers;
+    // Enableds the G-code Analyzer.
+    // Extended markers will be added during G-code generation.
+    // The G-code Analyzer will remove these comments from the final G-code.
+    bool                                m_enable_analyzer;
+    ExtrusionRole                       m_last_analyzer_extrusion_role;
+    // How many times will change_layer() be called?
+    // change_layer() will update the progress bar.
+    unsigned int                        m_layer_count;
+    // Progress bar indicator. Increments from -1 up to layer_count.
+    int                                 m_layer_index;
+    // Current layer processed. Insequential printing mode, only a single copy will be printed.
+    // In non-sequential mode, all its copies will be printed.
+    const Layer*                        m_layer;
+    std::map<const PrintObject*,Point>  m_seam_position;
+    double                              m_volumetric_speed;
+    // Support for the extrusion role markers. Which marker is active?
+    ExtrusionRole                       m_last_extrusion_role;
+    // Support for G-Code Analyzer
+    double                              m_last_mm3_per_mm;
+    float                               m_last_width;
+    float                               m_last_height;
+
+    Point                               m_last_pos;
+    bool                                m_last_pos_defined;
+
+    std::unique_ptr<CoolingBuffer>      m_cooling_buffer;
+    std::unique_ptr<SpiralVase>         m_spiral_vase;
+    std::unique_ptr<PressureEqualizer>  m_pressure_equalizer;
+    std::unique_ptr<WipeTowerIntegration> m_wipe_tower;
+
+    // Heights at which the skirt has already been extruded.
+    std::vector<coordf_t>               m_skirt_done;
+    // Has the brim been extruded already? Brim is being extruded only for the first object of a multi-object print.
+    bool                                m_brim_done;
+    // Flag indicating whether the nozzle temperature changes from 1st to 2nd layer were performed.
+    bool                                m_second_layer_things_done;
+    // Index of a last object copy extruded.
+    std::pair<const PrintObject*, Point> m_last_obj_copy;
+    // Layer heights for colorprint - updated before the export and erased during the process
+    // so no toolchange occurs twice.
+    std::vector<float> m_colorprint_heights;
+
+    // Time estimators
+    GCodeTimeEstimator m_normal_time_estimator;
+    GCodeTimeEstimator m_silent_time_estimator;
+    bool m_silent_time_estimator_enabled;
+
+    // Analyzer
+    GCodeAnalyzer m_analyzer;
+
+    // Write a string into a file.
+    void _write(FILE* file, const std::string& what) { this->_write(file, what.c_str()); }
+    void _write(FILE* file, const char *what);
+
+    // Write a string into a file. 
+    // Add a newline, if the string does not end with a newline already.
+    // Used to export a custom G-code section processed by the PlaceholderParser.
+    void _writeln(FILE* file, const std::string& what);
+
+    // Formats and write into a file the given data. 
+    void _write_format(FILE* file, const char* format, ...);
+
+    std::string _extrude(const ExtrusionPath &path, std::string description = "", double speed = -1);
+    void print_machine_envelope(FILE *file, Print &print);
+    void _print_first_layer_bed_temperature(FILE *file, Print &print, const std::string &gcode, unsigned int first_printing_extruder_id, bool wait);
+    void _print_first_layer_extruder_temperatures(FILE *file, Print &print, const std::string &gcode, unsigned int first_printing_extruder_id, bool wait);
+    // this flag triggers first layer speeds
+    bool                                on_first_layer() const { return m_layer != nullptr && m_layer->id() == 0; }
+
+    friend ObjectByExtruder& object_by_extruder(
+        std::map<unsigned int, std::vector<ObjectByExtruder>> &by_extruder, 
+        unsigned int                                           extruder_id, 
+        size_t                                                 object_idx, 
+        size_t                                                 num_objects);
+    friend std::vector<ObjectByExtruder::Island>& object_islands_by_extruder(
+        std::map<unsigned int, std::vector<ObjectByExtruder>>  &by_extruder, 
+        unsigned int                                            extruder_id, 
+        size_t                                                  object_idx, 
+        size_t                                                  num_objects,
+        size_t                                                  num_islands);
+
+    friend class WipeTowerIntegration;
+};
+
+}
+
+#endif

src/libslic3r/GCode/Analyzer.cpp

@@ -0,0 +1,842 @@
+#include <memory.h>
+#include <string.h>
+#include <float.h>
+
+#include "../libslic3r.h"
+#include "../PrintConfig.hpp"
+#include "Print.hpp"
+
+#include "Analyzer.hpp"
+#include "PreviewData.hpp"
+
+static const std::string AXIS_STR = "XYZE";
+static const float MMMIN_TO_MMSEC = 1.0f / 60.0f;
+static const float INCHES_TO_MM = 25.4f;
+static const float DEFAULT_FEEDRATE = 0.0f;
+static const unsigned int DEFAULT_EXTRUDER_ID = 0;
+static const Slic3r::Vec3d DEFAULT_START_POSITION = Slic3r::Vec3d(0.0f, 0.0f, 0.0f);
+static const float DEFAULT_START_EXTRUSION = 0.0f;
+
+namespace Slic3r {
+
+const std::string GCodeAnalyzer::Extrusion_Role_Tag = "_ANALYZER_EXTR_ROLE:";
+const std::string GCodeAnalyzer::Mm3_Per_Mm_Tag = "_ANALYZER_MM3_PER_MM:";
+const std::string GCodeAnalyzer::Width_Tag = "_ANALYZER_WIDTH:";
+const std::string GCodeAnalyzer::Height_Tag = "_ANALYZER_HEIGHT:";
+
+const double GCodeAnalyzer::Default_mm3_per_mm = 0.0;
+const float GCodeAnalyzer::Default_Width = 0.0f;
+const float GCodeAnalyzer::Default_Height = 0.0f;
+
+GCodeAnalyzer::Metadata::Metadata()
+    : extrusion_role(erNone)
+    , extruder_id(DEFAULT_EXTRUDER_ID)
+    , mm3_per_mm(GCodeAnalyzer::Default_mm3_per_mm)
+    , width(GCodeAnalyzer::Default_Width)
+    , height(GCodeAnalyzer::Default_Height)
+    , feedrate(DEFAULT_FEEDRATE)
+{
+}
+
+GCodeAnalyzer::Metadata::Metadata(ExtrusionRole extrusion_role, unsigned int extruder_id, double mm3_per_mm, float width, float height, float feedrate)
+    : extrusion_role(extrusion_role)
+    , extruder_id(extruder_id)
+    , mm3_per_mm(mm3_per_mm)
+    , width(width)
+    , height(height)
+    , feedrate(feedrate)
+{
+}
+
+bool GCodeAnalyzer::Metadata::operator != (const GCodeAnalyzer::Metadata& other) const
+{
+    if (extrusion_role != other.extrusion_role)
+        return true;
+
+    if (extruder_id != other.extruder_id)
+        return true;
+
+    if (mm3_per_mm != other.mm3_per_mm)
+        return true;
+
+    if (width != other.width)
+        return true;
+
+    if (height != other.height)
+        return true;
+
+    if (feedrate != other.feedrate)
+        return true;
+
+    return false;
+}
+
+GCodeAnalyzer::GCodeMove::GCodeMove(GCodeMove::EType type, ExtrusionRole extrusion_role, unsigned int extruder_id, double mm3_per_mm, float width, float height, float feedrate, const Vec3d& start_position, const Vec3d& end_position, float delta_extruder)
+    : type(type)
+    , data(extrusion_role, extruder_id, mm3_per_mm, width, height, feedrate)
+    , start_position(start_position)
+    , end_position(end_position)
+    , delta_extruder(delta_extruder)
+{
+}
+
+GCodeAnalyzer::GCodeMove::GCodeMove(GCodeMove::EType type, const GCodeAnalyzer::Metadata& data, const Vec3d& start_position, const Vec3d& end_position, float delta_extruder)
+    : type(type)
+    , data(data)
+    , start_position(start_position)
+    , end_position(end_position)
+    , delta_extruder(delta_extruder)
+{
+}
+
+GCodeAnalyzer::GCodeAnalyzer()
+{
+    reset();
+}
+
+void GCodeAnalyzer::reset()
+{
+    _set_units(Millimeters);
+    _set_global_positioning_type(Absolute);
+    _set_e_local_positioning_type(Absolute);
+    _set_extrusion_role(erNone);
+    _set_extruder_id(DEFAULT_EXTRUDER_ID);
+    _set_mm3_per_mm(Default_mm3_per_mm);
+    _set_width(Default_Width);
+    _set_height(Default_Height);
+    _set_feedrate(DEFAULT_FEEDRATE);
+    _set_start_position(DEFAULT_START_POSITION);
+    _set_start_extrusion(DEFAULT_START_EXTRUSION);
+    _reset_axes_position();
+
+    m_moves_map.clear();
+}
+
+const std::string& GCodeAnalyzer::process_gcode(const std::string& gcode)
+{
+    m_process_output = "";
+
+    m_parser.parse_buffer(gcode,
+        [this](GCodeReader& reader, const GCodeReader::GCodeLine& line)
+    { this->_process_gcode_line(reader, line); });
+
+    return m_process_output;
+}
+
+void GCodeAnalyzer::calc_gcode_preview_data(GCodePreviewData& preview_data)
+{
+    // resets preview data
+    preview_data.reset();
+
+    // calculates extrusion layers
+    _calc_gcode_preview_extrusion_layers(preview_data);
+
+    // calculates travel
+    _calc_gcode_preview_travel(preview_data);
+
+    // calculates retractions
+    _calc_gcode_preview_retractions(preview_data);
+
+    // calculates unretractions
+    _calc_gcode_preview_unretractions(preview_data);
+}
+
+bool GCodeAnalyzer::is_valid_extrusion_role(ExtrusionRole role)
+{
+    return ((erPerimeter <= role) && (role < erMixed));
+}
+
+void GCodeAnalyzer::_process_gcode_line(GCodeReader&, const GCodeReader::GCodeLine& line)
+{
+    // processes 'special' comments contained in line
+    if (_process_tags(line))
+    {
+#if 0
+        // DEBUG ONLY: puts the line back into the gcode
+        m_process_output += line.raw() + "\n";
+#endif
+        return;
+    }
+
+    // sets new start position/extrusion
+    _set_start_position(_get_end_position());
+    _set_start_extrusion(_get_axis_position(E));
+
+    // processes 'normal' gcode lines
+    std::string cmd = line.cmd();
+    if (cmd.length() > 1)
+    {
+        switch (::toupper(cmd[0]))
+        {
+        case 'G':
+            {
+                switch (::atoi(&cmd[1]))
+                {
+                case 1: // Move
+                    {
+                        _processG1(line);
+                        break;
+                    }
+                case 10: // Retract
+                    {
+                        _processG10(line);
+                        break;
+                    }
+                case 11: // Unretract
+                    {
+                        _processG11(line);
+                        break;
+                    }
+                case 22: // Firmware controlled Retract
+                    {
+                        _processG22(line);
+                        break;
+                    }
+                case 23: // Firmware controlled Unretract
+                    {
+                        _processG23(line);
+                        break;
+                    }
+                case 90: // Set to Absolute Positioning
+                    {
+                        _processG90(line);
+                        break;
+                    }
+                case 91: // Set to Relative Positioning
+                    {
+                        _processG91(line);
+                        break;
+                    }
+                case 92: // Set Position
+                    {
+                        _processG92(line);
+                        break;
+                    }
+                }
+
+                break;
+            }
+        case 'M':
+            {
+                switch (::atoi(&cmd[1]))
+                {
+                case 82: // Set extruder to absolute mode
+                    {
+                        _processM82(line);
+                        break;
+                    }
+                case 83: // Set extruder to relative mode
+                    {
+                        _processM83(line);
+                        break;
+                    }
+                }
+
+                break;
+            }
+        case 'T': // Select Tools
+            {
+                _processT(line);
+                break;
+            }
+        }
+    }
+
+    // puts the line back into the gcode
+    m_process_output += line.raw() + "\n";
+}
+
+// Returns the new absolute position on the given axis in dependence of the given parameters
+float axis_absolute_position_from_G1_line(GCodeAnalyzer::EAxis axis, const GCodeReader::GCodeLine& lineG1, GCodeAnalyzer::EUnits units, bool is_relative, float current_absolute_position)
+{
+    float lengthsScaleFactor = (units == GCodeAnalyzer::Inches) ? INCHES_TO_MM : 1.0f;
+    if (lineG1.has(Slic3r::Axis(axis)))
+    {
+        float ret = lineG1.value(Slic3r::Axis(axis)) * lengthsScaleFactor;
+        return is_relative ? current_absolute_position + ret : ret;
+    }
+    else
+        return current_absolute_position;
+}
+
+void GCodeAnalyzer::_processG1(const GCodeReader::GCodeLine& line)
+{
+    // updates axes positions from line
+    EUnits units = _get_units();
+    float new_pos[Num_Axis];
+    for (unsigned char a = X; a < Num_Axis; ++a)
+    {
+        bool is_relative = (_get_global_positioning_type() == Relative);
+        if (a == E)
+            is_relative |= (_get_e_local_positioning_type() == Relative);
+
+        new_pos[a] = axis_absolute_position_from_G1_line((EAxis)a, line, units, is_relative, _get_axis_position((EAxis)a));
+    }
+
+    // updates feedrate from line, if present
+    if (line.has_f())
+        _set_feedrate(line.f() * MMMIN_TO_MMSEC);
+
+    // calculates movement deltas
+    float delta_pos[Num_Axis];
+    for (unsigned char a = X; a < Num_Axis; ++a)
+    {
+        delta_pos[a] = new_pos[a] - _get_axis_position((EAxis)a);
+    }
+
+    // Detects move type
+    GCodeMove::EType type = GCodeMove::Noop;
+
+    if (delta_pos[E] < 0.0f)
+    {
+        if ((delta_pos[X] != 0.0f) || (delta_pos[Y] != 0.0f) || (delta_pos[Z] != 0.0f))
+            type = GCodeMove::Move;
+        else
+            type = GCodeMove::Retract;
+    }
+    else if (delta_pos[E] > 0.0f)
+    {
+        if ((delta_pos[X] == 0.0f) && (delta_pos[Y] == 0.0f) && (delta_pos[Z] == 0.0f))
+            type = GCodeMove::Unretract;
+        else if ((delta_pos[X] != 0.0f) || (delta_pos[Y] != 0.0f))
+            type = GCodeMove::Extrude;
+    }
+    else if ((delta_pos[X] != 0.0f) || (delta_pos[Y] != 0.0f) || (delta_pos[Z] != 0.0f))
+        type = GCodeMove::Move;
+
+    ExtrusionRole role = _get_extrusion_role();
+    if ((type == GCodeMove::Extrude) && ((_get_width() == 0.0f) || (_get_height() == 0.0f) || !is_valid_extrusion_role(role)))
+        type = GCodeMove::Move;
+
+    // updates axis positions
+    for (unsigned char a = X; a < Num_Axis; ++a)
+    {
+        _set_axis_position((EAxis)a, new_pos[a]);
+    }
+
+    // stores the move
+    if (type != GCodeMove::Noop)
+        _store_move(type);
+}
+
+void GCodeAnalyzer::_processG10(const GCodeReader::GCodeLine& line)
+{
+    // stores retract move
+    _store_move(GCodeMove::Retract);
+}
+
+void GCodeAnalyzer::_processG11(const GCodeReader::GCodeLine& line)
+{
+    // stores unretract move
+    _store_move(GCodeMove::Unretract);
+}
+
+void GCodeAnalyzer::_processG22(const GCodeReader::GCodeLine& line)
+{
+    // stores retract move
+    _store_move(GCodeMove::Retract);
+}
+
+void GCodeAnalyzer::_processG23(const GCodeReader::GCodeLine& line)
+{
+    // stores unretract move
+    _store_move(GCodeMove::Unretract);
+}
+
+void GCodeAnalyzer::_processG90(const GCodeReader::GCodeLine& line)
+{
+    _set_global_positioning_type(Absolute);
+}
+
+void GCodeAnalyzer::_processG91(const GCodeReader::GCodeLine& line)
+{
+    _set_global_positioning_type(Relative);
+}
+
+void GCodeAnalyzer::_processG92(const GCodeReader::GCodeLine& line)
+{
+    float lengthsScaleFactor = (_get_units() == Inches) ? INCHES_TO_MM : 1.0f;
+    bool anyFound = false;
+
+    if (line.has_x())
+    {
+        _set_axis_position(X, line.x() * lengthsScaleFactor);
+        anyFound = true;
+    }
+
+    if (line.has_y())
+    {
+        _set_axis_position(Y, line.y() * lengthsScaleFactor);
+        anyFound = true;
+    }
+
+    if (line.has_z())
+    {
+        _set_axis_position(Z, line.z() * lengthsScaleFactor);
+        anyFound = true;
+    }
+
+    if (line.has_e())
+    {
+        _set_axis_position(E, line.e() * lengthsScaleFactor);
+        anyFound = true;
+    }
+
+    if (!anyFound)
+    {
+        for (unsigned char a = X; a < Num_Axis; ++a)
+        {
+            _set_axis_position((EAxis)a, 0.0f);
+        }
+    }
+}
+
+void GCodeAnalyzer::_processM82(const GCodeReader::GCodeLine& line)
+{
+    _set_e_local_positioning_type(Absolute);
+}
+
+void GCodeAnalyzer::_processM83(const GCodeReader::GCodeLine& line)
+{
+    _set_e_local_positioning_type(Relative);
+}
+
+void GCodeAnalyzer::_processT(const GCodeReader::GCodeLine& line)
+{
+    std::string cmd = line.cmd();
+    if (cmd.length() > 1)
+    {
+        unsigned int id = (unsigned int)::strtol(cmd.substr(1).c_str(), nullptr, 10);
+        if (_get_extruder_id() != id)
+        {
+            _set_extruder_id(id);
+
+            // stores tool change move
+            _store_move(GCodeMove::Tool_change);
+        }
+    }
+}
+
+bool GCodeAnalyzer::_process_tags(const GCodeReader::GCodeLine& line)
+{
+    std::string comment = line.comment();
+
+    // extrusion role tag
+    size_t pos = comment.find(Extrusion_Role_Tag);
+    if (pos != comment.npos)
+    {
+        _process_extrusion_role_tag(comment, pos);
+        return true;
+    }
+
+    // mm3 per mm tag
+    pos = comment.find(Mm3_Per_Mm_Tag);
+    if (pos != comment.npos)
+    {
+        _process_mm3_per_mm_tag(comment, pos);
+        return true;
+    }
+
+    // width tag
+    pos = comment.find(Width_Tag);
+    if (pos != comment.npos)
+    {
+        _process_width_tag(comment, pos);
+        return true;
+    }
+
+    // height tag
+    pos = comment.find(Height_Tag);
+    if (pos != comment.npos)
+    {
+        _process_height_tag(comment, pos);
+        return true;
+    }
+
+    return false;
+}
+
+void GCodeAnalyzer::_process_extrusion_role_tag(const std::string& comment, size_t pos)
+{
+    int role = (int)::strtol(comment.substr(pos + Extrusion_Role_Tag.length()).c_str(), nullptr, 10);
+    if (_is_valid_extrusion_role(role))
+        _set_extrusion_role((ExtrusionRole)role);
+    else
+    {
+        // todo: show some error ?
+    }
+}
+
+void GCodeAnalyzer::_process_mm3_per_mm_tag(const std::string& comment, size_t pos)
+{
+    _set_mm3_per_mm(::strtod(comment.substr(pos + Mm3_Per_Mm_Tag.length()).c_str(), nullptr));
+}
+
+void GCodeAnalyzer::_process_width_tag(const std::string& comment, size_t pos)
+{
+    _set_width((float)::strtod(comment.substr(pos + Width_Tag.length()).c_str(), nullptr));
+}
+
+void GCodeAnalyzer::_process_height_tag(const std::string& comment, size_t pos)
+{
+    _set_height((float)::strtod(comment.substr(pos + Height_Tag.length()).c_str(), nullptr));
+}
+
+void GCodeAnalyzer::_set_units(GCodeAnalyzer::EUnits units)
+{
+    m_state.units = units;
+}
+
+GCodeAnalyzer::EUnits GCodeAnalyzer::_get_units() const
+{
+    return m_state.units;
+}
+
+void GCodeAnalyzer::_set_global_positioning_type(GCodeAnalyzer::EPositioningType type)
+{
+    m_state.global_positioning_type = type;
+}
+
+GCodeAnalyzer::EPositioningType GCodeAnalyzer::_get_global_positioning_type() const
+{
+    return m_state.global_positioning_type;
+}
+
+void GCodeAnalyzer::_set_e_local_positioning_type(GCodeAnalyzer::EPositioningType type)
+{
+    m_state.e_local_positioning_type = type;
+}
+
+GCodeAnalyzer::EPositioningType GCodeAnalyzer::_get_e_local_positioning_type() const
+{
+    return m_state.e_local_positioning_type;
+}
+
+void GCodeAnalyzer::_set_extrusion_role(ExtrusionRole extrusion_role)
+{
+    m_state.data.extrusion_role = extrusion_role;
+}
+
+ExtrusionRole GCodeAnalyzer::_get_extrusion_role() const
+{
+    return m_state.data.extrusion_role;
+}
+
+void GCodeAnalyzer::_set_extruder_id(unsigned int id)
+{
+    m_state.data.extruder_id = id;
+}
+
+unsigned int GCodeAnalyzer::_get_extruder_id() const
+{
+    return m_state.data.extruder_id;
+}
+
+void GCodeAnalyzer::_set_mm3_per_mm(double value)
+{
+    m_state.data.mm3_per_mm = value;
+}
+
+double GCodeAnalyzer::_get_mm3_per_mm() const
+{
+    return m_state.data.mm3_per_mm;
+}
+
+void GCodeAnalyzer::_set_width(float width)
+{
+    m_state.data.width = width;
+}
+
+float GCodeAnalyzer::_get_width() const
+{
+    return m_state.data.width;
+}
+
+void GCodeAnalyzer::_set_height(float height)
+{
+    m_state.data.height = height;
+}
+
+float GCodeAnalyzer::_get_height() const
+{
+    return m_state.data.height;
+}
+
+void GCodeAnalyzer::_set_feedrate(float feedrate_mm_sec)
+{
+    m_state.data.feedrate = feedrate_mm_sec;
+}
+
+float GCodeAnalyzer::_get_feedrate() const
+{
+    return m_state.data.feedrate;
+}
+
+void GCodeAnalyzer::_set_axis_position(EAxis axis, float position)
+{
+    m_state.position[axis] = position;
+}
+
+float GCodeAnalyzer::_get_axis_position(EAxis axis) const
+{
+    return m_state.position[axis];
+}
+
+void GCodeAnalyzer::_reset_axes_position()
+{
+    ::memset((void*)m_state.position, 0, Num_Axis * sizeof(float));
+}
+
+void GCodeAnalyzer::_set_start_position(const Vec3d& position)
+{
+    m_state.start_position = position;
+}
+
+const Vec3d& GCodeAnalyzer::_get_start_position() const
+{
+    return m_state.start_position;
+}
+
+void GCodeAnalyzer::_set_start_extrusion(float extrusion)
+{
+    m_state.start_extrusion = extrusion;
+}
+
+float GCodeAnalyzer::_get_start_extrusion() const
+{
+    return m_state.start_extrusion;
+}
+
+float GCodeAnalyzer::_get_delta_extrusion() const
+{
+    return _get_axis_position(E) - m_state.start_extrusion;
+}
+
+Vec3d GCodeAnalyzer::_get_end_position() const
+{
+    return Vec3d(m_state.position[X], m_state.position[Y], m_state.position[Z]);
+}
+
+void GCodeAnalyzer::_store_move(GCodeAnalyzer::GCodeMove::EType type)
+{
+    // if type non mapped yet, map it
+    TypeToMovesMap::iterator it = m_moves_map.find(type);
+    if (it == m_moves_map.end())
+        it = m_moves_map.insert(TypeToMovesMap::value_type(type, GCodeMovesList())).first;
+
+    // store move
+    it->second.emplace_back(type, _get_extrusion_role(), _get_extruder_id(), _get_mm3_per_mm(), _get_width(), _get_height(), _get_feedrate(), _get_start_position(), _get_end_position(), _get_delta_extrusion());
+}
+
+bool GCodeAnalyzer::_is_valid_extrusion_role(int value) const
+{
+    return ((int)erNone <= value) && (value <= (int)erMixed);
+}
+
+void GCodeAnalyzer::_calc_gcode_preview_extrusion_layers(GCodePreviewData& preview_data)
+{
+    struct Helper
+    {
+        static GCodePreviewData::Extrusion::Layer& get_layer_at_z(GCodePreviewData::Extrusion::LayersList& layers, float z)
+        {
+            for (GCodePreviewData::Extrusion::Layer& layer : layers)
+            {
+                // if layer found, return it
+                if (layer.z == z)
+                    return layer;
+            }
+
+            // if layer not found, create and return it
+            layers.emplace_back(z, ExtrusionPaths());
+            return layers.back();
+        }
+
+        static void store_polyline(const Polyline& polyline, const Metadata& data, float z, GCodePreviewData& preview_data)
+        {
+            // if the polyline is valid, create the extrusion path from it and store it
+            if (polyline.is_valid())
+            {
+                ExtrusionPath path(data.extrusion_role, data.mm3_per_mm, data.width, data.height);
+                path.polyline = polyline;
+                path.feedrate = data.feedrate;
+                path.extruder_id = data.extruder_id;
+
+                get_layer_at_z(preview_data.extrusion.layers, z).paths.push_back(path);
+            }
+        }
+    };
+
+    TypeToMovesMap::iterator extrude_moves = m_moves_map.find(GCodeMove::Extrude);
+    if (extrude_moves == m_moves_map.end())
+        return;
+
+    Metadata data;
+    float z = FLT_MAX;
+    Polyline polyline;
+    Vec3d position(FLT_MAX, FLT_MAX, FLT_MAX);
+    float volumetric_rate = FLT_MAX;
+    GCodePreviewData::Range height_range;
+    GCodePreviewData::Range width_range;
+    GCodePreviewData::Range feedrate_range;
+    GCodePreviewData::Range volumetric_rate_range;
+
+    // constructs the polylines while traversing the moves
+    for (const GCodeMove& move : extrude_moves->second)
+    {
+        if ((data != move.data) || (z != move.start_position.z()) || (position != move.start_position) || (volumetric_rate != move.data.feedrate * (float)move.data.mm3_per_mm))
+        {
+            // store current polyline
+            polyline.remove_duplicate_points();
+            Helper::store_polyline(polyline, data, z, preview_data);
+
+            // reset current polyline
+            polyline = Polyline();
+
+            // add both vertices of the move
+            polyline.append(Point(scale_(move.start_position.x()), scale_(move.start_position.y())));
+            polyline.append(Point(scale_(move.end_position.x()), scale_(move.end_position.y())));
+
+            // update current values
+            data = move.data;
+            z = (float)move.start_position.z();
+            volumetric_rate = move.data.feedrate * (float)move.data.mm3_per_mm;
+            height_range.update_from(move.data.height);
+            width_range.update_from(move.data.width);
+            feedrate_range.update_from(move.data.feedrate);
+            volumetric_rate_range.update_from(volumetric_rate);
+        }
+        else
+            // append end vertex of the move to current polyline
+            polyline.append(Point(scale_(move.end_position.x()), scale_(move.end_position.y())));
+
+        // update current values
+        position = move.end_position;
+    }
+
+    // store last polyline
+    polyline.remove_duplicate_points();
+    Helper::store_polyline(polyline, data, z, preview_data);
+
+    // updates preview ranges data
+    preview_data.ranges.height.update_from(height_range);
+    preview_data.ranges.width.update_from(width_range);
+    preview_data.ranges.feedrate.update_from(feedrate_range);
+    preview_data.ranges.volumetric_rate.update_from(volumetric_rate_range);
+}
+
+void GCodeAnalyzer::_calc_gcode_preview_travel(GCodePreviewData& preview_data)
+{
+    struct Helper
+    {
+        static void store_polyline(const Polyline3& polyline, GCodePreviewData::Travel::EType type, GCodePreviewData::Travel::Polyline::EDirection direction, 
+            float feedrate, unsigned int extruder_id, GCodePreviewData& preview_data)
+        {
+            // if the polyline is valid, store it
+            if (polyline.is_valid())
+                preview_data.travel.polylines.emplace_back(type, direction, feedrate, extruder_id, polyline);
+        }
+    };
+
+    TypeToMovesMap::iterator travel_moves = m_moves_map.find(GCodeMove::Move);
+    if (travel_moves == m_moves_map.end())
+        return;
+
+    Polyline3 polyline;
+    Vec3d position(FLT_MAX, FLT_MAX, FLT_MAX);
+    GCodePreviewData::Travel::EType type = GCodePreviewData::Travel::Num_Types;
+    GCodePreviewData::Travel::Polyline::EDirection direction = GCodePreviewData::Travel::Polyline::Num_Directions;
+    float feedrate = FLT_MAX;
+    unsigned int extruder_id = -1;
+
+    GCodePreviewData::Range height_range;
+    GCodePreviewData::Range width_range;
+    GCodePreviewData::Range feedrate_range;
+
+    // constructs the polylines while traversing the moves
+    for (const GCodeMove& move : travel_moves->second)
+    {
+        GCodePreviewData::Travel::EType move_type = (move.delta_extruder < 0.0f) ? GCodePreviewData::Travel::Retract : ((move.delta_extruder > 0.0f) ? GCodePreviewData::Travel::Extrude : GCodePreviewData::Travel::Move);
+        GCodePreviewData::Travel::Polyline::EDirection move_direction = ((move.start_position.x() != move.end_position.x()) || (move.start_position.y() != move.end_position.y())) ? GCodePreviewData::Travel::Polyline::Generic : GCodePreviewData::Travel::Polyline::Vertical;
+
+        if ((type != move_type) || (direction != move_direction) || (feedrate != move.data.feedrate) || (position != move.start_position) || (extruder_id != move.data.extruder_id))
+        {
+            // store current polyline
+            polyline.remove_duplicate_points();
+            Helper::store_polyline(polyline, type, direction, feedrate, extruder_id, preview_data);
+
+            // reset current polyline
+            polyline = Polyline3();
+
+            // add both vertices of the move
+            polyline.append(Vec3crd(scale_(move.start_position.x()), scale_(move.start_position.y()), scale_(move.start_position.z())));
+            polyline.append(Vec3crd(scale_(move.end_position.x()), scale_(move.end_position.y()), scale_(move.end_position.z())));
+        }
+        else
+            // append end vertex of the move to current polyline
+            polyline.append(Vec3crd(scale_(move.end_position.x()), scale_(move.end_position.y()), scale_(move.end_position.z())));
+
+        // update current values
+        position = move.end_position;
+        type = move_type;
+        feedrate = move.data.feedrate;
+        extruder_id = move.data.extruder_id;
+        height_range.update_from(move.data.height);
+        width_range.update_from(move.data.width);
+        feedrate_range.update_from(move.data.feedrate);
+    }
+
+    // store last polyline
+    polyline.remove_duplicate_points();
+    Helper::store_polyline(polyline, type, direction, feedrate, extruder_id, preview_data);
+
+    // updates preview ranges data
+    preview_data.ranges.height.update_from(height_range);
+    preview_data.ranges.width.update_from(width_range);
+    preview_data.ranges.feedrate.update_from(feedrate_range);
+}
+
+void GCodeAnalyzer::_calc_gcode_preview_retractions(GCodePreviewData& preview_data)
+{
+    TypeToMovesMap::iterator retraction_moves = m_moves_map.find(GCodeMove::Retract);
+    if (retraction_moves == m_moves_map.end())
+        return;
+
+    for (const GCodeMove& move : retraction_moves->second)
+    {
+        // store position
+        Vec3crd position(scale_(move.start_position.x()), scale_(move.start_position.y()), scale_(move.start_position.z()));
+        preview_data.retraction.positions.emplace_back(position, move.data.width, move.data.height);
+    }
+}
+
+void GCodeAnalyzer::_calc_gcode_preview_unretractions(GCodePreviewData& preview_data)
+{
+    TypeToMovesMap::iterator unretraction_moves = m_moves_map.find(GCodeMove::Unretract);
+    if (unretraction_moves == m_moves_map.end())
+        return;
+
+    for (const GCodeMove& move : unretraction_moves->second)
+    {
+        // store position
+        Vec3crd position(scale_(move.start_position.x()), scale_(move.start_position.y()), scale_(move.start_position.z()));
+        preview_data.unretraction.positions.emplace_back(position, move.data.width, move.data.height);
+    }
+}
+
+GCodePreviewData::Color operator + (const GCodePreviewData::Color& c1, const GCodePreviewData::Color& c2)
+{
+    return GCodePreviewData::Color(clamp(0.0f, 1.0f, c1.rgba[0] + c2.rgba[0]),
+        clamp(0.0f, 1.0f, c1.rgba[1] + c2.rgba[1]),
+        clamp(0.0f, 1.0f, c1.rgba[2] + c2.rgba[2]),
+        clamp(0.0f, 1.0f, c1.rgba[3] + c2.rgba[3]));
+}
+
+GCodePreviewData::Color operator * (float f, const GCodePreviewData::Color& color)
+{
+    return GCodePreviewData::Color(clamp(0.0f, 1.0f, f * color.rgba[0]),
+        clamp(0.0f, 1.0f, f * color.rgba[1]),
+        clamp(0.0f, 1.0f, f * color.rgba[2]),
+        clamp(0.0f, 1.0f, f * color.rgba[3]));
+}
+
+} // namespace Slic3r

src/libslic3r/GCode/Analyzer.hpp

@@ -0,0 +1,233 @@
+#ifndef slic3r_GCode_Analyzer_hpp_
+#define slic3r_GCode_Analyzer_hpp_
+
+#include "../libslic3r.h"
+#include "../PrintConfig.hpp"
+#include "../ExtrusionEntity.hpp"
+
+#include "Point.hpp"
+#include "GCodeReader.hpp"
+
+namespace Slic3r {
+
+class GCodePreviewData;
+
+class GCodeAnalyzer
+{
+public:
+    static const std::string Extrusion_Role_Tag;
+    static const std::string Mm3_Per_Mm_Tag;
+    static const std::string Width_Tag;
+    static const std::string Height_Tag;
+
+    static const double Default_mm3_per_mm;
+    static const float Default_Width;
+    static const float Default_Height;
+
+    enum EUnits : unsigned char
+    {
+        Millimeters,
+        Inches
+    };
+
+    enum EAxis : unsigned char
+    {
+        X,
+        Y,
+        Z,
+        E,
+        Num_Axis
+    };
+
+    enum EPositioningType : unsigned char
+    {
+        Absolute,
+        Relative
+    };
+
+    struct Metadata
+    {
+        ExtrusionRole extrusion_role;
+        unsigned int extruder_id;
+        double mm3_per_mm;
+        float width;     // mm
+        float height;    // mm
+        float feedrate;  // mm/s
+
+        Metadata();
+        Metadata(ExtrusionRole extrusion_role, unsigned int extruder_id, double mm3_per_mm, float width, float height, float feedrate);
+
+        bool operator != (const Metadata& other) const;
+    };
+
+    struct GCodeMove
+    {
+        enum EType : unsigned char
+        {
+            Noop,
+            Retract,
+            Unretract,
+            Tool_change,
+            Move,
+            Extrude,
+            Num_Types
+        };
+
+        EType type;
+        Metadata data;
+        Vec3d start_position;
+        Vec3d end_position;
+        float delta_extruder;
+
+        GCodeMove(EType type, ExtrusionRole extrusion_role, unsigned int extruder_id, double mm3_per_mm, float width, float height, float feedrate, const Vec3d& start_position, const Vec3d& end_position, float delta_extruder);
+        GCodeMove(EType type, const Metadata& data, const Vec3d& start_position, const Vec3d& end_position, float delta_extruder);
+    };
+
+    typedef std::vector<GCodeMove> GCodeMovesList;
+    typedef std::map<GCodeMove::EType, GCodeMovesList> TypeToMovesMap;
+
+private:
+    struct State
+    {
+        EUnits units;
+        EPositioningType global_positioning_type;
+        EPositioningType e_local_positioning_type;
+        Metadata data;
+        Vec3d start_position = Vec3d::Zero();
+        float start_extrusion;
+        float position[Num_Axis];
+    };
+
+private:
+    State m_state;
+    GCodeReader m_parser;
+    TypeToMovesMap m_moves_map;
+
+    // The output of process_layer()
+    std::string m_process_output;
+
+public:
+    GCodeAnalyzer();
+
+    // Reinitialize the analyzer
+    void reset();
+
+    // Adds the gcode contained in the given string to the analysis and returns it after removing the workcodes
+    const std::string& process_gcode(const std::string& gcode);
+
+    // Calculates all data needed for gcode visualization
+    void calc_gcode_preview_data(GCodePreviewData& preview_data);
+
+    static bool is_valid_extrusion_role(ExtrusionRole role);
+
+private:
+    // Processes the given gcode line
+    void _process_gcode_line(GCodeReader& reader, const GCodeReader::GCodeLine& line);
+
+    // Move
+    void _processG1(const GCodeReader::GCodeLine& line);
+
+    // Retract
+    void _processG10(const GCodeReader::GCodeLine& line);
+
+    // Unretract
+    void _processG11(const GCodeReader::GCodeLine& line);
+
+    // Firmware controlled Retract
+    void _processG22(const GCodeReader::GCodeLine& line);
+
+    // Firmware controlled Unretract
+    void _processG23(const GCodeReader::GCodeLine& line);
+
+    // Set to Absolute Positioning
+    void _processG90(const GCodeReader::GCodeLine& line);
+
+    // Set to Relative Positioning
+    void _processG91(const GCodeReader::GCodeLine& line);
+
+    // Set Position
+    void _processG92(const GCodeReader::GCodeLine& line);
+
+    // Set extruder to absolute mode
+    void _processM82(const GCodeReader::GCodeLine& line);
+
+    // Set extruder to relative mode
+    void _processM83(const GCodeReader::GCodeLine& line);
+
+    // Processes T line (Select Tool)
+    void _processT(const GCodeReader::GCodeLine& line);
+
+    // Processes the tags
+    // Returns true if any tag has been processed
+    bool _process_tags(const GCodeReader::GCodeLine& line);
+
+    // Processes extrusion role tag
+    void _process_extrusion_role_tag(const std::string& comment, size_t pos);
+
+    // Processes mm3_per_mm tag
+    void _process_mm3_per_mm_tag(const std::string& comment, size_t pos);
+
+    // Processes width tag
+    void _process_width_tag(const std::string& comment, size_t pos);
+
+    // Processes height tag
+    void _process_height_tag(const std::string& comment, size_t pos);
+
+    void _set_units(EUnits units);
+    EUnits _get_units() const;
+
+    void _set_global_positioning_type(EPositioningType type);
+    EPositioningType _get_global_positioning_type() const;
+
+    void _set_e_local_positioning_type(EPositioningType type);
+    EPositioningType _get_e_local_positioning_type() const;
+
+    void _set_extrusion_role(ExtrusionRole extrusion_role);
+    ExtrusionRole _get_extrusion_role() const;
+
+    void _set_extruder_id(unsigned int id);
+    unsigned int _get_extruder_id() const;
+
+    void _set_mm3_per_mm(double value);
+    double _get_mm3_per_mm() const;
+
+    void _set_width(float width);
+    float _get_width() const;
+
+    void _set_height(float height);
+    float _get_height() const;
+
+    void _set_feedrate(float feedrate_mm_sec);
+    float _get_feedrate() const;
+
+    void _set_axis_position(EAxis axis, float position);
+    float _get_axis_position(EAxis axis) const;
+
+    // Sets axes position to zero
+    void _reset_axes_position();
+
+    void _set_start_position(const Vec3d& position);
+    const Vec3d& _get_start_position() const;
+
+    void _set_start_extrusion(float extrusion);
+    float _get_start_extrusion() const;
+    float _get_delta_extrusion() const;
+
+    // Returns current xyz position (from m_state.position[])
+    Vec3d _get_end_position() const;
+
+    // Adds a new move with the given data
+    void _store_move(GCodeMove::EType type);
+
+    // Checks if the given int is a valid extrusion role (contained into enum ExtrusionRole)
+    bool _is_valid_extrusion_role(int value) const;
+
+    void _calc_gcode_preview_extrusion_layers(GCodePreviewData& preview_data);
+    void _calc_gcode_preview_travel(GCodePreviewData& preview_data);
+    void _calc_gcode_preview_retractions(GCodePreviewData& preview_data);
+    void _calc_gcode_preview_unretractions(GCodePreviewData& preview_data);
+};
+
+} // namespace Slic3r
+
+#endif /* slic3r_GCode_Analyzer_hpp_ */

src/libslic3r/GCode/CoolingBuffer.cpp

@@ -0,0 +1,749 @@
+#include "../GCode.hpp"
+#include "CoolingBuffer.hpp"
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/replace.hpp>
+#include <iostream>
+#include <float.h>
+
+#if 0
+    #define DEBUG
+    #define _DEBUG
+    #undef NDEBUG
+#endif
+
+#include <assert.h>
+
+namespace Slic3r {
+
+CoolingBuffer::CoolingBuffer(GCode &gcodegen) : m_gcodegen(gcodegen), m_current_extruder(0)
+{
+    this->reset();
+}
+
+void CoolingBuffer::reset()
+{
+    m_current_pos.assign(5, 0.f);
+    Vec3d pos = m_gcodegen.writer().get_position();
+    m_current_pos[0] = float(pos(0));
+    m_current_pos[1] = float(pos(1));
+    m_current_pos[2] = float(pos(2));
+    m_current_pos[4] = float(m_gcodegen.config().travel_speed.value);
+}
+
+struct CoolingLine
+{
+    enum Type {
+        TYPE_SET_TOOL           = 1 << 0,
+        TYPE_EXTRUDE_END        = 1 << 1,
+        TYPE_BRIDGE_FAN_START   = 1 << 2,
+        TYPE_BRIDGE_FAN_END     = 1 << 3,
+        TYPE_G0                 = 1 << 4,
+        TYPE_G1                 = 1 << 5,
+        TYPE_ADJUSTABLE         = 1 << 6,
+        TYPE_EXTERNAL_PERIMETER = 1 << 7,
+        // The line sets a feedrate.
+        TYPE_HAS_F              = 1 << 8,
+        TYPE_WIPE               = 1 << 9,
+        TYPE_G4                 = 1 << 10,
+        TYPE_G92                = 1 << 11,
+    };
+
+    CoolingLine(unsigned int type, size_t  line_start, size_t  line_end) :
+        type(type), line_start(line_start), line_end(line_end),
+        length(0.f), feedrate(0.f), time(0.f), time_max(0.f), slowdown(false) {}
+
+    bool adjustable(bool slowdown_external_perimeters) const {
+        return (this->type & TYPE_ADJUSTABLE) && 
+               (! (this->type & TYPE_EXTERNAL_PERIMETER) || slowdown_external_perimeters) &&
+               this->time < this->time_max;
+    }
+
+    bool adjustable() const {
+        return (this->type & TYPE_ADJUSTABLE) && this->time < this->time_max;
+    }
+
+    size_t  type;
+    // Start of this line at the G-code snippet.
+    size_t  line_start;
+    // End of this line at the G-code snippet.
+    size_t  line_end;
+    // XY Euclidian length of this segment.
+    float   length;
+    // Current feedrate, possibly adjusted.
+    float   feedrate;
+    // Current duration of this segment.
+    float   time;
+    // Maximum duration of this segment.
+    float   time_max;
+    // If marked with the "slowdown" flag, the line has been slowed down.
+    bool    slowdown;
+};
+
+// Calculate the required per extruder time stretches.
+struct PerExtruderAdjustments 
+{
+    // Calculate the total elapsed time per this extruder, adjusted for the slowdown.
+    float elapsed_time_total() {
+        float time_total = 0.f;
+        for (const CoolingLine &line : lines)
+            time_total += line.time;
+        return time_total;
+    }
+    // Calculate the total elapsed time when slowing down 
+    // to the minimum extrusion feed rate defined for the current material.
+    float maximum_time_after_slowdown(bool slowdown_external_perimeters) {
+        float time_total = 0.f;
+        for (const CoolingLine &line : lines)
+            if (line.adjustable(slowdown_external_perimeters)) {
+                if (line.time_max == FLT_MAX)
+                    return FLT_MAX;
+                else
+                    time_total += line.time_max;
+            } else
+                time_total += line.time;
+        return time_total;
+    }
+    // Calculate the adjustable part of the total time.
+    float adjustable_time(bool slowdown_external_perimeters) {
+        float time_total = 0.f;
+        for (const CoolingLine &line : lines)
+            if (line.adjustable(slowdown_external_perimeters))
+                time_total += line.time;
+        return time_total;
+    }
+    // Calculate the non-adjustable part of the total time.
+    float non_adjustable_time(bool slowdown_external_perimeters) {
+        float time_total = 0.f;
+        for (const CoolingLine &line : lines)
+            if (! line.adjustable(slowdown_external_perimeters))
+                time_total += line.time;
+        return time_total;
+    }
+    // Slow down the adjustable extrusions to the minimum feedrate allowed for the current extruder material.
+    // Used by both proportional and non-proportional slow down.
+    float slowdown_to_minimum_feedrate(bool slowdown_external_perimeters) {
+        float time_total = 0.f;
+        for (CoolingLine &line : lines) {
+            if (line.adjustable(slowdown_external_perimeters)) {
+                assert(line.time_max >= 0.f && line.time_max < FLT_MAX);
+                line.slowdown = true;
+                line.time     = line.time_max;
+                line.feedrate = line.length / line.time;
+            }
+            time_total += line.time;
+        }
+        return time_total;
+    }
+    // Slow down each adjustable G-code line proportionally by a factor.
+    // Used by the proportional slow down.
+    float slow_down_proportional(float factor, bool slowdown_external_perimeters) {
+        assert(factor >= 1.f);
+        float time_total = 0.f;
+        for (CoolingLine &line : lines) {
+            if (line.adjustable(slowdown_external_perimeters)) {
+                line.slowdown = true;
+                line.time     = std::min(line.time_max, line.time * factor);
+                line.feedrate = line.length / line.time;
+            }
+            time_total += line.time;
+        }
+        return time_total;
+    }
+
+    // Sort the lines, adjustable first, higher feedrate first.
+    // Used by non-proportional slow down.
+    void sort_lines_by_decreasing_feedrate() {
+        std::sort(lines.begin(), lines.end(), [](const CoolingLine &l1, const CoolingLine &l2) {
+            bool adj1 = l1.adjustable();
+            bool adj2 = l2.adjustable();
+            return (adj1 == adj2) ? l1.feedrate > l2.feedrate : adj1;
+        });
+        for (n_lines_adjustable = 0; 
+            n_lines_adjustable < lines.size() && this->lines[n_lines_adjustable].adjustable();
+            ++ n_lines_adjustable);
+        time_non_adjustable = 0.f;
+        for (size_t i = n_lines_adjustable; i < lines.size(); ++ i)
+            time_non_adjustable += lines[i].time;
+    }
+
+    // Calculate the maximum time stretch when slowing down to min_feedrate.
+    // Slowdown to min_feedrate shall be allowed for this extruder's material.
+    // Used by non-proportional slow down.
+    float time_stretch_when_slowing_down_to_feedrate(float min_feedrate) {
+        float time_stretch = 0.f;
+        assert(this->min_print_speed < min_feedrate + EPSILON);
+        for (size_t i = 0; i < n_lines_adjustable; ++ i) {
+            const CoolingLine &line = lines[i];
+            if (line.feedrate > min_feedrate)
+                time_stretch += line.time * (line.feedrate / min_feedrate - 1.f);
+        }
+        return time_stretch;
+    }
+
+    // Slow down all adjustable lines down to min_feedrate.
+    // Slowdown to min_feedrate shall be allowed for this extruder's material.
+    // Used by non-proportional slow down.
+    void slow_down_to_feedrate(float min_feedrate) {
+        assert(this->min_print_speed < min_feedrate + EPSILON);
+        for (size_t i = 0; i < n_lines_adjustable; ++ i) {
+            CoolingLine &line = lines[i];
+            if (line.feedrate > min_feedrate) {
+                line.time *= std::max(1.f, line.feedrate / min_feedrate);
+                line.feedrate = min_feedrate;
+                line.slowdown = true;
+            }
+        }
+    }
+
+    // Extruder, for which the G-code will be adjusted.
+    unsigned int                extruder_id         = 0;
+    // Is the cooling slow down logic enabled for this extruder's material?
+    bool                        cooling_slow_down_enabled = false;
+    // Slow down the print down to min_print_speed if the total layer time is below slowdown_below_layer_time.
+    float                       slowdown_below_layer_time = 0.f;
+    // Minimum print speed allowed for this extruder.
+    float                       min_print_speed     = 0.f;
+
+    // Parsed lines.
+    std::vector<CoolingLine>    lines;
+    // The following two values are set by sort_lines_by_decreasing_feedrate():
+    // Number of adjustable lines, at the start of lines.
+    size_t                      n_lines_adjustable  = 0;
+    // Non-adjustable time of lines starting with n_lines_adjustable. 
+    float                       time_non_adjustable = 0;
+    // Current total time for this extruder.
+    float                       time_total          = 0;
+    // Maximum time for this extruder, when the maximum slow down is applied.
+    float                       time_maximum        = 0;
+
+    // Temporaries for processing the slow down. Both thresholds go from 0 to n_lines_adjustable.
+    size_t                      idx_line_begin      = 0;
+    size_t                      idx_line_end        = 0;
+};
+
+std::string CoolingBuffer::process_layer(const std::string &gcode, size_t layer_id)
+{
+    std::vector<PerExtruderAdjustments> per_extruder_adjustments = this->parse_layer_gcode(gcode, m_current_pos);
+    float layer_time_stretched = this->calculate_layer_slowdown(per_extruder_adjustments);
+    return this->apply_layer_cooldown(gcode, layer_id, layer_time_stretched, per_extruder_adjustments);
+}
+
+// Parse the layer G-code for the moves, which could be adjusted.
+// Return the list of parsed lines, bucketed by an extruder.
+std::vector<PerExtruderAdjustments> CoolingBuffer::parse_layer_gcode(const std::string &gcode, std::vector<float> &current_pos) const
+{
+    const FullPrintConfig       &config        = m_gcodegen.config();
+    const std::vector<Extruder> &extruders     = m_gcodegen.writer().extruders();
+    unsigned int                 num_extruders = 0;
+    for (const Extruder &ex : extruders)
+        num_extruders = std::max(ex.id() + 1, num_extruders);
+    
+    std::vector<PerExtruderAdjustments> per_extruder_adjustments(extruders.size());
+    std::vector<size_t>                 map_extruder_to_per_extruder_adjustment(num_extruders, 0);
+    for (size_t i = 0; i < extruders.size(); ++ i) {
+		PerExtruderAdjustments &adj			= per_extruder_adjustments[i];
+		unsigned int			extruder_id = extruders[i].id();
+		adj.extruder_id				  = extruder_id;
+		adj.cooling_slow_down_enabled = config.cooling.get_at(extruder_id);
+		adj.slowdown_below_layer_time = config.slowdown_below_layer_time.get_at(extruder_id);
+		adj.min_print_speed			  = config.min_print_speed.get_at(extruder_id);
+        map_extruder_to_per_extruder_adjustment[extruder_id] = i;
+    }
+
+    const std::string toolchange_prefix = m_gcodegen.writer().toolchange_prefix();
+    unsigned int      current_extruder  = m_current_extruder;
+    PerExtruderAdjustments *adjustment  = &per_extruder_adjustments[map_extruder_to_per_extruder_adjustment[current_extruder]];
+    const char       *line_start = gcode.c_str();
+    const char       *line_end   = line_start;
+    const char        extrusion_axis = config.get_extrusion_axis()[0];
+    // Index of an existing CoolingLine of the current adjustment, which holds the feedrate setting command
+    // for a sequence of extrusion moves.
+    size_t            active_speed_modifier = size_t(-1);
+
+    for (; *line_start != 0; line_start = line_end) 
+    {
+        while (*line_end != '\n' && *line_end != 0)
+            ++ line_end;
+        // sline will not contain the trailing '\n'.
+        std::string sline(line_start, line_end);
+        // CoolingLine will contain the trailing '\n'.
+        if (*line_end == '\n')
+            ++ line_end;
+        CoolingLine line(0, line_start - gcode.c_str(), line_end - gcode.c_str());
+        if (boost::starts_with(sline, "G0 "))
+            line.type = CoolingLine::TYPE_G0;
+        else if (boost::starts_with(sline, "G1 "))
+            line.type = CoolingLine::TYPE_G1;
+        else if (boost::starts_with(sline, "G92 "))
+            line.type = CoolingLine::TYPE_G92;
+        if (line.type) {
+            // G0, G1 or G92
+            // Parse the G-code line.
+            std::vector<float> new_pos(current_pos);
+            const char *c = sline.data() + 3;
+            for (;;) {
+                // Skip whitespaces.
+                for (; *c == ' ' || *c == '\t'; ++ c);
+                if (*c == 0 || *c == ';')
+                    break;
+                // Parse the axis.
+                size_t axis = (*c >= 'X' && *c <= 'Z') ? (*c - 'X') :
+                              (*c == extrusion_axis) ? 3 : (*c == 'F') ? 4 : size_t(-1);
+                if (axis != size_t(-1)) {
+                    new_pos[axis] = float(atof(++c));
+                    if (axis == 4) {
+                        // Convert mm/min to mm/sec.
+                        new_pos[4] /= 60.f;
+                        if ((line.type & CoolingLine::TYPE_G92) == 0)
+                            // This is G0 or G1 line and it sets the feedrate. This mark is used for reducing the duplicate F calls.
+                            line.type |= CoolingLine::TYPE_HAS_F;
+                    }
+                }
+                // Skip this word.
+                for (; *c != ' ' && *c != '\t' && *c != 0; ++ c);
+            }
+            bool external_perimeter = boost::contains(sline, ";_EXTERNAL_PERIMETER");
+            bool wipe               = boost::contains(sline, ";_WIPE");
+            if (external_perimeter)
+                line.type |= CoolingLine::TYPE_EXTERNAL_PERIMETER;
+            if (wipe)
+                line.type |= CoolingLine::TYPE_WIPE;
+            if (boost::contains(sline, ";_EXTRUDE_SET_SPEED") && ! wipe) {
+                line.type |= CoolingLine::TYPE_ADJUSTABLE;
+                active_speed_modifier = adjustment->lines.size();
+            }
+            if ((line.type & CoolingLine::TYPE_G92) == 0) {
+                // G0 or G1. Calculate the duration.
+                if (config.use_relative_e_distances.value)
+                    // Reset extruder accumulator.
+                    current_pos[3] = 0.f;
+                float dif[4];
+                for (size_t i = 0; i < 4; ++ i)
+                    dif[i] = new_pos[i] - current_pos[i];
+                float dxy2 = dif[0] * dif[0] + dif[1] * dif[1];
+                float dxyz2 = dxy2 + dif[2] * dif[2];
+                if (dxyz2 > 0.f) {
+                    // Movement in xyz, calculate time from the xyz Euclidian distance.
+                    line.length = sqrt(dxyz2);
+                } else if (std::abs(dif[3]) > 0.f) {
+                    // Movement in the extruder axis.
+                    line.length = std::abs(dif[3]);
+                }
+                line.feedrate = new_pos[4];
+                assert((line.type & CoolingLine::TYPE_ADJUSTABLE) == 0 || line.feedrate > 0.f);
+                if (line.length > 0)
+                    line.time = line.length / line.feedrate;
+                line.time_max = line.time;
+                if ((line.type & CoolingLine::TYPE_ADJUSTABLE) || active_speed_modifier != size_t(-1))
+                    line.time_max = (adjustment->min_print_speed == 0.f) ? FLT_MAX : std::max(line.time, line.length / adjustment->min_print_speed);
+                if (active_speed_modifier < adjustment->lines.size() && (line.type & CoolingLine::TYPE_G1)) {
+                    // Inside the ";_EXTRUDE_SET_SPEED" blocks, there must not be a G1 Fxx entry.
+                    assert((line.type & CoolingLine::TYPE_HAS_F) == 0);
+                    CoolingLine &sm = adjustment->lines[active_speed_modifier];
+                    assert(sm.feedrate > 0.f);
+                    sm.length   += line.length;
+                    sm.time     += line.time;
+                    if (sm.time_max != FLT_MAX) {
+                        if (line.time_max == FLT_MAX)
+                            sm.time_max = FLT_MAX;
+                        else
+                            sm.time_max += line.time_max;
+                    }
+                    // Don't store this line.
+                    line.type = 0;
+                }
+            }
+            current_pos = std::move(new_pos);
+        } else if (boost::starts_with(sline, ";_EXTRUDE_END")) {
+            line.type = CoolingLine::TYPE_EXTRUDE_END;
+            active_speed_modifier = size_t(-1);
+        } else if (boost::starts_with(sline, toolchange_prefix)) {
+            // Switch the tool.
+            line.type = CoolingLine::TYPE_SET_TOOL;
+            unsigned int new_extruder = (unsigned int)atoi(sline.c_str() + toolchange_prefix.size());
+            if (new_extruder != current_extruder) {
+                current_extruder = new_extruder;
+                adjustment         = &per_extruder_adjustments[map_extruder_to_per_extruder_adjustment[current_extruder]];
+            }
+        } else if (boost::starts_with(sline, ";_BRIDGE_FAN_START")) {
+            line.type = CoolingLine::TYPE_BRIDGE_FAN_START;
+        } else if (boost::starts_with(sline, ";_BRIDGE_FAN_END")) {
+            line.type = CoolingLine::TYPE_BRIDGE_FAN_END;
+        } else if (boost::starts_with(sline, "G4 ")) {
+            // Parse the wait time.
+            line.type = CoolingLine::TYPE_G4;
+            size_t pos_S = sline.find('S', 3);
+            size_t pos_P = sline.find('P', 3);
+            line.time = line.time_max = float(
+                (pos_S > 0) ? atof(sline.c_str() + pos_S + 1) :
+                (pos_P > 0) ? atof(sline.c_str() + pos_P + 1) * 0.001 : 0.);
+        }
+        if (line.type != 0)
+            adjustment->lines.emplace_back(std::move(line));
+    }
+
+    return per_extruder_adjustments;
+}
+
+// Slow down an extruder range proportionally down to slowdown_below_layer_time.
+// Return the total time for the complete layer.
+static inline float extruder_range_slow_down_proportional(
+    std::vector<PerExtruderAdjustments*>::iterator it_begin,
+    std::vector<PerExtruderAdjustments*>::iterator it_end,
+    // Elapsed time for the extruders already processed.
+    float elapsed_time_total0,
+    // Initial total elapsed time before slow down.
+    float elapsed_time_before_slowdown,
+    // Target time for the complete layer (all extruders applied).
+    float slowdown_below_layer_time)
+{
+    // Total layer time after the slow down has been applied.
+    float total_after_slowdown = elapsed_time_before_slowdown;
+    // Now decide, whether the external perimeters shall be slowed down as well.
+    float max_time_nep = elapsed_time_total0;
+    for (auto it = it_begin; it != it_end; ++ it)
+        max_time_nep += (*it)->maximum_time_after_slowdown(false);
+    if (max_time_nep > slowdown_below_layer_time) {
+        // It is sufficient to slow down the non-external perimeter moves to reach the target layer time.
+        // Slow down the non-external perimeters proportionally.
+        float non_adjustable_time = elapsed_time_total0;
+        for (auto it = it_begin; it != it_end; ++ it)
+            non_adjustable_time += (*it)->non_adjustable_time(false);
+        // The following step is a linear programming task due to the minimum movement speeds of the print moves.
+        // Run maximum 5 iterations until a good enough approximation is reached.
+        for (size_t iter = 0; iter < 5; ++ iter) {
+            float factor = (slowdown_below_layer_time - non_adjustable_time) / (total_after_slowdown - non_adjustable_time);
+            assert(factor > 1.f);
+            total_after_slowdown = elapsed_time_total0;
+            for (auto it = it_begin; it != it_end; ++ it)
+                total_after_slowdown += (*it)->slow_down_proportional(factor, false);
+            if (total_after_slowdown > 0.95f * slowdown_below_layer_time)
+                break;
+        }
+    } else {
+        // Slow down everything. First slow down the non-external perimeters to maximum.
+        for (auto it = it_begin; it != it_end; ++ it)
+            (*it)->slowdown_to_minimum_feedrate(false);
+        // Slow down the external perimeters proportionally.
+        float non_adjustable_time = elapsed_time_total0;
+        for (auto it = it_begin; it != it_end; ++ it)
+            non_adjustable_time += (*it)->non_adjustable_time(true);
+        for (size_t iter = 0; iter < 5; ++ iter) {
+            float factor = (slowdown_below_layer_time - non_adjustable_time) / (total_after_slowdown - non_adjustable_time);
+            assert(factor > 1.f);
+            total_after_slowdown = elapsed_time_total0;
+            for (auto it = it_begin; it != it_end; ++ it)
+                total_after_slowdown += (*it)->slow_down_proportional(factor, true);
+            if (total_after_slowdown > 0.95f * slowdown_below_layer_time)
+                break;
+        }
+    }
+    return total_after_slowdown;
+}
+
+// Slow down an extruder range to slowdown_below_layer_time.
+// Return the total time for the complete layer.
+static inline void extruder_range_slow_down_non_proportional(
+    std::vector<PerExtruderAdjustments*>::iterator it_begin,
+    std::vector<PerExtruderAdjustments*>::iterator it_end,
+    float time_stretch)
+{
+    // Slow down. Try to equalize the feedrates.
+    std::vector<PerExtruderAdjustments*> by_min_print_speed(it_begin, it_end);
+    // Find the next highest adjustable feedrate among the extruders.
+    float feedrate = 0;
+	for (PerExtruderAdjustments *adj : by_min_print_speed) {
+		adj->idx_line_begin = 0;
+		adj->idx_line_end   = 0;
+		assert(adj->idx_line_begin < adj->n_lines_adjustable);
+		if (adj->lines[adj->idx_line_begin].feedrate > feedrate)
+			feedrate = adj->lines[adj->idx_line_begin].feedrate;
+	}
+	assert(feedrate > 0.f);
+    // Sort by min_print_speed, maximum speed first.
+    std::sort(by_min_print_speed.begin(), by_min_print_speed.end(), 
+        [](const PerExtruderAdjustments *p1, const PerExtruderAdjustments *p2){ return p1->min_print_speed > p2->min_print_speed; });
+    // Slow down, fast moves first.
+    for (;;) {
+        // For each extruder, find the span of lines with a feedrate close to feedrate.
+        for (PerExtruderAdjustments *adj : by_min_print_speed) {
+            for (adj->idx_line_end = adj->idx_line_begin;
+                adj->idx_line_end < adj->n_lines_adjustable && adj->lines[adj->idx_line_end].feedrate > feedrate - EPSILON;
+                 ++ adj->idx_line_end) ;
+        }
+        // Find the next highest adjustable feedrate among the extruders.
+        float feedrate_next = 0.f;
+        for (PerExtruderAdjustments *adj : by_min_print_speed)
+            if (adj->idx_line_end < adj->n_lines_adjustable && adj->lines[adj->idx_line_end].feedrate > feedrate_next)
+                feedrate_next = adj->lines[adj->idx_line_end].feedrate;
+        // Slow down, limited by max(feedrate_next, min_print_speed).
+        for (auto adj = by_min_print_speed.begin(); adj != by_min_print_speed.end();) {
+            // Slow down at most by time_stretch.
+            if ((*adj)->min_print_speed == 0.f) {
+                // All the adjustable speeds are now lowered to the same speed,
+                // and the minimum speed is set to zero.
+                float time_adjustable = 0.f;
+                for (auto it = adj; it != by_min_print_speed.end(); ++ it)
+                    time_adjustable += (*it)->adjustable_time(true);
+                float rate = (time_adjustable + time_stretch) / time_adjustable;
+                for (auto it = adj; it != by_min_print_speed.end(); ++ it)
+                    (*it)->slow_down_proportional(rate, true);
+                return;
+            } else {
+                float feedrate_limit = std::max(feedrate_next, (*adj)->min_print_speed);
+                bool  done           = false;
+                float time_stretch_max = 0.f;
+                for (auto it = adj; it != by_min_print_speed.end(); ++ it)
+                    time_stretch_max += (*it)->time_stretch_when_slowing_down_to_feedrate(feedrate_limit);
+                if (time_stretch_max >= time_stretch) {
+                    feedrate_limit = feedrate - (feedrate - feedrate_limit) * time_stretch / time_stretch_max;
+                    done = true;
+                } else
+                    time_stretch -= time_stretch_max;
+                for (auto it = adj; it != by_min_print_speed.end(); ++ it)
+                    (*it)->slow_down_to_feedrate(feedrate_limit);
+                if (done)
+                    return;
+            }
+            // Skip the other extruders with nearly the same min_print_speed, as they have been processed already.
+            auto next = adj;
+            for (++ next; next != by_min_print_speed.end() && (*next)->min_print_speed > (*adj)->min_print_speed - EPSILON; ++ next);
+            adj = next;
+        }
+        if (feedrate_next == 0.f)
+            // There are no other extrusions available for slow down.
+            break;
+        for (PerExtruderAdjustments *adj : by_min_print_speed) {
+            adj->idx_line_begin = adj->idx_line_end;
+            feedrate = feedrate_next;
+        }
+    }
+}
+
+// Calculate slow down for all the extruders.
+float CoolingBuffer::calculate_layer_slowdown(std::vector<PerExtruderAdjustments> &per_extruder_adjustments)
+{
+    // Sort the extruders by an increasing slowdown_below_layer_time.
+    // The layers with a lower slowdown_below_layer_time are slowed down
+    // together with all the other layers with slowdown_below_layer_time above.
+    std::vector<PerExtruderAdjustments*> by_slowdown_time;
+    by_slowdown_time.reserve(per_extruder_adjustments.size());
+    // Only insert entries, which are adjustable (have cooling enabled and non-zero stretchable time).
+    // Collect total print time of non-adjustable extruders.
+    float elapsed_time_total0 = 0.f;
+    for (PerExtruderAdjustments &adj : per_extruder_adjustments) {
+        // Curren total time for this extruder.
+        adj.time_total  = adj.elapsed_time_total();
+        // Maximum time for this extruder, when all extrusion moves are slowed down to min_extrusion_speed.
+        adj.time_maximum = adj.maximum_time_after_slowdown(true);
+        if (adj.cooling_slow_down_enabled && adj.lines.size() > 0) {
+            by_slowdown_time.emplace_back(&adj);
+            if (! m_cooling_logic_proportional)
+                // sorts the lines, also sets adj.time_non_adjustable
+                adj.sort_lines_by_decreasing_feedrate();
+        } else
+            elapsed_time_total0 += adj.elapsed_time_total();
+    }
+    std::sort(by_slowdown_time.begin(), by_slowdown_time.end(),
+        [](const PerExtruderAdjustments *adj1, const PerExtruderAdjustments *adj2)
+            { return adj1->slowdown_below_layer_time < adj2->slowdown_below_layer_time; });
+
+    for (auto cur_begin = by_slowdown_time.begin(); cur_begin != by_slowdown_time.end(); ++ cur_begin) {
+        PerExtruderAdjustments &adj = *(*cur_begin);
+        // Calculate the current adjusted elapsed_time_total over the non-finalized extruders.
+        float total = elapsed_time_total0;
+        for (auto it = cur_begin; it != by_slowdown_time.end(); ++ it)
+            total += (*it)->time_total;
+        float slowdown_below_layer_time = adj.slowdown_below_layer_time * 1.001f;
+        if (total > slowdown_below_layer_time) {
+            // The current total time is above the minimum threshold of the rest of the extruders, don't adjust anything.
+        } else {
+            // Adjust this and all the following (higher config.slowdown_below_layer_time) extruders.
+            // Sum maximum slow down time as if everything was slowed down including the external perimeters.
+            float max_time = elapsed_time_total0;
+            for (auto it = cur_begin; it != by_slowdown_time.end(); ++ it)
+                max_time += (*it)->time_maximum;
+            if (max_time > slowdown_below_layer_time) {
+                if (m_cooling_logic_proportional)
+                    extruder_range_slow_down_proportional(cur_begin, by_slowdown_time.end(), elapsed_time_total0, total, slowdown_below_layer_time);
+                else
+                    extruder_range_slow_down_non_proportional(cur_begin, by_slowdown_time.end(), slowdown_below_layer_time - total);
+            } else {
+                // Slow down to maximum possible.
+                for (auto it = cur_begin; it != by_slowdown_time.end(); ++ it)
+                    (*it)->slowdown_to_minimum_feedrate(true);
+            }
+        }
+        elapsed_time_total0 += adj.elapsed_time_total();
+    }
+
+    return elapsed_time_total0;
+}
+
+// Apply slow down over G-code lines stored in per_extruder_adjustments, enable fan if needed.
+// Returns the adjusted G-code.
+std::string CoolingBuffer::apply_layer_cooldown(
+    // Source G-code for the current layer.
+    const std::string                      &gcode,
+    // ID of the current layer, used to disable fan for the first n layers.
+    size_t                                  layer_id, 
+    // Total time of this layer after slow down, used to control the fan.
+    float                                   layer_time,
+    // Per extruder list of G-code lines and their cool down attributes.
+    std::vector<PerExtruderAdjustments>    &per_extruder_adjustments)
+{
+    // First sort the adjustment lines by of multiple extruders by their position in the source G-code.
+    std::vector<const CoolingLine*> lines;
+    {
+        size_t n_lines = 0;
+        for (const PerExtruderAdjustments &adj : per_extruder_adjustments)
+            n_lines += adj.lines.size();
+        lines.reserve(n_lines);
+        for (const PerExtruderAdjustments &adj : per_extruder_adjustments)
+            for (const CoolingLine &line : adj.lines)
+                lines.emplace_back(&line);
+        std::sort(lines.begin(), lines.end(), [](const CoolingLine *ln1, const CoolingLine *ln2) { return ln1->line_start < ln2->line_start; } );
+    }
+    // Second generate the adjusted G-code.
+    std::string new_gcode;
+    new_gcode.reserve(gcode.size() * 2);
+    int  fan_speed          = -1;
+    bool bridge_fan_control = false;
+    int  bridge_fan_speed   = 0;
+    auto change_extruder_set_fan = [ this, layer_id, layer_time, &new_gcode, &fan_speed, &bridge_fan_control, &bridge_fan_speed ]() {
+        const FullPrintConfig &config = m_gcodegen.config();
+#define EXTRUDER_CONFIG(OPT) config.OPT.get_at(m_current_extruder)
+        int min_fan_speed = EXTRUDER_CONFIG(min_fan_speed);
+        int fan_speed_new = EXTRUDER_CONFIG(fan_always_on) ? min_fan_speed : 0;
+        if (layer_id >= EXTRUDER_CONFIG(disable_fan_first_layers)) {
+            int   max_fan_speed             = EXTRUDER_CONFIG(max_fan_speed);
+            float slowdown_below_layer_time = float(EXTRUDER_CONFIG(slowdown_below_layer_time));
+            float fan_below_layer_time      = float(EXTRUDER_CONFIG(fan_below_layer_time));
+            if (EXTRUDER_CONFIG(cooling)) {
+                if (layer_time < slowdown_below_layer_time) {
+                    // Layer time very short. Enable the fan to a full throttle.
+                    fan_speed_new = max_fan_speed;
+                } else if (layer_time < fan_below_layer_time) {
+                    // Layer time quite short. Enable the fan proportionally according to the current layer time.
+                    assert(layer_time >= slowdown_below_layer_time);
+                    double t = (layer_time - slowdown_below_layer_time) / (fan_below_layer_time - slowdown_below_layer_time);
+                    fan_speed_new = int(floor(t * min_fan_speed + (1. - t) * max_fan_speed) + 0.5);
+                }
+            }
+            bridge_fan_speed   = EXTRUDER_CONFIG(bridge_fan_speed);
+#undef EXTRUDER_CONFIG
+            bridge_fan_control = bridge_fan_speed > fan_speed_new;
+        } else {
+            bridge_fan_control = false;
+            bridge_fan_speed   = 0;
+            fan_speed_new      = 0;
+        }
+        if (fan_speed_new != fan_speed) {
+            fan_speed = fan_speed_new;
+            new_gcode += m_gcodegen.writer().set_fan(fan_speed);
+        }
+    };
+
+    const char         *pos               = gcode.c_str();
+    int                 current_feedrate  = 0;
+    const std::string   toolchange_prefix = m_gcodegen.writer().toolchange_prefix();
+    change_extruder_set_fan();
+    for (const CoolingLine *line : lines) {
+        const char *line_start  = gcode.c_str() + line->line_start;
+        const char *line_end    = gcode.c_str() + line->line_end;
+        if (line_start > pos)
+            new_gcode.append(pos, line_start - pos);
+        if (line->type & CoolingLine::TYPE_SET_TOOL) {
+            unsigned int new_extruder = (unsigned int)atoi(line_start + toolchange_prefix.size());
+            if (new_extruder != m_current_extruder) {
+                m_current_extruder = new_extruder;
+                change_extruder_set_fan();
+            }
+            new_gcode.append(line_start, line_end - line_start);
+        } else if (line->type & CoolingLine::TYPE_BRIDGE_FAN_START) {
+            if (bridge_fan_control)
+                new_gcode += m_gcodegen.writer().set_fan(bridge_fan_speed, true);
+        } else if (line->type & CoolingLine::TYPE_BRIDGE_FAN_END) {
+            if (bridge_fan_control)
+                new_gcode += m_gcodegen.writer().set_fan(fan_speed, true);
+        } else if (line->type & CoolingLine::TYPE_EXTRUDE_END) {
+            // Just remove this comment.
+        } else if (line->type & (CoolingLine::TYPE_ADJUSTABLE | CoolingLine::TYPE_EXTERNAL_PERIMETER | CoolingLine::TYPE_WIPE | CoolingLine::TYPE_HAS_F)) {
+            // Find the start of a comment, or roll to the end of line.
+            const char *end = line_start;
+            for (; end < line_end && *end != ';'; ++ end);
+            // Find the 'F' word.
+            const char *fpos            = strstr(line_start + 2, " F") + 2;
+            int         new_feedrate    = current_feedrate;
+            bool        modify          = false;
+            assert(fpos != nullptr);
+            if (line->slowdown) {
+                modify       = true;
+                new_feedrate = int(floor(60. * line->feedrate + 0.5));
+            } else {
+                new_feedrate = atoi(fpos);
+                if (new_feedrate != current_feedrate) {
+                    // Append the line without the comment.
+                    new_gcode.append(line_start, end - line_start);
+                    current_feedrate = new_feedrate;
+                } else if ((line->type & (CoolingLine::TYPE_ADJUSTABLE | CoolingLine::TYPE_EXTERNAL_PERIMETER | CoolingLine::TYPE_WIPE)) || line->length == 0.) {
+                    // Feedrate does not change and this line does not move the print head. Skip the complete G-code line including the G-code comment.
+                    end = line_end;
+                } else {
+                    // Remove the feedrate from the G0/G1 line.
+                    modify = true;
+                }
+            }
+            if (modify) {
+                if (new_feedrate != current_feedrate) {
+                    // Replace the feedrate.
+                    new_gcode.append(line_start, fpos - line_start);
+                    current_feedrate = new_feedrate;
+                    char buf[64];
+                    sprintf(buf, "%d", int(current_feedrate));
+                    new_gcode += buf;
+                } else {
+                    // Remove the feedrate word.
+                    const char *f = fpos;
+                    // Roll the pointer before the 'F' word.
+                    for (f -= 2; f > line_start && (*f == ' ' || *f == '\t'); -- f);
+                    // Append up to the F word, without the trailing whitespace.
+                    new_gcode.append(line_start, f - line_start + 1);
+                }
+                // Skip the non-whitespaces of the F parameter up the comment or end of line.
+                for (; fpos != end && *fpos != ' ' && *fpos != ';' && *fpos != '\n'; ++fpos);
+                // Append the rest of the line without the comment.
+                if (fpos < end)
+                    new_gcode.append(fpos, end - fpos);
+                // There should never be an empty G1 statement emited by the filter. Such lines should be removed completely.
+                assert(new_gcode.size() < 4 || new_gcode.substr(new_gcode.size() - 4) != "G1 \n");
+            }
+            // Process the rest of the line.
+            if (end < line_end) {
+                if (line->type & (CoolingLine::TYPE_ADJUSTABLE | CoolingLine::TYPE_EXTERNAL_PERIMETER | CoolingLine::TYPE_WIPE)) {
+                    // Process comments, remove ";_EXTRUDE_SET_SPEED", ";_EXTERNAL_PERIMETER", ";_WIPE"
+                    std::string comment(end, line_end);
+                    boost::replace_all(comment, ";_EXTRUDE_SET_SPEED", "");
+                    if (line->type & CoolingLine::TYPE_EXTERNAL_PERIMETER)
+                        boost::replace_all(comment, ";_EXTERNAL_PERIMETER", "");
+                    if (line->type & CoolingLine::TYPE_WIPE)
+                        boost::replace_all(comment, ";_WIPE", "");
+                    new_gcode += comment;
+                } else {
+                    // Just attach the rest of the source line.
+                    new_gcode.append(end, line_end - end);
+                }
+            }
+        } else {
+            new_gcode.append(line_start, line_end - line_start);
+        }
+        pos = line_end;
+    }
+    const char *gcode_end = gcode.c_str() + gcode.size();
+    if (pos < gcode_end)
+        new_gcode.append(pos, gcode_end - pos);
+
+    return new_gcode;
+}
+
+} // namespace Slic3r

src/libslic3r/GCode/CoolingBuffer.hpp

@@ -0,0 +1,53 @@
+#ifndef slic3r_CoolingBuffer_hpp_
+#define slic3r_CoolingBuffer_hpp_
+
+#include "libslic3r.h"
+#include <map>
+#include <string>
+
+namespace Slic3r {
+
+class GCode;
+class Layer;
+class PerExtruderAdjustments;
+
+// A standalone G-code filter, to control cooling of the print.
+// The G-code is processed per layer. Once a layer is collected, fan start / stop commands are edited
+// and the print is modified to stretch over a minimum layer time.
+//
+// The simple it sounds, the actual implementation is significantly more complex.
+// Namely, for a multi-extruder print, each material may require a different cooling logic.
+// For example, some materials may not like to print too slowly, while with some materials 
+// we may slow down significantly.
+//
+class CoolingBuffer {
+public:
+    CoolingBuffer(GCode &gcodegen);
+    void        reset();
+    void        set_current_extruder(unsigned int extruder_id) { m_current_extruder = extruder_id; }
+    std::string process_layer(const std::string &gcode, size_t layer_id);
+    GCode* 	    gcodegen() { return &m_gcodegen; }
+
+private:
+	CoolingBuffer& operator=(const CoolingBuffer&) = delete;
+    std::vector<PerExtruderAdjustments> parse_layer_gcode(const std::string &gcode, std::vector<float> &current_pos) const;
+    float       calculate_layer_slowdown(std::vector<PerExtruderAdjustments> &per_extruder_adjustments);
+    // Apply slow down over G-code lines stored in per_extruder_adjustments, enable fan if needed.
+    // Returns the adjusted G-code.
+    std::string apply_layer_cooldown(const std::string &gcode, size_t layer_id, float layer_time, std::vector<PerExtruderAdjustments> &per_extruder_adjustments);
+
+    GCode&              m_gcodegen;
+    std::string         m_gcode;
+    // Internal data.
+    // X,Y,Z,E,F
+    std::vector<char>   m_axis;
+    std::vector<float>  m_current_pos;
+    unsigned int        m_current_extruder;
+
+    // Old logic: proportional.
+    bool                m_cooling_logic_proportional = false;
+};
+
+}
+
+#endif

src/libslic3r/GCode/PostProcessor.cpp

@@ -0,0 +1,60 @@
+#include "PostProcessor.hpp"
+
+#if 1
+//#ifdef WIN32
+
+namespace Slic3r {
+
+//FIXME Ignore until we include boost::process
+void run_post_process_scripts(const std::string &path, const PrintConfig &config)
+{
+}
+
+} // namespace Slic3r
+
+#else
+
+#include <boost/process/system.hpp>
+
+namespace Slic3r {
+
+void run_post_process_scripts(const std::string &path, const PrintConfig &config)
+{
+    if (config.post_process.values.empty())
+        return;
+    config.setenv_();
+    for (std::string script: config.post_process.values) {
+        // Ignore empty post processing script lines.
+        boost::trim(script);
+        if (script.empty())
+            continue;
+        BOOST_LOG_TRIVIAL(info) << "Executing script " << script << " on file " << path;
+        if (! boost::filesystem::exists(boost::filesystem::path(path)))
+            throw std::runtime_exception(std::string("The configured post-processing script does not exist: ") + path);
+#ifndef WIN32
+        file_status fs = boost::filesystem::status(path);
+        //FIXME test if executible by the effective UID / GID.
+        // throw std::runtime_exception(std::string("The configured post-processing script is not executable: check permissions. ") + path));
+#endif
+        int result = 0;
+#ifdef WIN32
+        if (boost::iends_with(file, ".gcode")) {
+            // The current process may be slic3r.exe or slic3r-console.exe.
+            // Find the path of the process:
+            wchar_t wpath_exe[_MAX_PATH + 1];
+            ::GetModuleFileNameW(nullptr, wpath_exe, _MAX_PATH);
+            boost::filesystem::path path_exe(wpath_exe);
+            // Replace it with the current perl interpreter.
+            result = boost::process::system((path_exe.parent_path() / "perl5.24.0.exe").string(), script, output_file);
+        } else
+#else
+        result = boost::process::system(script, output_file);
+#endif
+        if (result < 0)
+            BOOST_LOG_TRIVIAL(error) << "Script " << script << " on file " << path << " failed. Negative error code returned.";
+    }
+}
+
+} // namespace Slic3r
+
+#endif

src/libslic3r/GCode/PostProcessor.hpp

@@ -0,0 +1,15 @@
+#ifndef slic3r_GCode_PostProcessor_hpp_
+#define slic3r_GCode_PostProcessor_hpp_
+
+#include <string>
+
+#include "../libslic3r.h"
+#include "../PrintConfig.hpp"
+
+namespace Slic3r {
+
+extern void run_post_process_scripts(const std::string &path, const PrintConfig &config);
+
+} // namespace Slic3r
+
+#endif /* slic3r_GCode_PostProcessor_hpp_ */

src/libslic3r/GCode/PressureEqualizer.cpp

@@ -0,0 +1,621 @@
+#include <memory.h>
+#include <string.h>
+#include <float.h>
+
+#include "../libslic3r.h"
+#include "../PrintConfig.hpp"
+
+#include "PressureEqualizer.hpp"
+
+namespace Slic3r {
+
+PressureEqualizer::PressureEqualizer(const Slic3r::GCodeConfig *config) : 
+    m_config(config)
+{
+    reset();
+}
+
+PressureEqualizer::~PressureEqualizer()
+{
+}
+
+void PressureEqualizer::reset()
+{
+    circular_buffer_pos     = 0;
+    circular_buffer_size    = 100;
+    circular_buffer_items   = 0;
+    circular_buffer.assign(circular_buffer_size, GCodeLine());
+
+    // Preallocate some data, so that output_buffer.data() will return an empty string.
+    output_buffer.assign(32, 0);
+    output_buffer_length    = 0;
+
+    m_current_extruder = 0;
+    // Zero the position of the XYZE axes + the current feed
+    memset(m_current_pos, 0, sizeof(float) * 5);
+    m_current_extrusion_role = erNone;
+    // Expect the first command to fill the nozzle (deretract).
+    m_retracted = true;
+
+    // Calculate filamet crossections for the multiple extruders.
+    m_filament_crossections.clear();
+    for (size_t i = 0; i < m_config->filament_diameter.values.size(); ++ i) {
+        double r = m_config->filament_diameter.values[i];
+        double a = 0.25f*M_PI*r*r;
+        m_filament_crossections.push_back(float(a));
+    }
+
+    m_max_segment_length = 20.f;
+    // Volumetric rate of a 0.45mm x 0.2mm extrusion at 60mm/s XY movement: 0.45*0.2*60*60=5.4*60 = 324 mm^3/min
+    // Volumetric rate of a 0.45mm x 0.2mm extrusion at 20mm/s XY movement: 0.45*0.2*20*60=1.8*60 = 108 mm^3/min
+    // Slope of the volumetric rate, changing from 20mm/s to 60mm/s over 2 seconds: (5.4-1.8)*60*60/2=60*60*1.8 = 6480 mm^3/min^2 = 1.8 mm^3/s^2
+    m_max_volumetric_extrusion_rate_slope_positive = (m_config == NULL) ? 6480.f :
+        m_config->max_volumetric_extrusion_rate_slope_positive.value * 60.f * 60.f;
+    m_max_volumetric_extrusion_rate_slope_negative = (m_config == NULL) ? 6480.f :
+        m_config->max_volumetric_extrusion_rate_slope_negative.value * 60.f * 60.f;
+
+    for (size_t i = 0; i < numExtrusionRoles; ++ i) {
+        m_max_volumetric_extrusion_rate_slopes[i].negative = m_max_volumetric_extrusion_rate_slope_negative;
+        m_max_volumetric_extrusion_rate_slopes[i].positive = m_max_volumetric_extrusion_rate_slope_positive;
+    }
+
+    // Don't regulate the pressure in infill.
+    m_max_volumetric_extrusion_rate_slopes[erBridgeInfill].negative = 0;
+    m_max_volumetric_extrusion_rate_slopes[erBridgeInfill].positive = 0;
+    // Don't regulate the pressure in gap fill.
+    m_max_volumetric_extrusion_rate_slopes[erGapFill].negative = 0;
+    m_max_volumetric_extrusion_rate_slopes[erGapFill].positive = 0;
+
+    m_stat.reset();
+    line_idx = 0;
+}
+
+const char* PressureEqualizer::process(const char *szGCode, bool flush)
+{
+    // Reset length of the output_buffer.
+    output_buffer_length = 0;
+
+    if (szGCode != 0) {
+        const char *p = szGCode;
+        while (*p != 0) {
+            // Find end of the line.
+            const char *endl = p;
+            // Slic3r always generates end of lines in a Unix style.
+            for (; *endl != 0 && *endl != '\n'; ++ endl) ;
+            if (circular_buffer_items == circular_buffer_size)
+                // Buffer is full. Push out the oldest line.
+                output_gcode_line(circular_buffer[circular_buffer_pos]);
+            else
+                ++ circular_buffer_items;
+            // Process a G-code line, store it into the provided GCodeLine object.
+            size_t idx_tail = circular_buffer_pos;
+            circular_buffer_pos = circular_buffer_idx_next(circular_buffer_pos);
+            if (! process_line(p, endl - p, circular_buffer[idx_tail])) {
+                // The line has to be forgotten. It contains comment marks, which shall be
+                // filtered out of the target g-code.
+                circular_buffer_pos = idx_tail;
+                -- circular_buffer_items;
+            }
+            p = endl;
+            if (*p == '\n') 
+                ++ p;
+        }
+    }
+
+    if (flush) {
+        // Flush the remaining valid lines of the circular buffer.
+        for (size_t idx = circular_buffer_idx_head(); circular_buffer_items > 0; -- circular_buffer_items) {
+            output_gcode_line(circular_buffer[idx]);
+            if (++ idx == circular_buffer_size)
+                idx = 0;
+        }
+        // Reset the index pointer.
+        assert(circular_buffer_items == 0);
+        circular_buffer_pos = 0;
+
+#if 1 
+        printf("Statistics: \n"); 
+        printf("Minimum volumetric extrusion rate: %f\n", m_stat.volumetric_extrusion_rate_min);
+        printf("Maximum volumetric extrusion rate: %f\n", m_stat.volumetric_extrusion_rate_max);
+        if (m_stat.extrusion_length > 0)
+            m_stat.volumetric_extrusion_rate_avg /= m_stat.extrusion_length;
+        printf("Average volumetric extrusion rate: %f\n", m_stat.volumetric_extrusion_rate_avg);
+        m_stat.reset();
+#endif
+    } 
+
+    return output_buffer.data();
+}
+
+// Is a white space?
+static inline bool is_ws(const char c) { return c == ' ' || c == '\t'; }
+// Is it an end of line? Consider a comment to be an end of line as well.
+static inline bool is_eol(const char c) { return c == 0 || c == '\r' || c == '\n' || c == ';'; };
+// Is it a white space or end of line?
+static inline bool is_ws_or_eol(const char c) { return is_ws(c) || is_eol(c); };
+
+// Eat whitespaces.
+static void eatws(const char *&line)
+{
+    while (is_ws(*line)) 
+        ++ line;
+}
+
+// Parse an int starting at the current position of a line.
+// If succeeded, the line pointer is advanced.
+static inline int parse_int(const char *&line)
+{
+    char *endptr = NULL;
+    long result = strtol(line, &endptr, 10);
+    if (endptr == NULL || !is_ws_or_eol(*endptr))
+        throw std::runtime_error("PressureEqualizer: Error parsing an int");
+    line = endptr;
+    return int(result);
+};
+
+// Parse an int starting at the current position of a line.
+// If succeeded, the line pointer is advanced.
+static inline float parse_float(const char *&line)
+{
+    char *endptr = NULL;
+    float result = strtof(line, &endptr);
+    if (endptr == NULL || !is_ws_or_eol(*endptr))
+        throw std::runtime_error("PressureEqualizer: Error parsing a float");
+    line = endptr;
+    return result;
+};
+
+#define EXTRUSION_ROLE_TAG ";_EXTRUSION_ROLE:"
+bool PressureEqualizer::process_line(const char *line, const size_t len, GCodeLine &buf)
+{
+    if (strncmp(line, EXTRUSION_ROLE_TAG, strlen(EXTRUSION_ROLE_TAG)) == 0) {
+        line += strlen(EXTRUSION_ROLE_TAG);
+        int role = atoi(line);
+        m_current_extrusion_role = ExtrusionRole(role);
+        ++ line_idx;
+        return false;
+    }
+
+    // Set the type, copy the line to the buffer.
+    buf.type = GCODELINETYPE_OTHER;
+    buf.modified = false;
+    if (buf.raw.size() < len + 1)
+        buf.raw.assign(line, line + len + 1);
+    else
+        memcpy(buf.raw.data(), line, len);
+    buf.raw[len] = 0;
+    buf.raw_length = len;
+
+    memcpy(buf.pos_start, m_current_pos, sizeof(float)*5);
+    memcpy(buf.pos_end, m_current_pos, sizeof(float)*5);
+    memset(buf.pos_provided, 0, 5);
+
+    buf.volumetric_extrusion_rate = 0.f;
+    buf.volumetric_extrusion_rate_start = 0.f;
+    buf.volumetric_extrusion_rate_end = 0.f;
+    buf.max_volumetric_extrusion_rate_slope_positive = 0.f;
+    buf.max_volumetric_extrusion_rate_slope_negative = 0.f;
+	buf.extrusion_role = m_current_extrusion_role;
+
+    // Parse the G-code line, store the result into the buf.
+    switch (toupper(*line ++)) {
+    case 'G': {
+        int gcode = parse_int(line);
+        eatws(line);
+        switch (gcode) {
+        case 0:
+        case 1:
+        {
+            // G0, G1: A FFF 3D printer does not make a difference between the two.
+            float new_pos[5];
+            memcpy(new_pos, m_current_pos, sizeof(float)*5);
+            bool  changed[5] = { false, false, false, false, false };
+            while (!is_eol(*line)) {
+                char axis = toupper(*line++);
+                int  i = -1;
+                switch (axis) {
+                case 'X':
+                case 'Y':
+                case 'Z':
+                    i = axis - 'X';
+                    break;
+                case 'E':
+                    i = 3;
+                    break;
+                case 'F':
+                    i = 4;
+                    break;
+                default:
+                    assert(false);
+                }
+                if (i == -1)
+                    throw std::runtime_error(std::string("GCode::PressureEqualizer: Invalid axis for G0/G1: ") + axis);
+                buf.pos_provided[i] = true;
+                new_pos[i] = parse_float(line);
+                if (i == 3 && m_config->use_relative_e_distances.value)
+                    new_pos[i] += m_current_pos[i];
+                changed[i] = new_pos[i] != m_current_pos[i];
+                eatws(line);
+            }
+            if (changed[3]) {
+                // Extrusion, retract or unretract.
+                float diff = new_pos[3] - m_current_pos[3];
+                if (diff < 0) {
+                    buf.type = GCODELINETYPE_RETRACT;
+                    m_retracted = true;
+                } else if (! changed[0] && ! changed[1] && ! changed[2]) {
+                    // assert(m_retracted);
+                    buf.type = GCODELINETYPE_UNRETRACT;
+                    m_retracted = false;
+                } else {
+                    assert(changed[0] || changed[1]);
+                    // Moving in XY plane.
+                    buf.type = GCODELINETYPE_EXTRUDE;
+                    // Calculate the volumetric extrusion rate.
+                    float diff[4];
+                    for (size_t i = 0; i < 4; ++ i)
+                        diff[i] = new_pos[i] - m_current_pos[i];
+                    // volumetric extrusion rate = A_filament * F_xyz * L_e / L_xyz [mm^3/min]
+                    float len2 = diff[0]*diff[0]+diff[1]*diff[1]+diff[2]*diff[2];
+                    float rate = m_filament_crossections[m_current_extruder] * new_pos[4] * sqrt((diff[3]*diff[3])/len2);
+                    buf.volumetric_extrusion_rate       = rate;
+                    buf.volumetric_extrusion_rate_start = rate;
+                    buf.volumetric_extrusion_rate_end   = rate;
+                    m_stat.update(rate, sqrt(len2));
+                    if (rate < 40.f) {
+                    	printf("Extremely low flow rate: %f. Line %d, Length: %f, extrusion: %f Old position: (%f, %f, %f), new position: (%f, %f, %f)\n", 
+                            rate, 
+                            int(line_idx),
+                            sqrt(len2), sqrt((diff[3]*diff[3])/len2),
+                            m_current_pos[0], m_current_pos[1], m_current_pos[2],
+                            new_pos[0], new_pos[1], new_pos[2]);
+                    }
+                }
+            } else if (changed[0] || changed[1] || changed[2]) {
+                // Moving without extrusion.
+                buf.type = GCODELINETYPE_MOVE;
+            }
+            memcpy(m_current_pos, new_pos, sizeof(float) * 5);
+            break;
+        }
+        case 92: 
+        {
+            // G92 : Set Position
+            // Set a logical coordinate position to a new value without actually moving the machine motors.
+            // Which axes to set?
+            bool set = false;
+            while (!is_eol(*line)) {
+                char axis = toupper(*line++);
+                switch (axis) {
+                case 'X':
+                case 'Y':
+                case 'Z':
+                    m_current_pos[axis - 'X'] = (!is_ws_or_eol(*line)) ? parse_float(line) : 0.f;
+                    set = true;
+                    break;
+                case 'E':
+                    m_current_pos[3] = (!is_ws_or_eol(*line)) ? parse_float(line) : 0.f;
+                    set = true;
+                    break;
+                default:
+                    throw std::runtime_error(std::string("GCode::PressureEqualizer: Incorrect axis in a G92 G-code: ") + axis);
+                }
+                eatws(line);
+            }
+            assert(set);
+            break;
+        }
+        case 10:
+        case 22:
+            // Firmware retract.
+            buf.type = GCODELINETYPE_RETRACT;
+            m_retracted = true;
+            break;
+        case 11:
+        case 23:
+            // Firmware unretract.
+            buf.type = GCODELINETYPE_UNRETRACT;
+            m_retracted = false;
+            break;
+        default:
+            // Ignore the rest.
+        break;
+        }
+        break;
+    }
+    case 'M': {
+        int mcode = parse_int(line);
+        eatws(line);
+        switch (mcode) {
+        default:
+            // Ignore the rest of the M-codes.
+        break;
+        }
+        break;
+    }
+    case 'T':
+    {
+        // Activate an extruder head.
+        int new_extruder = parse_int(line);
+        if (new_extruder != m_current_extruder) {
+            m_current_extruder = new_extruder;
+            m_retracted = true;
+            buf.type = GCODELINETYPE_TOOL_CHANGE;
+        } else {
+            buf.type = GCODELINETYPE_NOOP;
+        }
+        break;
+    }
+    }
+
+    buf.extruder_id = m_current_extruder;
+    memcpy(buf.pos_end, m_current_pos, sizeof(float)*5);
+
+    adjust_volumetric_rate();
+    ++ line_idx;
+	return true;
+}
+
+void PressureEqualizer::output_gcode_line(GCodeLine &line)
+{
+    if (! line.modified) {
+        push_to_output(line.raw.data(), line.raw_length, true);
+        return;
+    }
+
+    // The line was modified.
+    // Find the comment.
+    const char *comment = line.raw.data();
+    while (*comment != ';' && *comment != 0) ++comment;
+    if (*comment != ';')
+        comment = NULL;
+    
+    // Emit the line with lowered extrusion rates.
+    float l2 = line.dist_xyz2();
+    float l = sqrt(l2);
+    size_t nSegments = size_t(ceil(l / m_max_segment_length));
+    if (nSegments == 1) {
+        // Just update this segment.
+        push_line_to_output(line, line.feedrate() * line.volumetric_correction_avg(), comment);
+    } else {
+        bool accelerating = line.volumetric_extrusion_rate_start < line.volumetric_extrusion_rate_end;
+        // Update the initial and final feed rate values.
+        line.pos_start[4] = line.volumetric_extrusion_rate_start * line.pos_end[4] / line.volumetric_extrusion_rate;
+        line.pos_end  [4] = line.volumetric_extrusion_rate_end   * line.pos_end[4] / line.volumetric_extrusion_rate;
+        float feed_avg = 0.5f * (line.pos_start[4] + line.pos_end[4]);
+        // Limiting volumetric extrusion rate slope for this segment.
+        float max_volumetric_extrusion_rate_slope = accelerating ?
+            line.max_volumetric_extrusion_rate_slope_positive : line.max_volumetric_extrusion_rate_slope_negative; 
+        // Total time for the segment, corrected for the possibly lowered volumetric feed rate,
+        // if accelerating / decelerating over the complete segment.
+        float t_total = line.dist_xyz() / feed_avg;
+        // Time of the acceleration / deceleration part of the segment, if accelerating / decelerating
+        // with the maximum volumetric extrusion rate slope.
+        float t_acc    = 0.5f * (line.volumetric_extrusion_rate_start + line.volumetric_extrusion_rate_end) / max_volumetric_extrusion_rate_slope;
+        float l_acc    = l;
+        float l_steady = 0.f;
+        if (t_acc < t_total) {
+            // One may achieve higher print speeds if part of the segment is not speed limited.
+            float l_acc    = t_acc * feed_avg;
+            float l_steady = l - l_acc;
+            if (l_steady < 0.5f * m_max_segment_length) {
+                l_acc    = l;
+                l_steady = 0.f;
+            } else
+                nSegments = size_t(ceil(l_acc / m_max_segment_length));
+        }
+        float pos_start[5];
+        float pos_end  [5];
+        float pos_end2 [4];
+        memcpy(pos_start, line.pos_start, sizeof(float)*5);
+        memcpy(pos_end  , line.pos_end  , sizeof(float)*5);
+        if (l_steady > 0.f) {
+            // There will be a steady feed segment emitted.
+            if (accelerating) {
+                // Prepare the final steady feed rate segment.
+                memcpy(pos_end2, pos_end, sizeof(float)*4);
+                float t = l_acc / l;
+                for (int i = 0; i < 4; ++ i) {
+                    pos_end[i] = pos_start[i] + (pos_end[i] - pos_start[i]) * t;
+                    line.pos_provided[i] = true;
+                }
+            } else {
+                // Emit the steady feed rate segment.
+                float t = l_steady / l;
+                for (int i = 0; i < 4; ++ i) {
+                    line.pos_end[i] = pos_start[i] + (pos_end[i] - pos_start[i]) * t;
+                    line.pos_provided[i] = true;
+                }
+                push_line_to_output(line, pos_start[4], comment);
+                comment = NULL;
+                memcpy(line.pos_start, line.pos_end, sizeof(float)*5);
+                memcpy(pos_start, line.pos_end, sizeof(float)*5);
+            }
+        }
+        // Split the segment into pieces.
+        for (size_t i = 1; i < nSegments; ++ i) {
+            float t = float(i) / float(nSegments);
+            for (size_t j = 0; j < 4; ++ j) {
+                line.pos_end[j] = pos_start[j] + (pos_end[j] - pos_start[j]) * t;
+                line.pos_provided[j] = true;
+            } 
+            // Interpolate the feed rate at the center of the segment.
+            push_line_to_output(line, pos_start[4] + (pos_end[4] - pos_start[4]) * (float(i) - 0.5f) / float(nSegments), comment);
+            comment = NULL;
+            memcpy(line.pos_start, line.pos_end, sizeof(float)*5);
+        }
+		if (l_steady > 0.f && accelerating) {
+            for (int i = 0; i < 4; ++ i) {
+                line.pos_end[i] = pos_end2[i];
+                line.pos_provided[i] = true;
+            }
+            push_line_to_output(line, pos_end[4], comment);
+        }
+    }
+}
+
+void PressureEqualizer::adjust_volumetric_rate()
+{
+    if (circular_buffer_items < 2)
+        return;
+
+    // Go back from the current circular_buffer_pos and lower the feedtrate to decrease the slope of the extrusion rate changes.
+    const size_t idx_head = circular_buffer_idx_head();
+    const size_t idx_tail = circular_buffer_idx_prev(circular_buffer_idx_tail());
+    size_t idx = idx_tail;
+    if (idx == idx_head || ! circular_buffer[idx].extruding())
+        // Nothing to do, the last move is not extruding.
+        return;
+
+    float feedrate_per_extrusion_role[numExtrusionRoles];
+    for (size_t i = 0; i < numExtrusionRoles; ++ i)
+        feedrate_per_extrusion_role[i] = FLT_MAX;
+    feedrate_per_extrusion_role[circular_buffer[idx].extrusion_role] = circular_buffer[idx].volumetric_extrusion_rate_start;
+
+    bool modified = true;
+    while (modified && idx != idx_head) {
+        size_t idx_prev = circular_buffer_idx_prev(idx);
+        for (; ! circular_buffer[idx_prev].extruding() && idx_prev != idx_head; idx_prev = circular_buffer_idx_prev(idx_prev)) ;
+        if (! circular_buffer[idx_prev].extruding())
+        	break;
+        // Volumetric extrusion rate at the start of the succeding segment.
+        float rate_succ = circular_buffer[idx].volumetric_extrusion_rate_start;
+        // What is the gradient of the extrusion rate between idx_prev and idx?
+        idx = idx_prev;
+        GCodeLine &line = circular_buffer[idx];
+        for (size_t iRole = 1; iRole < numExtrusionRoles; ++ iRole) {
+            float rate_slope = m_max_volumetric_extrusion_rate_slopes[iRole].negative;
+            if (rate_slope == 0)
+                // The negative rate is unlimited.
+                continue;
+            float rate_end = feedrate_per_extrusion_role[iRole];
+            if (iRole == line.extrusion_role && rate_succ < rate_end)
+                // Limit by the succeeding volumetric flow rate.
+                rate_end = rate_succ;
+            if (line.volumetric_extrusion_rate_end > rate_end) {
+                line.volumetric_extrusion_rate_end = rate_end;
+                line.modified = true;
+            } else if (iRole == line.extrusion_role) {
+                rate_end = line.volumetric_extrusion_rate_end;
+            } else if (rate_end == FLT_MAX) {
+                // The rate for ExtrusionRole iRole is unlimited.
+                continue;
+            } else {
+                // Use the original, 'floating' extrusion rate as a starting point for the limiter.
+            }
+//            modified = false;
+            float rate_start = rate_end + rate_slope * line.time_corrected();
+            if (rate_start < line.volumetric_extrusion_rate_start) {
+                // Limit the volumetric extrusion rate at the start of this segment due to a segment 
+                // of ExtrusionType iRole, which will be extruded in the future.
+                line.volumetric_extrusion_rate_start = rate_start;
+                line.max_volumetric_extrusion_rate_slope_negative = rate_slope;
+                line.modified = true;
+//              modified = true;
+            }
+            feedrate_per_extrusion_role[iRole] = (iRole == line.extrusion_role) ? line.volumetric_extrusion_rate_start : rate_start;
+        }
+    }
+
+    // Go forward and adjust the feedrate to decrease the slope of the extrusion rate changes.
+    for (size_t i = 0; i < numExtrusionRoles; ++ i)
+        feedrate_per_extrusion_role[i] = FLT_MAX;
+    feedrate_per_extrusion_role[circular_buffer[idx].extrusion_role] = circular_buffer[idx].volumetric_extrusion_rate_end;
+
+    assert(circular_buffer[idx].extruding());
+    while (idx != idx_tail) {
+        size_t idx_next = circular_buffer_idx_next(idx);
+        for (; ! circular_buffer[idx_next].extruding() && idx_next != idx_tail; idx_next = circular_buffer_idx_next(idx_next)) ;
+        if (! circular_buffer[idx_next].extruding())
+        	break;
+        float rate_prec = circular_buffer[idx].volumetric_extrusion_rate_end;
+        // What is the gradient of the extrusion rate between idx_prev and idx?
+        idx = idx_next;
+        GCodeLine &line = circular_buffer[idx];
+        for (size_t iRole = 1; iRole < numExtrusionRoles; ++ iRole) {
+            float rate_slope = m_max_volumetric_extrusion_rate_slopes[iRole].positive;
+            if (rate_slope == 0)
+                // The positive rate is unlimited.
+                continue;
+            float rate_start = feedrate_per_extrusion_role[iRole];
+            if (iRole == line.extrusion_role && rate_prec < rate_start)
+                rate_start = rate_prec;
+            if (line.volumetric_extrusion_rate_start > rate_start) {
+                line.volumetric_extrusion_rate_start = rate_start;
+                line.modified = true;
+            } else if (iRole == line.extrusion_role) {
+                rate_start = line.volumetric_extrusion_rate_start;
+            } else if (rate_start == FLT_MAX) {
+                // The rate for ExtrusionRole iRole is unlimited.
+                continue;
+            } else {
+                // Use the original, 'floating' extrusion rate as a starting point for the limiter.
+            }
+            float rate_end = (rate_slope == 0) ? FLT_MAX : rate_start + rate_slope * line.time_corrected();
+            if (rate_end < line.volumetric_extrusion_rate_end) {
+                // Limit the volumetric extrusion rate at the start of this segment due to a segment 
+                // of ExtrusionType iRole, which was extruded before.
+                line.volumetric_extrusion_rate_end = rate_end;
+                line.max_volumetric_extrusion_rate_slope_positive = rate_slope;
+                line.modified = true;
+            }
+            feedrate_per_extrusion_role[iRole] = (iRole == line.extrusion_role) ? line.volumetric_extrusion_rate_end : rate_end;
+        }
+    }
+}
+
+void PressureEqualizer::push_axis_to_output(const char axis, const float value, bool add_eol)
+{
+    char buf[2048];
+    int len = sprintf(buf, 
+        (axis == 'E') ? " %c%.3f" : " %c%.5f",
+        axis, value);
+    push_to_output(buf, len, add_eol);
+}
+
+void PressureEqualizer::push_to_output(const char *text, const size_t len, bool add_eol)
+{
+    // New length of the output buffer content.
+    size_t len_new = output_buffer_length + len + 1;
+    if (add_eol)
+        ++ len_new;
+
+    // Resize the output buffer to a power of 2 higher than the required memory.
+    if (output_buffer.size() < len_new) {
+        size_t v = len_new;
+        // Compute the next highest power of 2 of 32-bit v
+        // http://graphics.stanford.edu/~seander/bithacks.html
+        v--;
+        v |= v >> 1;
+        v |= v >> 2;
+        v |= v >> 4;
+        v |= v >> 8;
+        v |= v >> 16;
+        v++;
+        output_buffer.resize(v);
+    }
+
+    // Copy the text to the output.
+    if (len != 0) {
+        memcpy(output_buffer.data() + output_buffer_length, text, len);
+        output_buffer_length += len;
+    }
+    if (add_eol)
+        output_buffer[output_buffer_length ++] = '\n';
+    output_buffer[output_buffer_length] = 0;
+}
+
+void PressureEqualizer::push_line_to_output(const GCodeLine &line, const float new_feedrate, const char *comment)
+{
+    push_to_output("G1", 2, false);
+    for (char i = 0; i < 3; ++ i)
+        if (line.pos_provided[i])
+            push_axis_to_output('X'+i, line.pos_end[i]);
+    push_axis_to_output('E', m_config->use_relative_e_distances.value ? (line.pos_end[3] - line.pos_start[3]) : line.pos_end[3]);
+//    if (line.pos_provided[4] || fabs(line.feedrate() - new_feedrate) > 1e-5)
+        push_axis_to_output('F', new_feedrate);
+    // output comment and EOL
+    push_to_output(comment, (comment == NULL) ? 0 : strlen(comment), true);
+} 
+
+} // namespace Slic3r

src/libslic3r/GCode/PressureEqualizer.hpp

@@ -0,0 +1,212 @@
+#ifndef slic3r_GCode_PressureEqualizer_hpp_
+#define slic3r_GCode_PressureEqualizer_hpp_
+
+#include "../libslic3r.h"
+#include "../PrintConfig.hpp"
+#include "../ExtrusionEntity.hpp"
+
+namespace Slic3r {
+
+// Processes a G-code. Finds changes in the volumetric extrusion speed and adjusts the transitions
+// between these paths to limit fast changes in the volumetric extrusion speed.
+class PressureEqualizer
+{
+public:
+    PressureEqualizer(const Slic3r::GCodeConfig *config);
+    ~PressureEqualizer();
+
+    void reset();
+
+    // Process a next batch of G-code lines. Flush the internal buffers if asked for.
+    const char* process(const char *szGCode, bool flush);
+
+    size_t get_output_buffer_length() const { return output_buffer_length; }
+
+private:
+    struct Statistics
+    {
+        void reset() {
+			volumetric_extrusion_rate_min = std::numeric_limits<float>::max();
+            volumetric_extrusion_rate_max = 0.f;
+            volumetric_extrusion_rate_avg = 0.f;
+            extrusion_length = 0.f;
+        }
+        void update(float volumetric_extrusion_rate, float length) {
+            volumetric_extrusion_rate_min = std::min(volumetric_extrusion_rate_min, volumetric_extrusion_rate);
+            volumetric_extrusion_rate_max = std::max(volumetric_extrusion_rate_max, volumetric_extrusion_rate);
+            volumetric_extrusion_rate_avg += volumetric_extrusion_rate * length;
+            extrusion_length += length;          
+        }
+        float volumetric_extrusion_rate_min;
+        float volumetric_extrusion_rate_max;
+        float volumetric_extrusion_rate_avg;
+        float extrusion_length;
+    };
+
+    struct Statistics m_stat;
+
+    // Keeps the reference, does not own the config.
+    const Slic3r::GCodeConfig *m_config;
+
+    // Private configuration values
+    // How fast could the volumetric extrusion rate increase / decrase? mm^3/sec^2
+    struct ExtrusionRateSlope {
+        float positive;
+        float negative;
+    };
+    enum { numExtrusionRoles = erSupportMaterialInterface + 1 };
+    ExtrusionRateSlope              m_max_volumetric_extrusion_rate_slopes[numExtrusionRoles];
+    float                           m_max_volumetric_extrusion_rate_slope_positive;
+    float                           m_max_volumetric_extrusion_rate_slope_negative;
+    // Maximum segment length to split a long segment, if the initial and the final flow rate differ.
+    float                           m_max_segment_length;
+
+    // Configuration extracted from config.
+    // Area of the crossestion of each filament. Necessary to calculate the volumetric flow rate.
+    std::vector<float>              m_filament_crossections;
+
+    // Internal data.
+    // X,Y,Z,E,F
+    float                           m_current_pos[5];
+    size_t                          m_current_extruder;
+    ExtrusionRole                   m_current_extrusion_role;
+    bool                            m_retracted;
+
+    enum GCodeLineType
+    {
+        GCODELINETYPE_INVALID,
+        GCODELINETYPE_NOOP,
+        GCODELINETYPE_OTHER,
+        GCODELINETYPE_RETRACT,
+        GCODELINETYPE_UNRETRACT,
+        GCODELINETYPE_TOOL_CHANGE,
+        GCODELINETYPE_MOVE,
+        GCODELINETYPE_EXTRUDE,
+    };
+
+    struct GCodeLine
+    {
+        GCodeLine() : 
+            type(GCODELINETYPE_INVALID),
+            raw_length(0),
+            modified(false),
+            extruder_id(0), 
+            volumetric_extrusion_rate(0.f), 
+            volumetric_extrusion_rate_start(0.f), 
+            volumetric_extrusion_rate_end(0.f) 
+            {}
+
+        bool        moving_xy()     const { return fabs(pos_end[0] - pos_start[0]) > 0.f || fabs(pos_end[1] - pos_start[1]) > 0.f; }
+        bool        moving_z ()     const { return fabs(pos_end[2] - pos_start[2]) > 0.f; }
+        bool        extruding()     const { return moving_xy() && pos_end[3] > pos_start[3]; }
+        bool        retracting()    const { return pos_end[3] < pos_start[3]; }
+        bool        deretracting()  const { return ! moving_xy() && pos_end[3] > pos_start[3]; }
+
+        float       dist_xy2()      const { return (pos_end[0] - pos_start[0]) * (pos_end[0] - pos_start[0]) + (pos_end[1] - pos_start[1]) * (pos_end[1] - pos_start[1]); }
+        float       dist_xyz2()     const { return (pos_end[0] - pos_start[0]) * (pos_end[0] - pos_start[0]) + (pos_end[1] - pos_start[1]) * (pos_end[1] - pos_start[1]) + (pos_end[2] - pos_start[2]) * (pos_end[2] - pos_start[2]); }
+        float       dist_xy()       const { return sqrt(dist_xy2()); }
+        float       dist_xyz()      const { return sqrt(dist_xyz2()); }
+        float       dist_e()        const { return fabs(pos_end[3] - pos_start[3]); }
+
+        float       feedrate()      const { return pos_end[4]; }
+        float       time()          const { return dist_xyz() / feedrate(); }
+        float       time_inv()      const { return feedrate() / dist_xyz(); }
+        float       volumetric_correction_avg() const { 
+            float avg_correction = 0.5f * (volumetric_extrusion_rate_start + volumetric_extrusion_rate_end) / volumetric_extrusion_rate; 
+            assert(avg_correction > 0.f);
+            assert(avg_correction <= 1.00000001f);
+            return avg_correction;
+        }
+        float       time_corrected()  const { return time() * volumetric_correction_avg(); }
+
+        GCodeLineType type;
+
+        // We try to keep the string buffer once it has been allocated, so it will not be reallocated over and over.
+        std::vector<char>   raw;
+        size_t              raw_length;
+        // If modified, the raw text has to be adapted by the new extrusion rate,
+        // or maybe the line needs to be split into multiple lines.
+        bool                modified;
+
+        // float       timeStart;
+        // float       timeEnd;
+        // X,Y,Z,E,F. Storing the state of the currently active extruder only.
+        float       pos_start[5];
+        float       pos_end[5];
+        // Was the axis found on the G-code line? X,Y,Z,F
+        bool        pos_provided[5];
+
+        // Index of the active extruder.
+        size_t      extruder_id;
+        // Extrusion role of this segment.
+        ExtrusionRole extrusion_role;
+
+        // Current volumetric extrusion rate.
+        float       volumetric_extrusion_rate;
+        // Volumetric extrusion rate at the start of this segment.
+        float       volumetric_extrusion_rate_start;
+        // Volumetric extrusion rate at the end of this segment.
+        float       volumetric_extrusion_rate_end;
+
+        // Volumetric extrusion rate slope limiting this segment.
+        // If set to zero, the slope is unlimited.
+        float       max_volumetric_extrusion_rate_slope_positive;
+        float       max_volumetric_extrusion_rate_slope_negative;
+    };
+
+    // Circular buffer of GCode lines. The circular buffer size will be limited to circular_buffer_size.
+    std::vector<GCodeLine>          circular_buffer;
+    // Current position of the circular buffer (index, where to write the next line to, the line has to be pushed out before it is overwritten).
+    size_t                          circular_buffer_pos;
+    // Circular buffer size, configuration value.
+    size_t                          circular_buffer_size;
+    // Number of valid lines in the circular buffer. Lower or equal to circular_buffer_size.
+    size_t                          circular_buffer_items;
+
+    // Output buffer will only grow. It will not be reallocated over and over.
+    std::vector<char>               output_buffer;
+    size_t                          output_buffer_length;
+
+    // For debugging purposes. Index of the G-code line processed.
+    size_t                          line_idx;
+
+    bool process_line(const char *line, const size_t len, GCodeLine &buf);
+    void output_gcode_line(GCodeLine &buf);
+
+    // Go back from the current circular_buffer_pos and lower the feedtrate to decrease the slope of the extrusion rate changes.
+    // Then go forward and adjust the feedrate to decrease the slope of the extrusion rate changes.
+    void adjust_volumetric_rate();
+
+    // Push the text to the end of the output_buffer.
+    void push_to_output(const char *text, const size_t len, bool add_eol = true);
+    // Push an axis assignment to the end of the output buffer.
+    void push_axis_to_output(const char axis, const float value, bool add_eol = false);
+    // Push a G-code line to the output, 
+    void push_line_to_output(const GCodeLine &line, const float new_feedrate, const char *comment);
+
+    size_t circular_buffer_idx_head() const {
+        size_t idx = circular_buffer_pos + circular_buffer_size - circular_buffer_items;
+        if (idx >= circular_buffer_size)
+            idx -= circular_buffer_size;
+        return idx;
+    }
+
+    size_t circular_buffer_idx_tail() const { return circular_buffer_pos; }
+
+    size_t circular_buffer_idx_prev(size_t idx) const {
+        idx += circular_buffer_size - 1;
+        if (idx >= circular_buffer_size)
+            idx -= circular_buffer_size;
+        return idx;
+    }
+
+    size_t circular_buffer_idx_next(size_t idx) const {
+        if (++ idx >= circular_buffer_size)
+            idx -= circular_buffer_size;
+        return idx;
+    }
+};
+
+} // namespace Slic3r
+
+#endif /* slic3r_GCode_PressureEqualizer_hpp_ */

src/libslic3r/GCode/PreviewData.cpp

@@ -0,0 +1,455 @@
+#include "Analyzer.hpp"
+#include "PreviewData.hpp"
+#include <float.h>
+#include <I18N.hpp>
+
+#include <boost/format.hpp>
+
+//! macro used to mark string used at localization, 
+#define L(s) (s)
+
+namespace Slic3r {
+
+const GCodePreviewData::Color GCodePreviewData::Color::Dummy(0.0f, 0.0f, 0.0f, 0.0f);
+
+GCodePreviewData::Color::Color()
+{
+    rgba[0] = 1.0f;
+    rgba[1] = 1.0f;
+    rgba[2] = 1.0f;
+    rgba[3] = 1.0f;
+}
+
+GCodePreviewData::Color::Color(float r, float g, float b, float a)
+{
+    rgba[0] = r;
+    rgba[1] = g;
+    rgba[2] = b;
+    rgba[3] = a;
+}
+
+std::vector<unsigned char> GCodePreviewData::Color::as_bytes() const
+{
+    std::vector<unsigned char> ret;
+    for (unsigned int i = 0; i < 4; ++i)
+    {
+        ret.push_back((unsigned char)(255.0f * rgba[i]));
+    }
+    return ret;
+}
+
+GCodePreviewData::Extrusion::Layer::Layer(float z, const ExtrusionPaths& paths)
+    : z(z)
+    , paths(paths)
+{
+}
+
+GCodePreviewData::Travel::Polyline::Polyline(EType type, EDirection direction, float feedrate, unsigned int extruder_id, const Polyline3& polyline)
+    : type(type)
+    , direction(direction)
+    , feedrate(feedrate)
+    , extruder_id(extruder_id)
+    , polyline(polyline)
+{
+}
+
+const GCodePreviewData::Color GCodePreviewData::Range::Default_Colors[Colors_Count] =
+{
+    Color(0.043f, 0.173f, 0.478f, 1.0f),
+    Color(0.075f, 0.349f, 0.522f, 1.0f),
+    Color(0.110f, 0.533f, 0.569f, 1.0f),
+    Color(0.016f, 0.839f, 0.059f, 1.0f),
+    Color(0.667f, 0.949f, 0.000f, 1.0f),
+    Color(0.988f, 0.975f, 0.012f, 1.0f),
+    Color(0.961f, 0.808f, 0.039f, 1.0f),
+    Color(0.890f, 0.533f, 0.125f, 1.0f),
+    Color(0.820f, 0.408f, 0.188f, 1.0f),
+    Color(0.761f, 0.322f, 0.235f, 1.0f)
+};
+
+GCodePreviewData::Range::Range()
+{
+    reset();
+}
+
+void GCodePreviewData::Range::reset()
+{
+    min = FLT_MAX;
+    max = -FLT_MAX;
+}
+
+bool GCodePreviewData::Range::empty() const
+{
+    return min == max;
+}
+
+void GCodePreviewData::Range::update_from(float value)
+{
+    min = std::min(min, value);
+    max = std::max(max, value);
+}
+
+void GCodePreviewData::Range::update_from(const Range& other)
+{
+    min = std::min(min, other.min);
+    max = std::max(max, other.max);
+}
+
+void GCodePreviewData::Range::set_from(const Range& other)
+{
+    min = other.min;
+    max = other.max;
+}
+
+float GCodePreviewData::Range::step_size() const
+{
+    return (max - min) / (float)(Colors_Count - 1);
+}
+
+GCodePreviewData::Color GCodePreviewData::Range::get_color_at(float value) const
+{
+    if (empty())
+        return Color::Dummy;
+
+    float global_t = (value - min) / step_size();
+
+    unsigned int low = (unsigned int)global_t;
+    unsigned int high = clamp((unsigned int)0, Colors_Count - 1, low + 1);
+
+    Color color_low = colors[low];
+    Color color_high = colors[high];
+
+    float local_t = global_t - (float)low;
+
+    // interpolate in RGB space
+    Color ret;
+    for (unsigned int i = 0; i < 4; ++i)
+    {
+        ret.rgba[i] = lerp(color_low.rgba[i], color_high.rgba[i], local_t);
+    }
+    return ret;
+}
+
+GCodePreviewData::LegendItem::LegendItem(const std::string& text, const GCodePreviewData::Color& color)
+    : text(text)
+    , color(color)
+{
+}
+
+const GCodePreviewData::Color GCodePreviewData::Extrusion::Default_Extrusion_Role_Colors[Num_Extrusion_Roles] =
+{
+    Color(0.0f, 0.0f, 0.0f, 1.0f),   // erNone
+    Color(1.0f, 0.0f, 0.0f, 1.0f),   // erPerimeter
+    Color(0.0f, 1.0f, 0.0f, 1.0f),   // erExternalPerimeter
+    Color(0.0f, 0.0f, 1.0f, 1.0f),   // erOverhangPerimeter
+    Color(1.0f, 1.0f, 0.0f, 1.0f),   // erInternalInfill
+    Color(1.0f, 0.0f, 1.0f, 1.0f),   // erSolidInfill
+    Color(0.0f, 1.0f, 1.0f, 1.0f),   // erTopSolidInfill
+    Color(0.5f, 0.5f, 0.5f, 1.0f),   // erBridgeInfill
+    Color(1.0f, 1.0f, 1.0f, 1.0f),   // erGapFill
+    Color(0.5f, 0.0f, 0.0f, 1.0f),   // erSkirt
+    Color(0.0f, 0.5f, 0.0f, 1.0f),   // erSupportMaterial
+    Color(0.0f, 0.0f, 0.5f, 1.0f),   // erSupportMaterialInterface
+    Color(0.7f, 0.89f, 0.67f, 1.0f), // erWipeTower
+    Color(1.0f, 1.0f, 0.0f, 1.0f),   // erCustom
+    Color(0.0f, 0.0f, 0.0f, 1.0f)    // erMixed
+};
+
+// todo: merge with Slic3r::ExtrusionRole2String() from GCode.cpp
+const std::string GCodePreviewData::Extrusion::Default_Extrusion_Role_Names[Num_Extrusion_Roles]
+{
+    L("None"),
+    L("Perimeter"),
+    L("External perimeter"),
+    L("Overhang perimeter"),
+    L("Internal infill"),
+    L("Solid infill"),
+    L("Top solid infill"),
+    L("Bridge infill"),
+    L("Gap fill"),
+    L("Skirt"),
+    L("Support material"),
+    L("Support material interface"),
+    L("Wipe tower"),
+    L("Custom"),
+    L("Mixed")
+};
+
+const GCodePreviewData::Extrusion::EViewType GCodePreviewData::Extrusion::Default_View_Type = GCodePreviewData::Extrusion::FeatureType;
+
+void GCodePreviewData::Extrusion::set_default()
+{
+    view_type = Default_View_Type;
+
+    ::memcpy((void*)role_colors, (const void*)Default_Extrusion_Role_Colors, Num_Extrusion_Roles * sizeof(Color));
+
+    for (unsigned int i = 0; i < Num_Extrusion_Roles; ++i)
+    {
+        role_names[i] = Default_Extrusion_Role_Names[i];
+    }
+
+    role_flags = 0;
+    for (unsigned int i = 0; i < Num_Extrusion_Roles; ++i)
+    {
+        role_flags |= 1 << i;
+    }
+}
+
+bool GCodePreviewData::Extrusion::is_role_flag_set(ExtrusionRole role) const
+{
+    return is_role_flag_set(role_flags, role);
+}
+
+bool GCodePreviewData::Extrusion::is_role_flag_set(unsigned int flags, ExtrusionRole role)
+{
+    return GCodeAnalyzer::is_valid_extrusion_role(role) && (flags & (1 << (role - erPerimeter))) != 0;
+}
+
+const float GCodePreviewData::Travel::Default_Width = 0.075f;
+const float GCodePreviewData::Travel::Default_Height = 0.075f;
+const GCodePreviewData::Color GCodePreviewData::Travel::Default_Type_Colors[Num_Types] =
+{
+    Color(0.0f, 0.0f, 0.75f, 1.0f), // Move
+    Color(0.0f, 0.75f, 0.0f, 1.0f), // Extrude
+    Color(0.75f, 0.0f, 0.0f, 1.0f), // Retract
+};
+
+void GCodePreviewData::Travel::set_default()
+{
+    width = Default_Width;
+    height = Default_Height;
+    ::memcpy((void*)type_colors, (const void*)Default_Type_Colors, Num_Types * sizeof(Color));
+
+    is_visible = false;
+}
+
+const GCodePreviewData::Color GCodePreviewData::Retraction::Default_Color = GCodePreviewData::Color(1.0f, 1.0f, 1.0f, 1.0f);
+
+GCodePreviewData::Retraction::Position::Position(const Vec3crd& position, float width, float height)
+    : position(position)
+    , width(width)
+    , height(height)
+{
+}
+
+void GCodePreviewData::Retraction::set_default()
+{
+    color = Default_Color;
+    is_visible = false;
+}
+
+void GCodePreviewData::Shell::set_default()
+{
+    is_visible = false;
+}
+
+GCodePreviewData::GCodePreviewData()
+{
+    set_default();
+}
+
+void GCodePreviewData::set_default()
+{
+    ::memcpy((void*)ranges.height.colors, (const void*)Range::Default_Colors, Range::Colors_Count * sizeof(Color));
+    ::memcpy((void*)ranges.width.colors, (const void*)Range::Default_Colors, Range::Colors_Count * sizeof(Color));
+    ::memcpy((void*)ranges.feedrate.colors, (const void*)Range::Default_Colors, Range::Colors_Count * sizeof(Color));
+    ::memcpy((void*)ranges.volumetric_rate.colors, (const void*)Range::Default_Colors, Range::Colors_Count * sizeof(Color));
+
+    extrusion.set_default();
+    travel.set_default();
+    retraction.set_default();
+    unretraction.set_default();
+    shell.set_default();
+}
+
+void GCodePreviewData::reset()
+{
+    ranges.width.reset();
+    ranges.height.reset();
+    ranges.feedrate.reset();
+    ranges.volumetric_rate.reset();
+    extrusion.layers.clear();
+    travel.polylines.clear();
+    retraction.positions.clear();
+    unretraction.positions.clear();
+}
+
+bool GCodePreviewData::empty() const
+{
+    return extrusion.layers.empty() && travel.polylines.empty() && retraction.positions.empty() && unretraction.positions.empty();
+}
+
+GCodePreviewData::Color GCodePreviewData::get_extrusion_role_color(ExtrusionRole role) const
+{
+    return extrusion.role_colors[role];
+}
+
+GCodePreviewData::Color GCodePreviewData::get_height_color(float height) const
+{
+    return ranges.height.get_color_at(height);
+}
+
+GCodePreviewData::Color GCodePreviewData::get_width_color(float width) const
+{
+    return ranges.width.get_color_at(width);
+}
+
+GCodePreviewData::Color GCodePreviewData::get_feedrate_color(float feedrate) const
+{
+    return ranges.feedrate.get_color_at(feedrate);
+}
+
+GCodePreviewData::Color GCodePreviewData::get_volumetric_rate_color(float rate) const
+{
+    return ranges.volumetric_rate.get_color_at(rate);
+}
+
+void GCodePreviewData::set_extrusion_role_color(const std::string& role_name, float red, float green, float blue, float alpha)
+{
+    for (unsigned int i = 0; i < Extrusion::Num_Extrusion_Roles; ++i)
+    {
+        if (role_name == extrusion.role_names[i])
+        {
+            extrusion.role_colors[i] = Color(red, green, blue, alpha);
+            break;
+        }
+    }
+}
+
+void GCodePreviewData::set_extrusion_paths_colors(const std::vector<std::string>& colors)
+{
+    unsigned int size = (unsigned int)colors.size();
+
+    if (size % 2 != 0)
+        return;
+
+    for (unsigned int i = 0; i < size; i += 2)
+    {
+        const std::string& color_str = colors[i + 1];
+
+        if (color_str.size() == 6)
+        {
+            bool valid = true;
+            for (int c = 0; c < 6; ++c)
+            {
+                if (::isxdigit(color_str[c]) == 0)
+                {
+                    valid = false;
+                    break;
+                }
+            }
+
+            if (valid)
+            {
+                unsigned int color;
+                std::stringstream ss;
+                ss << std::hex << color_str;
+                ss >> color;
+
+                float den = 1.0f / 255.0f;
+
+                float r = (float)((color & 0xFF0000) >> 16) * den;
+                float g = (float)((color & 0x00FF00) >> 8) * den;
+                float b = (float)(color & 0x0000FF) * den;
+
+                this->set_extrusion_role_color(colors[i], r, g, b, 1.0f);
+            }
+        }
+    }
+}
+
+std::string GCodePreviewData::get_legend_title() const
+{
+    switch (extrusion.view_type)
+    {
+    case Extrusion::FeatureType:
+        return L("Feature type");
+    case Extrusion::Height:
+        return L("Height (mm)");
+    case Extrusion::Width:
+        return L("Width (mm)");
+    case Extrusion::Feedrate:
+        return L("Speed (mm/s)");
+    case Extrusion::VolumetricRate:
+        return L("Volumetric flow rate (mm3/s)");
+    case Extrusion::Tool:
+        return L("Tool");
+    }
+
+    return "";
+}
+
+GCodePreviewData::LegendItemsList GCodePreviewData::get_legend_items(const std::vector<float>& tool_colors) const
+{
+    struct Helper
+    {
+        static void FillListFromRange(LegendItemsList& list, const Range& range, unsigned int decimals, float scale_factor)
+        {
+            list.reserve(Range::Colors_Count);
+
+            float step = range.step_size();
+            for (int i = Range::Colors_Count - 1; i >= 0; --i)
+            {
+                char buf[1024];
+                sprintf(buf, "%.*f", decimals, scale_factor * (range.min + (float)i * step));
+                list.emplace_back(buf, range.colors[i]);
+            }
+        }
+    };
+
+    LegendItemsList items;
+
+    switch (extrusion.view_type)
+    {
+    case Extrusion::FeatureType:
+        {
+            ExtrusionRole first_valid = erPerimeter;
+            ExtrusionRole last_valid = erCustom;
+
+            items.reserve(last_valid - first_valid + 1);
+            for (unsigned int i = (unsigned int)first_valid; i <= (unsigned int)last_valid; ++i)
+            {
+                items.emplace_back(Slic3r::I18N::translate(extrusion.role_names[i]), extrusion.role_colors[i]);
+            }
+
+            break;
+        }
+    case Extrusion::Height:
+        {
+            Helper::FillListFromRange(items, ranges.height, 3, 1.0f);
+            break;
+        }
+    case Extrusion::Width:
+        {
+            Helper::FillListFromRange(items, ranges.width, 3, 1.0f);
+            break;
+        }
+    case Extrusion::Feedrate:
+        {
+            Helper::FillListFromRange(items, ranges.feedrate, 1, 1.0f);
+            break;
+        }
+    case Extrusion::VolumetricRate:
+        {
+            Helper::FillListFromRange(items, ranges.volumetric_rate, 3, 1.0f);
+            break;
+        }
+    case Extrusion::Tool:
+        {
+            unsigned int tools_colors_count = tool_colors.size() / 4;
+            items.reserve(tools_colors_count);
+            for (unsigned int i = 0; i < tools_colors_count; ++i)
+            {
+                GCodePreviewData::Color color;
+                ::memcpy((void*)color.rgba, (const void*)(tool_colors.data() + i * 4), 4 * sizeof(float));
+                items.emplace_back((boost::format(Slic3r::I18N::translate(L("Extruder %d"))) % (i + 1)).str(), color);
+            }
+
+            break;
+        }
+    }
+
+    return items;
+}
+
+} // namespace Slic3r

src/libslic3r/GCode/PreviewData.hpp

@@ -0,0 +1,208 @@
+#ifndef slic3r_GCode_PreviewData_hpp_
+#define slic3r_GCode_PreviewData_hpp_
+
+#include "../libslic3r.h"
+#include "../ExtrusionEntity.hpp"
+
+#include "Point.hpp"
+
+namespace Slic3r {
+
+class GCodePreviewData
+{
+public:
+    struct Color
+    {
+        float rgba[4];
+
+        Color();
+        Color(float r, float g, float b, float a);
+
+        std::vector<unsigned char> as_bytes() const;
+
+        static const Color Dummy;
+    };
+
+    struct Range
+    {
+        static const unsigned int Colors_Count = 10;
+        static const Color Default_Colors[Colors_Count];
+
+        Color colors[Colors_Count];
+        float min;
+        float max;
+
+        Range();
+
+        void reset();
+        bool empty() const;
+        void update_from(float value);
+        void update_from(const Range& other);
+        void set_from(const Range& other);
+        float step_size() const;
+
+        Color get_color_at(float value) const;
+    };
+
+    struct Ranges
+    {
+        Range height;
+        Range width;
+        Range feedrate;
+        Range volumetric_rate;
+    };
+
+    struct LegendItem
+    {
+        std::string text;
+        Color color;
+
+        LegendItem(const std::string& text, const Color& color);
+    };
+
+    typedef std::vector<LegendItem> LegendItemsList;
+
+    struct Extrusion
+    {
+        enum EViewType : unsigned char
+        {
+            FeatureType,
+            Height,
+            Width,
+            Feedrate,
+            VolumetricRate,
+            Tool,
+            Num_View_Types
+        };
+
+        static const unsigned int Num_Extrusion_Roles = (unsigned int)erMixed + 1;
+        static const Color Default_Extrusion_Role_Colors[Num_Extrusion_Roles];
+        static const std::string Default_Extrusion_Role_Names[Num_Extrusion_Roles];
+        static const EViewType Default_View_Type;
+
+        struct Layer
+        {
+            float z;
+            ExtrusionPaths paths;
+
+            Layer(float z, const ExtrusionPaths& paths);
+        };
+
+        typedef std::vector<Layer> LayersList;
+
+        EViewType view_type;
+        Color role_colors[Num_Extrusion_Roles];
+        std::string role_names[Num_Extrusion_Roles];
+        LayersList layers;
+        unsigned int role_flags;
+
+        void set_default();
+        bool is_role_flag_set(ExtrusionRole role) const;
+
+        static bool is_role_flag_set(unsigned int flags, ExtrusionRole role);
+    };
+
+    struct Travel
+    {
+        enum EType : unsigned char
+        {
+            Move,
+            Extrude,
+            Retract,
+            Num_Types
+        };
+
+        static const float Default_Width;
+        static const float Default_Height;
+        static const Color Default_Type_Colors[Num_Types];
+
+        struct Polyline
+        {
+            enum EDirection
+            {
+                Vertical,
+                Generic,
+                Num_Directions
+            };
+
+            EType type;
+            EDirection direction;
+            float feedrate;
+            unsigned int extruder_id;
+            Polyline3 polyline;
+
+            Polyline(EType type, EDirection direction, float feedrate, unsigned int extruder_id, const Polyline3& polyline);
+        };
+
+        typedef std::vector<Polyline> PolylinesList;
+
+        PolylinesList polylines;
+        float width;
+        float height;
+        Color type_colors[Num_Types];
+        bool is_visible;
+
+        void set_default();
+    };
+
+    struct Retraction
+    {
+        static const Color Default_Color;
+
+        struct Position
+        {
+            Vec3crd position;
+            float width;
+            float height;
+
+            Position(const Vec3crd& position, float width, float height);
+        };
+
+        typedef std::vector<Position> PositionsList;
+
+        PositionsList positions;
+        Color color;
+        bool is_visible;
+
+        void set_default();
+    };
+
+    struct Shell
+    {
+        bool is_visible;
+
+        void set_default();
+    };
+
+    Extrusion extrusion;
+    Travel travel;
+    Retraction retraction;
+    Retraction unretraction;
+    Shell shell;
+    Ranges ranges;
+
+    GCodePreviewData();
+
+    void set_default();
+    void reset();
+    bool empty() const;
+
+    Color get_extrusion_role_color(ExtrusionRole role) const;
+    Color get_height_color(float height) const;
+    Color get_width_color(float width) const;
+    Color get_feedrate_color(float feedrate) const;
+    Color get_volumetric_rate_color(float rate) const;
+
+    void set_extrusion_role_color(const std::string& role_name, float red, float green, float blue, float alpha);
+    void set_extrusion_paths_colors(const std::vector<std::string>& colors);
+
+    std::string get_legend_title() const;
+    LegendItemsList get_legend_items(const std::vector<float>& tool_colors) const;
+};
+
+GCodePreviewData::Color operator + (const GCodePreviewData::Color& c1, const GCodePreviewData::Color& c2);
+GCodePreviewData::Color operator * (float f, const GCodePreviewData::Color& color);
+
+} // namespace Slic3r
+
+#endif /* slic3r_GCode_PreviewData_hpp_ */

src/libslic3r/GCode/PrintExtents.cpp

@@ -0,0 +1,186 @@
+// Calculate extents of the extrusions assigned to Print / PrintObject.
+// The extents are used for assessing collisions of the print with the priming towers,
+// to decide whether to pause the print after the priming towers are extruded
+// to let the operator remove them from the print bed.
+
+#include "../BoundingBox.hpp"
+#include "../ExtrusionEntity.hpp"
+#include "../ExtrusionEntityCollection.hpp"
+#include "../Print.hpp"
+
+#include "PrintExtents.hpp"
+#include "WipeTower.hpp"
+
+namespace Slic3r {
+
+static inline BoundingBox extrusion_polyline_extents(const Polyline &polyline, const coord_t radius)
+{
+    BoundingBox bbox;
+    if (! polyline.points.empty())
+        bbox.merge(polyline.points.front());
+    for (const Point &pt : polyline.points) {
+        bbox.min(0) = std::min(bbox.min(0), pt(0) - radius);
+        bbox.min(1) = std::min(bbox.min(1), pt(1) - radius);
+        bbox.max(0) = std::max(bbox.max(0), pt(0) + radius);
+        bbox.max(1) = std::max(bbox.max(1), pt(1) + radius);
+    }
+    return bbox;
+}
+
+static inline BoundingBoxf extrusionentity_extents(const ExtrusionPath &extrusion_path)
+{
+    BoundingBox bbox = extrusion_polyline_extents(extrusion_path.polyline, scale_(0.5 * extrusion_path.width));
+    BoundingBoxf bboxf;
+    if (! empty(bbox)) {
+        bboxf.min = unscale(bbox.min);
+        bboxf.max = unscale(bbox.max);
+		bboxf.defined = true;
+    }
+    return bboxf;
+}
+
+static inline BoundingBoxf extrusionentity_extents(const ExtrusionLoop &extrusion_loop)
+{
+    BoundingBox bbox;
+    for (const ExtrusionPath &extrusion_path : extrusion_loop.paths)
+        bbox.merge(extrusion_polyline_extents(extrusion_path.polyline, scale_(0.5 * extrusion_path.width)));
+    BoundingBoxf bboxf;
+    if (! empty(bbox)) {
+        bboxf.min = unscale(bbox.min);
+        bboxf.max = unscale(bbox.max);
+		bboxf.defined = true;
+	}
+    return bboxf;
+}
+
+static inline BoundingBoxf extrusionentity_extents(const ExtrusionMultiPath &extrusion_multi_path)
+{
+    BoundingBox bbox;
+    for (const ExtrusionPath &extrusion_path : extrusion_multi_path.paths)
+        bbox.merge(extrusion_polyline_extents(extrusion_path.polyline, scale_(0.5 * extrusion_path.width)));
+    BoundingBoxf bboxf;
+    if (! empty(bbox)) {
+        bboxf.min = unscale(bbox.min);
+        bboxf.max = unscale(bbox.max);
+		bboxf.defined = true;
+	}
+    return bboxf;
+}
+
+static BoundingBoxf extrusionentity_extents(const ExtrusionEntity *extrusion_entity);
+
+static inline BoundingBoxf extrusionentity_extents(const ExtrusionEntityCollection &extrusion_entity_collection)
+{
+    BoundingBoxf bbox;
+    for (const ExtrusionEntity *extrusion_entity : extrusion_entity_collection.entities)
+        bbox.merge(extrusionentity_extents(extrusion_entity));
+    return bbox;
+}
+
+static BoundingBoxf extrusionentity_extents(const ExtrusionEntity *extrusion_entity)
+{
+    if (extrusion_entity == nullptr)
+        return BoundingBoxf();
+    auto *extrusion_path = dynamic_cast<const ExtrusionPath*>(extrusion_entity);
+    if (extrusion_path != nullptr)
+        return extrusionentity_extents(*extrusion_path);
+    auto *extrusion_loop = dynamic_cast<const ExtrusionLoop*>(extrusion_entity);
+    if (extrusion_loop != nullptr)
+        return extrusionentity_extents(*extrusion_loop);
+    auto *extrusion_multi_path = dynamic_cast<const ExtrusionMultiPath*>(extrusion_entity);
+    if (extrusion_multi_path != nullptr)
+        return extrusionentity_extents(*extrusion_multi_path);
+    auto *extrusion_entity_collection = dynamic_cast<const ExtrusionEntityCollection*>(extrusion_entity);
+    if (extrusion_entity_collection != nullptr)
+        return extrusionentity_extents(*extrusion_entity_collection);
+    throw std::runtime_error("Unexpected extrusion_entity type in extrusionentity_extents()");
+    return BoundingBoxf();
+}
+
+BoundingBoxf get_print_extrusions_extents(const Print &print)
+{
+    BoundingBoxf bbox(extrusionentity_extents(print.brim()));
+    bbox.merge(extrusionentity_extents(print.skirt()));
+    return bbox;
+}
+
+BoundingBoxf get_print_object_extrusions_extents(const PrintObject &print_object, const coordf_t max_print_z)
+{
+    BoundingBoxf bbox;
+    for (const Layer *layer : print_object.layers()) {
+        if (layer->print_z > max_print_z)
+            break;
+        BoundingBoxf bbox_this;
+        for (const LayerRegion *layerm : layer->regions()) {
+            bbox_this.merge(extrusionentity_extents(layerm->perimeters));
+            for (const ExtrusionEntity *ee : layerm->fills.entities)
+                // fill represents infill extrusions of a single island.
+                bbox_this.merge(extrusionentity_extents(*dynamic_cast<const ExtrusionEntityCollection*>(ee)));
+        }
+        const SupportLayer *support_layer = dynamic_cast<const SupportLayer*>(layer);
+        if (support_layer)
+            for (const ExtrusionEntity *extrusion_entity : support_layer->support_fills.entities)
+                bbox_this.merge(extrusionentity_extents(extrusion_entity));
+        for (const Point &offset : print_object.copies()) {
+            BoundingBoxf bbox_translated(bbox_this);
+            bbox_translated.translate(unscale(offset));
+            bbox.merge(bbox_translated);
+        }
+    }
+    return bbox;
+}
+
+// Returns a bounding box of a projection of the wipe tower for the layers <= max_print_z.
+// The projection does not contain the priming regions.
+BoundingBoxf get_wipe_tower_extrusions_extents(const Print &print, const coordf_t max_print_z)
+{
+    // Wipe tower extrusions are saved as if the tower was at the origin with no rotation
+    // We need to get position and angle of the wipe tower to transform them to actual position.
+    Transform2d trafo =
+        Eigen::Translation2d(print.config().wipe_tower_x.value, print.config().wipe_tower_y.value) *
+        Eigen::Rotation2Dd(print.config().wipe_tower_rotation_angle.value);
+
+    BoundingBoxf bbox;
+    for (const std::vector<WipeTower::ToolChangeResult> &tool_changes : print.wipe_tower_data().tool_changes) {
+        if (! tool_changes.empty() && tool_changes.front().print_z > max_print_z)
+            break;
+        for (const WipeTower::ToolChangeResult &tcr : tool_changes) {
+            for (size_t i = 1; i < tcr.extrusions.size(); ++ i) {
+                const WipeTower::Extrusion &e = tcr.extrusions[i];
+                if (e.width > 0) {
+                    Vec2d delta = 0.5 * Vec2d(e.width, e.width);
+                    Vec2d p1 = trafo * Vec2d((&e - 1)->pos.x, (&e - 1)->pos.y);
+                    Vec2d p2 = trafo * Vec2d(e.pos.x, e.pos.y);
+                    bbox.merge(p1.cwiseMin(p2) - delta);
+                    bbox.merge(p1.cwiseMax(p2) + delta);
+                }
+            }
+        }
+    }
+    return bbox;
+}
+
+// Returns a bounding box of the wipe tower priming extrusions.
+BoundingBoxf get_wipe_tower_priming_extrusions_extents(const Print &print)
+{
+    BoundingBoxf bbox;
+    if (print.wipe_tower_data().priming != nullptr) {
+        const WipeTower::ToolChangeResult &tcr = *print.wipe_tower_data().priming;
+        for (size_t i = 1; i < tcr.extrusions.size(); ++ i) {
+            const WipeTower::Extrusion &e = tcr.extrusions[i];
+            if (e.width > 0) {
+                Vec2d  p1((&e - 1)->pos.x, (&e - 1)->pos.y);
+                Vec2d  p2(e.pos.x, e.pos.y);
+                bbox.merge(p1);
+                coordf_t radius = 0.5 * e.width;
+                bbox.min(0) = std::min(bbox.min(0), std::min(p1(0), p2(0)) - radius);
+                bbox.min(1) = std::min(bbox.min(1), std::min(p1(1), p2(1)) - radius);
+                bbox.max(0) = std::max(bbox.max(0), std::max(p1(0), p2(0)) + radius);
+                bbox.max(1) = std::max(bbox.max(1), std::max(p1(1), p2(1)) + radius);
+            }
+        }
+    }
+    return bbox;
+}
+
+}

src/libslic3r/GCode/PrintExtents.hpp

@@ -0,0 +1,30 @@
+// Measure extents of the planned extrusions.
+// To be used for collision reporting.
+
+#ifndef slic3r_PrintExtents_hpp_
+#define slic3r_PrintExtents_hpp_
+
+#include "libslic3r.h"
+
+namespace Slic3r {
+
+class Print;
+class PrintObject;
+class BoundingBoxf;
+
+// Returns a bounding box of a projection of the brim and skirt.
+BoundingBoxf get_print_extrusions_extents(const Print &print);
+
+// Returns a bounding box of a projection of the object extrusions at z <= max_print_z.
+BoundingBoxf get_print_object_extrusions_extents(const PrintObject &print_object, const coordf_t max_print_z);
+
+// Returns a bounding box of a projection of the wipe tower for the layers <= max_print_z.
+// The projection does not contain the priming regions.
+BoundingBoxf get_wipe_tower_extrusions_extents(const Print &print, const coordf_t max_print_z);
+
+// Returns a bounding box of the wipe tower priming extrusions.
+BoundingBoxf get_wipe_tower_priming_extrusions_extents(const Print &print);
+
+};
+
+#endif /* slic3r_PrintExtents_hpp_ */

src/libslic3r/GCode/SpiralVase.cpp

@@ -0,0 +1,87 @@
+#include "SpiralVase.hpp"
+#include "GCode.hpp"
+#include <sstream>
+
+namespace Slic3r {
+
+std::string SpiralVase::process_layer(const std::string &gcode)
+{
+    /*  This post-processor relies on several assumptions:
+        - all layers are processed through it, including those that are not supposed
+          to be transformed, in order to update the reader with the XY positions
+        - each call to this method includes a full layer, with a single Z move
+          at the beginning
+        - each layer is composed by suitable geometry (i.e. a single complete loop)
+        - loops were not clipped before calling this method  */
+    
+    // If we're not going to modify G-code, just feed it to the reader
+    // in order to update positions.
+    if (!this->enable) {
+        this->_reader.parse_buffer(gcode);
+        return gcode;
+    }
+    
+    // Get total XY length for this layer by summing all extrusion moves.
+    float total_layer_length = 0;
+    float layer_height = 0;
+    float z;
+    bool set_z = false;
+    
+    {
+        //FIXME Performance warning: This copies the GCodeConfig of the reader.
+        GCodeReader r = this->_reader;  // clone
+        r.parse_buffer(gcode, [&total_layer_length, &layer_height, &z, &set_z]
+            (GCodeReader &reader, const GCodeReader::GCodeLine &line) {
+            if (line.cmd_is("G1")) {
+                if (line.extruding(reader)) {
+                    total_layer_length += line.dist_XY(reader);
+                } else if (line.has(Z)) {
+                    layer_height += line.dist_Z(reader);
+                    if (!set_z) {
+                        z = line.new_Z(reader);
+                        set_z = true;
+                    }
+                }
+            }
+        });
+    }
+    
+    // Remove layer height from initial Z.
+    z -= layer_height;
+    
+    std::string new_gcode;
+    this->_reader.parse_buffer(gcode, [&new_gcode, &z, &layer_height, &total_layer_length]
+        (GCodeReader &reader, GCodeReader::GCodeLine line) {
+        if (line.cmd_is("G1")) {
+            if (line.has_z()) {
+                // If this is the initial Z move of the layer, replace it with a
+                // (redundant) move to the last Z of previous layer.
+                line.set(reader, Z, z);
+                new_gcode += line.raw() + '\n';
+                return;
+            } else {
+                float dist_XY = line.dist_XY(reader);
+                if (dist_XY > 0) {
+                    // horizontal move
+                    if (line.extruding(reader)) {
+                        z += dist_XY * layer_height / total_layer_length;
+                        line.set(reader, Z, z);
+                        new_gcode += line.raw() + '\n';
+                    }
+                    return;
+                
+                    /*  Skip travel moves: the move to first perimeter point will
+                        cause a visible seam when loops are not aligned in XY; by skipping
+                        it we blend the first loop move in the XY plane (although the smoothness
+                        of such blend depend on how long the first segment is; maybe we should
+                        enforce some minimum length?).  */
+                }
+            }
+        }
+        new_gcode += line.raw() + '\n';
+    });
+    
+    return new_gcode;
+}
+
+}

src/libslic3r/GCode/SpiralVase.hpp

@@ -0,0 +1,28 @@
+#ifndef slic3r_SpiralVase_hpp_
+#define slic3r_SpiralVase_hpp_
+
+#include "libslic3r.h"
+#include "GCodeReader.hpp"
+
+namespace Slic3r {
+
+class SpiralVase {
+    public:
+    bool enable;
+    
+    SpiralVase(const PrintConfig &config)
+        : enable(false), _config(&config)
+    {
+        this->_reader.z() = this->_config->z_offset;
+        this->_reader.apply_config(*this->_config);
+    };
+    std::string process_layer(const std::string &gcode);
+    
+    private:
+    const PrintConfig* _config;
+    GCodeReader _reader;
+};
+
+}
+
+#endif

src/libslic3r/GCode/ToolOrdering.cpp

@@ -0,0 +1,629 @@
+#include "Print.hpp"
+#include "ToolOrdering.hpp"
+
+// #define SLIC3R_DEBUG
+
+// Make assert active if SLIC3R_DEBUG
+#ifdef SLIC3R_DEBUG
+    #define DEBUG
+    #define _DEBUG
+    #undef NDEBUG
+#endif
+
+#include <cassert>
+#include <limits>
+
+namespace Slic3r {
+
+
+// Returns true in case that extruder a comes before b (b does not have to be present). False otherwise.
+bool LayerTools::is_extruder_order(unsigned int a, unsigned int b) const
+{
+    if (a==b)
+        return false;
+
+    for (auto extruder : extruders) {
+        if (extruder == a)
+            return true;
+        if (extruder == b)
+            return false;
+    }
+
+    return false;
+}
+
+
+// For the use case when each object is printed separately
+// (print.config().complete_objects is true).
+ToolOrdering::ToolOrdering(const PrintObject &object, unsigned int first_extruder, bool prime_multi_material)
+{
+    if (object.layers().empty())
+        return;
+
+    // Initialize the print layers for just a single object.
+    {
+        std::vector<coordf_t> zs;
+        zs.reserve(zs.size() + object.layers().size() + object.support_layers().size());
+        for (auto layer : object.layers())
+            zs.emplace_back(layer->print_z);
+        for (auto layer : object.support_layers())
+            zs.emplace_back(layer->print_z);
+        this->initialize_layers(zs);
+    }
+
+    // Collect extruders reuqired to print the layers.
+    this->collect_extruders(object);
+
+    // Reorder the extruders to minimize tool switches.
+    this->reorder_extruders(first_extruder);
+
+    this->fill_wipe_tower_partitions(object.print()->config(), object.layers().front()->print_z - object.layers().front()->height);
+
+    this->collect_extruder_statistics(prime_multi_material);
+}
+
+// For the use case when all objects are printed at once.
+// (print.config().complete_objects is false).
+ToolOrdering::ToolOrdering(const Print &print, unsigned int first_extruder, bool prime_multi_material)
+{
+    m_print_config_ptr = &print.config();
+
+    // Initialize the print layers for all objects and all layers.
+    coordf_t object_bottom_z = 0.;
+    {
+        std::vector<coordf_t> zs;
+        for (auto object : print.objects()) {
+            zs.reserve(zs.size() + object->layers().size() + object->support_layers().size());
+            for (auto layer : object->layers())
+                zs.emplace_back(layer->print_z);
+            for (auto layer : object->support_layers())
+                zs.emplace_back(layer->print_z);
+            if (! object->layers().empty())
+                object_bottom_z = object->layers().front()->print_z - object->layers().front()->height;
+        }
+        this->initialize_layers(zs);
+    }
+
+    // Collect extruders reuqired to print the layers.
+    for (auto object : print.objects())
+        this->collect_extruders(*object);
+
+    // Reorder the extruders to minimize tool switches.
+    this->reorder_extruders(first_extruder);
+
+    this->fill_wipe_tower_partitions(print.config(), object_bottom_z);
+
+    this->collect_extruder_statistics(prime_multi_material);
+}
+
+
+LayerTools& ToolOrdering::tools_for_layer(coordf_t print_z)
+{
+    auto it_layer_tools = std::lower_bound(m_layer_tools.begin(), m_layer_tools.end(), LayerTools(print_z - EPSILON));
+    assert(it_layer_tools != m_layer_tools.end());
+    coordf_t dist_min = std::abs(it_layer_tools->print_z - print_z);
+	for (++ it_layer_tools; it_layer_tools != m_layer_tools.end(); ++it_layer_tools) {
+        coordf_t d = std::abs(it_layer_tools->print_z - print_z);
+        if (d >= dist_min)
+            break;
+        dist_min = d;
+    }
+    -- it_layer_tools;
+    assert(dist_min < EPSILON);
+    return *it_layer_tools;
+}
+
+void ToolOrdering::initialize_layers(std::vector<coordf_t> &zs)
+{
+    sort_remove_duplicates(zs);
+    // Merge numerically very close Z values.
+    for (size_t i = 0; i < zs.size();) {
+        // Find the last layer with roughly the same print_z.
+        size_t j = i + 1;
+        coordf_t zmax = zs[i] + EPSILON;
+        for (; j < zs.size() && zs[j] <= zmax; ++ j) ;
+        // Assign an average print_z to the set of layers with nearly equal print_z.
+        m_layer_tools.emplace_back(LayerTools(0.5 * (zs[i] + zs[j-1]), m_print_config_ptr));
+        i = j;
+    }
+}
+
+// Collect extruders reuqired to print layers.
+void ToolOrdering::collect_extruders(const PrintObject &object)
+{
+    // Collect the support extruders.
+    for (auto support_layer : object.support_layers()) {
+        LayerTools   &layer_tools = this->tools_for_layer(support_layer->print_z);
+        ExtrusionRole role = support_layer->support_fills.role();
+        bool         has_support        = role == erMixed || role == erSupportMaterial;
+        bool         has_interface      = role == erMixed || role == erSupportMaterialInterface;
+        unsigned int extruder_support   = object.config().support_material_extruder.value;
+        unsigned int extruder_interface = object.config().support_material_interface_extruder.value;
+        if (has_support)
+            layer_tools.extruders.push_back(extruder_support);
+        if (has_interface)
+            layer_tools.extruders.push_back(extruder_interface);
+        if (has_support || has_interface)
+            layer_tools.has_support = true;
+    }
+    // Collect the object extruders.
+    for (auto layer : object.layers()) {
+        LayerTools &layer_tools = this->tools_for_layer(layer->print_z);
+        // What extruders are required to print this object layer?
+        for (size_t region_id = 0; region_id < object.region_volumes.size(); ++ region_id) {
+			const LayerRegion *layerm = (region_id < layer->regions().size()) ? layer->regions()[region_id] : nullptr;
+            if (layerm == nullptr)
+                continue;
+            const PrintRegion &region = *object.print()->regions()[region_id];
+
+            if (! layerm->perimeters.entities.empty()) {
+                bool something_nonoverriddable = true;
+
+                if (m_print_config_ptr) { // in this case complete_objects is false (see ToolOrdering constructors)
+                    something_nonoverriddable = false;
+                    for (const auto& eec : layerm->perimeters.entities) // let's check if there are nonoverriddable entities
+                        if (!layer_tools.wiping_extrusions().is_overriddable(dynamic_cast<const ExtrusionEntityCollection&>(*eec), *m_print_config_ptr, object, region)) {
+                            something_nonoverriddable = true;
+                            break;
+                        }
+                }
+
+                if (something_nonoverriddable)
+                        layer_tools.extruders.push_back(region.config().perimeter_extruder.value);
+
+                layer_tools.has_object = true;
+            }
+
+
+            bool has_infill       = false;
+            bool has_solid_infill = false;
+            bool something_nonoverriddable = false;
+            for (const ExtrusionEntity *ee : layerm->fills.entities) {
+                // fill represents infill extrusions of a single island.
+                const auto *fill = dynamic_cast<const ExtrusionEntityCollection*>(ee);
+                ExtrusionRole role = fill->entities.empty() ? erNone : fill->entities.front()->role();
+                if (is_solid_infill(role))
+                    has_solid_infill = true;
+                else if (role != erNone)
+                    has_infill = true;
+
+                if (m_print_config_ptr) {
+                    if (!something_nonoverriddable && !layer_tools.wiping_extrusions().is_overriddable(*fill, *m_print_config_ptr, object, region))
+                        something_nonoverriddable = true;
+                }
+            }
+
+            if (something_nonoverriddable || !m_print_config_ptr)
+            {
+                if (has_solid_infill)
+                    layer_tools.extruders.push_back(region.config().solid_infill_extruder);
+                if (has_infill)
+                    layer_tools.extruders.push_back(region.config().infill_extruder);
+            }
+            if (has_solid_infill || has_infill)
+                layer_tools.has_object = true;
+        }
+    }
+
+    for (auto& layer : m_layer_tools) {
+        // Sort and remove duplicates
+        sort_remove_duplicates(layer.extruders);
+
+        // make sure that there are some tools for each object layer (e.g. tall wiping object will result in empty extruders vector)
+        if (layer.extruders.empty() && layer.has_object)
+            layer.extruders.push_back(0); // 0="dontcare" extruder - it will be taken care of in reorder_extruders
+    }
+}
+
+// Reorder extruders to minimize layer changes.
+void ToolOrdering::reorder_extruders(unsigned int last_extruder_id)
+{
+    if (m_layer_tools.empty())
+        return;
+
+    if (last_extruder_id == (unsigned int)-1) {
+        // The initial print extruder has not been decided yet.
+        // Initialize the last_extruder_id with the first non-zero extruder id used for the print.
+        last_extruder_id = 0;
+        for (size_t i = 0; i < m_layer_tools.size() && last_extruder_id == 0; ++ i) {
+            const LayerTools &lt = m_layer_tools[i];
+            for (unsigned int extruder_id : lt.extruders)
+                if (extruder_id > 0) {
+                    last_extruder_id = extruder_id;
+                    break;
+                }
+        }
+        if (last_extruder_id == 0)
+            // Nothing to extrude.
+            return;
+    } else
+        // 1 based index
+        ++ last_extruder_id;
+
+    for (LayerTools &lt : m_layer_tools) {
+        if (lt.extruders.empty())
+            continue;
+        if (lt.extruders.size() == 1 && lt.extruders.front() == 0)
+            lt.extruders.front() = last_extruder_id;
+        else {
+            if (lt.extruders.front() == 0)
+                // Pop the "don't care" extruder, the "don't care" region will be merged with the next one.
+                lt.extruders.erase(lt.extruders.begin());
+            // Reorder the extruders to start with the last one.
+            for (size_t i = 1; i < lt.extruders.size(); ++ i)
+                if (lt.extruders[i] == last_extruder_id) {
+                    // Move the last extruder to the front.
+                    memmove(lt.extruders.data() + 1, lt.extruders.data(), i * sizeof(unsigned int));
+                    lt.extruders.front() = last_extruder_id;
+                    break;
+                }
+        }
+        last_extruder_id = lt.extruders.back();
+    }
+
+    // Reindex the extruders, so they are zero based, not 1 based.
+    for (LayerTools &lt : m_layer_tools)
+        for (unsigned int &extruder_id : lt.extruders) {
+            assert(extruder_id > 0);
+            -- extruder_id;
+        }
+}
+
+
+
+void ToolOrdering::fill_wipe_tower_partitions(const PrintConfig &config, coordf_t object_bottom_z)
+{
+    if (m_layer_tools.empty())
+        return;
+
+    // Count the minimum number of tool changes per layer.
+    size_t last_extruder = size_t(-1);
+    for (LayerTools &lt : m_layer_tools) {
+        lt.wipe_tower_partitions = lt.extruders.size();
+        if (! lt.extruders.empty()) {
+            if (last_extruder == size_t(-1) || last_extruder == lt.extruders.front())
+                // The first extruder on this layer is equal to the current one, no need to do an initial tool change.
+                -- lt.wipe_tower_partitions;
+            last_extruder = lt.extruders.back();
+        }
+    }
+
+    // Propagate the wipe tower partitions down to support the upper partitions by the lower partitions.
+    for (int i = int(m_layer_tools.size()) - 2; i >= 0; -- i)
+        m_layer_tools[i].wipe_tower_partitions = std::max(m_layer_tools[i + 1].wipe_tower_partitions, m_layer_tools[i].wipe_tower_partitions);
+
+    //FIXME this is a hack to get the ball rolling.
+    for (LayerTools &lt : m_layer_tools)
+        lt.has_wipe_tower = (lt.has_object && lt.wipe_tower_partitions > 0) || lt.print_z < object_bottom_z + EPSILON;
+
+    // Test for a raft, insert additional wipe tower layer to fill in the raft separation gap.
+    double max_layer_height = std::numeric_limits<double>::max();
+    for (size_t i = 0; i < config.nozzle_diameter.values.size(); ++ i) {
+        double mlh = config.max_layer_height.values[i];
+        if (mlh == 0.)
+            mlh = 0.75 * config.nozzle_diameter.values[i];
+        max_layer_height = std::min(max_layer_height, mlh);
+    }
+    for (size_t i = 0; i + 1 < m_layer_tools.size(); ++ i) {
+        const LayerTools &lt      = m_layer_tools[i];
+        const LayerTools &lt_next = m_layer_tools[i + 1];
+        if (lt.print_z < object_bottom_z + EPSILON && lt_next.print_z >= object_bottom_z + EPSILON) {
+            // lt is the last raft layer. Find the 1st object layer.
+            size_t j = i + 1;
+            for (; j < m_layer_tools.size() && ! m_layer_tools[j].has_wipe_tower; ++ j);
+            if (j < m_layer_tools.size()) {
+                const LayerTools &lt_object = m_layer_tools[j];
+                coordf_t gap = lt_object.print_z - lt.print_z;
+                assert(gap > 0.f);
+                if (gap > max_layer_height + EPSILON) {
+                    // Insert one additional wipe tower layer between lh.print_z and lt_object.print_z.
+                    LayerTools lt_new(0.5f * (lt.print_z + lt_object.print_z));
+                    // Find the 1st layer above lt_new.
+                    for (j = i + 1; j < m_layer_tools.size() && m_layer_tools[j].print_z < lt_new.print_z - EPSILON; ++ j);
+					if (std::abs(m_layer_tools[j].print_z - lt_new.print_z) < EPSILON) {
+						m_layer_tools[j].has_wipe_tower = true;
+					} else {
+						LayerTools &lt_extra = *m_layer_tools.insert(m_layer_tools.begin() + j, lt_new);
+                        LayerTools &lt_prev  = m_layer_tools[j - 1];
+                        LayerTools &lt_next  = m_layer_tools[j + 1];
+                        assert(! lt_prev.extruders.empty() && ! lt_next.extruders.empty());
+                        assert(lt_prev.extruders.back() == lt_next.extruders.front());
+						lt_extra.has_wipe_tower = true;
+                        lt_extra.extruders.push_back(lt_next.extruders.front());
+						lt_extra.wipe_tower_partitions = lt_next.wipe_tower_partitions;
+					}
+                }
+            }
+            break;
+        }
+    }
+
+    // Calculate the wipe_tower_layer_height values.
+    coordf_t wipe_tower_print_z_last = 0.;
+    for (LayerTools &lt : m_layer_tools)
+        if (lt.has_wipe_tower) {
+            lt.wipe_tower_layer_height = lt.print_z - wipe_tower_print_z_last;
+            wipe_tower_print_z_last = lt.print_z;
+        }
+}
+
+void ToolOrdering::collect_extruder_statistics(bool prime_multi_material)
+{
+    m_first_printing_extruder = (unsigned int)-1;
+    for (const auto &lt : m_layer_tools)
+        if (! lt.extruders.empty()) {
+            m_first_printing_extruder = lt.extruders.front();
+            break;
+        }
+
+    m_last_printing_extruder = (unsigned int)-1;
+    for (auto lt_it = m_layer_tools.rbegin(); lt_it != m_layer_tools.rend(); ++ lt_it)
+        if (! lt_it->extruders.empty()) {
+            m_last_printing_extruder = lt_it->extruders.back();
+            break;
+        }
+
+    m_all_printing_extruders.clear();
+    for (const auto &lt : m_layer_tools) {
+        append(m_all_printing_extruders, lt.extruders);
+        sort_remove_duplicates(m_all_printing_extruders);
+    }
+
+    if (prime_multi_material && ! m_all_printing_extruders.empty()) {
+        // Reorder m_all_printing_extruders in the sequence they will be primed, the last one will be m_first_printing_extruder.
+        // Then set m_first_printing_extruder to the 1st extruder primed.
+        m_all_printing_extruders.erase(
+            std::remove_if(m_all_printing_extruders.begin(), m_all_printing_extruders.end(), 
+                [ this ](const unsigned int eid) { return eid == m_first_printing_extruder; }),
+            m_all_printing_extruders.end());
+        m_all_printing_extruders.emplace_back(m_first_printing_extruder);
+        m_first_printing_extruder = m_all_printing_extruders.front();
+    }
+}
+
+
+
+// This function is called from Print::mark_wiping_extrusions and sets extruder this entity should be printed with (-1 .. as usual)
+void WipingExtrusions::set_extruder_override(const ExtrusionEntity* entity, unsigned int copy_id, int extruder, unsigned int num_of_copies)
+{
+    something_overridden = true;
+
+    auto entity_map_it = (entity_map.insert(std::make_pair(entity, std::vector<int>()))).first; // (add and) return iterator
+    auto& copies_vector = entity_map_it->second;
+    if (copies_vector.size() < num_of_copies)
+        copies_vector.resize(num_of_copies, -1);
+
+    if (copies_vector[copy_id] != -1)
+        std::cout << "ERROR: Entity extruder overriden multiple times!!!\n";    // A debugging message - this must never happen.
+
+    copies_vector[copy_id] = extruder;
+}
+
+
+// Finds first non-soluble extruder on the layer
+int WipingExtrusions::first_nonsoluble_extruder_on_layer(const PrintConfig& print_config) const
+{
+    const LayerTools& lt = *m_layer_tools;
+    for (auto extruders_it = lt.extruders.begin(); extruders_it != lt.extruders.end(); ++extruders_it)
+        if (!print_config.filament_soluble.get_at(*extruders_it))
+            return (*extruders_it);
+
+    return (-1);
+}
+
+// Finds last non-soluble extruder on the layer
+int WipingExtrusions::last_nonsoluble_extruder_on_layer(const PrintConfig& print_config) const
+{
+    const LayerTools& lt = *m_layer_tools;
+    for (auto extruders_it = lt.extruders.rbegin(); extruders_it != lt.extruders.rend(); ++extruders_it)
+        if (!print_config.filament_soluble.get_at(*extruders_it))
+            return (*extruders_it);
+
+    return (-1);
+}
+
+
+// Decides whether this entity could be overridden
+bool WipingExtrusions::is_overriddable(const ExtrusionEntityCollection& eec, const PrintConfig& print_config, const PrintObject& object, const PrintRegion& region) const
+{
+    if (print_config.filament_soluble.get_at(Print::get_extruder(eec, region)))
+        return false;
+
+    if (object.config().wipe_into_objects)
+        return true;
+
+    if (!region.config().wipe_into_infill || eec.role() != erInternalInfill)
+        return false;
+
+    return true;
+}
+
+
+// Following function iterates through all extrusions on the layer, remembers those that could be used for wiping after toolchange
+// and returns volume that is left to be wiped on the wipe tower.
+float WipingExtrusions::mark_wiping_extrusions(const Print& print, unsigned int old_extruder, unsigned int new_extruder, float volume_to_wipe)
+{
+    const LayerTools& lt = *m_layer_tools;
+    const float min_infill_volume = 0.f; // ignore infill with smaller volume than this
+
+    if (print.config().filament_soluble.get_at(old_extruder) || print.config().filament_soluble.get_at(new_extruder))
+        return volume_to_wipe;      // Soluble filament cannot be wiped in a random infill, neither the filament after it
+
+    // we will sort objects so that dedicated for wiping are at the beginning:
+    PrintObjectPtrs object_list = print.objects();
+    std::sort(object_list.begin(), object_list.end(), [](const PrintObject* a, const PrintObject* b) { return a->config().wipe_into_objects; });
+
+    // We will now iterate through
+    //  - first the dedicated objects to mark perimeters or infills (depending on infill_first)
+    //  - second through the dedicated ones again to mark infills or perimeters (depending on infill_first)
+    //  - then all the others to mark infills (in case that !infill_first, we must also check that the perimeter is finished already
+    // this is controlled by the following variable:
+    bool perimeters_done = false;
+
+    for (int i=0 ; i<(int)object_list.size() + (perimeters_done ? 0 : 1); ++i) {
+        if (!perimeters_done && (i==(int)object_list.size() || !object_list[i]->config().wipe_into_objects)) { // we passed the last dedicated object in list
+            perimeters_done = true;
+            i=-1;   // let's go from the start again
+            continue;
+        }
+
+        const auto& object = object_list[i];
+
+        // Finds this layer:
+        auto this_layer_it = std::find_if(object->layers().begin(), object->layers().end(), [&lt](const Layer* lay) { return std::abs(lt.print_z - lay->print_z)<EPSILON; });
+        if (this_layer_it == object->layers().end())
+            continue;
+        const Layer* this_layer = *this_layer_it;
+        unsigned int num_of_copies = object->copies().size();
+
+        for (unsigned int copy = 0; copy < num_of_copies; ++copy) {    // iterate through copies first, so that we mark neighbouring infills to minimize travel moves
+
+            for (size_t region_id = 0; region_id < object->region_volumes.size(); ++ region_id) {
+                const auto& region = *object->print()->regions()[region_id];
+
+                if (!region.config().wipe_into_infill && !object->config().wipe_into_objects)
+                    continue;
+
+
+                if ((!print.config().infill_first ? perimeters_done : !perimeters_done) || (!object->config().wipe_into_objects && region.config().wipe_into_infill)) {
+                    for (const ExtrusionEntity* ee : this_layer->regions()[region_id]->fills.entities) {                      // iterate through all infill Collections
+                        auto* fill = dynamic_cast<const ExtrusionEntityCollection*>(ee);
+
+                        if (!is_overriddable(*fill, print.config(), *object, region))
+                            continue;
+
+                        // What extruder would this normally be printed with?
+                        unsigned int correct_extruder = Print::get_extruder(*fill, region);
+
+                        if (volume_to_wipe<=0)
+                            continue;
+
+                        if (!object->config().wipe_into_objects && !print.config().infill_first && region.config().wipe_into_infill)
+                            // In this case we must check that the original extruder is used on this layer before the one we are overridding
+                            // (and the perimeters will be finished before the infill is printed):
+                            if (!lt.is_extruder_order(region.config().perimeter_extruder - 1, new_extruder))
+                                continue;
+
+                        if ((!is_entity_overridden(fill, copy) && fill->total_volume() > min_infill_volume)) {     // this infill will be used to wipe this extruder
+                            set_extruder_override(fill, copy, new_extruder, num_of_copies);
+                            volume_to_wipe -= fill->total_volume();
+                        }
+                    }
+                }
+
+                // Now the same for perimeters - see comments above for explanation:
+                if (object->config().wipe_into_objects && (print.config().infill_first ? perimeters_done : !perimeters_done))
+                {
+                    for (const ExtrusionEntity* ee : this_layer->regions()[region_id]->perimeters.entities) {
+                        auto* fill = dynamic_cast<const ExtrusionEntityCollection*>(ee);
+                        if (!is_overriddable(*fill, print.config(), *object, region))
+                            continue;
+
+                        if (volume_to_wipe<=0)
+                            continue;
+
+                        if ((!is_entity_overridden(fill, copy) && fill->total_volume() > min_infill_volume)) {
+                            set_extruder_override(fill, copy, new_extruder, num_of_copies);
+                            volume_to_wipe -= fill->total_volume();
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return std::max(0.f, volume_to_wipe);
+}
+
+
+
+// Called after all toolchanges on a layer were mark_infill_overridden. There might still be overridable entities,
+// that were not actually overridden. If they are part of a dedicated object, printing them with the extruder
+// they were initially assigned to might mean violating the perimeter-infill order. We will therefore go through
+// them again and make sure we override it.
+void WipingExtrusions::ensure_perimeters_infills_order(const Print& print)
+{
+    const LayerTools& lt = *m_layer_tools;
+    unsigned int first_nonsoluble_extruder = first_nonsoluble_extruder_on_layer(print.config());
+    unsigned int last_nonsoluble_extruder = last_nonsoluble_extruder_on_layer(print.config());
+
+    for (const PrintObject* object : print.objects()) {
+        // Finds this layer:
+        auto this_layer_it = std::find_if(object->layers().begin(), object->layers().end(), [&lt](const Layer* lay) { return std::abs(lt.print_z - lay->print_z)<EPSILON; });
+        if (this_layer_it == object->layers().end())
+            continue;
+        const Layer* this_layer = *this_layer_it;
+        unsigned int num_of_copies = object->copies().size();
+
+        for (unsigned int copy = 0; copy < num_of_copies; ++copy) {    // iterate through copies first, so that we mark neighbouring infills to minimize travel moves
+            for (size_t region_id = 0; region_id < object->region_volumes.size(); ++ region_id) {
+                const auto& region = *object->print()->regions()[region_id];
+
+                if (!region.config().wipe_into_infill && !object->config().wipe_into_objects)
+                    continue;
+
+                for (const ExtrusionEntity* ee : this_layer->regions()[region_id]->fills.entities) {                      // iterate through all infill Collections
+                    auto* fill = dynamic_cast<const ExtrusionEntityCollection*>(ee);
+
+                    if (!is_overriddable(*fill, print.config(), *object, region)
+                     || is_entity_overridden(fill, copy) )
+                        continue;
+
+                    // This infill could have been overridden but was not - unless we do something, it could be
+                    // printed before its perimeter, or not be printed at all (in case its original extruder has
+                    // not been added to LayerTools
+                    // Either way, we will now force-override it with something suitable:
+                    if (print.config().infill_first
+                    || object->config().wipe_into_objects  // in this case the perimeter is overridden, so we can override by the last one safely
+                    || lt.is_extruder_order(region.config().perimeter_extruder - 1, last_nonsoluble_extruder    // !infill_first, but perimeter is already printed when last extruder prints
+                    || std::find(lt.extruders.begin(), lt.extruders.end(), region.config().infill_extruder - 1) == lt.extruders.end()) // we have to force override - this could violate infill_first (FIXME)
+                      )
+                        set_extruder_override(fill, copy, (print.config().infill_first ? first_nonsoluble_extruder : last_nonsoluble_extruder), num_of_copies);
+                    else {
+                        // In this case we can (and should) leave it to be printed normally.
+                        // Force overriding would mean it gets printed before its perimeter.
+                    }
+                }
+
+                // Now the same for perimeters - see comments above for explanation:
+                for (const ExtrusionEntity* ee : this_layer->regions()[region_id]->perimeters.entities) {                      // iterate through all perimeter Collections
+                    auto* fill = dynamic_cast<const ExtrusionEntityCollection*>(ee);
+                    if (!is_overriddable(*fill, print.config(), *object, region)
+                     || is_entity_overridden(fill, copy) )
+                        continue;
+
+                    set_extruder_override(fill, copy, (print.config().infill_first ? last_nonsoluble_extruder : first_nonsoluble_extruder), num_of_copies);
+                }
+            }
+        }
+    }
+}
+
+
+
+
+
+
+
+// Following function is called from process_layer and returns pointer to vector with information about which extruders should be used for given copy of this entity.
+// It first makes sure the pointer is valid (creates the vector if it does not exist) and contains a record for each copy
+// It also modifies the vector in place and changes all -1 to correct_extruder_id (at the time the overrides were created, correct extruders were not known,
+// so -1 was used as "print as usual".
+// The resulting vector has to keep track of which extrusions are the ones that were overridden and which were not. In the extruder is used as overridden,
+// its number is saved as it is (zero-based index). Usual extrusions are saved as -number-1 (unfortunately there is no negative zero).
+const std::vector<int>* WipingExtrusions::get_extruder_overrides(const ExtrusionEntity* entity, int correct_extruder_id, int num_of_copies)
+{
+    auto entity_map_it = entity_map.find(entity);
+    if (entity_map_it == entity_map.end())
+        entity_map_it = (entity_map.insert(std::make_pair(entity, std::vector<int>()))).first;
+
+    // Now the entity_map_it should be valid, let's make sure the vector is long enough:
+    entity_map_it->second.resize(num_of_copies, -1);
+
+    // Each -1 now means "print as usual" - we will replace it with actual extruder id (shifted it so we don't lose that information):
+    std::replace(entity_map_it->second.begin(), entity_map_it->second.end(), -1, -correct_extruder_id-1);
+
+    return &(entity_map_it->second);
+}
+    
+
+} // namespace Slic3r

src/libslic3r/GCode/ToolOrdering.hpp

@@ -0,0 +1,162 @@
+// Ordering of the tools to minimize tool switches.
+
+#ifndef slic3r_ToolOrdering_hpp_
+#define slic3r_ToolOrdering_hpp_
+
+#include "libslic3r.h"
+
+namespace Slic3r {
+
+class Print;
+class PrintObject;
+class LayerTools;
+
+
+
+// Object of this class holds information about whether an extrusion is printed immediately
+// after a toolchange (as part of infill/perimeter wiping) or not. One extrusion can be a part
+// of several copies - this has to be taken into account.
+class WipingExtrusions
+{
+public:
+    bool is_anything_overridden() const {   // if there are no overrides, all the agenda can be skipped - this function can tell us if that's the case
+        return something_overridden;
+    }
+
+    // This is called from GCode::process_layer - see implementation for further comments:
+    const std::vector<int>* get_extruder_overrides(const ExtrusionEntity* entity, int correct_extruder_id, int num_of_copies);
+
+    // This function goes through all infill entities, decides which ones will be used for wiping and
+    // marks them by the extruder id. Returns volume that remains to be wiped on the wipe tower:
+    float mark_wiping_extrusions(const Print& print, unsigned int old_extruder, unsigned int new_extruder, float volume_to_wipe);
+
+    void ensure_perimeters_infills_order(const Print& print);
+
+    bool is_overriddable(const ExtrusionEntityCollection& ee, const PrintConfig& print_config, const PrintObject& object, const PrintRegion& region) const;
+
+    void set_layer_tools_ptr(const LayerTools* lt) { m_layer_tools = lt; }
+
+private:
+    int first_nonsoluble_extruder_on_layer(const PrintConfig& print_config) const;
+    int last_nonsoluble_extruder_on_layer(const PrintConfig& print_config) const;
+
+    // This function is called from mark_wiping_extrusions and sets extruder that it should be printed with (-1 .. as usual)
+    void set_extruder_override(const ExtrusionEntity* entity, unsigned int copy_id, int extruder, unsigned int num_of_copies);
+
+    // Returns true in case that entity is not printed with its usual extruder for a given copy:
+    bool is_entity_overridden(const ExtrusionEntity* entity, int copy_id) const {
+        return (entity_map.find(entity) == entity_map.end() ? false : entity_map.at(entity).at(copy_id) != -1);
+    }
+
+    std::map<const ExtrusionEntity*, std::vector<int>> entity_map;  // to keep track of who prints what
+    bool something_overridden = false;
+    const LayerTools* m_layer_tools;    // so we know which LayerTools object this belongs to
+};
+
+
+
+class LayerTools
+{
+public:
+    LayerTools(const coordf_t z, const PrintConfig* print_config_ptr = nullptr) :
+        print_z(z),
+        has_object(false),
+        has_support(false),
+        has_wipe_tower(false),
+        wipe_tower_partitions(0),
+        wipe_tower_layer_height(0.) {}
+
+    // Changing these operators to epsilon version can make a problem in cases where support and object layers get close to each other.
+    // In case someone tries to do it, make sure you know what you're doing and test it properly (slice multiple objects at once with supports).
+    bool operator< (const LayerTools &rhs) const { return print_z < rhs.print_z; }
+    bool operator==(const LayerTools &rhs) const { return print_z == rhs.print_z; }
+
+    bool is_extruder_order(unsigned int a, unsigned int b) const;
+
+    coordf_t 					print_z;
+    bool 						has_object;
+    bool						has_support;
+    // Zero based extruder IDs, ordered to minimize tool switches.
+    std::vector<unsigned int> 	extruders;
+    // Will there be anything extruded on this layer for the wipe tower?
+    // Due to the support layers possibly interleaving the object layers,
+    // wipe tower will be disabled for some support only layers.
+    bool 						has_wipe_tower;
+    // Number of wipe tower partitions to support the required number of tool switches
+    // and to support the wipe tower partitions above this one.
+    size_t                      wipe_tower_partitions;
+    coordf_t 					wipe_tower_layer_height;
+
+    WipingExtrusions& wiping_extrusions() {
+        m_wiping_extrusions.set_layer_tools_ptr(this);
+        return m_wiping_extrusions;
+    }
+
+private:
+    // This object holds list of extrusion that will be used for extruder wiping
+    WipingExtrusions m_wiping_extrusions;
+};
+
+
+
+class ToolOrdering
+{
+public:
+	ToolOrdering() {}
+
+	// For the use case when each object is printed separately
+	// (print.config.complete_objects is true).
+	ToolOrdering(const PrintObject &object, unsigned int first_extruder = (unsigned int)-1, bool prime_multi_material = false);
+
+	// For the use case when all objects are printed at once.
+	// (print.config.complete_objects is false).
+	ToolOrdering(const Print &print, unsigned int first_extruder = (unsigned int)-1, bool prime_multi_material = false);
+
+	void 				clear() { m_layer_tools.clear(); }
+
+	// Get the first extruder printing, including the extruder priming areas, returns -1 if there is no layer printed.
+	unsigned int   		first_extruder() const { return m_first_printing_extruder; }
+
+	// Get the first extruder printing the layer_tools, returns -1 if there is no layer printed.
+	unsigned int   		last_extruder() const { return m_last_printing_extruder; }
+
+	// For a multi-material print, the printing extruders are ordered in the order they shall be primed.
+	const std::vector<unsigned int>& all_extruders() const { return m_all_printing_extruders; }
+
+	// Find LayerTools with the closest print_z.
+	LayerTools&			tools_for_layer(coordf_t print_z);
+	const LayerTools&	tools_for_layer(coordf_t print_z) const 
+		{ return *const_cast<const LayerTools*>(&const_cast<const ToolOrdering*>(this)->tools_for_layer(print_z)); }
+
+	const LayerTools&   front()       const { return m_layer_tools.front(); }
+	const LayerTools&   back()        const { return m_layer_tools.back(); }
+	std::vector<LayerTools>::const_iterator begin() const { return m_layer_tools.begin(); }
+	std::vector<LayerTools>::const_iterator end()   const { return m_layer_tools.end(); }
+	bool 				empty()       const { return m_layer_tools.empty(); }
+	std::vector<LayerTools>& layer_tools() { return m_layer_tools; }
+	bool 				has_wipe_tower() const { return ! m_layer_tools.empty() && m_first_printing_extruder != (unsigned int)-1 && m_layer_tools.front().wipe_tower_partitions > 0; }
+
+private:
+	void				initialize_layers(std::vector<coordf_t> &zs);
+	void 				collect_extruders(const PrintObject &object);
+	void				reorder_extruders(unsigned int last_extruder_id);
+	void 				fill_wipe_tower_partitions(const PrintConfig &config, coordf_t object_bottom_z);
+    void 				collect_extruder_statistics(bool prime_multi_material);
+
+    std::vector<LayerTools>    m_layer_tools;
+    // First printing extruder, including the multi-material priming sequence.
+    unsigned int               m_first_printing_extruder = (unsigned int)-1;
+    // Final printing extruder.
+    unsigned int               m_last_printing_extruder  = (unsigned int)-1;
+    // All extruders, which extrude some material over m_layer_tools.
+    std::vector<unsigned int>  m_all_printing_extruders;
+
+
+    const PrintConfig*         m_print_config_ptr = nullptr;
+};
+
+
+
+} // namespace SLic3r
+
+#endif /* slic3r_ToolOrdering_hpp_ */

src/libslic3r/GCode/WipeTower.hpp

@@ -0,0 +1,168 @@
+#ifndef slic3r_WipeTower_hpp_
+#define slic3r_WipeTower_hpp_
+
+#include <math.h>
+#include <utility>
+#include <string>
+#include <vector>
+
+namespace Slic3r
+{
+
+// A pure virtual WipeTower definition.
+class WipeTower
+{
+public:
+	// Internal point class, to make the wipe tower independent from other slic3r modules.
+	// This is important for Prusa Research as we want to build the wipe tower post-processor independently from slic3r.
+	struct xy
+	{
+		xy(float x = 0.f, float y = 0.f) : x(x), y(y) {}
+		xy(const xy& pos,float xp,float yp) : x(pos.x+xp), y(pos.y+yp) {}
+		xy  operator+(const xy &rhs) const { xy out(*this); out.x += rhs.x; out.y += rhs.y; return out; }
+		xy  operator-(const xy &rhs) const { xy out(*this); out.x -= rhs.x; out.y -= rhs.y; return out; }
+		xy& operator+=(const xy &rhs) { x += rhs.x; y += rhs.y; return *this; }
+		xy& operator-=(const xy &rhs) { x -= rhs.x; y -= rhs.y; return *this; }
+		bool operator==(const xy &rhs) const { return x == rhs.x && y == rhs.y; }
+		bool operator!=(const xy &rhs) const { return x != rhs.x || y != rhs.y; }
+		
+		// Rotate the point around center of the wipe tower about given angle (in degrees)
+		xy rotate(float width, float depth, float angle) const {
+			xy out(0,0);
+			float temp_x = x - width / 2.f;
+			float temp_y = y - depth / 2.f;
+			angle *= float(M_PI/180.);
+			out.x += temp_x * cos(angle)  -  temp_y * sin(angle) + width / 2.f;
+			out.y += temp_x * sin(angle)  +  temp_y * cos(angle) + depth / 2.f;
+			return out;
+		}
+        
+        // Rotate the point around origin about given angle in degrees
+        void rotate(float angle) {
+            float temp_x = x * cos(angle)  -  y * sin(angle);
+			y = x * sin(angle)  +  y * cos(angle);
+            x = temp_x;
+		}
+
+        void translate(const xy& vect) {
+            x += vect.x;
+            y += vect.y;
+        }
+
+		float x;
+		float y;
+	};
+
+	WipeTower() {}
+	virtual ~WipeTower() {}
+
+	// Return the wipe tower position.
+	virtual const xy& position() const = 0;
+
+	// Return the wipe tower width.
+	virtual float     width() const = 0;
+
+	// The wipe tower is finished, there should be no more tool changes or wipe tower prints.
+	virtual bool 	  finished() const = 0;
+
+	// Switch to a next layer.
+	virtual void 	  set_layer(
+		// Print height of this layer.
+		float  print_z,
+		// Layer height, used to calculate extrusion the rate. 
+		float  layer_height, 
+		// Maximum number of tool changes on this layer or the layers below.
+		size_t max_tool_changes, 
+		// Is this the first layer of the print? In that case print the brim first.
+		bool   is_first_layer,
+		// Is this the last layer of the wipe tower?
+		bool   is_last_layer) = 0;
+
+	enum Purpose {
+		PURPOSE_MOVE_TO_TOWER,
+		PURPOSE_EXTRUDE,
+		PURPOSE_MOVE_TO_TOWER_AND_EXTRUDE,
+	};
+
+	// Extrusion path of the wipe tower, for 3D preview of the generated tool paths.
+	struct Extrusion
+	{
+		Extrusion(const xy &pos, float width, unsigned int tool) : pos(pos), width(width), tool(tool) {}
+		// End position of this extrusion.
+		xy				pos;
+		// Width of a squished extrusion, corrected for the roundings of the squished extrusions.
+		// This is left zero if it is a travel move.
+		float 			width;
+		// Current extruder index.
+		unsigned int    tool;
+	};
+
+	struct ToolChangeResult
+	{
+		// Print heigh of this tool change.
+		float					print_z;
+		float 					layer_height;
+		// G-code section to be directly included into the output G-code.
+		std::string				gcode;
+		// For path preview.
+		std::vector<Extrusion> 	extrusions;
+		// Initial position, at which the wipe tower starts its action.
+		// At this position the extruder is loaded and there is no Z-hop applied.
+		xy						start_pos;
+		// Last point, at which the normal G-code generator of Slic3r shall continue.
+		// At this position the extruder is loaded and there is no Z-hop applied.
+		xy						end_pos;
+		// Time elapsed over this tool change.
+		// This is useful not only for the print time estimation, but also for the control of layer cooling.
+		float  				    elapsed_time;
+
+        // Is this a priming extrusion? (If so, the wipe tower rotation & translation will not be applied later)
+        bool                    priming;
+
+		// Sum the total length of the extrusion.
+		float total_extrusion_length_in_plane() {
+			float e_length = 0.f;
+			for (size_t i = 1; i < this->extrusions.size(); ++ i) {
+				const Extrusion &e = this->extrusions[i];
+				if (e.width > 0) {
+					xy v = e.pos - (&e - 1)->pos;
+					e_length += sqrt(v.x*v.x+v.y*v.y);
+				}
+			}
+			return e_length;
+		}
+	};
+
+	// Returns gcode to prime the nozzles at the front edge of the print bed.
+	virtual ToolChangeResult prime(
+		// print_z of the first layer.
+		float 						first_layer_height, 
+		// Extruder indices, in the order to be primed. The last extruder will later print the wipe tower brim, print brim and the object.
+		const std::vector<unsigned int> &tools,
+		// If true, the last priming are will be the same as the other priming areas, and the rest of the wipe will be performed inside the wipe tower.
+		// If false, the last priming are will be large enough to wipe the last extruder sufficiently.
+		bool 						last_wipe_inside_wipe_tower) = 0;
+
+	// Returns gcode for toolchange and the end position.
+	// if new_tool == -1, just unload the current filament over the wipe tower.
+	virtual ToolChangeResult tool_change(unsigned int new_tool, bool last_in_layer) = 0;
+
+	// Close the current wipe tower layer with a perimeter and possibly fill the unfilled space with a zig-zag.
+	// Call this method only if layer_finished() is false.
+	virtual ToolChangeResult finish_layer() = 0;
+
+	// Is the current layer finished? A layer is finished if either the wipe tower is finished, or
+	// the wipe tower has been completely covered by the tool change extrusions,
+	// or the rest of the tower has been filled by a sparse infill with the finish_layer() method.
+	virtual bool 		     layer_finished() const = 0;
+
+    // Returns used filament length per extruder:
+    virtual std::vector<float> get_used_filament() const = 0;
+
+    // Returns total number of toolchanges:
+    virtual int get_number_of_toolchanges() const = 0;
+};
+
+}; // namespace Slic3r
+
+#endif /* slic3r_WipeTower_hpp_ */

src/libslic3r/GCode/WipeTowerPrusaMM.hpp

@@ -0,0 +1,374 @@
+#ifndef WipeTowerPrusaMM_hpp_
+#define WipeTowerPrusaMM_hpp_
+
+#include <cmath>
+#include <string>
+#include <sstream>
+#include <utility>
+#include <algorithm>
+
+#include "WipeTower.hpp"
+
+
+namespace Slic3r
+{
+
+namespace PrusaMultiMaterial {
+	class Writer;
+};
+
+
+
+class WipeTowerPrusaMM : public WipeTower
+{
+public:
+	enum material_type
+	{
+		INVALID = -1,
+		PLA   = 0,		// E:210C	B:55C
+		ABS   = 1,		// E:255C	B:100C
+		PET   = 2,		// E:240C	B:90C
+		HIPS  = 3,		// E:220C	B:100C
+		FLEX  = 4,		// E:245C	B:80C
+		SCAFF = 5,		// E:215C	B:55C
+		EDGE  = 6,		// E:240C	B:80C
+		NGEN  = 7,		// E:230C	B:80C
+		PVA   = 8	    // E:210C	B:80C
+	};
+
+	// Parse material name into material_type.
+	static material_type parse_material(const char *name);
+
+	// x			-- x coordinates of wipe tower in mm ( left bottom corner )
+	// y			-- y coordinates of wipe tower in mm ( left bottom corner )
+	// width		-- width of wipe tower in mm ( default 60 mm - leave as it is )
+	// wipe_area	-- space available for one toolchange in mm
+	WipeTowerPrusaMM(float x, float y, float width, float rotation_angle, float cooling_tube_retraction,
+                     float cooling_tube_length, float parking_pos_retraction, float extra_loading_move, float bridging,
+                     const std::vector<std::vector<float>>& wiping_matrix, unsigned int initial_tool) :
+    m_wipe_tower_pos(x, y),
+		m_wipe_tower_width(width),
+		m_wipe_tower_rotation_angle(rotation_angle),
+		m_y_shift(0.f),
+		m_z_pos(0.f),
+		m_is_first_layer(false),
+        m_cooling_tube_retraction(cooling_tube_retraction),
+        m_cooling_tube_length(cooling_tube_length),
+        m_parking_pos_retraction(parking_pos_retraction),
+        m_extra_loading_move(extra_loading_move),
+		m_bridging(bridging),
+        m_current_tool(initial_tool),
+        wipe_volumes(wiping_matrix)
+        {}
+
+	virtual ~WipeTowerPrusaMM() {}
+
+
+	// Set the extruder properties.
+	void set_extruder(size_t idx, material_type material, int temp, int first_layer_temp, float loading_speed, float loading_speed_start,
+                      float unloading_speed, float unloading_speed_start, float delay, int cooling_moves,
+                      float cooling_initial_speed, float cooling_final_speed, std::string ramming_parameters, float nozzle_diameter)
+	{
+        //while (m_filpar.size() < idx+1)   // makes sure the required element is in the vector
+        m_filpar.push_back(FilamentParameters());
+
+        m_filpar[idx].material = material;
+        m_filpar[idx].temperature = temp;
+        m_filpar[idx].first_layer_temperature = first_layer_temp;
+        m_filpar[idx].loading_speed = loading_speed;
+        m_filpar[idx].loading_speed_start = loading_speed_start;
+        m_filpar[idx].unloading_speed = unloading_speed;
+        m_filpar[idx].unloading_speed_start = unloading_speed_start;
+        m_filpar[idx].delay = delay;
+        m_filpar[idx].cooling_moves = cooling_moves;
+        m_filpar[idx].cooling_initial_speed = cooling_initial_speed;
+        m_filpar[idx].cooling_final_speed = cooling_final_speed;
+        m_filpar[idx].nozzle_diameter = nozzle_diameter; // to be used in future with (non-single) multiextruder MM
+
+        m_perimeter_width = nozzle_diameter * Width_To_Nozzle_Ratio; // all extruders are now assumed to have the same diameter
+
+        std::stringstream stream{ramming_parameters};
+        float speed = 0.f;
+        stream >> m_filpar[idx].ramming_line_width_multiplicator >> m_filpar[idx].ramming_step_multiplicator;
+        m_filpar[idx].ramming_line_width_multiplicator /= 100;
+        m_filpar[idx].ramming_step_multiplicator /= 100;
+        while (stream >> speed)
+            m_filpar[idx].ramming_speed.push_back(speed);
+
+        m_used_filament_length.resize(std::max(m_used_filament_length.size(), idx + 1)); // makes sure that the vector is big enough so we don't have to check later
+	}
+
+
+	// Appends into internal structure m_plan containing info about the future wipe tower
+	// to be used before building begins. The entries must be added ordered in z.
+	void plan_toolchange(float z_par, float layer_height_par, unsigned int old_tool, unsigned int new_tool, bool brim, float wipe_volume = 0.f);
+
+	// Iterates through prepared m_plan, generates ToolChangeResults and appends them to "result"
+	void generate(std::vector<std::vector<WipeTower::ToolChangeResult>> &result);
+
+    float get_depth() const { return m_wipe_tower_depth; }
+
+
+
+	// Switch to a next layer.
+	virtual void set_layer(
+		// Print height of this layer.
+		float print_z,
+		// Layer height, used to calculate extrusion the rate.
+		float layer_height,
+		// Maximum number of tool changes on this layer or the layers below.
+		size_t max_tool_changes,
+		// Is this the first layer of the print? In that case print the brim first.
+		bool is_first_layer,
+		// Is this the last layer of the waste tower?
+		bool is_last_layer)
+	{
+		m_z_pos 				= print_z;
+		m_layer_height			= layer_height;
+		m_is_first_layer 		= is_first_layer;
+		m_print_brim = is_first_layer;
+		m_depth_traversed  = 0.f;
+		m_current_shape = (! is_first_layer && m_current_shape == SHAPE_NORMAL) ? SHAPE_REVERSED : SHAPE_NORMAL;
+		if (is_first_layer) {
+            this->m_num_layer_changes 	= 0;
+            this->m_num_tool_changes 	= 0;
+        }
+        else
+            ++ m_num_layer_changes;
+		
+		// Calculate extrusion flow from desired line width, nozzle diameter, filament diameter and layer_height:
+		m_extrusion_flow = extrusion_flow(layer_height);
+
+        // Advance m_layer_info iterator, making sure we got it right
+		while (!m_plan.empty() && m_layer_info->z < print_z - WT_EPSILON && m_layer_info+1 != m_plan.end())
+			++m_layer_info;
+	}
+
+	// Return the wipe tower position.
+	virtual const xy& 		 position() const { return m_wipe_tower_pos; }
+	// Return the wipe tower width.
+	virtual float     		 width()    const { return m_wipe_tower_width; }
+	// The wipe tower is finished, there should be no more tool changes or wipe tower prints.
+	virtual bool 	  		 finished() const { return m_max_color_changes == 0; }
+
+	// Returns gcode to prime the nozzles at the front edge of the print bed.
+	virtual ToolChangeResult prime(
+		// print_z of the first layer.
+		float 						first_layer_height, 
+		// Extruder indices, in the order to be primed. The last extruder will later print the wipe tower brim, print brim and the object.
+		const std::vector<unsigned int> &tools,
+		// If true, the last priming are will be the same as the other priming areas, and the rest of the wipe will be performed inside the wipe tower.
+		// If false, the last priming are will be large enough to wipe the last extruder sufficiently.
+		bool 						last_wipe_inside_wipe_tower);
+
+	// Returns gcode for a toolchange and a final print head position.
+	// On the first layer, extrude a brim around the future wipe tower first.
+	virtual ToolChangeResult tool_change(unsigned int new_tool, bool last_in_layer);
+
+	// Fill the unfilled space with a sparse infill.
+	// Call this method only if layer_finished() is false.
+	virtual ToolChangeResult finish_layer();
+
+	// Is the current layer finished?
+	virtual bool 			 layer_finished() const {
+		return ( (m_is_first_layer ? m_wipe_tower_depth - m_perimeter_width : m_layer_info->depth) - WT_EPSILON < m_depth_traversed);
+	}
+
+    virtual std::vector<float> get_used_filament() const override { return m_used_filament_length; }
+    virtual int get_number_of_toolchanges() const override { return m_num_tool_changes; }
+
+
+private:
+	WipeTowerPrusaMM();
+
+	enum wipe_shape // A fill-in direction
+	{
+		SHAPE_NORMAL = 1,
+		SHAPE_REVERSED = -1
+	};
+
+
+    const bool  m_peters_wipe_tower   = false; // sparse wipe tower inspired by Peter's post processor - not finished yet
+    const float Filament_Area         = M_PI * 1.75f * 1.75f / 4.f; // filament area in mm^2
+    const float Width_To_Nozzle_Ratio = 1.25f; // desired line width (oval) in multiples of nozzle diameter - may not be actually neccessary to adjust
+    const float WT_EPSILON            = 1e-3f;
+
+
+	xy 	   m_wipe_tower_pos; 			// Left front corner of the wipe tower in mm.
+	float  m_wipe_tower_width; 			// Width of the wipe tower.
+	float  m_wipe_tower_depth 	= 0.f; 	// Depth of the wipe tower
+	float  m_wipe_tower_rotation_angle = 0.f; // Wipe tower rotation angle in degrees (with respect to x axis)
+    float  m_internal_rotation  = 0.f;
+	float  m_y_shift			= 0.f;  // y shift passed to writer
+	float  m_z_pos 				= 0.f;  // Current Z position.
+	float  m_layer_height 		= 0.f; 	// Current layer height.
+	size_t m_max_color_changes 	= 0; 	// Maximum number of color changes per layer.
+	bool   m_is_first_layer 	= false;// Is this the 1st layer of the print? If so, print the brim around the waste tower.
+    int    m_old_temperature    = -1;   // To keep track of what was the last temp that we set (so we don't issue the command when not neccessary)
+
+	// G-code generator parameters.
+    float           m_cooling_tube_retraction   = 0.f;
+    float           m_cooling_tube_length       = 0.f;
+    float           m_parking_pos_retraction    = 0.f;
+    float           m_extra_loading_move        = 0.f;
+    float           m_bridging                  = 0.f;
+    bool            m_adhesion                  = true;
+
+	float m_perimeter_width = 0.4 * Width_To_Nozzle_Ratio; // Width of an extrusion line, also a perimeter spacing for 100% infill.
+	float m_extrusion_flow = 0.038; //0.029f;// Extrusion flow is derived from m_perimeter_width, layer height and filament diameter.
+
+
+    struct FilamentParameters {
+        material_type 	    material = PLA;
+        int  			    temperature = 0;
+        int  			    first_layer_temperature = 0;
+        float               loading_speed = 0.f;
+        float               loading_speed_start = 0.f;
+        float               unloading_speed = 0.f;
+        float               unloading_speed_start = 0.f;
+        float               delay = 0.f ;
+        int                 cooling_moves = 0;
+        float               cooling_initial_speed = 0.f;
+        float               cooling_final_speed = 0.f;
+        float               ramming_line_width_multiplicator = 0.f;
+        float               ramming_step_multiplicator = 0.f;
+        std::vector<float>  ramming_speed;
+        float               nozzle_diameter;
+    };
+
+	// Extruder specific parameters.
+    std::vector<FilamentParameters> m_filpar;
+
+
+	// State of the wipe tower generator.
+	unsigned int m_num_layer_changes = 0; // Layer change counter for the output statistics.
+	unsigned int m_num_tool_changes  = 0; // Tool change change counter for the output statistics.
+	///unsigned int 	m_idx_tool_change_in_layer = 0; // Layer change counter in this layer. Counting up to m_max_color_changes.
+	bool m_print_brim = true;
+	// A fill-in direction (positive Y, negative Y) alternates with each layer.
+	wipe_shape   	m_current_shape = SHAPE_NORMAL;
+	unsigned int 	m_current_tool  = 0;
+    const std::vector<std::vector<float>> wipe_volumes;
+
+	float           m_depth_traversed = 0.f; // Current y position at the wipe tower.
+	bool 			m_left_to_right   = true;
+	float			m_extra_spacing   = 1.f;
+
+	// Calculates extrusion flow needed to produce required line width for given layer height
+	float extrusion_flow(float layer_height = -1.f) const	// negative layer_height - return current m_extrusion_flow
+	{
+		if ( layer_height < 0 )
+			return m_extrusion_flow;
+		return layer_height * ( m_perimeter_width - layer_height * (1-M_PI/4.f)) / Filament_Area;
+	}
+
+	// Calculates length of extrusion line to extrude given volume
+	float volume_to_length(float volume, float line_width, float layer_height) const {
+		return std::max(0., volume / (layer_height * (line_width - layer_height * (1. - M_PI / 4.))));
+	}
+
+	// Calculates depth for all layers and propagates them downwards
+	void plan_tower();
+
+	// Goes through m_plan and recalculates depths and width of the WT to make it exactly square - experimental
+	void make_wipe_tower_square();
+
+    // Goes through m_plan, calculates border and finish_layer extrusions and subtracts them from last wipe
+    void save_on_last_wipe();
+
+
+	struct box_coordinates
+	{
+		box_coordinates(float left, float bottom, float width, float height) :
+			ld(left        , bottom         ),
+			lu(left        , bottom + height),
+			rd(left + width, bottom         ),
+			ru(left + width, bottom + height) {}
+		box_coordinates(const xy &pos, float width, float height) : box_coordinates(pos.x, pos.y, width, height) {}
+		void translate(const xy &shift) {
+			ld += shift; lu += shift;
+			rd += shift; ru += shift;
+		}
+		void translate(const float dx, const float dy) { translate(xy(dx, dy)); }
+		void expand(const float offset) {
+			ld += xy(- offset, - offset);
+			lu += xy(- offset,   offset);
+			rd += xy(  offset, - offset);
+			ru += xy(  offset,   offset);
+		}
+		void expand(const float offset_x, const float offset_y) {
+			ld += xy(- offset_x, - offset_y);
+			lu += xy(- offset_x,   offset_y);
+			rd += xy(  offset_x, - offset_y);
+			ru += xy(  offset_x,   offset_y);
+		}
+		xy ld;  // left down
+		xy lu;	// left upper 
+		xy rd;	// right lower
+		xy ru;  // right upper
+	};
+
+
+	// to store information about tool changes for a given layer
+	struct WipeTowerInfo{
+		struct ToolChange {
+			unsigned int old_tool;
+			unsigned int new_tool;
+			float required_depth;
+            float ramming_depth;
+            float first_wipe_line;
+            float wipe_volume;
+			ToolChange(unsigned int old, unsigned int newtool, float depth=0.f, float ramming_depth=0.f, float fwl=0.f, float wv=0.f)
+            : old_tool{old}, new_tool{newtool}, required_depth{depth}, ramming_depth{ramming_depth}, first_wipe_line{fwl}, wipe_volume{wv} {}
+		};
+		float z;		// z position of the layer
+		float height;	// layer height
+		float depth;	// depth of the layer based on all layers above
+		float extra_spacing;
+		float toolchanges_depth() const { float sum = 0.f; for (const auto &a : tool_changes) sum += a.required_depth; return sum; }
+
+		std::vector<ToolChange> tool_changes;
+
+		WipeTowerInfo(float z_par, float layer_height_par)
+			: z{z_par}, height{layer_height_par}, depth{0}, extra_spacing{1.f} {}
+	};
+
+	std::vector<WipeTowerInfo> m_plan; 	// Stores information about all layers and toolchanges for the future wipe tower (filled by plan_toolchange(...))
+	std::vector<WipeTowerInfo>::iterator m_layer_info = m_plan.end();
+
+    // Stores information about used filament length per extruder:
+    std::vector<float> m_used_filament_length;
+
+
+	// Returns gcode for wipe tower brim
+	// sideOnly			-- set to false -- experimental, draw brim on sides of wipe tower
+	// offset			-- set to 0		-- experimental, offset to replace brim in front / rear of wipe tower
+	ToolChangeResult toolchange_Brim(bool sideOnly = false, float y_offset = 0.f);
+
+	void toolchange_Unload(
+		PrusaMultiMaterial::Writer &writer,
+		const box_coordinates  &cleaning_box, 
+		const material_type	 	current_material,
+		const int 				new_temperature);
+
+	void toolchange_Change(
+		PrusaMultiMaterial::Writer &writer,
+		const unsigned int		new_tool,
+		material_type 			new_material);
+	
+	void toolchange_Load(
+		PrusaMultiMaterial::Writer &writer,
+		const box_coordinates  &cleaning_box);
+	
+	void toolchange_Wipe(
+		PrusaMultiMaterial::Writer &writer,
+		const box_coordinates  &cleaning_box,
+		float wipe_volume);
+};
+
+
+
+
+}; // namespace Slic3r
+
+#endif /* WipeTowerPrusaMM_hpp_ */

src/libslic3r/GCodeReader.cpp

@@ -0,0 +1,199 @@
+#include "GCodeReader.hpp"
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/split.hpp>
+#include <fstream>
+#include <iostream>
+
+#include <Shiny/Shiny.h>
+
+namespace Slic3r {
+
+void GCodeReader::apply_config(const GCodeConfig &config)
+{
+    m_config = config;
+    m_extrusion_axis = m_config.get_extrusion_axis()[0];
+}
+
+void GCodeReader::apply_config(const DynamicPrintConfig &config)
+{
+    m_config.apply(config, true);
+    m_extrusion_axis = m_config.get_extrusion_axis()[0];
+}
+
+const char* GCodeReader::parse_line_internal(const char *ptr, GCodeLine &gline, std::pair<const char*, const char*> &command)
+{
+    PROFILE_FUNC();
+    
+    // command and args
+    const char *c = ptr;
+    {
+        PROFILE_BLOCK(command_and_args);
+        // Skip the whitespaces.
+        command.first = skip_whitespaces(c);
+        // Skip the command.
+        c = command.second = skip_word(command.first);
+        // Up to the end of line or comment.
+		while (! is_end_of_gcode_line(*c)) {
+            // Skip whitespaces.
+            c = skip_whitespaces(c);
+			if (is_end_of_gcode_line(*c))
+				break;
+            // Check the name of the axis.
+            Axis axis = NUM_AXES;
+            switch (*c) {
+            case 'X': axis = X; break;
+            case 'Y': axis = Y; break;
+            case 'Z': axis = Z; break;
+            case 'F': axis = F; break;
+            default:
+                if (*c == m_extrusion_axis)
+                    axis = E;
+                break;
+            }
+            if (axis != NUM_AXES) {
+                // Try to parse the numeric value.
+                char   *pend = nullptr;
+                double  v = strtod(++ c, &pend);
+                if (pend != nullptr && is_end_of_word(*pend)) {
+                    // The axis value has been parsed correctly.
+                    gline.m_axis[int(axis)] = float(v);
+                    gline.m_mask |= 1 << int(axis);
+                    c = pend;
+                } else
+                    // Skip the rest of the word.
+                    c = skip_word(c);
+            } else
+                // Skip the rest of the word.
+                c = skip_word(c);
+        }
+    }
+    
+    if (gline.has(E) && m_config.use_relative_e_distances)
+        m_position[E] = 0;
+
+    // Skip the rest of the line.
+    for (; ! is_end_of_line(*c); ++ c);
+
+    // Copy the raw string including the comment, without the trailing newlines.
+    if (c > ptr) {
+        PROFILE_BLOCK(copy_raw_string);
+        gline.m_raw.assign(ptr, c);
+    }
+
+    // Skip the trailing newlines.
+	if (*c == '\r')
+		++ c;
+	if (*c == '\n')
+		++ c;
+
+    if (m_verbose)
+        std::cout << gline.m_raw << std::endl;
+
+    return c;
+}
+
+void GCodeReader::update_coordinates(GCodeLine &gline, std::pair<const char*, const char*> &command)
+{
+    PROFILE_FUNC();
+    if (*command.first == 'G') {
+        int cmd_len = int(command.second - command.first);
+        if ((cmd_len == 2 && (command.first[1] == '0' || command.first[1] == '1')) ||
+            (cmd_len == 3 &&  command.first[1] == '9' && command.first[2] == '2')) {
+            for (size_t i = 0; i < NUM_AXES; ++ i)
+                if (gline.has(Axis(i)))
+                    m_position[i] = gline.value(Axis(i));
+        }
+    }
+}
+
+void GCodeReader::parse_file(const std::string &file, callback_t callback)
+{
+    std::ifstream f(file);
+    std::string line;
+    while (std::getline(f, line))
+        this->parse_line(line, callback);
+}
+
+bool GCodeReader::GCodeLine::has(char axis) const
+{
+    const char *c = m_raw.c_str();
+    // Skip the whitespaces.
+    c = skip_whitespaces(c);
+    // Skip the command.
+    c = skip_word(c);
+    // Up to the end of line or comment.
+    while (! is_end_of_gcode_line(*c)) {
+        // Skip whitespaces.
+        c = skip_whitespaces(c);
+        if (is_end_of_gcode_line(*c))
+            break;
+        // Check the name of the axis.
+        if (*c == axis)
+            return true;
+        // Skip the rest of the word.
+        c = skip_word(c);
+    }
+    return false;
+}
+
+bool GCodeReader::GCodeLine::has_value(char axis, float &value) const
+{
+    const char *c = m_raw.c_str();
+    // Skip the whitespaces.
+    c = skip_whitespaces(c);
+    // Skip the command.
+    c = skip_word(c);
+    // Up to the end of line or comment.
+    while (! is_end_of_gcode_line(*c)) {
+        // Skip whitespaces.
+        c = skip_whitespaces(c);
+        if (is_end_of_gcode_line(*c))
+            break;
+        // Check the name of the axis.
+        if (*c == axis) {
+            // Try to parse the numeric value.
+            char   *pend = nullptr;
+            double  v = strtod(++ c, &pend);
+            if (pend != nullptr && is_end_of_word(*pend)) {
+                // The axis value has been parsed correctly.
+                value = float(v);
+                return true;
+            }
+        }
+        // Skip the rest of the word.
+        c = skip_word(c);
+    }
+    return false;
+}
+
+void GCodeReader::GCodeLine::set(const GCodeReader &reader, const Axis axis, const float new_value, const int decimal_digits)
+{
+    std::ostringstream ss;
+    ss << std::fixed << std::setprecision(decimal_digits) << new_value;
+
+    char match[3] = " X";
+    if (int(axis) < 3)
+        match[1] += int(axis);
+    else if (axis == F)
+        match[1] = 'F';
+    else {
+        assert(axis == E);
+        match[1] = reader.extrusion_axis();
+    }
+
+    if (this->has(axis)) {
+        size_t pos = m_raw.find(match)+2;
+        size_t end = m_raw.find(' ', pos+1);
+        m_raw = m_raw.replace(pos, end-pos, ss.str());
+    } else {
+        size_t pos = m_raw.find(' ');
+        if (pos == std::string::npos)
+            m_raw += std::string(match) + ss.str();
+        else
+            m_raw = m_raw.replace(pos, 0, std::string(match) + ss.str());
+    }
+    m_axis[axis] = new_value;
+    m_mask |= 1 << int(axis);
+}
+
+}

src/libslic3r/GCodeReader.hpp

@@ -0,0 +1,140 @@
+#ifndef slic3r_GCodeReader_hpp_
+#define slic3r_GCodeReader_hpp_
+
+#include "libslic3r.h"
+#include <cmath>
+#include <cstdlib>
+#include <functional>
+#include <string>
+#include "PrintConfig.hpp"
+
+namespace Slic3r {
+
+class GCodeReader {
+public:
+    class GCodeLine {
+    public:
+        GCodeLine() { reset(); }
+        void reset() { m_mask = 0; memset(m_axis, 0, sizeof(m_axis)); m_raw.clear(); }
+
+        const std::string&  raw() const { return m_raw; }
+        const std::string   cmd() const { 
+            const char *cmd = GCodeReader::skip_whitespaces(m_raw.c_str());
+            return std::string(cmd, GCodeReader::skip_word(cmd));
+        }
+        const std::string   comment() const
+            { size_t pos = m_raw.find(';'); return (pos == std::string::npos) ? "" : m_raw.substr(pos + 1); }
+
+        bool  has(Axis axis) const { return (m_mask & (1 << int(axis))) != 0; }
+        float value(Axis axis) const { return m_axis[axis]; }
+        bool  has(char axis) const;
+        bool  has_value(char axis, float &value) const;
+        float new_Z(const GCodeReader &reader) const { return this->has(Z) ? this->z() : reader.z(); }
+        float new_E(const GCodeReader &reader) const { return this->has(E) ? this->e() : reader.e(); }
+        float new_F(const GCodeReader &reader) const { return this->has(F) ? this->f() : reader.f(); }
+        float dist_X(const GCodeReader &reader) const { return this->has(X) ? (this->x() - reader.x()) : 0; }
+        float dist_Y(const GCodeReader &reader) const { return this->has(Y) ? (this->y() - reader.y()) : 0; }
+        float dist_Z(const GCodeReader &reader) const { return this->has(Z) ? (this->z() - reader.z()) : 0; }
+        float dist_E(const GCodeReader &reader) const { return this->has(E) ? (this->e() - reader.e()) : 0; }
+        float dist_XY(const GCodeReader &reader) const {
+            float x = this->has(X) ? (this->x() - reader.x()) : 0;
+            float y = this->has(Y) ? (this->y() - reader.y()) : 0;
+            return sqrt(x*x + y*y);
+        }
+        bool cmd_is(const char *cmd_test) const {
+            const char *cmd = GCodeReader::skip_whitespaces(m_raw.c_str());
+            int len = strlen(cmd_test); 
+            return strncmp(cmd, cmd_test, len) == 0 && GCodeReader::is_end_of_word(cmd[len]);
+        }
+        bool extruding(const GCodeReader &reader)  const { return this->cmd_is("G1") && this->dist_E(reader) > 0; }
+        bool retracting(const GCodeReader &reader) const { return this->cmd_is("G1") && this->dist_E(reader) < 0; }
+        bool travel()     const { return this->cmd_is("G1") && ! this->has(E); }
+        void set(const GCodeReader &reader, const Axis axis, const float new_value, const int decimal_digits = 3);
+
+        bool  has_x() const { return this->has(X); }
+        bool  has_y() const { return this->has(Y); }
+        bool  has_z() const { return this->has(Z); }
+        bool  has_e() const { return this->has(E); }
+        bool  has_f() const { return this->has(F); }
+        float x() const { return m_axis[X]; }
+        float y() const { return m_axis[Y]; }
+        float z() const { return m_axis[Z]; }
+        float e() const { return m_axis[E]; }
+        float f() const { return m_axis[F]; }
+
+    private:
+        std::string      m_raw;
+        float            m_axis[NUM_AXES];
+        uint32_t         m_mask;
+        friend class GCodeReader;
+    };
+
+    typedef std::function<void(GCodeReader&, const GCodeLine&)> callback_t;
+    
+    GCodeReader() : m_verbose(false), m_extrusion_axis('E') { memset(m_position, 0, sizeof(m_position)); }
+    void apply_config(const GCodeConfig &config);
+    void apply_config(const DynamicPrintConfig &config);
+
+    template<typename Callback>
+    void parse_buffer(const std::string &buffer, Callback callback)
+    {
+        const char *ptr = buffer.c_str();
+        GCodeLine gline;
+        while (*ptr != 0) {
+            gline.reset();
+            ptr = this->parse_line(ptr, gline, callback);
+        }
+    }
+
+    void parse_buffer(const std::string &buffer)
+        { this->parse_buffer(buffer, [](GCodeReader&, const GCodeReader::GCodeLine&){}); }
+
+    template<typename Callback>
+    const char* parse_line(const char *ptr, GCodeLine &gline, Callback &callback)
+    {
+        std::pair<const char*, const char*> cmd;
+        const char *end = parse_line_internal(ptr, gline, cmd);
+        callback(*this, gline);
+        update_coordinates(gline, cmd);
+        return end;
+    }
+
+    template<typename Callback>
+    void parse_line(const std::string &line, Callback callback)
+        { GCodeLine gline; this->parse_line(line.c_str(), gline, callback); }
+
+    void parse_file(const std::string &file, callback_t callback);
+
+    float& x()       { return m_position[X]; }
+    float  x() const { return m_position[X]; }
+    float& y()       { return m_position[Y]; }
+    float  y() const { return m_position[Y]; }
+    float& z()       { return m_position[Z]; }
+    float  z() const { return m_position[Z]; }
+    float& e()       { return m_position[E]; }
+    float  e() const { return m_position[E]; }
+    float& f()       { return m_position[F]; }
+    float  f() const { return m_position[F]; }
+
+    char   extrusion_axis() const { return m_extrusion_axis; }
+
+private:
+    const char* parse_line_internal(const char *ptr, GCodeLine &gline, std::pair<const char*, const char*> &command);
+    void        update_coordinates(GCodeLine &gline, std::pair<const char*, const char*> &command);
+
+    static bool         is_whitespace(char c)           { return c == ' ' || c == '\t'; }
+    static bool         is_end_of_line(char c)          { return c == '\r' || c == '\n' || c == 0; }
+    static bool         is_end_of_gcode_line(char c)    { return c == ';' || is_end_of_line(c); }
+    static bool         is_end_of_word(char c)          { return is_whitespace(c) || is_end_of_gcode_line(c); }
+    static const char*  skip_whitespaces(const char *c) { for (; is_whitespace(*c); ++ c); return c; }
+    static const char*  skip_word(const char *c)        { for (; ! is_end_of_word(*c); ++ c); return c; }
+
+    GCodeConfig m_config;
+    char        m_extrusion_axis;
+    float       m_position[NUM_AXES];
+    bool        m_verbose;
+};
+
+} /* namespace Slic3r */
+
+#endif /* slic3r_GCodeReader_hpp_ */

src/libslic3r/GCodeSender.cpp

@@ -0,0 +1,580 @@
+#include "GCodeSender.hpp"
+#include <iostream>
+#include <istream>
+#include <string>
+#include <thread>
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/algorithm/string/trim.hpp>
+#include <boost/date_time/posix_time/posix_time.hpp>
+#include <boost/lexical_cast.hpp>
+
+#if defined(__APPLE__) || defined(__OpenBSD__)
+#include <termios.h>
+#endif
+#ifdef __APPLE__
+#include <sys/ioctl.h>
+#include <IOKit/serial/ioss.h>
+#endif
+#ifdef __linux__
+#include <sys/ioctl.h>
+#include <fcntl.h>
+#include "/usr/include/asm-generic/ioctls.h"
+
+/* The following definitions are kindly borrowed from:
+   /usr/include/asm-generic/termbits.h
+   Unfortunately we cannot just include that one because
+   it would redefine the "struct termios" already defined
+   the <termios.h> already included by Boost.ASIO. */
+#define K_NCCS 19
+struct termios2 {
+	tcflag_t c_iflag;
+	tcflag_t c_oflag;
+	tcflag_t c_cflag;
+	tcflag_t c_lflag;
+	cc_t c_line;
+	cc_t c_cc[K_NCCS];
+	speed_t c_ispeed;
+	speed_t c_ospeed;
+};
+#define BOTHER CBAUDEX
+
+#endif
+
+//#define DEBUG_SERIAL
+#ifdef DEBUG_SERIAL
+#include <cstdlib>
+#include <fstream>
+std::fstream fs;
+#endif
+
+#define KEEP_SENT 20
+
+namespace Slic3r {
+
+GCodeSender::GCodeSender()
+    : io(), serial(io), can_send(false), sent(0), open(false), error(false),
+      connected(false), queue_paused(false)
+{
+#ifdef DEBUG_SERIAL
+    std::srand(std::time(nullptr));
+#endif
+}
+
+GCodeSender::~GCodeSender()
+{
+    this->disconnect();
+}
+
+bool
+GCodeSender::connect(std::string devname, unsigned int baud_rate)
+{
+    this->disconnect();
+    
+    this->set_error_status(false);
+    try {
+        this->serial.open(devname);
+        
+        this->serial.set_option(boost::asio::serial_port_base::parity(boost::asio::serial_port_base::parity::odd));
+        this->serial.set_option(boost::asio::serial_port_base::character_size(boost::asio::serial_port_base::character_size(8)));
+        this->serial.set_option(boost::asio::serial_port_base::flow_control(boost::asio::serial_port_base::flow_control::none));
+        this->serial.set_option(boost::asio::serial_port_base::stop_bits(boost::asio::serial_port_base::stop_bits::one));
+        this->set_baud_rate(baud_rate);
+    
+        this->serial.close();
+        this->serial.open(devname);
+        this->serial.set_option(boost::asio::serial_port_base::parity(boost::asio::serial_port_base::parity::none));
+    
+        // set baud rate again because set_option overwrote it
+        this->set_baud_rate(baud_rate);
+        this->open = true;
+        this->reset();
+    } catch (boost::system::system_error &) {
+        this->set_error_status(true);
+        return false;
+    }
+    
+    // a reset firmware expect line numbers to start again from 1
+    this->sent = 0;
+    this->last_sent.clear();
+
+    /* Initialize debugger */
+#ifdef DEBUG_SERIAL
+    fs.open("serial.txt", std::fstream::out | std::fstream::trunc);
+#endif
+    
+    // this gives some work to the io_service before it is started
+    // (post() runs the supplied function in its thread)
+    this->io.post(boost::bind(&GCodeSender::do_read, this));
+    
+    // start reading in the background thread
+    boost::thread t(boost::bind(&boost::asio::io_service::run, &this->io));
+    this->background_thread.swap(t);
+    
+    // always send a M105 to check for connection because firmware might be silent on connect
+    //FIXME Vojtech: This is being sent too early, leading to line number synchronization issues,
+    // from which the GCodeSender never recovers.
+    // this->send("M105", true);
+    
+    return true;
+}
+
+void
+GCodeSender::set_baud_rate(unsigned int baud_rate)
+{
+    try {
+        // This does not support speeds > 115200
+        this->serial.set_option(boost::asio::serial_port_base::baud_rate(baud_rate));
+    } catch (boost::system::system_error &) {
+        boost::asio::serial_port::native_handle_type handle = this->serial.native_handle();
+
+#if __APPLE__
+        termios ios;
+        ::tcgetattr(handle, &ios);
+        ::cfsetspeed(&ios, baud_rate);
+        speed_t newSpeed = baud_rate;
+        ioctl(handle, IOSSIOSPEED, &newSpeed);
+        ::tcsetattr(handle, TCSANOW, &ios);
+#elif __linux
+        termios2 ios;
+        if (ioctl(handle, TCGETS2, &ios))
+            printf("Error in TCGETS2: %s\n", strerror(errno));
+        ios.c_ispeed = ios.c_ospeed = baud_rate;
+        ios.c_cflag &= ~CBAUD;
+        ios.c_cflag |= BOTHER | CLOCAL | CREAD;
+        ios.c_cc[VMIN] = 1; // Minimum of characters to read, prevents eof errors when 0 bytes are read
+        ios.c_cc[VTIME] = 1;
+        if (ioctl(handle, TCSETS2, &ios))
+            printf("Error in TCSETS2: %s\n", strerror(errno));
+		
+#elif __OpenBSD__
+		struct termios ios;
+		::tcgetattr(handle, &ios);
+		::cfsetspeed(&ios, baud_rate);
+		if (::tcsetattr(handle, TCSAFLUSH, &ios) != 0)
+			printf("Failed to set baud rate: %s\n", strerror(errno));
+#else
+        //throw invalid_argument ("OS does not currently support custom bauds");
+#endif
+    }
+}
+
+void
+GCodeSender::disconnect()
+{
+    if (!this->open) return;
+    this->open = false;
+    this->connected = false;
+    this->io.post(boost::bind(&GCodeSender::do_close, this));
+    this->background_thread.join();
+    this->io.reset();
+    /*
+    if (this->error_status()) {
+        throw(boost::system::system_error(boost::system::error_code(),
+            "Error while closing the device"));
+    }
+    */
+    
+#ifdef DEBUG_SERIAL
+    fs << "DISCONNECTED" << std::endl << std::flush;
+    fs.close();
+#endif
+}
+
+bool
+GCodeSender::is_connected() const
+{
+    return this->connected;
+}
+
+bool
+GCodeSender::wait_connected(unsigned int timeout) const
+{
+    using namespace boost::posix_time;
+    ptime t0 = second_clock::local_time() + seconds(timeout);
+    while (!this->connected) {
+        if (second_clock::local_time() > t0) return false;
+        boost::this_thread::sleep(boost::posix_time::milliseconds(100));
+    }
+    return true;
+}
+
+size_t
+GCodeSender::queue_size() const
+{
+    boost::lock_guard<boost::mutex> l(this->queue_mutex);
+    return this->queue.size();
+}
+
+void
+GCodeSender::pause_queue()
+{
+    boost::lock_guard<boost::mutex> l(this->queue_mutex);
+    this->queue_paused = true;
+}
+
+void
+GCodeSender::resume_queue()
+{
+    {
+        boost::lock_guard<boost::mutex> l(this->queue_mutex);
+        this->queue_paused = false;
+    }
+    this->send();
+}
+
+void
+GCodeSender::purge_queue(bool priority)
+{
+    boost::lock_guard<boost::mutex> l(this->queue_mutex);
+    if (priority) {
+        // clear priority queue
+        std::list<std::string> empty;
+        std::swap(this->priqueue, empty);
+    } else {
+        // clear queue
+        std::queue<std::string> empty;
+        std::swap(this->queue, empty);
+        this->queue_paused = false;
+    }
+}
+
+// purge log and return its contents
+std::vector<std::string>
+GCodeSender::purge_log()
+{
+    boost::lock_guard<boost::mutex> l(this->log_mutex);
+    std::vector<std::string> retval;
+    retval.reserve(this->log.size());
+    while (!this->log.empty()) {
+        retval.push_back(this->log.front());
+        this->log.pop();
+    }
+    return retval;
+}
+
+std::string
+GCodeSender::getT() const
+{
+    boost::lock_guard<boost::mutex> l(this->log_mutex);
+    return this->T;
+}
+
+std::string
+GCodeSender::getB() const
+{
+    boost::lock_guard<boost::mutex> l(this->log_mutex);
+    return this->B;
+}
+
+void
+GCodeSender::do_close()
+{
+    this->set_error_status(false);
+    boost::system::error_code ec;
+    this->serial.cancel(ec);
+    if (ec) this->set_error_status(true);
+    this->serial.close(ec);
+    if (ec) this->set_error_status(true);
+}
+
+void
+GCodeSender::set_error_status(bool e)
+{
+    boost::lock_guard<boost::mutex> l(this->error_mutex);
+    this->error = e;
+}
+
+bool
+GCodeSender::error_status() const
+{
+    boost::lock_guard<boost::mutex> l(this->error_mutex);
+    return this->error;
+}
+
+void
+GCodeSender::do_read()
+{
+    // read one line
+    boost::asio::async_read_until(
+        this->serial,
+        this->read_buffer,
+        '\n',
+        boost::bind(
+            &GCodeSender::on_read,
+            this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred
+        )
+    );
+}
+
+void
+GCodeSender::on_read(const boost::system::error_code& error,
+    size_t bytes_transferred)
+{
+    this->set_error_status(false);
+    if (error) {
+        #ifdef __APPLE__
+        if (error.value() == 45) {
+            // OS X bug: http://osdir.com/ml/lib.boost.asio.user/2008-08/msg00004.html
+            this->do_read();
+            return;
+        }
+        #endif
+    
+        // printf("ERROR: [%d] %s\n", error.value(), error.message().c_str());
+        // error can be true even because the serial port was closed.
+        // In this case it is not a real error, so ignore.
+        if (this->open) {
+            this->do_close();
+            this->set_error_status(true);
+        }
+        return;
+    }
+    
+    std::istream is(&this->read_buffer);
+    std::string line;
+    std::getline(is, line);
+    if (!line.empty()) {
+#ifdef DEBUG_SERIAL
+    fs << "<< " << line << std::endl << std::flush;
+#endif
+        
+        // note that line might contain \r at its end
+        // parse incoming line
+        if (!this->connected
+            && (boost::starts_with(line, "start")
+             || boost::starts_with(line, "Grbl ")
+             || boost::starts_with(line, "ok")
+             || boost::contains(line, "T:"))) {
+            this->connected = true;
+            {
+                boost::lock_guard<boost::mutex> l(this->queue_mutex);
+                this->can_send = true;
+            }
+            this->send();
+        } else if (boost::starts_with(line, "ok")) {
+            {
+                boost::lock_guard<boost::mutex> l(this->queue_mutex);
+                this->can_send = true;
+            }
+            this->send();
+        } else if (boost::istarts_with(line, "resend")  // Marlin uses "Resend: "
+                || boost::istarts_with(line, "rs")) {
+            // extract the first number from line
+            boost::algorithm::trim_left_if(line, !boost::algorithm::is_digit());
+            size_t toresend = boost::lexical_cast<size_t>(line.substr(0, line.find_first_not_of("0123456789")));
+            
+#ifdef DEBUG_SERIAL
+            fs << "!! line num out of sync: toresend = " << toresend << ", sent = " << sent << ", last_sent.size = " << last_sent.size() << std::endl;
+#endif
+
+            if (toresend > this->sent - this->last_sent.size() && toresend <= this->sent) {
+                {
+                    boost::lock_guard<boost::mutex> l(this->queue_mutex);
+                    
+                    const auto lines_to_resend = this->sent - toresend + 1;
+#ifdef DEBUG_SERIAL
+            fs << "!! resending " << lines_to_resend << " lines" << std::endl;
+#endif
+                    // move the unsent lines to priqueue
+                    this->priqueue.insert(
+                        this->priqueue.begin(),  // insert at the beginning
+                        this->last_sent.begin() + this->last_sent.size() - lines_to_resend,
+                        this->last_sent.end()
+                    );
+                    
+                    // we can empty last_sent because it's not useful anymore
+                    this->last_sent.clear();
+                    
+                    // start resending with the requested line number
+                    this->sent = toresend - 1;
+                    this->can_send = true;
+                }
+                this->send();
+            } else {
+                printf("Cannot resend " PRINTF_ZU " (oldest we have is " PRINTF_ZU ")\n", toresend, this->sent - this->last_sent.size());
+            }
+        } else if (boost::starts_with(line, "wait")) {
+            // ignore
+        } else {
+            // push any other line into the log
+            boost::lock_guard<boost::mutex> l(this->log_mutex);
+            this->log.push(line);
+        }
+    
+        // parse temperature info
+        {
+            size_t pos = line.find("T:");
+            if (pos != std::string::npos && line.size() > pos + 2) {
+                // we got temperature info
+                boost::lock_guard<boost::mutex> l(this->log_mutex);
+                this->T = line.substr(pos+2, line.find_first_not_of("0123456789.", pos+2) - (pos+2));
+        
+                pos = line.find("B:");
+                if (pos != std::string::npos && line.size() > pos + 2) {
+                    // we got bed temperature info
+                    this->B = line.substr(pos+2, line.find_first_not_of("0123456789.", pos+2) - (pos+2));
+                }
+            }
+        }
+    }
+    this->do_read();
+}
+
+void
+GCodeSender::send(const std::vector<std::string> &lines, bool priority)
+{
+    // append lines to queue
+    {
+        boost::lock_guard<boost::mutex> l(this->queue_mutex);
+        for (std::vector<std::string>::const_iterator line = lines.begin(); line != lines.end(); ++line) {
+            if (priority) {
+                this->priqueue.push_back(*line);
+            } else {
+                this->queue.push(*line);
+            }
+        }
+    }
+    this->send();
+}
+
+void
+GCodeSender::send(const std::string &line, bool priority)
+{
+    // append line to queue
+    {
+        boost::lock_guard<boost::mutex> l(this->queue_mutex);
+        if (priority) {
+            this->priqueue.push_back(line);
+        } else {
+            this->queue.push(line);
+        }
+    }
+    this->send();
+}
+
+void
+GCodeSender::send()
+{
+    this->io.post(boost::bind(&GCodeSender::do_send, this));
+}
+
+void
+GCodeSender::do_send()
+{
+    boost::lock_guard<boost::mutex> l(this->queue_mutex);
+    
+    // printer is not connected or we're still waiting for the previous ack
+    if (!this->can_send) return;
+    
+    std::string line;
+    while (!this->priqueue.empty() || (!this->queue.empty() && !this->queue_paused)) {
+        if (!this->priqueue.empty()) {
+            line = this->priqueue.front();
+            this->priqueue.pop_front();
+        } else {
+            line = this->queue.front();
+            this->queue.pop();
+        }
+        
+        // strip comments
+        size_t comment_pos = line.find_first_of(';');
+        if (comment_pos != std::string::npos)
+            line.erase(comment_pos, std::string::npos);
+        boost::algorithm::trim(line);
+        
+        // if line is not empty, send it
+        if (!line.empty()) break;
+        // if line is empty, process next item in queue
+    }
+    if (line.empty()) return;
+    
+    // compute full line
+    ++ this->sent;
+#ifndef DEBUG_SERIAL
+    const auto line_num = this->sent;
+#else
+    // In DEBUG_SERIAL mode, test line re-synchronization by sending bad line number 1/4 of the time
+    const auto line_num = std::rand() < RAND_MAX/4 ? 0 : this->sent;
+#endif
+    std::string full_line = "N" + boost::lexical_cast<std::string>(line_num) + " " + line;
+    
+    // calculate checksum
+    int cs = 0;
+    for (std::string::const_iterator it = full_line.begin(); it != full_line.end(); ++it)
+       cs = cs ^ *it;
+    
+    // write line to device
+    full_line += "*";
+    full_line += boost::lexical_cast<std::string>(cs);
+    full_line += "\n";
+    
+#ifdef DEBUG_SERIAL
+    fs << ">> " << full_line << std::flush;
+#endif
+    
+    this->last_sent.push_back(line);
+    this->can_send = false;
+    
+    while (this->last_sent.size() > KEEP_SENT) {
+        this->last_sent.pop_front();
+    }
+    
+    // we can't supply boost::asio::buffer(full_line) to async_write() because full_line is on the
+    // stack and the buffer would lose its underlying storage causing memory corruption
+    std::ostream os(&this->write_buffer);
+    os << full_line;
+    boost::asio::async_write(this->serial, this->write_buffer, boost::bind(&GCodeSender::on_write, this, boost::asio::placeholders::error,
+                boost::asio::placeholders::bytes_transferred));
+}
+
+void
+GCodeSender::on_write(const boost::system::error_code& error,
+    size_t bytes_transferred)
+{
+    this->set_error_status(false);
+    if (error) {
+        if (this->open) {
+            this->do_close();
+            this->set_error_status(true);
+        }
+        return;
+    }
+    
+    this->do_send();
+}
+
+void
+GCodeSender::set_DTR(bool on)
+{
+#if defined(_WIN32) && !defined(__SYMBIAN32__)
+    boost::asio::serial_port_service::native_handle_type handle = this->serial.native_handle();
+    if (on)
+        EscapeCommFunction(handle, SETDTR);
+    else
+        EscapeCommFunction(handle, CLRDTR);
+#else
+    int fd = this->serial.native_handle();
+    int status;
+    ioctl(fd, TIOCMGET, &status);
+    if (on)
+        status |= TIOCM_DTR;
+    else
+        status &= ~TIOCM_DTR;
+    ioctl(fd, TIOCMSET, &status);
+#endif
+}
+
+void
+GCodeSender::reset()
+{
+    set_DTR(false);
+    std::this_thread::sleep_for(std::chrono::milliseconds(200));
+    set_DTR(true);
+    std::this_thread::sleep_for(std::chrono::milliseconds(200));
+    set_DTR(false);
+    std::this_thread::sleep_for(std::chrono::milliseconds(500));
+}
+
+} // namespace Slic3r

src/libslic3r/GCodeSender.hpp

@@ -0,0 +1,73 @@
+#ifndef slic3r_GCodeSender_hpp_
+#define slic3r_GCodeSender_hpp_
+
+#include "libslic3r.h"
+#include <queue>
+#include <string>
+#include <vector>
+#include <boost/asio.hpp>
+#include <boost/bind.hpp>
+#include <boost/thread.hpp>
+
+namespace Slic3r {
+
+namespace asio = boost::asio;
+
+class GCodeSender : private boost::noncopyable {
+    public:
+    GCodeSender();
+    ~GCodeSender();
+    bool connect(std::string devname, unsigned int baud_rate);
+    void send(const std::vector<std::string> &lines, bool priority = false);
+    void send(const std::string &s, bool priority = false);
+    void disconnect();
+    bool error_status() const;
+    bool is_connected() const;
+    bool wait_connected(unsigned int timeout = 3) const;
+    size_t queue_size() const;
+    void pause_queue();
+    void resume_queue();
+    void purge_queue(bool priority = false);
+    std::vector<std::string> purge_log();
+    std::string getT() const;
+    std::string getB() const;
+    void set_DTR(bool on);
+    void reset();
+    
+    private:
+    asio::io_service io;
+    asio::serial_port serial;
+    boost::thread background_thread;
+    boost::asio::streambuf read_buffer, write_buffer;
+    bool open;      // whether the serial socket is connected
+    bool connected; // whether the printer is online
+    bool error;
+    mutable boost::mutex error_mutex;
+    
+    // this mutex guards queue, priqueue, can_send, queue_paused, sent, last_sent
+    mutable boost::mutex queue_mutex;
+    std::queue<std::string> queue;
+    std::list<std::string> priqueue;
+    bool can_send;
+    bool queue_paused;
+    size_t sent;
+    std::deque<std::string> last_sent;
+    
+    // this mutex guards log, T, B
+    mutable boost::mutex log_mutex;
+    std::queue<std::string> log;
+    std::string T, B;
+    
+    void set_baud_rate(unsigned int baud_rate);
+    void set_error_status(bool e);
+    void do_send();
+    void on_write(const boost::system::error_code& error, size_t bytes_transferred);
+    void do_close();
+    void do_read();
+    void on_read(const boost::system::error_code& error, size_t bytes_transferred);
+    void send();
+};
+
+} // namespace Slic3r
+
+#endif /* slic3r_GCodeSender_hpp_ */

src/libslic3r/GCodeTimeEstimator.hpp

@@ -0,0 +1,436 @@
+#ifndef slic3r_GCodeTimeEstimator_hpp_
+#define slic3r_GCodeTimeEstimator_hpp_
+
+#include "libslic3r.h"
+#include "PrintConfig.hpp"
+#include "GCodeReader.hpp"
+
+#define ENABLE_MOVE_STATS 0
+
+namespace Slic3r {
+
+    //
+    // Some of the algorithms used by class GCodeTimeEstimator were inpired by
+    // Cura Engine's class TimeEstimateCalculator
+    // https://github.com/Ultimaker/CuraEngine/blob/master/src/timeEstimate.h
+    //
+    class GCodeTimeEstimator
+    {
+    public:
+        static const std::string Normal_First_M73_Output_Placeholder_Tag;
+        static const std::string Silent_First_M73_Output_Placeholder_Tag;
+
+        enum EMode : unsigned char
+        {
+            Normal,
+            Silent
+        };
+
+        enum EUnits : unsigned char
+        {
+            Millimeters,
+            Inches
+        };
+
+        enum EAxis : unsigned char
+        {
+            X,
+            Y,
+            Z,
+            E,
+            Num_Axis
+        };
+
+        enum EPositioningType : unsigned char
+        {
+            Absolute,
+            Relative
+        };
+
+    private:
+        struct Axis
+        {
+            float position;         // mm
+            float max_feedrate;     // mm/s
+            float max_acceleration; // mm/s^2
+            float max_jerk;         // mm/s
+        };
+
+        struct Feedrates
+        {
+            float feedrate;                    // mm/s
+            float axis_feedrate[Num_Axis];     // mm/s
+            float abs_axis_feedrate[Num_Axis]; // mm/s
+            float safe_feedrate;               // mm/s
+
+            void reset();
+        };
+
+        struct State
+        {
+            GCodeFlavor dialect;
+            EUnits units;
+            EPositioningType global_positioning_type;
+            EPositioningType e_local_positioning_type;
+            Axis axis[Num_Axis];
+            float feedrate;                     // mm/s
+            float acceleration;                 // mm/s^2
+            // hard limit for the acceleration, to which the firmware will clamp.
+            float max_acceleration;             // mm/s^2
+            float retract_acceleration;         // mm/s^2
+            float additional_time;              // s
+            float minimum_feedrate;             // mm/s
+            float minimum_travel_feedrate;      // mm/s
+            float extrude_factor_override_percentage;
+            // Additional load / unload times for a filament exchange sequence.
+            std::vector<float> filament_load_times;
+            std::vector<float> filament_unload_times;
+            unsigned int g1_line_id;
+            // extruder_id is currently used to correctly calculate filament load / unload times 
+            // into the total print time. This is currently only really used by the MK3 MMU2:
+            // Extruder id (-1) means no filament is loaded yet, all the filaments are parked in the MK3 MMU2 unit.
+            static const unsigned int extruder_id_unloaded = (unsigned int)-1;
+            unsigned int extruder_id;
+        };
+
+    public:
+        struct Block
+        {
+#if ENABLE_MOVE_STATS
+            enum EMoveType : unsigned char
+            {
+                Noop,
+                Retract,
+                Unretract,
+                Tool_change,
+                Move,
+                Extrude,
+                Num_Types
+            };
+#endif // ENABLE_MOVE_STATS
+
+            struct FeedrateProfile
+            {
+                float entry;  // mm/s
+                float cruise; // mm/s
+                float exit;   // mm/s
+            };
+
+            struct Trapezoid
+            {
+                float distance;         // mm
+                float accelerate_until; // mm
+                float decelerate_after; // mm
+                FeedrateProfile feedrate;
+
+                float acceleration_time(float acceleration) const;
+                float cruise_time() const;
+                float deceleration_time(float acceleration) const;
+                float cruise_distance() const;
+
+                // This function gives the time needed to accelerate from an initial speed to reach a final distance.
+                static float acceleration_time_from_distance(float initial_feedrate, float distance, float acceleration);
+
+                // This function gives the final speed while accelerating at the given constant acceleration from the given initial speed along the given distance.
+                static float speed_from_distance(float initial_feedrate, float distance, float acceleration);
+            };
+
+            struct Flags
+            {
+                bool recalculate;
+                bool nominal_length;
+            };
+
+#if ENABLE_MOVE_STATS
+            EMoveType move_type;
+#endif // ENABLE_MOVE_STATS
+            Flags flags;
+
+            float delta_pos[Num_Axis]; // mm
+            float acceleration;        // mm/s^2
+            float max_entry_speed;     // mm/s
+            float safe_feedrate;       // mm/s
+
+            FeedrateProfile feedrate;
+            Trapezoid trapezoid;
+            float elapsed_time;
+
+            Block();
+
+            // Returns the length of the move covered by this block, in mm
+            float move_length() const;
+
+            // Returns true if this block is a retract/unretract move only
+            float is_extruder_only_move() const;
+
+            // Returns true if this block is a move with no extrusion
+            float is_travel_move() const;
+
+            // Returns the time spent accelerating toward cruise speed, in seconds
+            float acceleration_time() const;
+
+            // Returns the time spent at cruise speed, in seconds
+            float cruise_time() const;
+
+            // Returns the time spent decelerating from cruise speed, in seconds
+            float deceleration_time() const;
+
+            // Returns the distance covered at cruise speed, in mm
+            float cruise_distance() const;
+
+            // Calculates this block's trapezoid
+            void calculate_trapezoid();
+
+            // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the 
+            // acceleration within the allotted distance.
+            static float max_allowable_speed(float acceleration, float target_velocity, float distance);
+
+            // Calculates the distance (not time) it takes to accelerate from initial_rate to target_rate using the given acceleration:
+            static float estimate_acceleration_distance(float initial_rate, float target_rate, float acceleration);
+
+            // This function gives you the point at which you must start braking (at the rate of -acceleration) if 
+            // you started at speed initial_rate and accelerated until this point and want to end at the final_rate after
+            // a total travel of distance. This can be used to compute the intersection point between acceleration and
+            // deceleration in the cases where the trapezoid has no plateau (i.e. never reaches maximum speed)
+            static float intersection_distance(float initial_rate, float final_rate, float acceleration, float distance);
+        };
+
+        typedef std::vector<Block> BlocksList;
+
+#if ENABLE_MOVE_STATS
+        struct MoveStats
+        {
+            unsigned int count;
+            float time;
+
+            MoveStats();
+        };
+
+        typedef std::map<Block::EMoveType, MoveStats> MovesStatsMap;
+#endif // ENABLE_MOVE_STATS
+
+        typedef std::map<unsigned int, unsigned int> G1LineIdToBlockIdMap;
+
+    private:
+        EMode _mode;
+        GCodeReader _parser;
+        State _state;
+        Feedrates _curr;
+        Feedrates _prev;
+        BlocksList _blocks;
+        // Map between g1 line id and blocks id, used to speed up export of remaining times
+        G1LineIdToBlockIdMap _g1_line_ids;
+        // Index of the last block already st_synchronized
+        int _last_st_synchronized_block_id;
+        float _time; // s
+
+#if ENABLE_MOVE_STATS
+        MovesStatsMap _moves_stats;
+#endif // ENABLE_MOVE_STATS
+
+    public:
+        explicit GCodeTimeEstimator(EMode mode);
+
+        // Adds the given gcode line
+        void add_gcode_line(const std::string& gcode_line);
+
+        void add_gcode_block(const char *ptr);
+        void add_gcode_block(const std::string &str) { this->add_gcode_block(str.c_str()); }
+
+        // Calculates the time estimate from the gcode lines added using add_gcode_line() or add_gcode_block()
+        // start_from_beginning:
+        // if set to true all blocks will be used to calculate the time estimate,
+        // if set to false only the blocks not yet processed will be used and the calculated time will be added to the current calculated time
+        void calculate_time(bool start_from_beginning);
+
+        // Calculates the time estimate from the given gcode in string format
+        void calculate_time_from_text(const std::string& gcode);
+
+        // Calculates the time estimate from the gcode contained in the file with the given filename
+        void calculate_time_from_file(const std::string& file);
+
+        // Calculates the time estimate from the gcode contained in given list of gcode lines
+        void calculate_time_from_lines(const std::vector<std::string>& gcode_lines);
+
+        // Process the gcode contained in the file with the given filename, 
+        // placing in it new lines (M73) containing the remaining time, at the given interval in seconds
+        // and saving the result back in the same file
+        // This time estimator should have been already used to calculate the time estimate for the gcode
+        // contained in the given file before to call this method
+        bool post_process_remaining_times(const std::string& filename, float interval_sec);
+
+        // Set current position on the given axis with the given value
+        void set_axis_position(EAxis axis, float position);
+
+        void set_axis_max_feedrate(EAxis axis, float feedrate_mm_sec);
+        void set_axis_max_acceleration(EAxis axis, float acceleration);
+        void set_axis_max_jerk(EAxis axis, float jerk);
+
+        // Returns current position on the given axis
+        float get_axis_position(EAxis axis) const;
+
+        float get_axis_max_feedrate(EAxis axis) const;
+        float get_axis_max_acceleration(EAxis axis) const;
+        float get_axis_max_jerk(EAxis axis) const;
+
+        void set_feedrate(float feedrate_mm_sec);
+        float get_feedrate() const;
+
+        void set_acceleration(float acceleration_mm_sec2);
+        float get_acceleration() const;
+
+        // Maximum acceleration for the machine. The firmware simulator will clamp the M204 Sxxx to this maximum.
+        void set_max_acceleration(float acceleration_mm_sec2);
+        float get_max_acceleration() const;
+
+        void set_retract_acceleration(float acceleration_mm_sec2);
+        float get_retract_acceleration() const;
+
+        void set_minimum_feedrate(float feedrate_mm_sec);
+        float get_minimum_feedrate() const;
+
+        void set_minimum_travel_feedrate(float feedrate_mm_sec);
+        float get_minimum_travel_feedrate() const;
+
+        void set_filament_load_times(const std::vector<double> &filament_load_times);
+        void set_filament_unload_times(const std::vector<double> &filament_unload_times);
+        float get_filament_load_time(unsigned int id_extruder);
+        float get_filament_unload_time(unsigned int id_extruder);
+
+        void set_extrude_factor_override_percentage(float percentage);
+        float get_extrude_factor_override_percentage() const;
+
+        void set_dialect(GCodeFlavor dialect);
+        GCodeFlavor get_dialect() const;
+
+        void set_units(EUnits units);
+        EUnits get_units() const;
+
+        void set_global_positioning_type(EPositioningType type);
+        EPositioningType get_global_positioning_type() const;
+
+        void set_e_local_positioning_type(EPositioningType type);
+        EPositioningType get_e_local_positioning_type() const;
+
+        int get_g1_line_id() const;
+        void increment_g1_line_id();
+        void reset_g1_line_id();
+
+        void set_extruder_id(unsigned int id);
+        unsigned int get_extruder_id() const;
+        void reset_extruder_id();
+
+        void add_additional_time(float timeSec);
+        void set_additional_time(float timeSec);
+        float get_additional_time() const;
+
+        void set_default();
+
+        // Call this method before to start adding lines using add_gcode_line() when reusing an instance of GCodeTimeEstimator
+        void reset();
+
+        // Returns the estimated time, in seconds
+        float get_time() const;
+
+        // Returns the estimated time, in format DDd HHh MMm SSs
+        std::string get_time_dhms() const;
+
+        // Returns the estimated time, in minutes (integer)
+        std::string get_time_minutes() const;
+
+    private:
+        void _reset();
+        void _reset_time();
+        void _reset_blocks();
+
+        // Calculates the time estimate
+        void _calculate_time();
+
+        // Processes the given gcode line
+        void _process_gcode_line(GCodeReader&, const GCodeReader::GCodeLine& line);
+
+        // Move
+        void _processG1(const GCodeReader::GCodeLine& line);
+
+        // Dwell
+        void _processG4(const GCodeReader::GCodeLine& line);
+
+        // Set Units to Inches
+        void _processG20(const GCodeReader::GCodeLine& line);
+
+        // Set Units to Millimeters
+        void _processG21(const GCodeReader::GCodeLine& line);
+
+        // Move to Origin (Home)
+        void _processG28(const GCodeReader::GCodeLine& line);
+
+        // Set to Absolute Positioning
+        void _processG90(const GCodeReader::GCodeLine& line);
+
+        // Set to Relative Positioning
+        void _processG91(const GCodeReader::GCodeLine& line);
+
+        // Set Position
+        void _processG92(const GCodeReader::GCodeLine& line);
+
+        // Sleep or Conditional stop
+        void _processM1(const GCodeReader::GCodeLine& line);
+
+        // Set extruder to absolute mode
+        void _processM82(const GCodeReader::GCodeLine& line);
+
+        // Set extruder to relative mode
+        void _processM83(const GCodeReader::GCodeLine& line);
+
+        // Set Extruder Temperature and Wait
+        void _processM109(const GCodeReader::GCodeLine& line);
+
+        // Set max printing acceleration
+        void _processM201(const GCodeReader::GCodeLine& line);
+
+        // Set maximum feedrate
+        void _processM203(const GCodeReader::GCodeLine& line);
+
+        // Set default acceleration
+        void _processM204(const GCodeReader::GCodeLine& line);
+
+        // Advanced settings
+        void _processM205(const GCodeReader::GCodeLine& line);
+
+        // Set extrude factor override percentage
+        void _processM221(const GCodeReader::GCodeLine& line);
+
+        // Set allowable instantaneous speed change
+        void _processM566(const GCodeReader::GCodeLine& line);
+
+        // Unload the current filament into the MK3 MMU2 unit at the end of print.
+        void _processM702(const GCodeReader::GCodeLine& line);
+
+        // Processes T line (Select Tool)
+        void _processT(const GCodeReader::GCodeLine& line);
+
+        // Simulates firmware st_synchronize() call
+        void _simulate_st_synchronize();
+
+        void _forward_pass();
+        void _reverse_pass();
+
+        void _planner_forward_pass_kernel(Block& prev, Block& curr);
+        void _planner_reverse_pass_kernel(Block& curr, Block& next);
+
+        void _recalculate_trapezoids();
+
+        // Returns the given time is seconds in format DDd HHh MMm SSs
+        static std::string _get_time_dhms(float time_in_secs);
+
+        // Returns the given, in minutes (integer)
+        static std::string _get_time_minutes(float time_in_secs);
+
+#if ENABLE_MOVE_STATS
+        void _log_moves_stats() const;
+#endif // ENABLE_MOVE_STATS
+    };
+
+} /* namespace Slic3r */
+
+#endif /* slic3r_GCodeTimeEstimator_hpp_ */

src/libslic3r/GCodeWriter.cpp

@@ -0,0 +1,509 @@
+#include "GCodeWriter.hpp"
+#include <algorithm>
+#include <iomanip>
+#include <iostream>
+#include <map>
+#include <assert.h>
+
+#define FLAVOR_IS(val) this->config.gcode_flavor == val
+#define FLAVOR_IS_NOT(val) this->config.gcode_flavor != val
+#define COMMENT(comment) if (this->config.gcode_comments && !comment.empty()) gcode << " ; " << comment;
+#define PRECISION(val, precision) std::fixed << std::setprecision(precision) << val
+#define XYZF_NUM(val) PRECISION(val, 3)
+#define E_NUM(val) PRECISION(val, 5)
+
+namespace Slic3r {
+
+void GCodeWriter::apply_print_config(const PrintConfig &print_config)
+{
+    this->config.apply(print_config, true);
+    m_extrusion_axis = this->config.get_extrusion_axis();
+    m_single_extruder_multi_material = print_config.single_extruder_multi_material.value;
+    m_max_acceleration = (print_config.gcode_flavor.value == gcfMarlin) ?
+        print_config.machine_max_acceleration_extruding.values.front() : 0;
+}
+
+void GCodeWriter::set_extruders(const std::vector<unsigned int> &extruder_ids)
+{
+    m_extruders.clear();
+    m_extruders.reserve(extruder_ids.size());
+    for (unsigned int extruder_id : extruder_ids)
+        m_extruders.emplace_back(Extruder(extruder_id, &this->config));
+    
+    /*  we enable support for multiple extruder if any extruder greater than 0 is used
+        (even if prints only uses that one) since we need to output Tx commands
+        first extruder has index 0 */
+    this->multiple_extruders = (*std::max_element(extruder_ids.begin(), extruder_ids.end())) > 0;
+}
+
+std::string GCodeWriter::preamble()
+{
+    std::ostringstream gcode;
+    
+    if (FLAVOR_IS_NOT(gcfMakerWare)) {
+        gcode << "G21 ; set units to millimeters\n";
+        gcode << "G90 ; use absolute coordinates\n";
+    }
+    if (FLAVOR_IS(gcfRepRap) || FLAVOR_IS(gcfMarlin) || FLAVOR_IS(gcfTeacup) || FLAVOR_IS(gcfRepetier) || FLAVOR_IS(gcfSmoothie)) {
+        if (this->config.use_relative_e_distances) {
+            gcode << "M83 ; use relative distances for extrusion\n";
+        } else {
+            gcode << "M82 ; use absolute distances for extrusion\n";
+        }
+        gcode << this->reset_e(true);
+    }
+    
+    return gcode.str();
+}
+
+std::string GCodeWriter::postamble() const
+{
+    std::ostringstream gcode;
+    if (FLAVOR_IS(gcfMachinekit))
+          gcode << "M2 ; end of program\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::set_temperature(unsigned int temperature, bool wait, int tool) const
+{
+    if (wait && (FLAVOR_IS(gcfMakerWare) || FLAVOR_IS(gcfSailfish)))
+        return "";
+    
+    std::string code, comment;
+    if (wait && FLAVOR_IS_NOT(gcfTeacup)) {
+        code = "M109";
+        comment = "set temperature and wait for it to be reached";
+    } else {
+        code = "M104";
+        comment = "set temperature";
+    }
+    
+    std::ostringstream gcode;
+    gcode << code << " ";
+    if (FLAVOR_IS(gcfMach3) || FLAVOR_IS(gcfMachinekit)) {
+        gcode << "P";
+    } else {
+        gcode << "S";
+    }
+    gcode << temperature;
+    if (tool != -1 && 
+        ( (this->multiple_extruders && ! m_single_extruder_multi_material) ||
+          FLAVOR_IS(gcfMakerWare) || FLAVOR_IS(gcfSailfish)) ) {
+        gcode << " T" << tool;
+    }
+    gcode << " ; " << comment << "\n";
+    
+    if (FLAVOR_IS(gcfTeacup) && wait)
+        gcode << "M116 ; wait for temperature to be reached\n";
+    
+    return gcode.str();
+}
+
+std::string GCodeWriter::set_bed_temperature(unsigned int temperature, bool wait)
+{
+    if (temperature == m_last_bed_temperature && (! wait || m_last_bed_temperature_reached))
+        return std::string();
+
+    m_last_bed_temperature = temperature;
+    m_last_bed_temperature_reached = wait;
+
+    std::string code, comment;
+    if (wait && FLAVOR_IS_NOT(gcfTeacup)) {
+        if (FLAVOR_IS(gcfMakerWare) || FLAVOR_IS(gcfSailfish)) {
+            code = "M109";
+        } else {
+            code = "M190";
+        }
+        comment = "set bed temperature and wait for it to be reached";
+    } else {
+        code = "M140";
+        comment = "set bed temperature";
+    }
+    
+    std::ostringstream gcode;
+    gcode << code << " ";
+    if (FLAVOR_IS(gcfMach3) || FLAVOR_IS(gcfMachinekit)) {
+        gcode << "P";
+    } else {
+        gcode << "S";
+    }
+    gcode << temperature << " ; " << comment << "\n";
+    
+    if (FLAVOR_IS(gcfTeacup) && wait)
+        gcode << "M116 ; wait for bed temperature to be reached\n";
+    
+    return gcode.str();
+}
+
+std::string GCodeWriter::set_fan(unsigned int speed, bool dont_save)
+{
+    std::ostringstream gcode;
+    if (m_last_fan_speed != speed || dont_save) {
+        if (!dont_save) m_last_fan_speed = speed;
+        
+        if (speed == 0) {
+            if (FLAVOR_IS(gcfTeacup)) {
+                gcode << "M106 S0";
+            } else if (FLAVOR_IS(gcfMakerWare) || FLAVOR_IS(gcfSailfish)) {
+                gcode << "M127";
+            } else {
+                gcode << "M107";
+            }
+            if (this->config.gcode_comments) gcode << " ; disable fan";
+            gcode << "\n";
+        } else {
+            if (FLAVOR_IS(gcfMakerWare) || FLAVOR_IS(gcfSailfish)) {
+                gcode << "M126";
+            } else {
+                gcode << "M106 ";
+                if (FLAVOR_IS(gcfMach3) || FLAVOR_IS(gcfMachinekit)) {
+                    gcode << "P";
+                } else {
+                    gcode << "S";
+                }
+                gcode << (255.0 * speed / 100.0);
+            }
+            if (this->config.gcode_comments) gcode << " ; enable fan";
+            gcode << "\n";
+        }
+    }
+    return gcode.str();
+}
+
+std::string GCodeWriter::set_acceleration(unsigned int acceleration)
+{
+    // Clamp the acceleration to the allowed maximum.
+    if (m_max_acceleration > 0 && acceleration > m_max_acceleration)
+        acceleration = m_max_acceleration;
+
+    if (acceleration == 0 || acceleration == m_last_acceleration)
+        return std::string();
+    
+    m_last_acceleration = acceleration;
+    
+    std::ostringstream gcode;
+    if (FLAVOR_IS(gcfRepetier)) {
+        // M201: Set max printing acceleration
+        gcode << "M201 X" << acceleration << " Y" << acceleration;
+        if (this->config.gcode_comments) gcode << " ; adjust acceleration";
+        gcode << "\n";
+        // M202: Set max travel acceleration
+        gcode << "M202 X" << acceleration << " Y" << acceleration;
+    } else {
+        // M204: Set default acceleration
+        gcode << "M204 S" << acceleration;
+    }
+    if (this->config.gcode_comments) gcode << " ; adjust acceleration";
+    gcode << "\n";
+    
+    return gcode.str();
+}
+
+std::string GCodeWriter::reset_e(bool force)
+{
+    if (FLAVOR_IS(gcfMach3)
+        || FLAVOR_IS(gcfMakerWare)
+        || FLAVOR_IS(gcfSailfish))
+        return "";
+    
+    if (m_extruder != nullptr) {
+        if (m_extruder->E() == 0. && ! force)
+            return "";
+        m_extruder->reset_E();
+    }
+
+    if (! m_extrusion_axis.empty() && ! this->config.use_relative_e_distances) {
+        std::ostringstream gcode;
+        gcode << "G92 " << m_extrusion_axis << "0";
+        if (this->config.gcode_comments) gcode << " ; reset extrusion distance";
+        gcode << "\n";
+        return gcode.str();
+    } else {
+        return "";
+    }
+}
+
+std::string GCodeWriter::update_progress(unsigned int num, unsigned int tot, bool allow_100) const
+{
+    if (FLAVOR_IS_NOT(gcfMakerWare) && FLAVOR_IS_NOT(gcfSailfish))
+        return "";
+    
+    unsigned int percent = (unsigned int)floor(100.0 * num / tot + 0.5);
+    if (!allow_100) percent = std::min(percent, (unsigned int)99);
+    
+    std::ostringstream gcode;
+    gcode << "M73 P" << percent;
+    if (this->config.gcode_comments) gcode << " ; update progress";
+    gcode << "\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::toolchange_prefix() const
+{
+    return FLAVOR_IS(gcfMakerWare) ? "M135 T" :
+           FLAVOR_IS(gcfSailfish)  ? "M108 T" : "T";
+}
+
+std::string GCodeWriter::toolchange(unsigned int extruder_id)
+{
+    // set the new extruder
+    auto it_extruder = std::lower_bound(m_extruders.begin(), m_extruders.end(), Extruder::key(extruder_id));
+    assert(it_extruder != m_extruders.end());
+    m_extruder = const_cast<Extruder*>(&*it_extruder);
+
+    // return the toolchange command
+    // if we are running a single-extruder setup, just set the extruder and return nothing
+    std::ostringstream gcode;
+    if (this->multiple_extruders) {
+        gcode << this->toolchange_prefix() << extruder_id;
+        if (this->config.gcode_comments)
+            gcode << " ; change extruder";
+        gcode << "\n";
+        gcode << this->reset_e(true);
+    }
+    return gcode.str();
+}
+
+std::string GCodeWriter::set_speed(double F, const std::string &comment, const std::string &cooling_marker) const
+{
+    assert(F > 0.);
+    assert(F < 100000.);
+    std::ostringstream gcode;
+    gcode << "G1 F" << F;
+    COMMENT(comment);
+    gcode << cooling_marker;
+    gcode << "\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::travel_to_xy(const Vec2d &point, const std::string &comment)
+{
+    m_pos(0) = point(0);
+    m_pos(1) = point(1);
+    
+    std::ostringstream gcode;
+    gcode << "G1 X" << XYZF_NUM(point(0))
+          <<   " Y" << XYZF_NUM(point(1))
+          <<   " F" << XYZF_NUM(this->config.travel_speed.value * 60.0);
+    COMMENT(comment);
+    gcode << "\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::travel_to_xyz(const Vec3d &point, const std::string &comment)
+{
+    /*  If target Z is lower than current Z but higher than nominal Z we
+        don't perform the Z move but we only move in the XY plane and
+        adjust the nominal Z by reducing the lift amount that will be 
+        used for unlift. */
+    if (!this->will_move_z(point(2))) {
+        double nominal_z = m_pos(2) - m_lifted;
+        m_lifted = m_lifted - (point(2) - nominal_z);
+        return this->travel_to_xy(to_2d(point));
+    }
+    
+    /*  In all the other cases, we perform an actual XYZ move and cancel
+        the lift. */
+    m_lifted = 0;
+    m_pos = point;
+    
+    std::ostringstream gcode;
+    gcode << "G1 X" << XYZF_NUM(point(0))
+          <<   " Y" << XYZF_NUM(point(1))
+          <<   " Z" << XYZF_NUM(point(2))
+          <<   " F" << XYZF_NUM(this->config.travel_speed.value * 60.0);
+    COMMENT(comment);
+    gcode << "\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::travel_to_z(double z, const std::string &comment)
+{
+    /*  If target Z is lower than current Z but higher than nominal Z
+        we don't perform the move but we only adjust the nominal Z by
+        reducing the lift amount that will be used for unlift. */
+    if (!this->will_move_z(z)) {
+        double nominal_z = m_pos(2) - m_lifted;
+        m_lifted = m_lifted - (z - nominal_z);
+        return "";
+    }
+    
+    /*  In all the other cases, we perform an actual Z move and cancel
+        the lift. */
+    m_lifted = 0;
+    return this->_travel_to_z(z, comment);
+}
+
+std::string GCodeWriter::_travel_to_z(double z, const std::string &comment)
+{
+    m_pos(2) = z;
+    
+    std::ostringstream gcode;
+    gcode << "G1 Z" << XYZF_NUM(z)
+          <<   " F" << XYZF_NUM(this->config.travel_speed.value * 60.0);
+    COMMENT(comment);
+    gcode << "\n";
+    return gcode.str();
+}
+
+bool GCodeWriter::will_move_z(double z) const
+{
+    /* If target Z is lower than current Z but higher than nominal Z
+        we don't perform an actual Z move. */
+    if (m_lifted > 0) {
+        double nominal_z = m_pos(2) - m_lifted;
+        if (z >= nominal_z && z <= m_pos(2))
+            return false;
+    }
+    return true;
+}
+
+std::string GCodeWriter::extrude_to_xy(const Vec2d &point, double dE, const std::string &comment)
+{
+    m_pos(0) = point(0);
+    m_pos(1) = point(1);
+    m_extruder->extrude(dE);
+    
+    std::ostringstream gcode;
+    gcode << "G1 X" << XYZF_NUM(point(0))
+          <<   " Y" << XYZF_NUM(point(1))
+          <<    " " << m_extrusion_axis << E_NUM(m_extruder->E());
+    COMMENT(comment);
+    gcode << "\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::extrude_to_xyz(const Vec3d &point, double dE, const std::string &comment)
+{
+    m_pos = point;
+    m_lifted = 0;
+    m_extruder->extrude(dE);
+    
+    std::ostringstream gcode;
+    gcode << "G1 X" << XYZF_NUM(point(0))
+          <<   " Y" << XYZF_NUM(point(1))
+          <<   " Z" << XYZF_NUM(point(2))
+          <<    " " << m_extrusion_axis << E_NUM(m_extruder->E());
+    COMMENT(comment);
+    gcode << "\n";
+    return gcode.str();
+}
+
+std::string GCodeWriter::retract(bool before_wipe)
+{
+    double factor = before_wipe ? m_extruder->retract_before_wipe() : 1.;
+    assert(factor >= 0. && factor <= 1. + EPSILON);
+    return this->_retract(
+        factor * m_extruder->retract_length(),
+        factor * m_extruder->retract_restart_extra(),
+        "retract"
+    );
+}
+
+std::string GCodeWriter::retract_for_toolchange(bool before_wipe)
+{
+    double factor = before_wipe ? m_extruder->retract_before_wipe() : 1.;
+    assert(factor >= 0. && factor <= 1. + EPSILON);
+    return this->_retract(
+        factor * m_extruder->retract_length_toolchange(),
+        factor * m_extruder->retract_restart_extra_toolchange(),
+        "retract for toolchange"
+    );
+}
+
+std::string GCodeWriter::_retract(double length, double restart_extra, const std::string &comment)
+{
+    std::ostringstream gcode;
+    
+    /*  If firmware retraction is enabled, we use a fake value of 1
+        since we ignore the actual configured retract_length which 
+        might be 0, in which case the retraction logic gets skipped. */
+    if (this->config.use_firmware_retraction) length = 1;
+    
+    // If we use volumetric E values we turn lengths into volumes */
+    if (this->config.use_volumetric_e) {
+        double d = m_extruder->filament_diameter();
+        double area = d * d * PI/4;
+        length = length * area;
+        restart_extra = restart_extra * area;
+    }
+    
+    double dE = m_extruder->retract(length, restart_extra);
+    if (dE != 0) {
+        if (this->config.use_firmware_retraction) {
+            if (FLAVOR_IS(gcfMachinekit))
+                gcode << "G22 ; retract\n";
+            else
+                gcode << "G10 ; retract\n";
+        } else {
+            gcode << "G1 " << m_extrusion_axis << E_NUM(m_extruder->E())
+                           << " F" << float(m_extruder->retract_speed() * 60.);
+            COMMENT(comment);
+            gcode << "\n";
+        }
+    }
+    
+    if (FLAVOR_IS(gcfMakerWare))
+        gcode << "M103 ; extruder off\n";
+    
+    return gcode.str();
+}
+
+std::string GCodeWriter::unretract()
+{
+    std::ostringstream gcode;
+    
+    if (FLAVOR_IS(gcfMakerWare))
+        gcode << "M101 ; extruder on\n";
+    
+    double dE = m_extruder->unretract();
+    if (dE != 0) {
+        if (this->config.use_firmware_retraction) {
+            if (FLAVOR_IS(gcfMachinekit))
+                 gcode << "G23 ; unretract\n";
+            else
+                 gcode << "G11 ; unretract\n";
+            gcode << this->reset_e();
+        } else {
+            // use G1 instead of G0 because G0 will blend the restart with the previous travel move
+            gcode << "G1 " << m_extrusion_axis << E_NUM(m_extruder->E())
+                           << " F" << float(m_extruder->deretract_speed() * 60.);
+            if (this->config.gcode_comments) gcode << " ; unretract";
+            gcode << "\n";
+        }
+    }
+    
+    return gcode.str();
+}
+
+/*  If this method is called more than once before calling unlift(),
+    it will not perform subsequent lifts, even if Z was raised manually
+    (i.e. with travel_to_z()) and thus _lifted was reduced. */
+std::string GCodeWriter::lift()
+{
+    // check whether the above/below conditions are met
+    double target_lift = 0;
+    {
+        double above = this->config.retract_lift_above.get_at(m_extruder->id());
+        double below = this->config.retract_lift_below.get_at(m_extruder->id());
+        if (m_pos(2) >= above && (below == 0 || m_pos(2) <= below))
+            target_lift = this->config.retract_lift.get_at(m_extruder->id());
+    }
+    if (m_lifted == 0 && target_lift > 0) {
+        m_lifted = target_lift;
+        return this->_travel_to_z(m_pos(2) + target_lift, "lift Z");
+    }
+    return "";
+}
+
+std::string GCodeWriter::unlift()
+{
+    std::string gcode;
+    if (m_lifted > 0) {
+        gcode += this->_travel_to_z(m_pos(2) - m_lifted, "restore layer Z");
+        m_lifted = 0;
+    }
+    return gcode;
+}
+
+}

src/libslic3r/GCodeWriter.hpp

@@ -0,0 +1,92 @@
+#ifndef slic3r_GCodeWriter_hpp_
+#define slic3r_GCodeWriter_hpp_
+
+#include "libslic3r.h"
+#include <string>
+#include "Extruder.hpp"
+#include "Point.hpp"
+#include "PrintConfig.hpp"
+#include "GCode/CoolingBuffer.hpp"
+
+namespace Slic3r {
+
+class GCodeWriter {
+public:
+    GCodeConfig config;
+    bool multiple_extruders;
+    
+    GCodeWriter() : 
+        multiple_extruders(false), m_extrusion_axis("E"), m_extruder(nullptr),
+        m_single_extruder_multi_material(false),
+        m_last_acceleration(0), m_max_acceleration(0), m_last_fan_speed(0), 
+        m_last_bed_temperature(0), m_last_bed_temperature_reached(true), 
+        m_lifted(0)
+        {}
+    Extruder*            extruder()             { return m_extruder; }
+    const Extruder*      extruder()     const   { return m_extruder; }
+
+    std::string          extrusion_axis() const { return m_extrusion_axis; }
+    void                 apply_print_config(const PrintConfig &print_config);
+    // Extruders are expected to be sorted in an increasing order.
+    void                 set_extruders(const std::vector<unsigned int> &extruder_ids);
+    const std::vector<Extruder>& extruders() const { return m_extruders; }
+    std::vector<unsigned int> extruder_ids() const { 
+        std::vector<unsigned int> out; 
+        out.reserve(m_extruders.size()); 
+        for (const Extruder &e : m_extruders) 
+            out.push_back(e.id()); 
+        return out;
+    }
+    std::string preamble();
+    std::string postamble() const;
+    std::string set_temperature(unsigned int temperature, bool wait = false, int tool = -1) const;
+    std::string set_bed_temperature(unsigned int temperature, bool wait = false);
+    std::string set_fan(unsigned int speed, bool dont_save = false);
+    std::string set_acceleration(unsigned int acceleration);
+    std::string reset_e(bool force = false);
+    std::string update_progress(unsigned int num, unsigned int tot, bool allow_100 = false) const;
+    // return false if this extruder was already selected
+    bool        need_toolchange(unsigned int extruder_id) const 
+        { return m_extruder == nullptr || m_extruder->id() != extruder_id; }
+    std::string set_extruder(unsigned int extruder_id)
+        { return this->need_toolchange(extruder_id) ? this->toolchange(extruder_id) : ""; }
+    // Prefix of the toolchange G-code line, to be used by the CoolingBuffer to separate sections of the G-code
+    // printed with the same extruder.
+    std::string toolchange_prefix() const;
+    std::string toolchange(unsigned int extruder_id);
+    std::string set_speed(double F, const std::string &comment = std::string(), const std::string &cooling_marker = std::string()) const;
+    std::string travel_to_xy(const Vec2d &point, const std::string &comment = std::string());
+    std::string travel_to_xyz(const Vec3d &point, const std::string &comment = std::string());
+    std::string travel_to_z(double z, const std::string &comment = std::string());
+    bool        will_move_z(double z) const;
+    std::string extrude_to_xy(const Vec2d &point, double dE, const std::string &comment = std::string());
+    std::string extrude_to_xyz(const Vec3d &point, double dE, const std::string &comment = std::string());
+    std::string retract(bool before_wipe = false);
+    std::string retract_for_toolchange(bool before_wipe = false);
+    std::string unretract();
+    std::string lift();
+    std::string unlift();
+    Vec3d       get_position() const { return m_pos; }
+
+private:
+    std::vector<Extruder>    m_extruders;
+    std::string     m_extrusion_axis;
+    bool            m_single_extruder_multi_material;
+    Extruder*       m_extruder;
+    unsigned int    m_last_acceleration;
+    // Limit for setting the acceleration, to respect the machine limits set for the Marlin firmware.
+    // If set to zero, the limit is not in action.
+    unsigned int    m_max_acceleration;
+    unsigned int    m_last_fan_speed;
+    unsigned int    m_last_bed_temperature;
+    bool            m_last_bed_temperature_reached;
+    double          m_lifted;
+    Vec3d           m_pos = Vec3d::Zero();
+
+    std::string _travel_to_z(double z, const std::string &comment);
+    std::string _retract(double length, double restart_extra, const std::string &comment);
+};
+
+} /* namespace Slic3r */
+
+#endif /* slic3r_GCodeWriter_hpp_ */

src/libslic3r/Geometry.hpp

@@ -0,0 +1,263 @@
+#ifndef slic3r_Geometry_hpp_
+#define slic3r_Geometry_hpp_
+
+#include "libslic3r.h"
+#include "BoundingBox.hpp"
+#include "ExPolygon.hpp"
+#include "Polygon.hpp"
+#include "Polyline.hpp"
+
+#include "boost/polygon/voronoi.hpp"
+using boost::polygon::voronoi_builder;
+using boost::polygon::voronoi_diagram;
+
+namespace Slic3r { namespace Geometry {
+
+// Generic result of an orientation predicate.
+enum Orientation
+{
+    ORIENTATION_CCW = 1,
+    ORIENTATION_CW = -1,
+    ORIENTATION_COLINEAR = 0
+};
+
+// Return orientation of the three points (clockwise, counter-clockwise, colinear)
+// The predicate is exact for the coord_t type, using 64bit signed integers for the temporaries.
+// which means, the coord_t types must not have some of the topmost bits utilized.
+// As the points are limited to 30 bits + signum,
+// the temporaries u, v, w are limited to 61 bits + signum,
+// and d is limited to 63 bits + signum and we are good.
+static inline Orientation orient(const Point &a, const Point &b, const Point &c)
+{
+    // BOOST_STATIC_ASSERT(sizeof(coord_t) * 2 == sizeof(int64_t));
+    int64_t u = int64_t(b(0)) * int64_t(c(1)) - int64_t(b(1)) * int64_t(c(0));
+    int64_t v = int64_t(a(0)) * int64_t(c(1)) - int64_t(a(1)) * int64_t(c(0));
+    int64_t w = int64_t(a(0)) * int64_t(b(1)) - int64_t(a(1)) * int64_t(b(0));
+    int64_t d = u - v + w;
+    return (d > 0) ? ORIENTATION_CCW : ((d == 0) ? ORIENTATION_COLINEAR : ORIENTATION_CW);
+}
+
+// Return orientation of the polygon by checking orientation of the left bottom corner of the polygon
+// using exact arithmetics. The input polygon must not contain duplicate points
+// (or at least the left bottom corner point must not have duplicates).
+static inline bool is_ccw(const Polygon &poly)
+{
+    // The polygon shall be at least a triangle.
+    assert(poly.points.size() >= 3);
+    if (poly.points.size() < 3)
+        return true;
+
+    // 1) Find the lowest lexicographical point.
+    unsigned int imin = 0;
+    for (unsigned int i = 1; i < poly.points.size(); ++ i) {
+        const Point &pmin = poly.points[imin];
+        const Point &p    = poly.points[i];
+        if (p(0) < pmin(0) || (p(0) == pmin(0) && p(1) < pmin(1)))
+            imin = i;
+    }
+
+    // 2) Detect the orientation of the corner imin.
+    size_t iPrev = ((imin == 0) ? poly.points.size() : imin) - 1;
+    size_t iNext = ((imin + 1 == poly.points.size()) ? 0 : imin + 1);
+    Orientation o = orient(poly.points[iPrev], poly.points[imin], poly.points[iNext]);
+    // The lowest bottom point must not be collinear if the polygon does not contain duplicate points
+    // or overlapping segments.
+    assert(o != ORIENTATION_COLINEAR);
+    return o == ORIENTATION_CCW;
+}
+
+inline bool ray_ray_intersection(const Vec2d &p1, const Vec2d &v1, const Vec2d &p2, const Vec2d &v2, Vec2d &res)
+{
+    double denom = v1(0) * v2(1) - v2(0) * v1(1);
+    if (std::abs(denom) < EPSILON)
+        return false;
+    double t = (v2(0) * (p1(1) - p2(1)) - v2(1) * (p1(0) - p2(0))) / denom;
+    res(0) = p1(0) + t * v1(0);
+    res(1) = p1(1) + t * v1(1);
+    return true;
+}
+
+inline bool segment_segment_intersection(const Vec2d &p1, const Vec2d &v1, const Vec2d &p2, const Vec2d &v2, Vec2d &res)
+{
+    double denom = v1(0) * v2(1) - v2(0) * v1(1);
+    if (std::abs(denom) < EPSILON)
+        // Lines are collinear.
+        return false;
+    double s12_x = p1(0) - p2(0);
+    double s12_y = p1(1) - p2(1);
+    double s_numer = v1(0) * s12_y - v1(1) * s12_x;
+    bool   denom_is_positive = false;
+    if (denom < 0.) {
+        denom_is_positive = true;
+        denom   = - denom;
+        s_numer = - s_numer;
+    }
+    if (s_numer < 0.)
+        // Intersection outside of the 1st segment.
+        return false;
+    double t_numer = v2(0) * s12_y - v2(1) * s12_x;
+    if (! denom_is_positive)
+        t_numer = - t_numer;
+    if (t_numer < 0. || s_numer > denom || t_numer > denom)
+        // Intersection outside of the 1st or 2nd segment.
+        return false;
+    // Intersection inside both of the segments.
+    double t = t_numer / denom;
+    res(0) = p1(0) + t * v1(0);
+    res(1) = p1(1) + t * v1(1);
+    return true;
+}
+
+Pointf3s convex_hull(Pointf3s points);
+Polygon convex_hull(Points points);
+Polygon convex_hull(const Polygons &polygons);
+
+void chained_path(const Points &points, std::vector<Points::size_type> &retval, Point start_near);
+void chained_path(const Points &points, std::vector<Points::size_type> &retval);
+template<class T> void chained_path_items(Points &points, T &items, T &retval);
+bool directions_parallel(double angle1, double angle2, double max_diff = 0);
+template<class T> bool contains(const std::vector<T> &vector, const Point &point);
+template<typename T> T rad2deg(T angle) { return T(180.0) * angle / T(PI); }
+double rad2deg_dir(double angle);
+template<typename T> T deg2rad(T angle) { return T(PI) * angle / T(180.0); }
+template<typename T> T angle_to_0_2PI(T angle)
+{
+    static const T TWO_PI = T(2) * T(PI);
+    while (angle < T(0))
+    {
+        angle += TWO_PI;
+    }
+    while (TWO_PI < angle)
+    {
+        angle -= TWO_PI;
+    }
+
+    return angle;
+}
+void simplify_polygons(const Polygons &polygons, double tolerance, Polygons* retval);
+
+double linint(double value, double oldmin, double oldmax, double newmin, double newmax);
+bool arrange(
+    // input
+    size_t num_parts, const Vec2d &part_size, coordf_t gap, const BoundingBoxf* bed_bounding_box, 
+    // output
+    Pointfs &positions);
+
+class MedialAxis {
+    public:
+    Lines lines;
+    const ExPolygon* expolygon;
+    double max_width;
+    double min_width;
+    MedialAxis(double _max_width, double _min_width, const ExPolygon* _expolygon = NULL)
+        : expolygon(_expolygon), max_width(_max_width), min_width(_min_width) {};
+    void build(ThickPolylines* polylines);
+    void build(Polylines* polylines);
+    
+    private:
+    class VD : public voronoi_diagram<double> {
+    public:
+        typedef double                                          coord_type;
+        typedef boost::polygon::point_data<coordinate_type>     point_type;
+        typedef boost::polygon::segment_data<coordinate_type>   segment_type;
+        typedef boost::polygon::rectangle_data<coordinate_type> rect_type;
+    };
+    VD vd;
+    std::set<const VD::edge_type*> edges, valid_edges;
+    std::map<const VD::edge_type*, std::pair<coordf_t,coordf_t> > thickness;
+    void process_edge_neighbors(const VD::edge_type* edge, ThickPolyline* polyline);
+    bool validate_edge(const VD::edge_type* edge);
+    const Line& retrieve_segment(const VD::cell_type* cell) const;
+    const Point& retrieve_endpoint(const VD::cell_type* cell) const;
+};
+
+// Sets the given transform by assembling the given transformations in the following order:
+// 1) mirror
+// 2) scale
+// 3) rotate X
+// 4) rotate Y
+// 5) rotate Z
+// 6) translate
+void assemble_transform(Transform3d& transform, const Vec3d& translation = Vec3d::Zero(), const Vec3d& rotation = Vec3d::Zero(), const Vec3d& scale = Vec3d::Ones(), const Vec3d& mirror = Vec3d::Ones());
+
+// Returns the transform obtained by assembling the given transformations in the following order:
+// 1) mirror
+// 2) scale
+// 3) rotate X
+// 4) rotate Y
+// 5) rotate Z
+// 6) translate
+Transform3d assemble_transform(const Vec3d& translation = Vec3d::Zero(), const Vec3d& rotation = Vec3d::Zero(), const Vec3d& scale = Vec3d::Ones(), const Vec3d& mirror = Vec3d::Ones());
+
+// Returns the euler angles extracted from the given rotation matrix
+// Warning -> The matrix should not contain any scale or shear !!!
+Vec3d extract_euler_angles(const Eigen::Matrix<double, 3, 3, Eigen::DontAlign>& rotation_matrix);
+
+// Returns the euler angles extracted from the given affine transform
+// Warning -> The transform should not contain any shear !!!
+Vec3d extract_euler_angles(const Transform3d& transform);
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+class Transformation
+{
+    struct Flags
+    {
+        bool dont_translate;
+        bool dont_rotate;
+        bool dont_scale;
+        bool dont_mirror;
+
+        Flags();
+
+        bool needs_update(bool dont_translate, bool dont_rotate, bool dont_scale, bool dont_mirror) const;
+        void set(bool dont_translate, bool dont_rotate, bool dont_scale, bool dont_mirror);
+    };
+
+    Vec3d m_offset;              // In unscaled coordinates
+    Vec3d m_rotation;            // Rotation around the three axes, in radians around mesh center point
+    Vec3d m_scaling_factor;      // Scaling factors along the three axes
+    Vec3d m_mirror;              // Mirroring along the three axes
+
+    mutable Transform3d m_matrix;
+    mutable Flags m_flags;
+    mutable bool m_dirty;
+
+public:
+    Transformation();
+    explicit Transformation(const Transform3d& transform);
+
+    const Vec3d& get_offset() const { return m_offset; }
+    double get_offset(Axis axis) const { return m_offset(axis); }
+
+    void set_offset(const Vec3d& offset);
+    void set_offset(Axis axis, double offset);
+
+    const Vec3d& get_rotation() const { return m_rotation; }
+    double get_rotation(Axis axis) const { return m_rotation(axis); }
+
+    void set_rotation(const Vec3d& rotation);
+    void set_rotation(Axis axis, double rotation);
+
+    Vec3d get_scaling_factor() const { return m_scaling_factor; }
+    double get_scaling_factor(Axis axis) const { return m_scaling_factor(axis); }
+
+    void set_scaling_factor(const Vec3d& scaling_factor);
+    void set_scaling_factor(Axis axis, double scaling_factor);
+
+    const Vec3d& get_mirror() const { return m_mirror; }
+    double get_mirror(Axis axis) const { return m_mirror(axis); }
+
+    void set_mirror(const Vec3d& mirror);
+    void set_mirror(Axis axis, double mirror);
+
+    void set_from_transform(const Transform3d& transform);
+
+    const Transform3d& get_matrix(bool dont_translate = false, bool dont_rotate = false, bool dont_scale = false, bool dont_mirror = false) const;
+
+    Transformation operator * (const Transformation& other) const;
+};
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+} }
+
+#endif

src/libslic3r/I18N.hpp

@@ -0,0 +1,18 @@
+#ifndef slic3r_I18N_hpp_
+#define slic3r_I18N_hpp_
+
+#include <string>
+
+namespace Slic3r {
+
+namespace I18N {
+	typedef std::string (*translate_fn_type)(const char*);
+	extern translate_fn_type translate_fn;
+	inline void set_translate_callback(translate_fn_type fn) { translate_fn = fn; }
+	inline std::string translate(const std::string &s) { return (translate_fn == nullptr) ? s : (*translate_fn)(s.c_str()); }
+	inline std::string translate(const char *ptr) { return (translate_fn == nullptr) ? std::string(ptr) : (*translate_fn)(ptr); }
+} // namespace I18N
+
+} // namespace Slic3r
+
+#endif /* slic3r_I18N_hpp_ */

src/libslic3r/Int128.hpp

@@ -0,0 +1,290 @@
+// This is an excerpt of from the Clipper library by Angus Johnson, see the license below,
+// implementing a 64 x 64 -> 128bit multiply, and 128bit addition, subtraction and compare
+// operations, to be used with exact geometric predicates.
+// The code has been extended by Vojtech Bubnik to use 128 bit intrinsic types
+// and/or 64x64->128 intrinsic functions where possible.
+
+/*******************************************************************************
+*                                                                              *
+* Author    :  Angus Johnson                                                   *
+* Version   :  6.2.9                                                           *
+* Date      :  16 February 2015                                                *
+* Website   :  http://www.angusj.com                                           *
+* Copyright :  Angus Johnson 2010-2015                                         *
+*                                                                              *
+* License:                                                                     *
+* Use, modification & distribution is subject to Boost Software License Ver 1. *
+* http://www.boost.org/LICENSE_1_0.txt                                         *
+*                                                                              *
+* Attributions:                                                                *
+* The code in this library is an extension of Bala Vatti's clipping algorithm: *
+* "A generic solution to polygon clipping"                                     *
+* Communications of the ACM, Vol 35, Issue 7 (July 1992) pp 56-63.             *
+* http://portal.acm.org/citation.cfm?id=129906                                 *
+*                                                                              *
+* Computer graphics and geometric modeling: implementation and algorithms      *
+* By Max K. Agoston                                                            *
+* Springer; 1 edition (January 4, 2005)                                        *
+* http://books.google.com/books?q=vatti+clipping+agoston                       *
+*                                                                              *
+* See also:                                                                    *
+* "Polygon Offsetting by Computing Winding Numbers"                            *
+* Paper no. DETC2005-85513 pp. 565-575                                         *
+* ASME 2005 International Design Engineering Technical Conferences             *
+* and Computers and Information in Engineering Conference (IDETC/CIE2005)      *
+* September 24-28, 2005 , Long Beach, California, USA                          *
+* http://www.me.berkeley.edu/~mcmains/pubs/DAC05OffsetPolygon.pdf              *
+*                                                                              *
+*******************************************************************************/
+
+// #define SLIC3R_DEBUG
+
+// Make assert active if SLIC3R_DEBUG
+#ifdef SLIC3R_DEBUG
+    #undef NDEBUG
+    #define DEBUG
+    #define _DEBUG
+    #undef assert 
+#endif
+
+#include <cassert>
+
+#if ! defined(_MSC_VER) && defined(__SIZEOF_INT128__)
+	#define HAS_INTRINSIC_128_TYPE
+#endif
+
+//------------------------------------------------------------------------------
+// Int128 class (enables safe math on signed 64bit integers)
+// eg Int128 val1((int64_t)9223372036854775807); //ie 2^63 -1
+//    Int128 val2((int64_t)9223372036854775807);
+//    Int128 val3 = val1 * val2;
+//------------------------------------------------------------------------------
+
+class Int128
+{
+
+#ifdef HAS_INTRINSIC_128_TYPE
+
+/******************************************** Using the intrinsic 128bit x 128bit multiply ************************************************/
+
+public:
+	__int128 value;
+
+	Int128(int64_t lo = 0) : value(lo) {}
+	Int128(const Int128 &v) : value(v.value) {}
+
+	Int128& operator=(const int64_t &rhs) { value = rhs; return *this; }
+
+	uint64_t lo()   const { return uint64_t(value); }
+	int64_t  hi()   const { return int64_t(value >> 64); }
+	int      sign() const { return (value > 0) - (value < 0); }
+
+	bool operator==(const Int128 &rhs) const { return value == rhs.value; }
+	bool operator!=(const Int128 &rhs) const { return value != rhs.value; }
+	bool operator> (const Int128 &rhs) const { return value >  rhs.value; }
+	bool operator< (const Int128 &rhs) const { return value <  rhs.value; }
+	bool operator>=(const Int128 &rhs) const { return value >= rhs.value; }
+	bool operator<=(const Int128 &rhs) const { return value <= rhs.value; }
+
+	Int128& operator+=(const Int128 &rhs) 		{ value += rhs.value; return *this; }
+	Int128  operator+ (const Int128 &rhs) const { return Int128(value + rhs.value); }
+	Int128& operator-=(const Int128 &rhs)		{ value -= rhs.value; return *this; }
+	Int128  operator -(const Int128 &rhs) const { return Int128(value - rhs.value); }
+	Int128  operator -()                  const { return Int128(- value); }
+
+	operator double() 				      const { return double(value); }
+
+	static inline Int128 multiply(int64_t lhs, int64_t rhs) { return Int128(__int128(lhs) * __int128(rhs)); }
+
+	// Evaluate signum of a 2x2 determinant.
+	static int sign_determinant_2x2(int64_t a11, int64_t a12, int64_t a21, int64_t a22)
+	{
+		__int128 det = __int128(a11) * __int128(a22) - __int128(a12) * __int128(a21);
+		return (det > 0) - (det < 0);
+	}
+
+	// Compare two rational numbers.
+	static int compare_rationals(int64_t p1, int64_t q1, int64_t p2, int64_t q2)
+	{
+		int invert = ((q1 < 0) == (q2 < 0)) ? 1 : -1;
+		__int128 det = __int128(p1) * __int128(q2) - __int128(p2) * __int128(q1);
+		return ((det > 0) - (det < 0)) * invert;
+	}
+
+#else /* HAS_INTRINSIC_128_TYPE */
+
+/******************************************** Splitting the 128bit number into two 64bit words *********************************************/
+
+	Int128(int64_t lo = 0) : m_lo((uint64_t)lo), m_hi((lo < 0) ? -1 : 0) {}
+	Int128(const Int128 &val) : m_lo(val.m_lo), m_hi(val.m_hi) {}
+	Int128(const int64_t& hi, const uint64_t& lo) : m_lo(lo), m_hi(hi) {}
+
+	Int128& operator = (const int64_t &val)
+	{
+		m_lo = (uint64_t)val;
+		m_hi = (val < 0) ? -1 : 0;
+		return *this;
+	}
+
+	uint64_t lo()   const { return m_lo; }
+	int64_t  hi()   const { return m_hi; }
+	int      sign() const { return (m_hi == 0) ? (m_lo > 0) : (m_hi > 0) - (m_hi < 0); }
+
+	bool operator == (const Int128 &val) const { return m_hi == val.m_hi && m_lo == val.m_lo; }
+	bool operator != (const Int128 &val) const { return ! (*this == val); }
+	bool operator >  (const Int128 &val) const { return (m_hi == val.m_hi) ? m_lo > val.m_lo : m_hi > val.m_hi; }
+	bool operator <  (const Int128 &val) const { return (m_hi == val.m_hi) ? m_lo < val.m_lo : m_hi < val.m_hi; }
+	bool operator >= (const Int128 &val) const { return ! (*this < val); }
+	bool operator <= (const Int128 &val) const { return ! (*this > val); }
+
+	Int128& operator += (const Int128 &rhs)
+	{
+		m_hi += rhs.m_hi;
+		m_lo += rhs.m_lo;
+		if (m_lo < rhs.m_lo) m_hi++;
+		return *this;
+	}
+
+	Int128 operator + (const Int128 &rhs) const
+	{
+		Int128 result(*this);
+		result+= rhs;
+		return result;
+	}
+
+	Int128& operator -= (const Int128 &rhs)
+	{
+		*this += -rhs;
+		return *this;
+	}
+
+	Int128 operator - (const Int128 &rhs) const
+	{
+		Int128 result(*this);
+		result -= rhs;
+		return result;
+	}
+
+	Int128 operator-() const { return (m_lo == 0) ? Int128(-m_hi, 0) : Int128(~m_hi, ~m_lo + 1); }
+
+	operator double() const
+	{
+		const double shift64 = 18446744073709551616.0; //2^64
+		return (m_hi < 0) ?
+		((m_lo == 0) ? 
+		(double)m_hi * shift64 :
+		-(double)(~m_lo + ~m_hi * shift64)) :
+		(double)(m_lo + m_hi * shift64);
+	}
+
+	static inline Int128 multiply(int64_t lhs, int64_t rhs)
+	{
+#if defined(_MSC_VER) && defined(_WIN64)
+		// On Visual Studio 64bit, use the _mul128() intrinsic function.
+		Int128 result;
+	    result.m_lo = (uint64_t)_mul128(lhs, rhs, &result.m_hi);
+	    return result;
+#else
+	    // This branch should only be executed in case there is neither __int16 type nor _mul128 intrinsic
+	    // function available. This is mostly on 32bit operating systems.
+	    // Use a pure C implementation of _mul128().
+
+		int negate = (lhs < 0) != (rhs < 0);
+
+		if (lhs < 0)
+			lhs = -lhs;
+		uint64_t int1Hi = uint64_t(lhs) >> 32;
+		uint64_t int1Lo = uint64_t(lhs & 0xFFFFFFFF);
+
+		if (rhs < 0)
+			rhs = -rhs;
+		uint64_t int2Hi = uint64_t(rhs) >> 32;
+		uint64_t int2Lo = uint64_t(rhs & 0xFFFFFFFF);
+
+		//because the high (sign) bits in both int1Hi & int2Hi have been zeroed,
+		//there's no risk of 64 bit overflow in the following assignment
+		//(ie: $7FFFFFFF*$FFFFFFFF + $7FFFFFFF*$FFFFFFFF < 64bits)
+		uint64_t a = int1Hi * int2Hi;
+		uint64_t b = int1Lo * int2Lo;
+		//Result = A shl 64 + C shl 32 + B ...
+		uint64_t c = int1Hi * int2Lo + int1Lo * int2Hi;
+
+		Int128 tmp;
+		tmp.m_hi = int64_t(a + (c >> 32));
+		tmp.m_lo = int64_t(c << 32);
+		tmp.m_lo += int64_t(b);
+		if (tmp.m_lo < b) 
+			++ tmp.m_hi;
+		if (negate) 
+			tmp = - tmp;
+		return tmp;
+#endif
+	}
+
+	// Evaluate signum of a 2x2 determinant.
+	static int sign_determinant_2x2(int64_t a11, int64_t a12, int64_t a21, int64_t a22)
+	{
+		return (Int128::multiply(a11, a22) - Int128::multiply(a12, a21)).sign();
+	}
+
+	// Compare two rational numbers.
+	static int compare_rationals(int64_t p1, int64_t q1, int64_t p2, int64_t q2)
+	{
+		int invert = ((q1 < 0) == (q2 < 0)) ? 1 : -1;
+		Int128 det = Int128::multiply(p1, q2) - Int128::multiply(p2, q1);
+		return det.sign() * invert;
+	}
+
+private:
+	uint64_t m_lo;
+	int64_t  m_hi;
+
+
+#endif /* HAS_INTRINSIC_128_TYPE */
+
+
+/******************************************** Common methods ************************************************/
+
+public:
+
+	// Evaluate signum of a 2x2 determinant, use a numeric filter to avoid 128 bit multiply if possible.
+	static int sign_determinant_2x2_filtered(int64_t a11, int64_t a12, int64_t a21, int64_t a22)
+	{
+		// First try to calculate the determinant over the upper 31 bits.
+		// Round p1, p2, q1, q2 to 31 bits.
+		int64_t a11s = (a11 + (1 << 31)) >> 32;
+		int64_t a12s = (a12 + (1 << 31)) >> 32;
+		int64_t a21s = (a21 + (1 << 31)) >> 32;
+		int64_t a22s = (a22 + (1 << 31)) >> 32;
+		// Result fits 63 bits, it is an approximate of the determinant divided by 2^64.
+		int64_t det  = a11s * a22s - a12s * a21s;
+		// Maximum absolute of the remainder of the exact determinant, divided by 2^64.
+		int64_t err  = ((std::abs(a11s) + std::abs(a12s) + std::abs(a21s) + std::abs(a22s)) << 1) + 1;
+		assert(std::abs(det) <= err || ((det > 0) ? 1 : -1) == sign_determinant_2x2(a11, a12, a21, a22));
+		return (std::abs(det) > err) ?
+			((det > 0) ? 1 : -1) :
+			sign_determinant_2x2(a11, a12, a21, a22);
+	}
+
+	// Compare two rational numbers, use a numeric filter to avoid 128 bit multiply if possible.
+	static int compare_rationals_filtered(int64_t p1, int64_t q1, int64_t p2, int64_t q2)
+	{
+		// First try to calculate the determinant over the upper 31 bits.
+		// Round p1, p2, q1, q2 to 31 bits.
+		int     invert = ((q1 < 0) == (q2 < 0)) ? 1 : -1;
+		int64_t q1s = (q1 + (1 << 31)) >> 32;
+		int64_t q2s = (q2 + (1 << 31)) >> 32;
+		if (q1s != 0 && q2s != 0) {
+			int64_t p1s = (p1 + (1 << 31)) >> 32;
+			int64_t p2s = (p2 + (1 << 31)) >> 32;
+			// Result fits 63 bits, it is an approximate of the determinant divided by 2^64.
+			int64_t det = p1s * q2s - p2s * q1s;
+			// Maximum absolute of the remainder of the exact determinant, divided by 2^64.
+			int64_t err = ((std::abs(p1s) + std::abs(q1s) + std::abs(p2s) + std::abs(q2s)) << 1) + 1;
+			assert(std::abs(det) <= err || ((det > 0) ? 1 : -1) * invert == compare_rationals(p1, q1, p2, q2));
+			if (std::abs(det) > err)
+				return ((det > 0) ? 1 : -1) * invert;
+		}
+		return sign_determinant_2x2(p1, q1, p2, q2) * invert;
+	}
+};

src/libslic3r/Layer.cpp

@@ -0,0 +1,213 @@
+#include "Layer.hpp"
+#include "ClipperUtils.hpp"
+#include "Geometry.hpp"
+#include "Print.hpp"
+#include "Fill/Fill.hpp"
+#include "SVG.hpp"
+
+#include <boost/log/trivial.hpp>
+
+namespace Slic3r {
+
+Layer::~Layer()
+{
+    this->lower_layer = this->upper_layer = nullptr;
+    for (LayerRegion *region : m_regions)
+        delete region;
+    m_regions.clear();
+}
+
+LayerRegion* Layer::add_region(PrintRegion* print_region)
+{
+    m_regions.emplace_back(new LayerRegion(this, print_region));
+    return m_regions.back();
+}
+
+// merge all regions' slices to get islands
+void Layer::make_slices()
+{
+    ExPolygons slices;
+    if (m_regions.size() == 1) {
+        // optimization: if we only have one region, take its slices
+        slices = m_regions.front()->slices;
+    } else {
+        Polygons slices_p;
+        for (LayerRegion *layerm : m_regions)
+            polygons_append(slices_p, to_polygons(layerm->slices));
+        slices = union_ex(slices_p);
+    }
+    
+    this->slices.expolygons.clear();
+    this->slices.expolygons.reserve(slices.size());
+    
+    // prepare ordering points
+    Points ordering_points;
+    ordering_points.reserve(slices.size());
+    for (const ExPolygon &ex : slices)
+        ordering_points.push_back(ex.contour.first_point());
+    
+    // sort slices
+    std::vector<Points::size_type> order;
+    Slic3r::Geometry::chained_path(ordering_points, order);
+    
+    // populate slices vector
+    for (size_t i : order)
+        this->slices.expolygons.push_back(std::move(slices[i]));
+}
+
+void Layer::merge_slices()
+{
+    if (m_regions.size() == 1) {
+        // Optimization, also more robust. Don't merge classified pieces of layerm->slices,
+        // but use the non-split islands of a layer. For a single region print, these shall be equal.
+        m_regions.front()->slices.set(this->slices.expolygons, stInternal);
+    } else {
+        for (LayerRegion *layerm : m_regions)
+            // without safety offset, artifacts are generated (GH #2494)
+            layerm->slices.set(union_ex(to_polygons(std::move(layerm->slices.surfaces)), true), stInternal);
+    }
+}
+
+// Here the perimeters are created cummulatively for all layer regions sharing the same parameters influencing the perimeters.
+// The perimeter paths and the thin fills (ExtrusionEntityCollection) are assigned to the first compatible layer region.
+// The resulting fill surface is split back among the originating regions.
+void Layer::make_perimeters()
+{
+    BOOST_LOG_TRIVIAL(trace) << "Generating perimeters for layer " << this->id();
+    
+    // keep track of regions whose perimeters we have already generated
+    std::set<size_t> done;
+    
+    for (LayerRegionPtrs::iterator layerm = m_regions.begin(); layerm != m_regions.end(); ++ layerm) {
+        size_t region_id = layerm - m_regions.begin();
+        if (done.find(region_id) != done.end()) continue;
+        BOOST_LOG_TRIVIAL(trace) << "Generating perimeters for layer " << this->id() << ", region " << region_id;
+        done.insert(region_id);
+        const PrintRegionConfig &config = (*layerm)->region()->config();
+        
+        // find compatible regions
+        LayerRegionPtrs layerms;
+        layerms.push_back(*layerm);
+        for (LayerRegionPtrs::const_iterator it = layerm + 1; it != m_regions.end(); ++it) {
+            LayerRegion* other_layerm = *it;
+            const PrintRegionConfig &other_config = other_layerm->region()->config();
+            
+            if (config.perimeter_extruder   == other_config.perimeter_extruder
+                && config.perimeters        == other_config.perimeters
+                && config.perimeter_speed   == other_config.perimeter_speed
+                && config.external_perimeter_speed == other_config.external_perimeter_speed
+                && config.gap_fill_speed    == other_config.gap_fill_speed
+                && config.overhangs         == other_config.overhangs
+                && config.serialize("perimeter_extrusion_width").compare(other_config.serialize("perimeter_extrusion_width")) == 0
+                && config.thin_walls        == other_config.thin_walls
+                && config.external_perimeters_first == other_config.external_perimeters_first) {
+                layerms.push_back(other_layerm);
+                done.insert(it - m_regions.begin());
+            }
+        }
+        
+        if (layerms.size() == 1) {  // optimization
+            (*layerm)->fill_surfaces.surfaces.clear();
+            (*layerm)->make_perimeters((*layerm)->slices, &(*layerm)->fill_surfaces);
+            (*layerm)->fill_expolygons = to_expolygons((*layerm)->fill_surfaces.surfaces);
+        } else {
+            SurfaceCollection new_slices;
+            {
+                // group slices (surfaces) according to number of extra perimeters
+                std::map<unsigned short,Surfaces> slices;  // extra_perimeters => [ surface, surface... ]
+                for (LayerRegionPtrs::iterator l = layerms.begin(); l != layerms.end(); ++l) {
+                    for (Surfaces::iterator s = (*l)->slices.surfaces.begin(); s != (*l)->slices.surfaces.end(); ++s) {
+                        slices[s->extra_perimeters].push_back(*s);
+                    }
+                }
+                // merge the surfaces assigned to each group
+                for (std::map<unsigned short,Surfaces>::const_iterator it = slices.begin(); it != slices.end(); ++it)
+                    new_slices.append(union_ex(it->second, true), it->second.front());
+            }
+            
+            // make perimeters
+            SurfaceCollection fill_surfaces;
+            (*layerm)->make_perimeters(new_slices, &fill_surfaces);
+
+            // assign fill_surfaces to each layer
+            if (!fill_surfaces.surfaces.empty()) { 
+                for (LayerRegionPtrs::iterator l = layerms.begin(); l != layerms.end(); ++l) {
+                    // Separate the fill surfaces.
+                    ExPolygons expp = intersection_ex(to_polygons(fill_surfaces), (*l)->slices);
+                    (*l)->fill_expolygons = expp;
+                    (*l)->fill_surfaces.set(std::move(expp), fill_surfaces.surfaces.front());
+                }
+            }
+        }
+    }
+    BOOST_LOG_TRIVIAL(trace) << "Generating perimeters for layer " << this->id() << " - Done";
+}
+
+void Layer::make_fills()
+{
+    #ifdef SLIC3R_DEBUG
+    printf("Making fills for layer " PRINTF_ZU "\n", this->id());
+    #endif
+    for (LayerRegion *layerm : m_regions) {
+        layerm->fills.clear();
+        make_fill(*layerm, layerm->fills);
+#ifndef NDEBUG
+        for (size_t i = 0; i < layerm->fills.entities.size(); ++ i)
+            assert(dynamic_cast<ExtrusionEntityCollection*>(layerm->fills.entities[i]) != NULL);
+#endif
+    }
+}
+
+void Layer::export_region_slices_to_svg(const char *path) const
+{
+    BoundingBox bbox;
+    for (const auto *region : m_regions)
+        for (const auto &surface : region->slices.surfaces)
+            bbox.merge(get_extents(surface.expolygon));
+    Point legend_size = export_surface_type_legend_to_svg_box_size();
+    Point legend_pos(bbox.min(0), bbox.max(1));
+    bbox.merge(Point(std::max(bbox.min(0) + legend_size(0), bbox.max(0)), bbox.max(1) + legend_size(1)));
+
+    SVG svg(path, bbox);
+    const float transparency = 0.5f;
+    for (const auto *region : m_regions)
+        for (const auto &surface : region->slices.surfaces)
+            svg.draw(surface.expolygon, surface_type_to_color_name(surface.surface_type), transparency);
+    export_surface_type_legend_to_svg(svg, legend_pos);
+    svg.Close(); 
+}
+
+// Export to "out/LayerRegion-name-%d.svg" with an increasing index with every export.
+void Layer::export_region_slices_to_svg_debug(const char *name) const
+{
+    static size_t idx = 0;
+    this->export_region_slices_to_svg(debug_out_path("Layer-slices-%s-%d.svg", name, idx ++).c_str());
+}
+
+void Layer::export_region_fill_surfaces_to_svg(const char *path) const
+{
+    BoundingBox bbox;
+    for (const auto *region : m_regions)
+        for (const auto &surface : region->slices.surfaces)
+            bbox.merge(get_extents(surface.expolygon));
+    Point legend_size = export_surface_type_legend_to_svg_box_size();
+    Point legend_pos(bbox.min(0), bbox.max(1));
+    bbox.merge(Point(std::max(bbox.min(0) + legend_size(0), bbox.max(0)), bbox.max(1) + legend_size(1)));
+
+    SVG svg(path, bbox);
+    const float transparency = 0.5f;
+    for (const auto *region : m_regions)
+        for (const auto &surface : region->slices.surfaces)
+            svg.draw(surface.expolygon, surface_type_to_color_name(surface.surface_type), transparency);
+    export_surface_type_legend_to_svg(svg, legend_pos);
+    svg.Close();
+}
+
+// Export to "out/LayerRegion-name-%d.svg" with an increasing index with every export.
+void Layer::export_region_fill_surfaces_to_svg_debug(const char *name) const
+{
+    static size_t idx = 0;
+    this->export_region_fill_surfaces_to_svg(debug_out_path("Layer-fill_surfaces-%s-%d.svg", name, idx ++).c_str());
+}
+
+}

src/libslic3r/Layer.hpp

@@ -0,0 +1,179 @@
+#ifndef slic3r_Layer_hpp_
+#define slic3r_Layer_hpp_
+
+#include "libslic3r.h"
+#include "Flow.hpp"
+#include "SurfaceCollection.hpp"
+#include "ExtrusionEntityCollection.hpp"
+#include "ExPolygonCollection.hpp"
+#include "PolylineCollection.hpp"
+
+
+namespace Slic3r {
+
+class Layer;
+class PrintRegion;
+class PrintObject;
+
+class LayerRegion
+{
+public:
+    Layer*                      layer()         { return m_layer; }
+    const Layer*                layer() const   { return m_layer; }
+    PrintRegion*                region()        { return m_region; }
+    const PrintRegion*          region() const  { return m_region; }
+
+    // collection of surfaces generated by slicing the original geometry
+    // divided by type top/bottom/internal
+    SurfaceCollection           slices;
+
+    // collection of extrusion paths/loops filling gaps
+    // These fills are generated by the perimeter generator.
+    // They are not printed on their own, but they are copied to this->fills during infill generation.
+    ExtrusionEntityCollection   thin_fills;
+
+    // Unspecified fill polygons, used for overhang detection ("ensure vertical wall thickness feature")
+    // and for re-starting of infills.
+    ExPolygons                  fill_expolygons;
+    // collection of surfaces for infill generation
+    SurfaceCollection           fill_surfaces;
+
+    // Collection of perimeter surfaces. This is a cached result of diff(slices, fill_surfaces).
+    // While not necessary, the memory consumption is meager and it speeds up calculation.
+    // The perimeter_surfaces keep the IDs of the slices (top/bottom/)
+    SurfaceCollection           perimeter_surfaces;
+
+    // collection of expolygons representing the bridged areas (thus not
+    // needing support material)
+    Polygons                    bridged;
+
+    // collection of polylines representing the unsupported bridge edges
+    PolylineCollection          unsupported_bridge_edges;
+
+    // ordered collection of extrusion paths/loops to build all perimeters
+    // (this collection contains only ExtrusionEntityCollection objects)
+    ExtrusionEntityCollection   perimeters;
+
+    // ordered collection of extrusion paths to fill surfaces
+    // (this collection contains only ExtrusionEntityCollection objects)
+    ExtrusionEntityCollection   fills;
+    
+    Flow    flow(FlowRole role, bool bridge = false, double width = -1) const;
+    void    slices_to_fill_surfaces_clipped();
+    void    prepare_fill_surfaces();
+    void    make_perimeters(const SurfaceCollection &slices, SurfaceCollection* fill_surfaces);
+    void    process_external_surfaces(const Layer* lower_layer);
+    double infill_area_threshold() const;
+
+    void    export_region_slices_to_svg(const char *path) const;
+    void    export_region_fill_surfaces_to_svg(const char *path) const;
+    // Export to "out/LayerRegion-name-%d.svg" with an increasing index with every export.
+    void    export_region_slices_to_svg_debug(const char *name) const;
+    void    export_region_fill_surfaces_to_svg_debug(const char *name) const;
+
+    // Is there any valid extrusion assigned to this LayerRegion?
+    bool    has_extrusions() const { return ! this->perimeters.entities.empty() || ! this->fills.entities.empty(); }
+
+protected:
+    friend class Layer;
+
+    LayerRegion(Layer *layer, PrintRegion *region) : m_layer(layer), m_region(region) {}
+    ~LayerRegion() {}
+
+private:
+    Layer       *m_layer;
+    PrintRegion *m_region;
+};
+
+
+typedef std::vector<LayerRegion*> LayerRegionPtrs;
+
+class Layer 
+{
+public:
+    size_t              id() const          { return m_id; }
+    void                set_id(size_t id)   { m_id = id; }
+    PrintObject*        object()            { return m_object; }
+    const PrintObject*  object() const      { return m_object; }
+
+    Layer              *upper_layer;
+    Layer              *lower_layer;
+    bool                slicing_errors;
+    coordf_t            slice_z;       // Z used for slicing in unscaled coordinates
+    coordf_t            print_z;       // Z used for printing in unscaled coordinates
+    coordf_t            height;        // layer height in unscaled coordinates
+
+    // collection of expolygons generated by slicing the original geometry;
+    // also known as 'islands' (all regions and surface types are merged here)
+    // The slices are chained by the shortest traverse distance and this traversal
+    // order will be recovered by the G-code generator.
+    ExPolygonCollection slices;
+
+    size_t                  region_count() const { return m_regions.size(); }
+    const LayerRegion*      get_region(int idx) const { return m_regions.at(idx); }
+    LayerRegion*            get_region(int idx) { return m_regions[idx]; }
+    LayerRegion*            add_region(PrintRegion* print_region);
+    const LayerRegionPtrs&  regions() const { return m_regions; }
+    
+    void                    make_slices();
+    void                    merge_slices();
+    template <class T> bool any_internal_region_slice_contains(const T &item) const {
+        for (const LayerRegion *layerm : m_regions) if (layerm->slices.any_internal_contains(item)) return true;
+        return false;
+    }
+    template <class T> bool any_bottom_region_slice_contains(const T &item) const {
+        for (const LayerRegion *layerm : m_regions) if (layerm->slices.any_bottom_contains(item)) return true;
+        return false;
+    }
+    void                    make_perimeters();
+    void                    make_fills();
+
+    void                    export_region_slices_to_svg(const char *path) const;
+    void                    export_region_fill_surfaces_to_svg(const char *path) const;
+    // Export to "out/LayerRegion-name-%d.svg" with an increasing index with every export.
+    void                    export_region_slices_to_svg_debug(const char *name) const;
+    void                    export_region_fill_surfaces_to_svg_debug(const char *name) const;
+
+    // Is there any valid extrusion assigned to this LayerRegion?
+    virtual bool            has_extrusions() const { for (auto layerm : m_regions) if (layerm->has_extrusions()) return true; return false; }
+
+protected:
+    friend class PrintObject;
+
+    Layer(size_t id, PrintObject *object, coordf_t height, coordf_t print_z, coordf_t slice_z) :
+        upper_layer(nullptr), lower_layer(nullptr), slicing_errors(false),
+        slice_z(slice_z), print_z(print_z), height(height),
+        m_id(id), m_object(object) {}
+    virtual ~Layer();
+
+private:
+    // sequential number of layer, 0-based
+    size_t              m_id;
+    PrintObject        *m_object;
+    LayerRegionPtrs     m_regions;
+};
+
+class SupportLayer : public Layer 
+{
+public:
+    // Polygons covered by the supports: base, interface and contact areas.
+    ExPolygonCollection         support_islands;
+    // Extrusion paths for the support base and for the support interface and contacts.
+    ExtrusionEntityCollection   support_fills;
+
+    // Is there any valid extrusion assigned to this LayerRegion?
+    virtual bool                has_extrusions() const { return ! support_fills.empty(); }
+
+protected:
+    friend class PrintObject;
+
+    // The constructor has been made public to be able to insert additional support layers for the skirt or a wipe tower
+    // between the raft and the object first layer.
+    SupportLayer(size_t id, PrintObject *object, coordf_t height, coordf_t print_z, coordf_t slice_z) :
+        Layer(id, object, height, print_z, slice_z) {}
+    virtual ~SupportLayer() {}
+};
+
+}
+
+#endif

src/libslic3r/LayerRegion.cpp

@@ -0,0 +1,443 @@
+#include "Layer.hpp"
+#include "BridgeDetector.hpp"
+#include "ClipperUtils.hpp"
+#include "Geometry.hpp"
+#include "PerimeterGenerator.hpp"
+#include "Print.hpp"
+#include "Surface.hpp"
+#include "BoundingBox.hpp"
+#include "SVG.hpp"
+
+#include <string>
+#include <map>
+
+#include <boost/log/trivial.hpp>
+
+namespace Slic3r {
+
+Flow LayerRegion::flow(FlowRole role, bool bridge, double width) const
+{
+    return m_region->flow(
+        role,
+        m_layer->height,
+        bridge,
+        m_layer->id() == 0,
+        width,
+        *m_layer->object()
+    );
+}
+
+// Fill in layerm->fill_surfaces by trimming the layerm->slices by the cummulative layerm->fill_surfaces.
+void LayerRegion::slices_to_fill_surfaces_clipped()
+{
+    // Note: this method should be idempotent, but fill_surfaces gets modified 
+    // in place. However we're now only using its boundaries (which are invariant)
+    // so we're safe. This guarantees idempotence of prepare_infill() also in case
+    // that combine_infill() turns some fill_surface into VOID surfaces.
+//    Polygons fill_boundaries = to_polygons(std::move(this->fill_surfaces));
+    Polygons fill_boundaries = to_polygons(this->fill_expolygons);
+    // Collect polygons per surface type.
+    std::vector<Polygons> polygons_by_surface;
+    polygons_by_surface.assign(size_t(stCount), Polygons());
+    for (Surface &surface : this->slices.surfaces)
+        polygons_append(polygons_by_surface[(size_t)surface.surface_type], surface.expolygon);
+    // Trim surfaces by the fill_boundaries.
+    this->fill_surfaces.surfaces.clear();
+    for (size_t surface_type = 0; surface_type < size_t(stCount); ++ surface_type) {
+        const Polygons &polygons = polygons_by_surface[surface_type];
+        if (! polygons.empty())
+            this->fill_surfaces.append(intersection_ex(polygons, fill_boundaries), SurfaceType(surface_type));
+    }
+}
+
+void LayerRegion::make_perimeters(const SurfaceCollection &slices, SurfaceCollection* fill_surfaces)
+{
+    this->perimeters.clear();
+    this->thin_fills.clear();
+    
+    PerimeterGenerator g(
+        // input:
+        &slices,
+        this->layer()->height,
+        this->flow(frPerimeter),
+        &this->region()->config(),
+        &this->layer()->object()->config(),
+        &this->layer()->object()->print()->config(),
+        
+        // output:
+        &this->perimeters,
+        &this->thin_fills,
+        fill_surfaces
+    );
+    
+    if (this->layer()->lower_layer != NULL)
+        // Cummulative sum of polygons over all the regions.
+        g.lower_slices = &this->layer()->lower_layer->slices;
+    
+    g.layer_id              = this->layer()->id();
+    g.ext_perimeter_flow    = this->flow(frExternalPerimeter);
+    g.overhang_flow         = this->region()->flow(frPerimeter, -1, true, false, -1, *this->layer()->object());
+    g.solid_infill_flow     = this->flow(frSolidInfill);
+    
+    g.process();
+}
+
+//#define EXTERNAL_SURFACES_OFFSET_PARAMETERS ClipperLib::jtMiter, 3.
+//#define EXTERNAL_SURFACES_OFFSET_PARAMETERS ClipperLib::jtMiter, 1.5
+#define EXTERNAL_SURFACES_OFFSET_PARAMETERS ClipperLib::jtSquare, 0.
+
+void LayerRegion::process_external_surfaces(const Layer* lower_layer)
+{
+    const Surfaces &surfaces = this->fill_surfaces.surfaces;
+    const double margin = scale_(EXTERNAL_INFILL_MARGIN);
+    
+#ifdef SLIC3R_DEBUG_SLICE_PROCESSING
+    export_region_fill_surfaces_to_svg_debug("3_process_external_surfaces-initial");
+#endif /* SLIC3R_DEBUG_SLICE_PROCESSING */
+
+    // 1) Collect bottom and bridge surfaces, each of them grown by a fixed 3mm offset
+    // for better anchoring.
+    // Bottom surfaces, grown.
+    Surfaces                    bottom;
+    // Bridge surfaces, initialy not grown.
+    Surfaces                    bridges;
+    // Top surfaces, grown.
+    Surfaces                    top;
+    // Internal surfaces, not grown.
+    Surfaces                    internal;
+    // Areas, where an infill of various types (top, bottom, bottom bride, sparse, void) could be placed.
+    //FIXME if non zero infill, then fill_boundaries could be cheaply initialized from layerm->fill_expolygons.
+    Polygons                    fill_boundaries;
+
+    // Collect top surfaces and internal surfaces.
+    // Collect fill_boundaries: If we're slicing with no infill, we can't extend external surfaces over non-existent infill.
+    // This loop destroys the surfaces (aliasing this->fill_surfaces.surfaces) by moving into top/internal/fill_boundaries!
+    {
+        // bottom_polygons are used to trim inflated top surfaces.
+        fill_boundaries.reserve(number_polygons(surfaces));
+        bool has_infill = this->region()->config().fill_density.value > 0.;
+        for (const Surface &surface : this->fill_surfaces.surfaces) {
+            if (surface.surface_type == stTop) {
+                // Collect the top surfaces, inflate them and trim them by the bottom surfaces.
+                // This gives the priority to bottom surfaces.
+                surfaces_append(top, offset_ex(surface.expolygon, float(margin), EXTERNAL_SURFACES_OFFSET_PARAMETERS), surface);
+            } else if (surface.surface_type == stBottom || (surface.surface_type == stBottomBridge && lower_layer == NULL)) {
+                // Grown by 3mm.
+                surfaces_append(bottom, offset_ex(surface.expolygon, float(margin), EXTERNAL_SURFACES_OFFSET_PARAMETERS), surface);
+            } else if (surface.surface_type == stBottomBridge) {
+                if (! surface.empty())
+                    bridges.push_back(surface);
+            }
+            bool internal_surface = surface.surface_type != stTop && ! surface.is_bottom();
+            if (has_infill || surface.surface_type != stInternal) {
+                if (internal_surface)
+                    // Make a copy as the following line uses the move semantics.
+                    internal.push_back(surface);
+                polygons_append(fill_boundaries, std::move(surface.expolygon));
+            } else if (internal_surface)
+                internal.push_back(std::move(surface));
+        }
+    }
+
+#if 0
+    {
+        static int iRun = 0;
+        bridges.export_to_svg(debug_out_path("bridges-before-grouping-%d.svg", iRun ++), true);
+    }
+#endif
+
+    if (bridges.empty())
+    {
+        fill_boundaries = union_(fill_boundaries, true);
+    } else
+    {
+        // 1) Calculate the inflated bridge regions, each constrained to its island.
+        ExPolygons               fill_boundaries_ex = union_ex(fill_boundaries, true);
+        std::vector<Polygons>    bridges_grown;
+        std::vector<BoundingBox> bridge_bboxes;
+
+#ifdef SLIC3R_DEBUG_SLICE_PROCESSING
+        {
+            static int iRun = 0;
+            SVG svg(debug_out_path("3_process_external_surfaces-fill_regions-%d.svg", iRun ++).c_str(), get_extents(fill_boundaries_ex));
+            svg.draw(fill_boundaries_ex);
+            svg.draw_outline(fill_boundaries_ex, "black", "blue", scale_(0.05)); 
+            svg.Close();
+        }
+
+//        export_region_fill_surfaces_to_svg_debug("3_process_external_surfaces-initial");
+#endif /* SLIC3R_DEBUG_SLICE_PROCESSING */
+ 
+        {
+            // Bridge expolygons, grown, to be tested for intersection with other bridge regions.
+            std::vector<BoundingBox> fill_boundaries_ex_bboxes = get_extents_vector(fill_boundaries_ex);
+            bridges_grown.reserve(bridges.size());
+            bridge_bboxes.reserve(bridges.size());
+            for (size_t i = 0; i < bridges.size(); ++ i) {
+                // Find the island of this bridge.
+                const Point pt = bridges[i].expolygon.contour.points.front();
+                int idx_island = -1;
+                for (int j = 0; j < int(fill_boundaries_ex.size()); ++ j)
+                    if (fill_boundaries_ex_bboxes[j].contains(pt) && 
+                        fill_boundaries_ex[j].contains(pt)) {
+                        idx_island = j;
+                        break;
+                    }
+                // Grown by 3mm.
+                Polygons polys = offset(to_polygons(bridges[i].expolygon), float(margin), EXTERNAL_SURFACES_OFFSET_PARAMETERS);
+                if (idx_island == -1) {
+                    printf("Bridge did not fall into the source region!\r\n");
+                } else {
+                    // Found an island, to which this bridge region belongs. Trim it,
+                    polys = intersection(polys, to_polygons(fill_boundaries_ex[idx_island]));
+                }
+                bridge_bboxes.push_back(get_extents(polys));
+                bridges_grown.push_back(std::move(polys));
+            }
+        }
+
+        // 2) Group the bridge surfaces by overlaps.
+        std::vector<size_t> bridge_group(bridges.size(), (size_t)-1);
+        size_t n_groups = 0; 
+        for (size_t i = 0; i < bridges.size(); ++ i) {
+            // A grup id for this bridge.
+            size_t group_id = (bridge_group[i] == -1) ? (n_groups ++) : bridge_group[i];
+            bridge_group[i] = group_id;
+            // For all possibly overlaping bridges:
+            for (size_t j = i + 1; j < bridges.size(); ++ j) {
+                if (! bridge_bboxes[i].overlap(bridge_bboxes[j]))
+                    continue;
+                if (intersection(bridges_grown[i], bridges_grown[j], false).empty())
+                    continue;
+                // The two bridge regions intersect. Give them the same group id.
+                if (bridge_group[j] != -1) {
+                    // The j'th bridge has been merged with some other bridge before.
+                    size_t group_id_new = bridge_group[j];
+                    for (size_t k = 0; k < j; ++ k)
+                        if (bridge_group[k] == group_id)
+                            bridge_group[k] = group_id_new;
+                    group_id = group_id_new;
+                }
+                bridge_group[j] = group_id;
+            }
+        }
+
+        // 3) Merge the groups with the same group id, detect bridges.
+        {
+			BOOST_LOG_TRIVIAL(trace) << "Processing external surface, detecting bridges. layer" << this->layer()->print_z << ", bridge groups: " << n_groups;
+            for (size_t group_id = 0; group_id < n_groups; ++ group_id) {
+                size_t n_bridges_merged = 0;
+                size_t idx_last = (size_t)-1;
+                for (size_t i = 0; i < bridges.size(); ++ i) {
+                    if (bridge_group[i] == group_id) {
+                        ++ n_bridges_merged;
+                        idx_last = i;
+                    }
+                }
+                if (n_bridges_merged == 0)
+                    // This group has no regions assigned as these were moved into another group.
+                    continue;
+                // Collect the initial ungrown regions and the grown polygons.
+                ExPolygons  initial;
+                Polygons    grown;
+                for (size_t i = 0; i < bridges.size(); ++ i) {
+                    if (bridge_group[i] != group_id)
+                        continue;
+                    initial.push_back(std::move(bridges[i].expolygon));
+                    polygons_append(grown, bridges_grown[i]);
+                }
+                // detect bridge direction before merging grown surfaces otherwise adjacent bridges
+                // would get merged into a single one while they need different directions
+                // also, supply the original expolygon instead of the grown one, because in case
+                // of very thin (but still working) anchors, the grown expolygon would go beyond them
+                BridgeDetector bd(
+                    initial,
+                    lower_layer->slices,
+                    this->flow(frInfill, true).scaled_width()
+                );
+                #ifdef SLIC3R_DEBUG
+                printf("Processing bridge at layer " PRINTF_ZU ":\n", this->layer()->id());
+                #endif
+                if (bd.detect_angle(Geometry::deg2rad(this->region()->config().bridge_angle.value))) {
+                    bridges[idx_last].bridge_angle = bd.angle;
+                    if (this->layer()->object()->config().support_material) {
+                        polygons_append(this->bridged, bd.coverage());
+                        this->unsupported_bridge_edges.append(bd.unsupported_edges()); 
+                    }
+                }
+                // without safety offset, artifacts are generated (GH #2494)
+                surfaces_append(bottom, union_ex(grown, true), bridges[idx_last]);
+            }
+
+            fill_boundaries = std::move(to_polygons(fill_boundaries_ex));
+			BOOST_LOG_TRIVIAL(trace) << "Processing external surface, detecting bridges - done";
+		}
+
+    #if 0
+        {
+            static int iRun = 0;
+            bridges.export_to_svg(debug_out_path("bridges-after-grouping-%d.svg", iRun ++), true);
+        }
+    #endif
+    }
+
+    Surfaces new_surfaces;
+    {
+        // Merge top and bottom in a single collection.
+        surfaces_append(top, std::move(bottom));
+        // Intersect the grown surfaces with the actual fill boundaries.
+        Polygons bottom_polygons = to_polygons(bottom);
+        for (size_t i = 0; i < top.size(); ++ i) {
+            Surface &s1 = top[i];
+            if (s1.empty())
+                continue;
+            Polygons polys;
+            polygons_append(polys, std::move(s1));
+            for (size_t j = i + 1; j < top.size(); ++ j) {
+                Surface &s2 = top[j];
+                if (! s2.empty() && surfaces_could_merge(s1, s2)) {
+                    polygons_append(polys, std::move(s2));
+                    s2.clear();
+                }
+            }
+            if (s1.surface_type == stTop)
+                // Trim the top surfaces by the bottom surfaces. This gives the priority to the bottom surfaces.
+                polys = diff(polys, bottom_polygons);
+            surfaces_append(
+                new_surfaces,
+                // Don't use a safety offset as fill_boundaries were already united using the safety offset.
+                std::move(intersection_ex(polys, fill_boundaries, false)),
+                s1);
+        }
+    }
+    
+    // Subtract the new top surfaces from the other non-top surfaces and re-add them.
+    Polygons new_polygons = to_polygons(new_surfaces);
+    for (size_t i = 0; i < internal.size(); ++ i) {
+        Surface &s1 = internal[i];
+        if (s1.empty())
+            continue;
+        Polygons polys;
+        polygons_append(polys, std::move(s1));
+        for (size_t j = i + 1; j < internal.size(); ++ j) {
+            Surface &s2 = internal[j];
+            if (! s2.empty() && surfaces_could_merge(s1, s2)) {
+                polygons_append(polys, std::move(s2));
+                s2.clear();
+            }
+        }
+        ExPolygons new_expolys = diff_ex(polys, new_polygons);
+        polygons_append(new_polygons, to_polygons(new_expolys));
+        surfaces_append(new_surfaces, std::move(new_expolys), s1);
+    }
+    
+    this->fill_surfaces.surfaces = std::move(new_surfaces);
+
+#ifdef SLIC3R_DEBUG_SLICE_PROCESSING
+    export_region_fill_surfaces_to_svg_debug("3_process_external_surfaces-final");
+#endif /* SLIC3R_DEBUG_SLICE_PROCESSING */
+}
+
+void LayerRegion::prepare_fill_surfaces()
+{
+#ifdef SLIC3R_DEBUG_SLICE_PROCESSING
+    export_region_slices_to_svg_debug("2_prepare_fill_surfaces-initial");
+    export_region_fill_surfaces_to_svg_debug("2_prepare_fill_surfaces-initial");
+#endif /* SLIC3R_DEBUG_SLICE_PROCESSING */ 
+
+    /*  Note: in order to make the psPrepareInfill step idempotent, we should never
+        alter fill_surfaces boundaries on which our idempotency relies since that's
+        the only meaningful information returned by psPerimeters. */
+    
+    // if no solid layers are requested, turn top/bottom surfaces to internal
+    if (this->region()->config().top_solid_layers == 0) {
+        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface)
+            if (surface->surface_type == stTop)
+                surface->surface_type = (this->layer()->object()->config().infill_only_where_needed) ? 
+                    stInternalVoid : stInternal;
+    }
+    if (this->region()->config().bottom_solid_layers == 0) {
+        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface) {
+            if (surface->surface_type == stBottom || surface->surface_type == stBottomBridge)
+                surface->surface_type = stInternal;
+        }
+    }
+        
+    // turn too small internal regions into solid regions according to the user setting
+    if (this->region()->config().fill_density.value > 0) {
+        // scaling an area requires two calls!
+        double min_area = scale_(scale_(this->region()->config().solid_infill_below_area.value));
+        for (Surfaces::iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface) {
+            if (surface->surface_type == stInternal && surface->area() <= min_area)
+                surface->surface_type = stInternalSolid;
+        }
+    }
+
+#ifdef SLIC3R_DEBUG_SLICE_PROCESSING
+    export_region_slices_to_svg_debug("2_prepare_fill_surfaces-final");
+    export_region_fill_surfaces_to_svg_debug("2_prepare_fill_surfaces-final");
+#endif /* SLIC3R_DEBUG_SLICE_PROCESSING */
+}
+
+double LayerRegion::infill_area_threshold() const
+{
+    double ss = this->flow(frSolidInfill).scaled_spacing();
+    return ss*ss;
+}
+
+void LayerRegion::export_region_slices_to_svg(const char *path) const
+{
+    BoundingBox bbox;
+    for (Surfaces::const_iterator surface = this->slices.surfaces.begin(); surface != this->slices.surfaces.end(); ++surface)
+        bbox.merge(get_extents(surface->expolygon));
+    Point legend_size = export_surface_type_legend_to_svg_box_size();
+    Point legend_pos(bbox.min(0), bbox.max(1));
+    bbox.merge(Point(std::max(bbox.min(0) + legend_size(0), bbox.max(0)), bbox.max(1) + legend_size(1)));
+
+    SVG svg(path, bbox);
+    const float transparency = 0.5f;
+    for (Surfaces::const_iterator surface = this->slices.surfaces.begin(); surface != this->slices.surfaces.end(); ++surface)
+        svg.draw(surface->expolygon, surface_type_to_color_name(surface->surface_type), transparency);
+    for (Surfaces::const_iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface)
+        svg.draw(surface->expolygon.lines(), surface_type_to_color_name(surface->surface_type));
+    export_surface_type_legend_to_svg(svg, legend_pos);
+    svg.Close();
+}
+
+// Export to "out/LayerRegion-name-%d.svg" with an increasing index with every export.
+void LayerRegion::export_region_slices_to_svg_debug(const char *name) const
+{
+    static std::map<std::string, size_t> idx_map;
+    size_t &idx = idx_map[name];
+    this->export_region_slices_to_svg(debug_out_path("LayerRegion-slices-%s-%d.svg", name, idx ++).c_str());
+}
+
+void LayerRegion::export_region_fill_surfaces_to_svg(const char *path) const
+{
+    BoundingBox bbox;
+    for (Surfaces::const_iterator surface = this->fill_surfaces.surfaces.begin(); surface != this->fill_surfaces.surfaces.end(); ++surface)
+        bbox.merge(get_extents(surface->expolygon));
+    Point legend_size = export_surface_type_legend_to_svg_box_size();
+    Point legend_pos(bbox.min(0), bbox.max(1));
+    bbox.merge(Point(std::max(bbox.min(0) + legend_size(0), bbox.max(0)), bbox.max(1) + legend_size(1)));
+
+    SVG svg(path, bbox);
+    const float transparency = 0.5f;
+    for (const Surface &surface : this->fill_surfaces.surfaces) {
+        svg.draw(surface.expolygon, surface_type_to_color_name(surface.surface_type), transparency);
+        svg.draw_outline(surface.expolygon, "black", "blue", scale_(0.05)); 
+    }
+    export_surface_type_legend_to_svg(svg, legend_pos);
+    svg.Close();
+}
+
+// Export to "out/LayerRegion-name-%d.svg" with an increasing index with every export.
+void LayerRegion::export_region_fill_surfaces_to_svg_debug(const char *name) const
+{
+    static std::map<std::string, size_t> idx_map;
+    size_t &idx = idx_map[name];
+    this->export_region_fill_surfaces_to_svg(debug_out_path("LayerRegion-fill_surfaces-%s-%d.svg", name, idx ++).c_str());
+}
+
+}
+ 

src/libslic3r/Line.cpp

@@ -0,0 +1,119 @@
+#include "Geometry.hpp"
+#include "Line.hpp"
+#include "Polyline.hpp"
+#include <algorithm>
+#include <cmath>
+#include <sstream>
+
+namespace Slic3r {
+
+Linef3 transform(const Linef3& line, const Transform3d& t)
+{
+    typedef Eigen::Matrix<double, 3, 2> LineInMatrixForm;
+
+    LineInMatrixForm world_line;
+    ::memcpy((void*)world_line.col(0).data(), (const void*)line.a.data(), 3 * sizeof(double));
+    ::memcpy((void*)world_line.col(1).data(), (const void*)line.b.data(), 3 * sizeof(double));
+
+    LineInMatrixForm local_line = t * world_line.colwise().homogeneous();
+    return Linef3(Vec3d(local_line(0, 0), local_line(1, 0), local_line(2, 0)), Vec3d(local_line(0, 1), local_line(1, 1), local_line(2, 1)));
+}
+
+bool Line::intersection_infinite(const Line &other, Point* point) const
+{
+    Vec2d a1 = this->a.cast<double>();
+    Vec2d a2 = other.a.cast<double>();
+    Vec2d v12 = (other.a - this->a).cast<double>();
+    Vec2d v1 = (this->b - this->a).cast<double>();
+    Vec2d v2 = (other.b - other.a).cast<double>();
+    double denom = cross2(v1, v2);
+    if (std::fabs(denom) < EPSILON)
+        return false;
+    double t1 = cross2(v12, v2) / denom;
+    *point = (a1 + t1 * v1).cast<coord_t>();
+    return true;
+}
+
+/* distance to the closest point of line */
+double Line::distance_to(const Point &point) const
+{
+    const Line   &line = *this;
+    const Vec2d   v  = (line.b - line.a).cast<double>();
+    const Vec2d   va = (point  - line.a).cast<double>();
+    const double  l2 = v.squaredNorm();  // avoid a sqrt
+    if (l2 == 0.0) 
+        // line.a == line.b case
+        return va.norm();
+    // Consider the line extending the segment, parameterized as line.a + t (line.b - line.a).
+    // We find projection of this point onto the line. 
+    // It falls where t = [(this-line.a) . (line.b-line.a)] / |line.b-line.a|^2
+    const double t = va.dot(v) / l2;
+    if (t < 0.0)      return va.norm();  // beyond the 'a' end of the segment
+    else if (t > 1.0) return (point - line.b).cast<double>().norm();  // beyond the 'b' end of the segment
+    return (t * v - va).norm();
+}
+
+double Line::perp_distance_to(const Point &point) const
+{
+    const Line  &line = *this;
+    const Vec2d  v  = (line.b - line.a).cast<double>();
+    const Vec2d  va = (point - line.a).cast<double>();
+    if (line.a == line.b)
+        return va.norm();
+    return std::abs(cross2(v, va)) / v.norm();
+}
+
+double Line::orientation() const
+{
+    double angle = this->atan2_();
+    if (angle < 0) angle = 2*PI + angle;
+    return angle;
+}
+
+double Line::direction() const
+{
+    double atan2 = this->atan2_();
+    return (fabs(atan2 - PI) < EPSILON) ? 0
+        : (atan2 < 0) ? (atan2 + PI)
+        : atan2;
+}
+
+bool Line::parallel_to(double angle) const
+{
+    return Slic3r::Geometry::directions_parallel(this->direction(), angle);
+}
+
+bool Line::intersection(const Line &l2, Point *intersection) const
+{
+    const Line  &l1  = *this;
+    const Vec2d  v1  = (l1.b - l1.a).cast<double>();
+    const Vec2d  v2  = (l2.b - l2.a).cast<double>();
+    const Vec2d  v12 = (l1.a - l2.a).cast<double>();
+    double       denom  = cross2(v1, v2);
+    double       nume_a = cross2(v2, v12);
+    double       nume_b = cross2(v1, v12);
+    if (fabs(denom) < EPSILON)
+#if 0
+        // Lines are collinear. Return true if they are coincident (overlappign).
+        return ! (fabs(nume_a) < EPSILON && fabs(nume_b) < EPSILON);
+#else
+        return false;
+#endif
+    double t1 = nume_a / denom;
+    double t2 = nume_b / denom;
+    if (t1 >= 0 && t1 <= 1.0f && t2 >= 0 && t2 <= 1.0f) {
+        // Get the intersection point.
+        (*intersection) = (l1.a.cast<double>() + t1 * v1).cast<coord_t>();
+        return true;
+    }
+    return false;  // not intersecting
+}
+
+Vec3d Linef3::intersect_plane(double z) const
+{
+    auto   v = (this->b - this->a).cast<double>();
+    double t = (z - this->a(2)) / v(2);
+    return Vec3d(this->a(0) + v(0) * t, this->a(1) + v(1) * t, z);
+}
+
+}

src/libslic3r/Line.hpp

@@ -0,0 +1,119 @@
+#ifndef slic3r_Line_hpp_
+#define slic3r_Line_hpp_
+
+#include "libslic3r.h"
+#include "Point.hpp"
+
+namespace Slic3r {
+
+class Line;
+class Line3;
+class Linef3;
+class Polyline;
+class ThickLine;
+typedef std::vector<Line> Lines;
+typedef std::vector<Line3> Lines3;
+typedef std::vector<ThickLine> ThickLines;
+
+Linef3 transform(const Linef3& line, const Transform3d& t);
+
+class Line
+{
+public:
+    Line() {}
+    Line(const Point& _a, const Point& _b) : a(_a), b(_b) {}
+    explicit operator Lines() const { Lines lines; lines.emplace_back(*this); return lines; }
+    void   scale(double factor) { this->a *= factor; this->b *= factor; }
+    void   translate(double x, double y) { Vector v(x, y); this->a += v; this->b += v; }
+    void   rotate(double angle, const Point &center) { this->a.rotate(angle, center); this->b.rotate(angle, center); }
+    void   reverse() { std::swap(this->a, this->b); }
+    double length() const { return (b - a).cast<double>().norm(); }
+    Point  midpoint() const { return (this->a + this->b) / 2; }
+    bool   intersection_infinite(const Line &other, Point* point) const;
+    bool   operator==(const Line &rhs) const { return this->a == rhs.a && this->b == rhs.b; }
+    double distance_to(const Point &point) const;
+    double perp_distance_to(const Point &point) const;
+    bool   parallel_to(double angle) const;
+    bool   parallel_to(const Line &line) const { return this->parallel_to(line.direction()); }
+    double atan2_() const { return atan2(this->b(1) - this->a(1), this->b(0) - this->a(0)); }
+    double orientation() const;
+    double direction() const;
+    Vector vector() const { return this->b - this->a; }
+    Vector normal() const { return Vector((this->b(1) - this->a(1)), -(this->b(0) - this->a(0))); }
+    bool   intersection(const Line& line, Point* intersection) const;
+    double ccw(const Point& point) const { return point.ccw(*this); }
+
+    Point a;
+    Point b;
+};
+
+class ThickLine : public Line
+{
+public:
+    ThickLine() : a_width(0), b_width(0) {}
+    ThickLine(const Point& a, const Point& b) : Line(a, b), a_width(0), b_width(0) {}
+    ThickLine(const Point& a, const Point& b, double wa, double wb) : Line(a, b), a_width(wa), b_width(wb) {}
+
+    double a_width, b_width;
+};
+
+class Line3
+{
+public:
+    Line3() : a(Vec3crd::Zero()), b(Vec3crd::Zero()) {}
+    Line3(const Vec3crd& _a, const Vec3crd& _b) : a(_a), b(_b) {}
+
+    double  length() const { return (this->a - this->b).cast<double>().norm(); }
+    Vec3crd vector() const { return this->b - this->a; }
+
+    Vec3crd a;
+    Vec3crd b;
+};
+
+class Linef
+{
+public:
+    Linef() : a(Vec2d::Zero()), b(Vec2d::Zero()) {}
+    Linef(const Vec2d& _a, const Vec2d& _b) : a(_a), b(_b) {}
+
+    Vec2d a;
+    Vec2d b;
+};
+
+class Linef3
+{
+public:
+    Linef3() : a(Vec3d::Zero()), b(Vec3d::Zero()) {}
+    Linef3(const Vec3d& _a, const Vec3d& _b) : a(_a), b(_b) {}
+
+    Vec3d   intersect_plane(double z) const;
+    void    scale(double factor) { this->a *= factor; this->b *= factor; }
+    Vec3d   vector() const { return this->b - this->a; }
+    Vec3d   unit_vector() const { return (length() == 0.0) ? Vec3d::Zero() : vector().normalized(); }
+    double  length() const { return vector().norm(); }
+
+    Vec3d a;
+    Vec3d b;
+};
+
+} // namespace Slic3r
+
+// start Boost
+#include <boost/polygon/polygon.hpp>
+namespace boost { namespace polygon {
+    template <>
+    struct geometry_concept<Slic3r::Line> { typedef segment_concept type; };
+
+    template <>
+    struct segment_traits<Slic3r::Line> {
+        typedef coord_t coordinate_type;
+        typedef Slic3r::Point point_type;
+    
+        static inline point_type get(const Slic3r::Line& line, direction_1d dir) {
+            return dir.to_int() ? line.b : line.a;
+        }
+    };
+} }
+// end Boost
+
+#endif

src/libslic3r/Model.hpp

@@ -0,0 +1,657 @@
+#ifndef slic3r_Model_hpp_
+#define slic3r_Model_hpp_
+
+#include "libslic3r.h"
+#include "PrintConfig.hpp"
+#include "Layer.hpp"
+#include "Point.hpp"
+#include "TriangleMesh.hpp"
+#include "Slicing.hpp"
+#include <map>
+#include <string>
+#include <utility>
+#include <vector>
+#if ENABLE_MODELVOLUME_TRANSFORM
+#include "Geometry.hpp"
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+namespace Slic3r {
+
+class Model;
+class ModelInstance;
+class ModelMaterial;
+class ModelObject;
+class ModelVolume;
+class Print;
+
+typedef std::string t_model_material_id;
+typedef std::string t_model_material_attribute;
+typedef std::map<t_model_material_attribute, std::string> t_model_material_attributes;
+
+typedef std::map<t_model_material_id, ModelMaterial*> ModelMaterialMap;
+typedef std::vector<ModelObject*> ModelObjectPtrs;
+typedef std::vector<ModelVolume*> ModelVolumePtrs;
+typedef std::vector<ModelInstance*> ModelInstancePtrs;
+
+// Unique identifier of a Model, ModelObject, ModelVolume, ModelInstance or ModelMaterial.
+// Used to synchronize the front end (UI) with the back end (BackgroundSlicingProcess / Print / PrintObject)
+// Valid IDs are strictly positive (non zero).
+// It is declared as an object, as some compilers (notably msvcc) consider a typedef size_t equivalent to size_t
+// for parameter overload.
+struct ModelID 
+{
+	ModelID(size_t id) : id(id) {}
+
+	bool operator==(const ModelID &rhs) const { return this->id == rhs.id; }
+	bool operator!=(const ModelID &rhs) const { return this->id != rhs.id; }
+	bool operator< (const ModelID &rhs) const { return this->id <  rhs.id; }
+	bool operator> (const ModelID &rhs) const { return this->id >  rhs.id; }
+	bool operator<=(const ModelID &rhs) const { return this->id <= rhs.id; }
+	bool operator>=(const ModelID &rhs) const { return this->id >= rhs.id; }
+
+	size_t	id;
+};
+
+// Base for Model, ModelObject, ModelVolume, ModelInstance or ModelMaterial to provide a unique ID
+// to synchronize the front end (UI) with the back end (BackgroundSlicingProcess / Print / PrintObject).
+// Achtung! The s_last_id counter is not thread safe, so it is expected, that the ModelBase derived instances
+// are only instantiated from the main thread.
+class ModelBase
+{
+public:
+    ModelID     id() const { return m_id; }
+
+protected:
+    // Constructors to be only called by derived classes.
+    // Default constructor to assign a unique ID.
+    ModelBase() : m_id(generate_new_id()) {}
+    // Constructor with ignored int parameter to assign an invalid ID, to be replaced
+    // by an existing ID copied from elsewhere.
+    ModelBase(int) : m_id(ModelID(0)) {}
+
+    // Use with caution!
+    void        set_new_unique_id() { m_id = generate_new_id(); }
+    void        set_invalid_id()    { m_id = 0; }
+    // Use with caution!
+    void        copy_id(const ModelBase &rhs) { m_id = rhs.id(); }
+
+    // Override this method if a ModelBase derived class owns other ModelBase derived instances.
+    void        assign_new_unique_ids_recursive() { this->set_new_unique_id(); }
+
+private:
+    ModelID                 m_id;
+
+	static inline ModelID   generate_new_id() { return ModelID(++ s_last_id); }
+    static size_t           s_last_id;
+};
+
+#define MODELBASE_DERIVED_COPY_MOVE_CLONE(TYPE) \
+    /* Copy a model, copy the IDs. The Print::apply() will call the TYPE::copy() method */ \
+    /* to make a private copy for background processing. */ \
+    static TYPE* new_copy(const TYPE &rhs)  { return new TYPE(rhs); } \
+    static TYPE* new_copy(TYPE &&rhs)       { return new TYPE(std::move(rhs)); } \
+    static TYPE  make_copy(const TYPE &rhs) { return TYPE(rhs); } \
+    static TYPE  make_copy(TYPE &&rhs)      { return TYPE(std::move(rhs)); } \
+    TYPE&        assign_copy(const TYPE &rhs); \
+    TYPE&        assign_copy(TYPE &&rhs); \
+    /* Copy a TYPE, generate new IDs. The front end will use this call. */ \
+    static TYPE* new_clone(const TYPE &rhs) { \
+        /* Default constructor assigning an invalid ID. */ \
+        auto obj = new TYPE(-1); \
+        obj->assign_clone(rhs); \
+        return obj; \
+	} \
+    TYPE         make_clone(const TYPE &rhs) { \
+        /* Default constructor assigning an invalid ID. */ \
+        TYPE obj(-1); \
+        obj.assign_clone(rhs); \
+        return obj; \
+    } \
+    TYPE&        assign_clone(const TYPE &rhs) { \
+        this->assign_copy(rhs); \
+        this->assign_new_unique_ids_recursive(); \
+		return *this; \
+    }
+
+#define MODELBASE_DERIVED_PRIVATE_COPY_MOVE(TYPE) \
+private: \
+    /* Private constructor with an unused int parameter will create a TYPE instance with an invalid ID. */ \
+    explicit TYPE(int) : ModelBase(-1) {}; \
+    void assign_new_unique_ids_recursive();
+
+// Material, which may be shared across multiple ModelObjects of a single Model.
+class ModelMaterial : public ModelBase
+{
+public:
+    // Attributes are defined by the AMF file format, but they don't seem to be used by Slic3r for any purpose.
+    t_model_material_attributes attributes;
+    // Dynamic configuration storage for the object specific configuration values, overriding the global configuration.
+    DynamicPrintConfig config;
+
+    Model* get_model() const { return m_model; }
+    void apply(const t_model_material_attributes &attributes)
+        { this->attributes.insert(attributes.begin(), attributes.end()); }
+
+protected:
+    friend class Model;
+	// Constructor, which assigns a new unique ID.
+	ModelMaterial(Model *model) : m_model(model) {}
+	// Copy constructor copies the ID and m_model!
+	ModelMaterial(const ModelMaterial &rhs) = default;
+	void set_model(Model *model) { m_model = model; }
+
+private:
+    // Parent, owning this material.
+    Model *m_model;
+    
+	ModelMaterial() = delete;
+	ModelMaterial(ModelMaterial &&rhs) = delete;
+	ModelMaterial& operator=(const ModelMaterial &rhs) = delete;
+    ModelMaterial& operator=(ModelMaterial &&rhs) = delete;
+};
+
+// A printable object, possibly having multiple print volumes (each with its own set of parameters and materials),
+// and possibly having multiple modifier volumes, each modifier volume with its set of parameters and materials.
+// Each ModelObject may be instantiated mutliple times, each instance having different placement on the print bed,
+// different rotation and different uniform scaling.
+class ModelObject : public ModelBase
+{
+    friend class Model;
+public:
+    std::string             name;
+    std::string             input_file;    // XXX: consider fs::path
+    // Instances of this ModelObject. Each instance defines a shift on the print bed, rotation around the Z axis and a uniform scaling.
+    // Instances are owned by this ModelObject.
+    ModelInstancePtrs       instances;
+    // Printable and modifier volumes, each with its material ID and a set of override parameters.
+    // ModelVolumes are owned by this ModelObject.
+    ModelVolumePtrs         volumes;
+    // Configuration parameters specific to a single ModelObject, overriding the global Slic3r settings.
+    DynamicPrintConfig      config;
+    // Variation of a layer thickness for spans of Z coordinates.
+    t_layer_height_ranges   layer_height_ranges;
+    // Profile of increasing z to a layer height, to be linearly interpolated when calculating the layers.
+    // The pairs of <z, layer_height> are packed into a 1D array to simplify handling by the Perl XS.
+    std::vector<coordf_t>   layer_height_profile;
+    // layer_height_profile is initialized when the layer editing mode is entered.
+    // Only if the user really modified the layer height, layer_height_profile_valid is set
+    // and used subsequently by the PrintObject.
+    bool                    layer_height_profile_valid;
+
+    // This vector holds position of selected support points for SLA. The data are
+    // saved in mesh coordinates to allow using them for several instances.
+    std::vector<Vec3f>      sla_support_points;
+
+    /* This vector accumulates the total translation applied to the object by the
+        center_around_origin() method. Callers might want to apply the same translation
+        to new volumes before adding them to this object in order to preserve alignment
+        when user expects that. */
+    Vec3d                   origin_translation;
+
+    Model*                  get_model() { return m_model; };
+	const Model*            get_model() const { return m_model; };
+
+    ModelVolume*            add_volume(const TriangleMesh &mesh);
+    ModelVolume*            add_volume(TriangleMesh &&mesh);
+    ModelVolume*            add_volume(const ModelVolume &volume);
+    ModelVolume*            add_volume(const ModelVolume &volume, TriangleMesh &&mesh);
+    void                    delete_volume(size_t idx);
+    void                    clear_volumes();
+    bool                    is_multiparts() const { return volumes.size() > 1; }
+
+    ModelInstance*          add_instance();
+    ModelInstance*          add_instance(const ModelInstance &instance);
+    ModelInstance*          add_instance(const Vec3d &offset, const Vec3d &scaling_factor, const Vec3d &rotation);
+    void                    delete_instance(size_t idx);
+    void                    delete_last_instance();
+    void                    clear_instances();
+
+    // Returns the bounding box of the transformed instances.
+    // This bounding box is approximate and not snug.
+    // This bounding box is being cached.
+    const BoundingBoxf3& bounding_box() const;
+    void invalidate_bounding_box() { m_bounding_box_valid = false; }
+
+    // A mesh containing all transformed instances of this object.
+    TriangleMesh mesh() const;
+    // Non-transformed (non-rotated, non-scaled, non-translated) sum of non-modifier object volumes.
+    // Currently used by ModelObject::mesh() and to calculate the 2D envelope for 2D platter.
+    TriangleMesh raw_mesh() const;
+    // A transformed snug bounding box around the non-modifier object volumes, without the translation applied.
+    // This bounding box is only used for the actual slicing.
+    BoundingBoxf3 raw_bounding_box() const;
+    // A snug bounding box around the transformed non-modifier object volumes.
+    BoundingBoxf3 instance_bounding_box(size_t instance_idx, bool dont_translate = false) const;
+    void center_around_origin();
+    void ensure_on_bed();
+    void translate_instances(const Vec3d& vector);
+    void translate_instance(size_t instance_idx, const Vec3d& vector);
+    void translate(const Vec3d &vector) { this->translate(vector(0), vector(1), vector(2)); }
+    void translate(double x, double y, double z);
+    void scale(const Vec3d &versor);
+    void scale(const double s) { this->scale(Vec3d(s, s, s)); }
+    void scale(double x, double y, double z) { this->scale(Vec3d(x, y, z)); }
+    void rotate(double angle, Axis axis);
+    void rotate(double angle, const Vec3d& axis);
+    void mirror(Axis axis);
+    size_t materials_count() const;
+    size_t facets_count() const;
+    bool needed_repair() const;
+    ModelObjectPtrs cut(size_t instance, coordf_t z);
+    void split(ModelObjectPtrs* new_objects);
+    void repair();
+
+    double get_min_z() const;
+    double get_instance_min_z(size_t instance_idx) const;
+
+    // Called by Print::validate() from the UI thread.
+    unsigned int check_instances_print_volume_state(const BoundingBoxf3& print_volume);
+
+    // Print object statistics to console.
+    void print_info() const;
+
+protected:
+    friend class Print;
+    // Called by Print::apply() to set the model pointer after making a copy.
+    void        set_model(Model *model) { m_model = model; }
+
+private:
+    ModelObject(Model *model) : layer_height_profile_valid(false), m_model(model), origin_translation(Vec3d::Zero()), m_bounding_box_valid(false) {}
+    ~ModelObject();
+
+    /* To be able to return an object from own copy / clone methods. Hopefully the compiler will do the "Copy elision" */
+    /* (Omits copy and move(since C++11) constructors, resulting in zero - copy pass - by - value semantics). */
+    ModelObject(const ModelObject &rhs) : ModelBase(-1), m_model(rhs.m_model) { this->assign_copy(rhs); }
+    explicit ModelObject(ModelObject &&rhs) : ModelBase(-1) { this->assign_copy(std::move(rhs)); }
+    ModelObject& operator=(const ModelObject &rhs) { this->assign_copy(rhs); m_model = rhs.m_model; return *this; }
+    ModelObject& operator=(ModelObject &&rhs) { this->assign_copy(std::move(rhs)); m_model = rhs.m_model; return *this; }
+
+    MODELBASE_DERIVED_COPY_MOVE_CLONE(ModelObject)
+	MODELBASE_DERIVED_PRIVATE_COPY_MOVE(ModelObject)
+
+    // Parent object, owning this ModelObject. Set to nullptr here, so the macros above will have it initialized.
+    Model                *m_model = nullptr;
+
+    // Bounding box, cached.
+    mutable BoundingBoxf3 m_bounding_box;
+    mutable bool          m_bounding_box_valid;
+};
+
+// An object STL, or a modifier volume, over which a different set of parameters shall be applied.
+// ModelVolume instances are owned by a ModelObject.
+class ModelVolume : public ModelBase
+{
+public:
+    std::string         name;
+    // The triangular model.
+    TriangleMesh        mesh;
+    // Configuration parameters specific to an object model geometry or a modifier volume, 
+    // overriding the global Slic3r settings and the ModelObject settings.
+    DynamicPrintConfig  config;
+
+    enum Type {
+        MODEL_TYPE_INVALID = -1,
+        MODEL_PART = 0,
+        PARAMETER_MODIFIER,
+        SUPPORT_ENFORCER,
+        SUPPORT_BLOCKER,
+    };
+
+    // A parent object owning this modifier volume.
+    ModelObject*        get_object() const { return this->object; };
+    Type                type() const { return m_type; }
+    void                set_type(const Type t) { m_type = t; }
+    bool                is_model_part()         const { return m_type == MODEL_PART; }
+    bool                is_modifier()           const { return m_type == PARAMETER_MODIFIER; }
+    bool                is_support_enforcer()   const { return m_type == SUPPORT_ENFORCER; }
+    bool                is_support_blocker()    const { return m_type == SUPPORT_BLOCKER; }
+    bool                is_support_modifier()   const { return m_type == SUPPORT_BLOCKER || m_type == SUPPORT_ENFORCER; }
+    t_model_material_id material_id() const { return m_material_id; }
+    void                set_material_id(t_model_material_id material_id);
+    ModelMaterial*      material() const;
+    void                set_material(t_model_material_id material_id, const ModelMaterial &material);
+    // Split this volume, append the result to the object owning this volume.
+    // Return the number of volumes created from this one.
+    // This is useful to assign different materials to different volumes of an object.
+    size_t              split(unsigned int max_extruders);
+    void                translate(double x, double y, double z) { translate(Vec3d(x, y, z)); }
+    void                translate(const Vec3d& displacement);
+    void                scale(const Vec3d& scaling_factors);
+    void                scale(double x, double y, double z) { scale(Vec3d(x, y, z)); }
+    void                scale(double s) { scale(Vec3d(s, s, s)); }
+    void                rotate(double angle, Axis axis);
+    void                rotate(double angle, const Vec3d& axis);
+    void                mirror(Axis axis);
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+    // translates the mesh and the convex hull so that the origin of their vertices is in the center of this volume's bounding box
+    void                center_geometry();
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+    void                calculate_convex_hull();
+    const TriangleMesh& get_convex_hull() const;
+
+    // Helpers for loading / storing into AMF / 3MF files.
+    static Type         type_from_string(const std::string &s);
+    static std::string  type_to_string(const Type t);
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+    const Geometry::Transformation& get_transformation() const { return m_transformation; }
+    void set_transformation(const Geometry::Transformation& transformation) { m_transformation = transformation; }
+
+    const Vec3d& get_offset() const { return m_transformation.get_offset(); }
+    double get_offset(Axis axis) const { return m_transformation.get_offset(axis); }
+
+    void set_offset(const Vec3d& offset) { m_transformation.set_offset(offset); }
+    void set_offset(Axis axis, double offset) { m_transformation.set_offset(axis, offset); }
+
+    const Vec3d& get_rotation() const { return m_transformation.get_rotation(); }
+    double get_rotation(Axis axis) const { return m_transformation.get_rotation(axis); }
+
+    void set_rotation(const Vec3d& rotation) { m_transformation.set_rotation(rotation); }
+    void set_rotation(Axis axis, double rotation) { m_transformation.set_rotation(axis, rotation); }
+
+    Vec3d get_scaling_factor() const { return m_transformation.get_scaling_factor(); }
+    double get_scaling_factor(Axis axis) const { return m_transformation.get_scaling_factor(axis); }
+
+    void set_scaling_factor(const Vec3d& scaling_factor) { m_transformation.set_scaling_factor(scaling_factor); }
+    void set_scaling_factor(Axis axis, double scaling_factor) { m_transformation.set_scaling_factor(axis, scaling_factor); }
+
+    const Vec3d& get_mirror() const { return m_transformation.get_mirror(); }
+    double get_mirror(Axis axis) const { return m_transformation.get_mirror(axis); }
+
+    void set_mirror(const Vec3d& mirror) { m_transformation.set_mirror(mirror); }
+    void set_mirror(Axis axis, double mirror) { m_transformation.set_mirror(axis, mirror); }
+
+    const Transform3d& get_matrix(bool dont_translate = false, bool dont_rotate = false, bool dont_scale = false, bool dont_mirror = false) const { return m_transformation.get_matrix(dont_translate, dont_rotate, dont_scale, dont_mirror); }
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+protected:
+	friend class Print;
+	friend class ModelObject;
+
+	explicit ModelVolume(const ModelVolume &rhs) = default;
+    void     set_model_object(ModelObject *model_object) { object = model_object; }
+
+private:
+    // Parent object owning this ModelVolume.
+    ModelObject*            object;
+    // Is it an object to be printed, or a modifier volume?
+    Type                    m_type;
+    t_model_material_id     m_material_id;
+    // The convex hull of this model's mesh.
+    TriangleMesh             m_convex_hull;
+#if ENABLE_MODELVOLUME_TRANSFORM
+    Geometry::Transformation m_transformation;
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+    ModelVolume(ModelObject *object, const TriangleMesh &mesh) : mesh(mesh), m_type(MODEL_PART), object(object)
+    {
+        if (mesh.stl.stats.number_of_facets > 1)
+            calculate_convex_hull();
+    }
+    ModelVolume(ModelObject *object, TriangleMesh &&mesh, TriangleMesh &&convex_hull) :
+        mesh(std::move(mesh)), m_convex_hull(std::move(convex_hull)), m_type(MODEL_PART), object(object) {}
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+    // Copying an existing volume, therefore this volume will get a copy of the ID assigned.
+    ModelVolume(ModelObject *object, const ModelVolume &other) :
+        ModelBase(other), // copy the ID
+        name(other.name), mesh(other.mesh), m_convex_hull(other.m_convex_hull), config(other.config), m_type(other.m_type), object(object), m_transformation(other.m_transformation)
+    {
+        this->set_material_id(other.material_id());
+    }
+    // Providing a new mesh, therefore this volume will get a new unique ID assigned.
+    ModelVolume(ModelObject *object, const ModelVolume &other, const TriangleMesh &&mesh) :
+        name(other.name), mesh(std::move(mesh)), config(other.config), m_type(other.m_type), object(object), m_transformation(other.m_transformation)
+    {
+        this->set_material_id(other.material_id());
+        if (mesh.stl.stats.number_of_facets > 1)
+            calculate_convex_hull();
+    }
+#else
+    // Copying an existing volume, therefore this volume will get a copy of the ID assigned.
+    ModelVolume(ModelObject *object, const ModelVolume &other) :
+        ModelBase(other), // copy the ID
+        name(other.name), mesh(other.mesh), m_convex_hull(other.m_convex_hull), config(other.config), m_type(other.m_type), object(object)
+    {
+		if (! other.material_id().empty())
+			this->set_material_id(other.material_id());
+    }
+    // Providing a new mesh, therefore this volume will get a new unique ID assigned.
+    ModelVolume(ModelObject *object, const ModelVolume &other, TriangleMesh &&mesh) :
+        name(other.name), mesh(std::move(mesh)), config(other.config), m_type(other.m_type), object(object)
+    {
+		if (! other.material_id().empty())
+			this->set_material_id(other.material_id());
+        if (mesh.stl.stats.number_of_facets > 1)
+            calculate_convex_hull();
+    }
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+    ModelVolume& operator=(ModelVolume &rhs) = delete;
+};
+
+// A single instance of a ModelObject.
+// Knows the affine transformation of an object.
+class ModelInstance : public ModelBase
+{
+public:
+    enum EPrintVolumeState : unsigned char
+    {
+        PVS_Inside,
+        PVS_Partly_Outside,
+        PVS_Fully_Outside,
+        Num_BedStates
+    };
+
+private:
+#if ENABLE_MODELVOLUME_TRANSFORM
+    Geometry::Transformation m_transformation;
+#else
+    Vec3d m_offset;              // in unscaled coordinates
+    Vec3d m_rotation;            // Rotation around the three axes, in radians around mesh center point
+    Vec3d m_scaling_factor;      // Scaling factors along the three axes
+    Vec3d m_mirror;              // Mirroring along the three axes
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+public:
+    // flag showing the position of this instance with respect to the print volume (set by Print::validate() using ModelObject::check_instances_print_volume_state())
+    EPrintVolumeState print_volume_state;
+
+    ModelObject* get_object() const { return this->object; }
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+    const Geometry::Transformation& get_transformation() const { return m_transformation; }
+    void set_transformation(const Geometry::Transformation& transformation) { m_transformation = transformation; }
+
+    const Vec3d& get_offset() const { return m_transformation.get_offset(); }
+    double get_offset(Axis axis) const { return m_transformation.get_offset(axis); }
+
+    void set_offset(const Vec3d& offset) { m_transformation.set_offset(offset); }
+    void set_offset(Axis axis, double offset) { m_transformation.set_offset(axis, offset); }
+
+    const Vec3d& get_rotation() const { return m_transformation.get_rotation(); }
+    double get_rotation(Axis axis) const { return m_transformation.get_rotation(axis); }
+
+    void set_rotation(const Vec3d& rotation) { m_transformation.set_rotation(rotation); }
+    void set_rotation(Axis axis, double rotation) { m_transformation.set_rotation(axis, rotation); }
+
+    Vec3d get_scaling_factor() const { return m_transformation.get_scaling_factor(); }
+    double get_scaling_factor(Axis axis) const { return m_transformation.get_scaling_factor(axis); }
+
+    void set_scaling_factor(const Vec3d& scaling_factor) { m_transformation.set_scaling_factor(scaling_factor); }
+    void set_scaling_factor(Axis axis, double scaling_factor) { m_transformation.set_scaling_factor(axis, scaling_factor); }
+
+    const Vec3d& get_mirror() const { return m_transformation.get_mirror(); }
+    double get_mirror(Axis axis) const { return m_transformation.get_mirror(axis); }
+
+    void set_mirror(const Vec3d& mirror) { m_transformation.set_mirror(mirror); }
+    void set_mirror(Axis axis, double mirror) { m_transformation.set_mirror(axis, mirror); }
+#else
+    const Vec3d& get_offset() const { return m_offset; }
+    double get_offset(Axis axis) const { return m_offset(axis); }
+
+    void set_offset(const Vec3d& offset) { m_offset = offset; }
+    void set_offset(Axis axis, double offset) { m_offset(axis) = offset; }
+
+    const Vec3d& get_rotation() const { return m_rotation; }
+    double get_rotation(Axis axis) const { return m_rotation(axis); }
+
+    void set_rotation(const Vec3d& rotation);
+    void set_rotation(Axis axis, double rotation);
+
+    Vec3d get_scaling_factor() const { return m_scaling_factor; }
+    double get_scaling_factor(Axis axis) const { return m_scaling_factor(axis); }
+
+    void set_scaling_factor(const Vec3d& scaling_factor);
+    void set_scaling_factor(Axis axis, double scaling_factor);
+
+    const Vec3d& get_mirror() const { return m_mirror; }
+    double get_mirror(Axis axis) const { return m_mirror(axis); }
+
+    void set_mirror(const Vec3d& mirror);
+    void set_mirror(Axis axis, double mirror);
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+    // To be called on an external mesh
+    void transform_mesh(TriangleMesh* mesh, bool dont_translate = false) const;
+    // Calculate a bounding box of a transformed mesh. To be called on an external mesh.
+    BoundingBoxf3 transform_mesh_bounding_box(const TriangleMesh& mesh, bool dont_translate = false) const;
+    // Transform an external bounding box.
+    BoundingBoxf3 transform_bounding_box(const BoundingBoxf3 &bbox, bool dont_translate = false) const;
+    // Transform an external vector.
+    Vec3d transform_vector(const Vec3d& v, bool dont_translate = false) const;
+    // To be called on an external polygon. It does not translate the polygon, only rotates and scales.
+    void transform_polygon(Polygon* polygon) const;
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+    const Transform3d& get_matrix(bool dont_translate = false, bool dont_rotate = false, bool dont_scale = false, bool dont_mirror = false) const { return m_transformation.get_matrix(dont_translate, dont_rotate, dont_scale, dont_mirror); }
+#else
+    Transform3d get_matrix(bool dont_translate = false, bool dont_rotate = false, bool dont_scale = false, bool dont_mirror = false) const;
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+    bool is_printable() const { return print_volume_state == PVS_Inside; }
+
+protected:
+    friend class Print;
+    friend class ModelObject;
+
+    explicit ModelInstance(const ModelInstance &rhs) = default;
+    void     set_model_object(ModelObject *model_object) { object = model_object; }
+
+private:
+    // Parent object, owning this instance.
+    ModelObject* object;
+
+#if ENABLE_MODELVOLUME_TRANSFORM
+    // Constructor, which assigns a new unique ID.
+    explicit ModelInstance(ModelObject *object) : object(object), print_volume_state(PVS_Inside) {}
+    // Constructor, which assigns a new unique ID.
+    explicit ModelInstance(ModelObject *object, const ModelInstance &other) :
+        m_transformation(other.m_transformation), object(object), print_volume_state(PVS_Inside) {}
+#else
+    explicit ModelInstance(ModelObject *object) : m_offset(Vec3d::Zero()), m_rotation(Vec3d::Zero()), m_scaling_factor(Vec3d::Ones()), m_mirror(Vec3d::Ones()), object(object), print_volume_state(PVS_Inside) {}
+    explicit ModelInstance(ModelObject *object, const ModelInstance &other) :
+        m_offset(other.m_offset), m_rotation(other.m_rotation), m_scaling_factor(other.m_scaling_factor), m_mirror(other.m_mirror), object(object), print_volume_state(PVS_Inside) {}
+#endif // ENABLE_MODELVOLUME_TRANSFORM
+
+    ModelInstance() = delete;
+    explicit ModelInstance(ModelInstance &&rhs) = delete;
+    ModelInstance& operator=(const ModelInstance &rhs) = delete;
+    ModelInstance& operator=(ModelInstance &&rhs) = delete;
+};
+
+// The print bed content.
+// Description of a triangular model with multiple materials, multiple instances with various affine transformations
+// and with multiple modifier meshes.
+// A model groups multiple objects, each object having possibly multiple instances,
+// all objects may share mutliple materials.
+class Model : public ModelBase
+{
+    static unsigned int s_auto_extruder_id;
+
+public:
+    // Materials are owned by a model and referenced by objects through t_model_material_id.
+    // Single material may be shared by multiple models.
+    ModelMaterialMap    materials;
+    // Objects are owned by a model. Each model may have multiple instances, each instance having its own transformation (shift, scale, rotation).
+    ModelObjectPtrs     objects;
+    
+    // Default constructor assigns a new ID to the model.
+    Model() {}
+    ~Model() { this->clear_objects(); this->clear_materials(); }
+
+    /* To be able to return an object from own copy / clone methods. Hopefully the compiler will do the "Copy elision" */
+    /* (Omits copy and move(since C++11) constructors, resulting in zero - copy pass - by - value semantics). */
+    Model(const Model &rhs) : ModelBase(-1) { this->assign_copy(rhs); }
+    explicit Model(Model &&rhs) : ModelBase(-1) { this->assign_copy(std::move(rhs)); }
+    Model& operator=(const Model &rhs) { this->assign_copy(rhs); return *this; }
+    Model& operator=(Model &&rhs) { this->assign_copy(std::move(rhs)); return *this; }
+
+    MODELBASE_DERIVED_COPY_MOVE_CLONE(Model)
+
+    static Model read_from_file(const std::string &input_file, DynamicPrintConfig *config = nullptr, bool add_default_instances = true);
+    static Model read_from_archive(const std::string &input_file, DynamicPrintConfig *config, bool add_default_instances = true);
+
+    /// Repair the ModelObjects of the current Model.
+    /// This function calls repair function on each TriangleMesh of each model object volume
+    void         repair();
+
+    // Add a new ModelObject to this Model, generate a new ID for this ModelObject.
+    ModelObject* add_object();
+    ModelObject* add_object(const char *name, const char *path, const TriangleMesh &mesh);
+    ModelObject* add_object(const char *name, const char *path, TriangleMesh &&mesh);
+    ModelObject* add_object(const ModelObject &other);
+    void         delete_object(size_t idx);
+    bool         delete_object(ModelID id);
+    bool         delete_object(ModelObject* object);
+    void         clear_objects();
+
+    ModelMaterial* add_material(t_model_material_id material_id);
+    ModelMaterial* add_material(t_model_material_id material_id, const ModelMaterial &other);
+    ModelMaterial* get_material(t_model_material_id material_id) {
+        ModelMaterialMap::iterator i = this->materials.find(material_id);
+        return (i == this->materials.end()) ? nullptr : i->second;
+    }
+
+    void          delete_material(t_model_material_id material_id);
+    void          clear_materials();
+    bool          add_default_instances();
+    // Returns approximate axis aligned bounding box of this model
+    BoundingBoxf3 bounding_box() const;
+    // Set the print_volume_state of PrintObject::instances, 
+    // return total number of printable objects.
+    unsigned int update_print_volume_state(const BoundingBoxf3 &print_volume);
+	// Returns true if any ModelObject was modified.
+    bool center_instances_around_point(const Vec2d &point);
+    void translate(coordf_t x, coordf_t y, coordf_t z) { for (ModelObject *o : this->objects) o->translate(x, y, z); }
+    TriangleMesh mesh() const;
+    bool arrange_objects(coordf_t dist, const BoundingBoxf* bb = NULL);
+    // Croaks if the duplicated objects do not fit the print bed.
+    void duplicate(size_t copies_num, coordf_t dist, const BoundingBoxf* bb = NULL);
+    void duplicate_objects(size_t copies_num, coordf_t dist, const BoundingBoxf* bb = NULL);
+    void duplicate_objects_grid(size_t x, size_t y, coordf_t dist);
+
+    bool looks_like_multipart_object() const;
+    void convert_multipart_object(unsigned int max_extruders);
+
+    // Ensures that the min z of the model is not negative
+    void adjust_min_z();
+
+    void print_info() const { for (const ModelObject *o : this->objects) o->print_info(); }
+
+    static unsigned int get_auto_extruder_id(unsigned int max_extruders);
+    static std::string get_auto_extruder_id_as_string(unsigned int max_extruders);
+    static void reset_auto_extruder_id();
+
+private:
+    MODELBASE_DERIVED_PRIVATE_COPY_MOVE(Model)
+};
+
+#undef MODELBASE_DERIVED_COPY_MOVE_CLONE
+#undef MODELBASE_DERIVED_PRIVATE_COPY_MOVE
+
+}
+
+#endif

src/libslic3r/ModelArrange.cpp

@@ -0,0 +1,763 @@
+#include "ModelArrange.hpp"
+#include "Model.hpp"
+#include "SVG.hpp"
+
+#include <libnest2d.h>
+
+#include <numeric>
+#include <ClipperUtils.hpp>
+
+#include <boost/geometry/index/rtree.hpp>
+
+namespace Slic3r {
+
+namespace arr {
+
+using namespace libnest2d;
+
+std::string toString(const Model& model, bool holes = true) {
+    std::stringstream  ss;
+
+    ss << "{\n";
+
+    for(auto objptr : model.objects) {
+        if(!objptr) continue;
+
+        auto rmesh = objptr->raw_mesh();
+
+        for(auto objinst : objptr->instances) {
+            if(!objinst) continue;
+
+            Slic3r::TriangleMesh tmpmesh = rmesh;
+            // CHECK_ME -> Is the following correct ?
+            tmpmesh.scale(objinst->get_scaling_factor());
+            objinst->transform_mesh(&tmpmesh);
+            ExPolygons expolys = tmpmesh.horizontal_projection();
+            for(auto& expoly_complex : expolys) {
+
+                auto tmp = expoly_complex.simplify(1.0/SCALING_FACTOR);
+                if(tmp.empty()) continue;
+                auto expoly = tmp.front();
+                expoly.contour.make_clockwise();
+                for(auto& h : expoly.holes) h.make_counter_clockwise();
+
+                ss << "\t{\n";
+                ss << "\t\t{\n";
+
+                for(auto v : expoly.contour.points) ss << "\t\t\t{"
+                                                    << v(0) << ", "
+                                                    << v(1) << "},\n";
+                {
+                    auto v = expoly.contour.points.front();
+                    ss << "\t\t\t{" << v(0) << ", " << v(1) << "},\n";
+                }
+                ss << "\t\t},\n";
+
+                // Holes:
+                ss << "\t\t{\n";
+                if(holes) for(auto h : expoly.holes) {
+                    ss << "\t\t\t{\n";
+                    for(auto v : h.points) ss << "\t\t\t\t{"
+                                           << v(0) << ", "
+                                           << v(1) << "},\n";
+                    {
+                        auto v = h.points.front();
+                        ss << "\t\t\t\t{" << v(0) << ", " << v(1) << "},\n";
+                    }
+                    ss << "\t\t\t},\n";
+                }
+                ss << "\t\t},\n";
+
+                ss << "\t},\n";
+            }
+        }
+    }
+
+    ss << "}\n";
+
+    return ss.str();
+}
+
+void toSVG(SVG& svg, const Model& model) {
+    for(auto objptr : model.objects) {
+        if(!objptr) continue;
+
+        auto rmesh = objptr->raw_mesh();
+
+        for(auto objinst : objptr->instances) {
+            if(!objinst) continue;
+
+            Slic3r::TriangleMesh tmpmesh = rmesh;
+            tmpmesh.scale(objinst->get_scaling_factor());
+            objinst->transform_mesh(&tmpmesh);
+            ExPolygons expolys = tmpmesh.horizontal_projection();
+            svg.draw(expolys);
+        }
+    }
+}
+
+namespace bgi = boost::geometry::index;
+
+using SpatElement = std::pair<Box, unsigned>;
+using SpatIndex = bgi::rtree< SpatElement, bgi::rstar<16, 4> >;
+using ItemGroup = std::vector<std::reference_wrapper<Item>>;
+template<class TBin>
+using TPacker = typename placers::_NofitPolyPlacer<PolygonImpl, TBin>;
+
+const double BIG_ITEM_TRESHOLD = 0.02;
+
+Box boundingBox(const Box& pilebb, const Box& ibb ) {
+    auto& pminc = pilebb.minCorner();
+    auto& pmaxc = pilebb.maxCorner();
+    auto& iminc = ibb.minCorner();
+    auto& imaxc = ibb.maxCorner();
+    PointImpl minc, maxc;
+
+    setX(minc, std::min(getX(pminc), getX(iminc)));
+    setY(minc, std::min(getY(pminc), getY(iminc)));
+
+    setX(maxc, std::max(getX(pmaxc), getX(imaxc)));
+    setY(maxc, std::max(getY(pmaxc), getY(imaxc)));
+    return Box(minc, maxc);
+}
+
+std::tuple<double /*score*/, Box /*farthest point from bin center*/>
+objfunc(const PointImpl& bincenter,
+        const shapelike::Shapes<PolygonImpl>& merged_pile,
+        const Box& pilebb,
+        const ItemGroup& items,
+        const Item &item,
+        double bin_area,
+        double norm,            // A norming factor for physical dimensions
+        // a spatial index to quickly get neighbors of the candidate item
+        const SpatIndex& spatindex,
+        const SpatIndex& smalls_spatindex,
+        const ItemGroup& remaining
+        )
+{
+    using Coord = TCoord<PointImpl>;
+
+    static const double ROUNDNESS_RATIO = 0.5;
+    static const double DENSITY_RATIO = 1.0 - ROUNDNESS_RATIO;
+
+    // We will treat big items (compared to the print bed) differently
+    auto isBig = [bin_area](double a) {
+        return a/bin_area > BIG_ITEM_TRESHOLD ;
+    };
+
+    // Candidate item bounding box
+    auto ibb = sl::boundingBox(item.transformedShape());
+
+    // Calculate the full bounding box of the pile with the candidate item
+    auto fullbb = boundingBox(pilebb, ibb);
+
+    // The bounding box of the big items (they will accumulate in the center
+    // of the pile
+    Box bigbb;
+    if(spatindex.empty()) bigbb = fullbb;
+    else {
+        auto boostbb = spatindex.bounds();
+        boost::geometry::convert(boostbb, bigbb);
+    }
+
+    // Will hold the resulting score
+    double score = 0;
+
+    if(isBig(item.area()) || spatindex.empty()) {
+        // This branch is for the bigger items..
+
+        auto minc = ibb.minCorner(); // bottom left corner
+        auto maxc = ibb.maxCorner(); // top right corner
+
+        // top left and bottom right corners
+        auto top_left = PointImpl{getX(minc), getY(maxc)};
+        auto bottom_right = PointImpl{getX(maxc), getY(minc)};
+
+        // Now the distance of the gravity center will be calculated to the
+        // five anchor points and the smallest will be chosen.
+        std::array<double, 5> dists;
+        auto cc = fullbb.center(); // The gravity center
+        dists[0] = pl::distance(minc, cc);
+        dists[1] = pl::distance(maxc, cc);
+        dists[2] = pl::distance(ibb.center(), cc);
+        dists[3] = pl::distance(top_left, cc);
+        dists[4] = pl::distance(bottom_right, cc);
+
+        // The smalles distance from the arranged pile center:
+        auto dist = *(std::min_element(dists.begin(), dists.end())) / norm;
+        auto bindist = pl::distance(ibb.center(), bincenter) / norm;
+        dist = 0.8*dist + 0.2*bindist;
+
+        // Density is the pack density: how big is the arranged pile
+        double density = 0;
+
+        if(remaining.empty()) {
+
+            auto mp = merged_pile;
+            mp.emplace_back(item.transformedShape());
+            auto chull = sl::convexHull(mp);
+
+            placers::EdgeCache<PolygonImpl> ec(chull);
+
+            double circ = ec.circumference() / norm;
+            double bcirc = 2.0*(fullbb.width() + fullbb.height()) / norm;
+            score = 0.5*circ + 0.5*bcirc;
+
+        } else {
+            // Prepare a variable for the alignment score.
+            // This will indicate: how well is the candidate item aligned with
+            // its neighbors. We will check the alignment with all neighbors and
+            // return the score for the best alignment. So it is enough for the
+            // candidate to be aligned with only one item.
+            auto alignment_score = 1.0;
+
+            density = std::sqrt((fullbb.width() / norm )*
+                                (fullbb.height() / norm));
+            auto querybb = item.boundingBox();
+
+            // Query the spatial index for the neighbors
+            std::vector<SpatElement> result;
+            result.reserve(spatindex.size());
+            if(isBig(item.area())) {
+                spatindex.query(bgi::intersects(querybb),
+                                std::back_inserter(result));
+            } else {
+                smalls_spatindex.query(bgi::intersects(querybb),
+                                       std::back_inserter(result));
+            }
+
+            for(auto& e : result) { // now get the score for the best alignment
+                auto idx = e.second;
+                Item& p = items[idx];
+                auto parea = p.area();
+                if(std::abs(1.0 - parea/item.area()) < 1e-6) {
+                    auto bb = boundingBox(p.boundingBox(), ibb);
+                    auto bbarea = bb.area();
+                    auto ascore = 1.0 - (item.area() + parea)/bbarea;
+
+                    if(ascore < alignment_score) alignment_score = ascore;
+                }
+            }
+
+            // The final mix of the score is the balance between the distance
+            // from the full pile center, the pack density and the
+            // alignment with the neighbors
+            if(result.empty())
+                score = 0.5 * dist + 0.5 * density;
+            else
+                score = 0.40 * dist + 0.40 * density + 0.2 * alignment_score;
+        }
+    } else {
+        // Here there are the small items that should be placed around the
+        // already processed bigger items.
+        // No need to play around with the anchor points, the center will be
+        // just fine for small items
+        score = pl::distance(ibb.center(), bigbb.center()) / norm;
+    }
+
+    return std::make_tuple(score, fullbb);
+}
+
+template<class PConf>
+void fillConfig(PConf& pcfg) {
+
+    // Align the arranged pile into the center of the bin
+    pcfg.alignment = PConf::Alignment::CENTER;
+
+    // Start placing the items from the center of the print bed
+    pcfg.starting_point = PConf::Alignment::CENTER;
+
+    // TODO cannot use rotations until multiple objects of same geometry can
+    // handle different rotations
+    // arranger.useMinimumBoundigBoxRotation();
+    pcfg.rotations = { 0.0 };
+
+    // The accuracy of optimization.
+    // Goes from 0.0 to 1.0 and scales performance as well
+    pcfg.accuracy = 0.65f;
+
+    pcfg.parallel = true;
+}
+
+template<class TBin>
+class AutoArranger {};
+
+template<class TBin>
+class _ArrBase {
+protected:
+
+    using Placer = TPacker<TBin>;
+    using Selector = FirstFitSelection;
+    using Packer = Nester<Placer, Selector>;
+    using PConfig = typename Packer::PlacementConfig;
+    using Distance = TCoord<PointImpl>;
+    using Pile = sl::Shapes<PolygonImpl>;
+
+    Packer m_pck;
+    PConfig m_pconf; // Placement configuration
+    double m_bin_area;
+    SpatIndex m_rtree;
+    SpatIndex m_smallsrtree;
+    double m_norm;
+    Pile m_merged_pile;
+    Box m_pilebb;
+    ItemGroup m_remaining;
+    ItemGroup m_items;
+public:
+
+    _ArrBase(const TBin& bin, Distance dist,
+             std::function<void(unsigned)> progressind,
+             std::function<bool(void)> stopcond):
+       m_pck(bin, dist), m_bin_area(sl::area(bin)),
+       m_norm(std::sqrt(sl::area(bin)))
+    {
+        fillConfig(m_pconf);
+
+        m_pconf.before_packing =
+        [this](const Pile& merged_pile,            // merged pile
+               const ItemGroup& items,             // packed items
+               const ItemGroup& remaining)         // future items to be packed
+        {
+            m_items = items;
+            m_merged_pile = merged_pile;
+            m_remaining = remaining;
+
+            m_pilebb = sl::boundingBox(merged_pile);
+
+            m_rtree.clear();
+            m_smallsrtree.clear();
+
+            // We will treat big items (compared to the print bed) differently
+            auto isBig = [this](double a) {
+                return a/m_bin_area > BIG_ITEM_TRESHOLD ;
+            };
+
+            for(unsigned idx = 0; idx < items.size(); ++idx) {
+                Item& itm = items[idx];
+                if(isBig(itm.area())) m_rtree.insert({itm.boundingBox(), idx});
+                m_smallsrtree.insert({itm.boundingBox(), idx});
+            }
+        };
+
+        m_pck.progressIndicator(progressind);
+        m_pck.stopCondition(stopcond);
+    }
+
+    template<class...Args> inline IndexedPackGroup operator()(Args&&...args) {
+        m_rtree.clear();
+        return m_pck.executeIndexed(std::forward<Args>(args)...);
+    }
+};
+
+template<>
+class AutoArranger<Box>: public _ArrBase<Box> {
+public:
+
+    AutoArranger(const Box& bin, Distance dist,
+                 std::function<void(unsigned)> progressind,
+                 std::function<bool(void)> stopcond):
+        _ArrBase<Box>(bin, dist, progressind, stopcond)
+    {
+
+        m_pconf.object_function = [this, bin] (const Item &item) {
+
+            auto result = objfunc(bin.center(),
+                                  m_merged_pile,
+                                  m_pilebb,
+                                  m_items,
+                                  item,
+                                  m_bin_area,
+                                  m_norm,
+                                  m_rtree,
+                                  m_smallsrtree,
+                                  m_remaining);
+
+            double score = std::get<0>(result);
+            auto& fullbb = std::get<1>(result);
+
+            double miss = Placer::overfit(fullbb, bin);
+            miss = miss > 0? miss : 0;
+            score += miss*miss;
+
+            return score;
+        };
+
+        m_pck.configure(m_pconf);
+    }
+};
+
+using lnCircle = libnest2d::_Circle<libnest2d::PointImpl>;
+
+inline lnCircle to_lnCircle(const Circle& circ) {
+    return lnCircle({circ.center()(0), circ.center()(1)}, circ.radius());
+}
+
+template<>
+class AutoArranger<lnCircle>: public _ArrBase<lnCircle> {
+public:
+
+    AutoArranger(const lnCircle& bin, Distance dist,
+                 std::function<void(unsigned)> progressind,
+                 std::function<bool(void)> stopcond):
+        _ArrBase<lnCircle>(bin, dist, progressind, stopcond) {
+
+        m_pconf.object_function = [this, &bin] (const Item &item) {
+
+            auto result = objfunc(bin.center(),
+                                  m_merged_pile,
+                                  m_pilebb,
+                                  m_items,
+                                  item,
+                                  m_bin_area,
+                                  m_norm,
+                                  m_rtree,
+                                  m_smallsrtree,
+                                  m_remaining);
+
+            double score = std::get<0>(result);
+
+            auto isBig = [this](const Item& itm) {
+                return itm.area()/m_bin_area > BIG_ITEM_TRESHOLD ;
+            };
+
+            if(isBig(item)) {
+                auto mp = m_merged_pile;
+                mp.push_back(item.transformedShape());
+                auto chull = sl::convexHull(mp);
+                double miss = Placer::overfit(chull, bin);
+                if(miss < 0) miss = 0;
+                score += miss*miss;
+            }
+
+            return score;
+        };
+
+        m_pck.configure(m_pconf);
+    }
+};
+
+template<>
+class AutoArranger<PolygonImpl>: public _ArrBase<PolygonImpl> {
+public:
+    AutoArranger(const PolygonImpl& bin, Distance dist,
+                 std::function<void(unsigned)> progressind,
+                 std::function<bool(void)> stopcond):
+        _ArrBase<PolygonImpl>(bin, dist, progressind, stopcond)
+    {
+        m_pconf.object_function = [this, &bin] (const Item &item) {
+
+            auto binbb = sl::boundingBox(bin);
+            auto result = objfunc(binbb.center(),
+                                  m_merged_pile,
+                                  m_pilebb,
+                                  m_items,
+                                  item,
+                                  m_bin_area,
+                                  m_norm,
+                                  m_rtree,
+                                  m_smallsrtree,
+                                  m_remaining);
+            double score = std::get<0>(result);
+
+            return score;
+        };
+
+        m_pck.configure(m_pconf);
+    }
+};
+
+template<> // Specialization with no bin
+class AutoArranger<bool>: public _ArrBase<Box> {
+public:
+
+    AutoArranger(Distance dist, std::function<void(unsigned)> progressind,
+                 std::function<bool(void)> stopcond):
+        _ArrBase<Box>(Box(0, 0), dist, progressind, stopcond)
+    {
+        this->m_pconf.object_function = [this] (const Item &item) {
+
+            auto result = objfunc({0, 0},
+                                  m_merged_pile,
+                                  m_pilebb,
+                                  m_items,
+                                  item,
+                                  0,
+                                  m_norm,
+                                  m_rtree,
+                                  m_smallsrtree,
+                                  m_remaining);
+            return std::get<0>(result);
+        };
+
+        this->m_pck.configure(m_pconf);
+    }
+};
+
+// A container which stores a pointer to the 3D object and its projected
+// 2D shape from top view.
+using ShapeData2D =
+    std::vector<std::pair<Slic3r::ModelInstance*, Item>>;
+
+ShapeData2D projectModelFromTop(const Slic3r::Model &model) {
+    ShapeData2D ret;
+
+    auto s = std::accumulate(model.objects.begin(), model.objects.end(), size_t(0),
+                    [](size_t s, ModelObject* o){
+        return s + o->instances.size();
+    });
+
+    ret.reserve(s);
+
+    for(auto objptr : model.objects) {
+        if(objptr) {
+
+            auto rmesh = objptr->raw_mesh();
+
+            for(auto objinst : objptr->instances) {
+                if(objinst) {
+                    Slic3r::TriangleMesh tmpmesh = rmesh;
+                    ClipperLib::PolygonImpl pn;
+
+                    // CHECK_ME -> is the following correct ?
+                    tmpmesh.scale(objinst->get_scaling_factor());
+
+                    // TODO export the exact 2D projection
+                    auto p = tmpmesh.convex_hull();
+
+                    p.make_clockwise();
+                    p.append(p.first_point());
+                    pn.Contour = Slic3rMultiPoint_to_ClipperPath( p );
+
+                    // Efficient conversion to item.
+                    Item item(std::move(pn));
+
+                    // Invalid geometries would throw exceptions when arranging
+                    if(item.vertexCount() > 3) {
+                        // CHECK_ME -> is the following correct or it should take in account all three rotations ?
+                        item.rotation(objinst->get_rotation(Z));
+                        item.translation({
+                        ClipperLib::cInt(objinst->get_offset(X)/SCALING_FACTOR),
+                        ClipperLib::cInt(objinst->get_offset(Y)/SCALING_FACTOR)
+                        });
+                        ret.emplace_back(objinst, item);
+                    }
+                }
+            }
+        }
+    }
+
+    return ret;
+}
+
+void applyResult(
+        IndexedPackGroup::value_type& group,
+        Coord batch_offset,
+        ShapeData2D& shapemap)
+{
+    for(auto& r : group) {
+        auto idx = r.first;     // get the original item index
+        Item& item = r.second;  // get the item itself
+
+        // Get the model instance from the shapemap using the index
+        ModelInstance *inst_ptr = shapemap[idx].first;
+
+        // Get the transformation data from the item object and scale it
+        // appropriately
+        auto off = item.translation();
+        Radians rot = item.rotation();
+        Vec3d foff(off.X*SCALING_FACTOR + batch_offset,
+                   off.Y*SCALING_FACTOR,
+                   inst_ptr->get_offset()(2));
+
+        // write the transformation data into the model instance
+        inst_ptr->set_rotation(Z, rot);
+        inst_ptr->set_offset(foff);
+    }
+}
+
+BedShapeHint bedShape(const Polyline &bed) {
+    BedShapeHint ret;
+
+    auto x = [](const Point& p) { return p(0); };
+    auto y = [](const Point& p) { return p(1); };
+
+    auto width = [x](const BoundingBox& box) {
+        return x(box.max) - x(box.min);
+    };
+
+    auto height = [y](const BoundingBox& box) {
+        return y(box.max) - y(box.min);
+    };
+
+    auto area = [&width, &height](const BoundingBox& box) {
+        double w = width(box);
+        double h = height(box);
+        return w*h;
+    };
+
+    auto poly_area = [](Polyline p) {
+        Polygon pp; pp.points.reserve(p.points.size() + 1);
+        pp.points = std::move(p.points);
+        pp.points.emplace_back(pp.points.front());
+        return std::abs(pp.area());
+    };
+
+    auto distance_to = [x, y](const Point& p1, const Point& p2) {
+        double dx = x(p2) - x(p1);
+        double dy = y(p2) - y(p1);
+        return std::sqrt(dx*dx + dy*dy);
+    };
+
+    auto bb = bed.bounding_box();
+
+    auto isCircle = [bb, distance_to](const Polyline& polygon) {
+        auto center = bb.center();
+        std::vector<double> vertex_distances;
+        double avg_dist = 0;
+        for (auto pt: polygon.points)
+        {
+            double distance = distance_to(center, pt);
+            vertex_distances.push_back(distance);
+            avg_dist += distance;
+        }
+
+        avg_dist /= vertex_distances.size();
+
+        Circle ret(center, avg_dist);
+        for (auto el: vertex_distances)
+        {
+            if (abs(el - avg_dist) > 10 * SCALED_EPSILON)
+                ret = Circle();
+            break;
+        }
+
+        return ret;
+    };
+
+    auto parea = poly_area(bed);
+
+    if( (1.0 - parea/area(bb)) < 1e-3 ) {
+        ret.type = BedShapeType::BOX;
+        ret.shape.box = bb;
+    }
+    else if(auto c = isCircle(bed)) {
+        ret.type = BedShapeType::CIRCLE;
+        ret.shape.circ = c;
+    } else {
+        ret.type = BedShapeType::IRREGULAR;
+        ret.shape.polygon = bed;
+    }
+
+    // Determine the bed shape by hand
+    return ret;
+}
+
+bool arrange(Model &model,
+             coord_t min_obj_distance,
+             const Polyline &bed,
+             BedShapeHint bedhint,
+             bool first_bin_only,
+             std::function<void (unsigned)> progressind,
+             std::function<bool ()> stopcondition)
+{
+    using ArrangeResult = _IndexedPackGroup<PolygonImpl>;
+
+    bool ret = true;
+
+    // Get the 2D projected shapes with their 3D model instance pointers
+    auto shapemap = arr::projectModelFromTop(model);
+
+    // Copy the references for the shapes only as the arranger expects a
+    // sequence of objects convertible to Item or ClipperPolygon
+    std::vector<std::reference_wrapper<Item>> shapes;
+    shapes.reserve(shapemap.size());
+    std::for_each(shapemap.begin(), shapemap.end(),
+                  [&shapes] (ShapeData2D::value_type& it)
+    {
+        shapes.push_back(std::ref(it.second));
+    });
+
+    IndexedPackGroup result;
+
+    // If there is no hint about the shape, we will try to guess
+    if(bedhint.type == BedShapeType::WHO_KNOWS) bedhint = bedShape(bed);
+
+    BoundingBox bbb(bed);
+
+    auto& cfn = stopcondition;
+
+    auto binbb = Box({
+                         static_cast<libnest2d::Coord>(bbb.min(0)),
+                         static_cast<libnest2d::Coord>(bbb.min(1))
+                     },
+    {
+                         static_cast<libnest2d::Coord>(bbb.max(0)),
+                         static_cast<libnest2d::Coord>(bbb.max(1))
+                     });
+
+    switch(bedhint.type) {
+    case BedShapeType::BOX: {
+
+        // Create the arranger for the box shaped bed
+        AutoArranger<Box> arrange(binbb, min_obj_distance, progressind, cfn);
+
+        // Arrange and return the items with their respective indices within the
+        // input sequence.
+        result = arrange(shapes.begin(), shapes.end());
+        break;
+    }
+    case BedShapeType::CIRCLE: {
+
+        auto c = bedhint.shape.circ;
+        auto cc = to_lnCircle(c);
+
+        AutoArranger<lnCircle> arrange(cc, min_obj_distance, progressind, cfn);
+        result = arrange(shapes.begin(), shapes.end());
+        break;
+    }
+    case BedShapeType::IRREGULAR:
+    case BedShapeType::WHO_KNOWS: {
+
+        using P = libnest2d::PolygonImpl;
+
+        auto ctour = Slic3rMultiPoint_to_ClipperPath(bed);
+        P irrbed = sl::create<PolygonImpl>(std::move(ctour));
+
+        AutoArranger<P> arrange(irrbed, min_obj_distance, progressind, cfn);
+
+        // Arrange and return the items with their respective indices within the
+        // input sequence.
+        result = arrange(shapes.begin(), shapes.end());
+        break;
+    }
+    };
+
+    if(result.empty() || stopcondition()) return false;
+
+    if(first_bin_only) {
+        applyResult(result.front(), 0, shapemap);
+    } else {
+
+        const auto STRIDE_PADDING = 1.2;
+
+        Coord stride = static_cast<Coord>(STRIDE_PADDING*
+                                          binbb.width()*SCALING_FACTOR);
+        Coord batch_offset = 0;
+
+        for(auto& group : result) {
+            applyResult(group, batch_offset, shapemap);
+
+            // Only the first pack group can be placed onto the print bed. The
+            // other objects which could not fit will be placed next to the
+            // print bed
+            batch_offset += stride;
+        }
+    }
+
+    for(auto objptr : model.objects) objptr->invalidate_bounding_box();
+
+    return ret && result.size() == 1;
+}
+
+}
+}

src/libslic3r/ModelArrange.hpp

@@ -0,0 +1,82 @@
+#ifndef MODELARRANGE_HPP
+#define MODELARRANGE_HPP
+
+#include "Model.hpp"
+
+namespace Slic3r {
+
+class Model;
+
+namespace arr {
+
+class Circle {
+    Point center_;
+    double radius_;
+public:
+
+    inline Circle(): center_(0, 0), radius_(std::nan("")) {}
+    inline Circle(const Point& c, double r): center_(c), radius_(r) {}
+
+    inline double radius() const { return radius_; }
+    inline const Point& center() const { return center_; }
+    inline operator bool() { return !std::isnan(radius_); }
+//    inline operator lnCircle() {
+//        return lnCircle({center_(0), center_(1)}, radius_);
+//    }
+};
+
+enum class BedShapeType {
+    BOX,
+    CIRCLE,
+    IRREGULAR,
+    WHO_KNOWS
+};
+
+struct BedShapeHint {
+    BedShapeType type;
+    /*union*/ struct {  // I know but who cares...
+        Circle circ;
+        BoundingBox box;
+        Polyline polygon;
+    } shape;
+};
+
+BedShapeHint bedShape(const Polyline& bed);
+
+/**
+ * \brief Arranges the model objects on the screen.
+ *
+ * The arrangement considers multiple bins (aka. print beds) for placing all
+ * the items provided in the model argument. If the items don't fit on one
+ * print bed, the remaining will be placed onto newly created print beds.
+ * The first_bin_only parameter, if set to true, disables this behavior and
+ * makes sure that only one print bed is filled and the remaining items will be
+ * untouched. When set to false, the items which could not fit onto the
+ * print bed will be placed next to the print bed so the user should see a
+ * pile of items on the print bed and some other piles outside the print
+ * area that can be dragged later onto the print bed as a group.
+ *
+ * \param model The model object with the 3D content.
+ * \param dist The minimum distance which is allowed for any pair of items
+ * on the print bed  in any direction.
+ * \param bb The bounding box of the print bed. It corresponds to the 'bin'
+ * for bin packing.
+ * \param first_bin_only This parameter controls whether to place the
+ * remaining items which do not fit onto the print area next to the print
+ * bed or leave them untouched (let the user arrange them by hand or remove
+ * them).
+ * \param progressind Progress indicator callback called when an object gets
+ * packed. The unsigned argument is the number of items remaining to pack.
+ * \param stopcondition A predicate returning true if abort is needed.
+ */
+bool arrange(Model &model, coord_t min_obj_distance,
+             const Slic3r::Polyline& bed,
+             BedShapeHint bedhint,
+             bool first_bin_only,
+             std::function<void(unsigned)> progressind,
+             std::function<bool(void)> stopcondition);
+
+}
+
+}
+#endif // MODELARRANGE_HPP