More refactoring to medial axis and gap fill, more robust

xs/src/libslic3r/ExPolygon.cpp

@@ -174,17 +174,10 @@ void
 ExPolygon::medial_axis(double max_width, double min_width, ThickPolylines* polylines) const
 {
     // init helper object
-    Slic3r::Geometry::MedialAxis ma(max_width, min_width);
-    ma.expolygon = this;
+    Slic3r::Geometry::MedialAxis ma(max_width, min_width, this);
+    ma.lines = this->lines();
     
-    // populate list of segments for the Voronoi diagram
-    ma.lines = this->contour.lines();
-    for (Polygons::const_iterator hole = this->holes.begin(); hole != this->holes.end(); ++hole) {
-        Lines lines = hole->lines();
-        ma.lines.insert(ma.lines.end(), lines.begin(), lines.end());
-    }
-    
-    // compute the Voronoi diagram
+    // compute the Voronoi diagram and extract medial axis polylines
     ThickPolylines pp;
     ma.build(&pp);
     
@@ -195,15 +188,14 @@ ExPolygon::medial_axis(double max_width, double min_width, ThickPolylines* polyl
     svg.Close();
     */
     
-    // find the maximum width returned
+    /* Find the maximum width returned; we're going to use this for validating and 
+       filtering the output segments. */
     double max_w = 0;
-    if (!pp.empty()) {
-        std::vector<double> widths;
-        for (ThickPolylines::const_iterator it = pp.begin(); it != pp.end(); ++it)
-            widths.insert(widths.end(), it->width.begin(), it->width.end());
-        max_w = *std::max_element(widths.begin(), widths.end());
-    }
+    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];
@@ -502,4 +494,15 @@ ExPolygon::lines() const
     return lines;
 }
 
+std::string
+ExPolygon::dump_perl() const
+{
+    std::ostringstream ret;
+    ret << "[" << this->contour.dump_perl();
+    for (Polygons::const_iterator h = this->holes.begin(); h != this->holes.end(); ++h)
+        ret << "," << h->dump_perl();
+    ret << "]";
+    return ret.str();
+}
+
 }

xs/src/libslic3r/ExPolygon.hpp

@@ -42,6 +42,7 @@ class ExPolygon
     void triangulate_pp(Polygons* polygons) const;
     void triangulate_p2t(Polygons* polygons) const;
     Lines lines() const;
+    std::string dump_perl() const;
 };
 
 }

xs/src/libslic3r/Geometry.cpp

@@ -324,7 +324,7 @@ MedialAxis::build(ThickPolylines* polylines)
             if (edge->is_secondary() || edge->is_infinite()) continue;
         
             // don't re-validate twins
-            if (seen_edges.find(&*edge) != seen_edges.end()) continue;
+            if (seen_edges.find(&*edge) != seen_edges.end()) continue;  // TODO: is this needed?
             seen_edges.insert(&*edge);
             seen_edges.insert(edge->twin());
             
@@ -445,49 +445,66 @@ MedialAxis::validate_edge(const VD::edge_type* edge)
     }
     
     // retrieve the original line segments which generated the edge we're checking
-    const VD::cell_type* cell1 = edge->cell();
-    const VD::cell_type* cell2 = edge->twin()->cell();
-    const Line &segment1 = this->retrieve_segment(cell1);
-    const Line &segment2 = this->retrieve_segment(cell2);
+    const VD::cell_type* cell_l = edge->cell();
+    const VD::cell_type* cell_r = edge->twin()->cell();
+    const Line &segment_l = this->retrieve_segment(cell_l);
+    const Line &segment_r = this->retrieve_segment(cell_r);
     
-    /*  Calculate thickness of the section at both the endpoints of this edge.
-        Our Voronoi edge is part of a CCW sequence going around its Voronoi cell
-        (segment1). This edge's twin goes around segment2. Thus, segment2 is 
-        oriented in the same direction as our main edge, and segment1 is oriented
+    /*
+    SVG svg("edge.svg");
+    svg.draw(*this->expolygon);
+    svg.draw(line);
+    svg.draw(segment_l, "red");
+    svg.draw(segment_r, "blue");
+    svg.Close();
+    */
+    
+    /*  Calculate thickness of the cross-section at both the endpoints of this edge.
+        Our Voronoi edge is part of a CCW sequence going around its Voronoi cell 
+        located on the left side. (segment_l).
+        This edge's twin goes around segment_r. Thus, segment_r is 
+        oriented in the same direction as our main edge, and segment_l is oriented
         in the same direction as our twin edge.
-        We used to only consider the (half-)distances to segment2, and that works
-        whenever segment1 and segment2 are almost specular and facing. However, 
+        We used to only consider the (half-)distances to segment_r, and that works
+        whenever segment_l and segment_r are almost specular and facing. However, 
         at curves they are staggered and they only face for a very little length
-        (such visibility actually coincides with our very short edge). This is why
-        we calculate w0 and w1 this way.
-        When cell1 or cell2 don't refer to the segment but only to an endpoint, we
+        (our very short edge represents such visibility).
+        Both w0 and w1 can be calculated either towards cell_l or cell_r with equal
+        results by Voronoi definition.
+        When cell_l or cell_r don't refer to the segment but only to an endpoint, we
         calculate the distance to that endpoint instead.  */
     
-    coordf_t w0 = cell2->contains_segment()
-        ? line.a.perp_distance_to(segment2)*2
-        : line.a.distance_to(this->retrieve_endpoint(cell2))*2;
+    coordf_t w0 = cell_r->contains_segment()
+        ? line.a.distance_to(segment_r)*2
+        : line.a.distance_to(this->retrieve_endpoint(cell_r))*2;
     
-    coordf_t w1 = cell1->contains_segment()
-        ? line.b.perp_distance_to(segment1)*2
-        : line.b.distance_to(this->retrieve_endpoint(cell1))*2;
+    coordf_t w1 = cell_l->contains_segment()
+        ? line.b.distance_to(segment_l)*2
+        : line.b.distance_to(this->retrieve_endpoint(cell_l))*2;
     
-    // if this edge is the centerline for a very thin area, we might want to skip it
-    // in case the area is too thin
-    if (w0 < SCALED_EPSILON || w1 < SCALED_EPSILON) {
-        if (cell1->contains_segment() && cell2->contains_segment()) {
-            // calculate the relative angle between the two boundary segments
-            double angle = fabs(segment2.orientation() - segment1.orientation());
+    if (cell_l->contains_segment() && cell_r->contains_segment()) {
+        // calculate the relative angle between the two boundary segments
+        double angle = fabs(segment_r.orientation() - segment_l.orientation());
+        if (angle > PI) angle = 2*PI - angle;
+        assert(angle >= 0 && angle <= PI);
+        
+        // fabs(angle) ranges from 0 (collinear, same direction) to PI (collinear, opposite direction)
+        // we're interested only in segments close to the second case (facing segments)
+        // so we allow some tolerance.
+        // this filter ensures that we're dealing with a narrow/oriented area (longer than thick)
+        // we don't run it on edges not generated by two segments (thus generated by one segment
+        // and the endpoint of another segment), since their orientation would not be meaningful
+        if (PI - angle > PI/8) {
+            // angle is not narrow enough
             
-            // fabs(angle) ranges from 0 (collinear, same direction) to PI (collinear, opposite direction)
-            // we're interested only in segments close to the second case (facing segments)
-            // so we allow some tolerance.
-            // this filter ensures that we're dealing with a narrow/oriented area (longer than thick)
-            // we don't run it on edges not generated by two segments (thus generated by one segment
-            // and the endpoint of another segment), since their orientation would not be meaningful
-            if (fabs(angle - PI) > PI/5) return false;
-        } else {
-            return false;
+            // only apply this filter to segments that are not too short otherwise their 
+            // angle could possibly be not meaningful
+            if (w0 < SCALED_EPSILON || w1 < SCALED_EPSILON || line.length() >= this->min_width)
+                return false;
         }
+    } else {
+        if (w0 < SCALED_EPSILON || w1 < SCALED_EPSILON)
+            return false;
     }
     
     if (w0 < this->min_width && w1 < this->min_width)

xs/src/libslic3r/Geometry.hpp

@@ -46,8 +46,8 @@ class MedialAxis {
     const ExPolygon* expolygon;
     double max_width;
     double min_width;
-    MedialAxis(double _max_width, double _min_width)
-        : max_width(_max_width), min_width(_min_width), expolygon(NULL) {};
+    MedialAxis(double _max_width, double _min_width, const ExPolygon* _expolygon = NULL)
+        : max_width(_max_width), min_width(_min_width), expolygon(_expolygon) {};
     void build(ThickPolylines* polylines);
     void build(Polylines* polylines);
     

xs/src/libslic3r/Line.cpp

@@ -212,6 +212,12 @@ Line::intersection(const Line& line, Point* intersection) const
     return false;  // not intersecting
 }
 
+double
+Line::ccw(const Point& point) const
+{
+    return point.ccw(*this);
+}
+
 Pointf3
 Linef3::intersect_plane(double z) const
 {

xs/src/libslic3r/Line.hpp

@@ -44,6 +44,7 @@ class Line
     void extend_end(double distance);
     void extend_start(double distance);
     bool intersection(const Line& line, Point* intersection) const;
+    double ccw(const Point& point) const;
 };
 
 class ThickLine : public Line

xs/src/libslic3r/MultiPoint.cpp

@@ -128,6 +128,19 @@ MultiPoint::intersection(const Line& line, Point* intersection) const
     return false;
 }
 
+std::string
+MultiPoint::dump_perl() const
+{
+    std::ostringstream ret;
+    ret << "[";
+    for (Points::const_iterator p = this->points.begin(); p != this->points.end(); ++p) {
+        ret << p->dump_perl();
+        if (p != this->points.end()-1) ret << ",";
+    }
+    ret << "]";
+    return ret.str();
+}
+
 Points
 MultiPoint::_douglas_peucker(const Points &points, const double tolerance)
 {

xs/src/libslic3r/MultiPoint.hpp

@@ -37,6 +37,7 @@ class MultiPoint
     void append(const Points &points);
     void append(const Points::const_iterator &begin, const Points::const_iterator &end);
     bool intersection(const Line& line, Point* intersection) const;
+    std::string dump_perl() const;
     
     static Points _douglas_peucker(const Points &points, const double tolerance);
 };

xs/src/libslic3r/PerimeterGenerator.cpp

@@ -92,7 +92,7 @@ PerimeterGenerator::process()
                         
                         // the following offset2 ensures almost nothing in @thin_walls is narrower than $min_width
                         // (actually, something larger than that still may exist due to mitering or other causes)
-                        coord_t min_width = scale_(this->ext_perimeter_flow.nozzle_diameter / 2);
+                        coord_t min_width = scale_(this->ext_perimeter_flow.nozzle_diameter / 3);
                         ExPolygons expp = offset2_ex(diffpp, -min_width/2, +min_width/2);
                         
                         // the maximum thickness of our thin wall area is equal to the minimum thickness of a single loop

xs/src/libslic3r/Point.cpp

@@ -26,6 +26,14 @@ Point::wkt() const
     return ss.str();
 }
 
+std::string
+Point::dump_perl() const
+{
+    std::ostringstream ss;
+    ss << "[" << this->x << "," << this->y << "]";
+    return ss.str();
+}
+
 void
 Point::scale(double factor)
 {
@@ -313,6 +321,14 @@ Pointf::wkt() const
     return ss.str();
 }
 
+std::string
+Pointf::dump_perl() const
+{
+    std::ostringstream ss;
+    ss << "[" << this->x << "," << this->y << "]";
+    return ss.str();
+}
+
 void
 Pointf::scale(double factor)
 {

xs/src/libslic3r/Point.hpp

@@ -38,6 +38,7 @@ class Point
     };
     bool operator==(const Point& rhs) const;
     std::string wkt() const;
+    std::string dump_perl() const;
     void scale(double factor);
     void translate(double x, double y);
     void translate(const Vector &vector);
@@ -87,6 +88,7 @@ class Pointf
         return Pointf(unscale(p.x), unscale(p.y));
     };
     std::string wkt() const;
+    std::string dump_perl() const;
     void scale(double factor);
     void translate(double x, double y);
     void translate(const Vectorf &vector);