OrcaSlicer/src/libslic3r/SLA/SLABasePool.cpp

705 lines
26 KiB
C++

#include "SLABasePool.hpp"
#include "SLABoilerPlate.hpp"
#include "boost/log/trivial.hpp"
#include "SLABoostAdapter.hpp"
#include "ClipperUtils.hpp"
#include "Tesselate.hpp"
#include "MTUtils.hpp"
// For debugging:
//#include <fstream>
//#include <libnest2d/tools/benchmark.h>
//#include "SVG.hpp"
namespace Slic3r { namespace sla {
/// This function will return a triangulation of a sheet connecting an upper
/// and a lower plate given as input polygons. It will not triangulate the
/// plates themselves only the sheet. The caller has to specify the lower and
/// upper z levels in world coordinates as well as the offset difference
/// between the sheets. If the lower_z_mm is higher than upper_z_mm or the
/// offset difference is negative, the resulting triangle orientation will be
/// reversed.
///
/// IMPORTANT: This is not a universal triangulation algorithm. It assumes
/// that the lower and upper polygons are offsetted versions of the same
/// original polygon. In general, it assumes that one of the polygons is
/// completely inside the other. The offset difference is the reference
/// distance from the inner polygon's perimeter to the outer polygon's
/// perimeter. The real distance will be variable as the clipper offset has
/// different strategies (rounding, etc...). This algorithm should have
/// O(2n + 3m) complexity where n is the number of upper vertices and m is the
/// number of lower vertices.
Contour3D walls(const Polygon& lower, const Polygon& upper,
double lower_z_mm, double upper_z_mm,
double offset_difference_mm, ThrowOnCancel thr)
{
Contour3D ret;
if(upper.points.size() < 3 || lower.size() < 3) return ret;
// The concept of the algorithm is relatively simple. It will try to find
// the closest vertices from the upper and the lower polygon and use those
// as starting points. Then it will create the triangles sequentially using
// an edge from the upper polygon and a vertex from the lower or vice versa,
// depending on the resulting triangle's quality.
// The quality is measured by a scalar value. So far it looks like it is
// enough to derive it from the slope of the triangle's two edges connecting
// the upper and the lower part. A reference slope is calculated from the
// height and the offset difference.
// Offset in the index array for the ceiling
const auto offs = upper.points.size();
// Shorthand for the vertex arrays
auto& upoints = upper.points, &lpoints = lower.points;
auto& rpts = ret.points; auto& ind = ret.indices;
// If the Z levels are flipped, or the offset difference is negative, we
// will interpret that as the triangles normals should be inverted.
bool inverted = upper_z_mm < lower_z_mm || offset_difference_mm < 0;
// Copy the points into the mesh, convert them from 2D to 3D
rpts.reserve(upoints.size() + lpoints.size());
ind.reserve(2 * upoints.size() + 2 * lpoints.size());
for (auto &p : upoints)
rpts.emplace_back(unscaled(p.x()), unscaled(p.y()), upper_z_mm);
for (auto &p : lpoints)
rpts.emplace_back(unscaled(p.x()), unscaled(p.y()), lower_z_mm);
// Create pointing indices into vertex arrays. u-upper, l-lower
size_t uidx = 0, lidx = offs, unextidx = 1, lnextidx = offs + 1;
// Simple squared distance calculation.
auto distfn = [](const Vec3d& p1, const Vec3d& p2) {
auto p = p1 - p2; return p.transpose() * p;
};
// We need to find the closest point on lower polygon to the first point on
// the upper polygon. These will be our starting points.
double distmin = std::numeric_limits<double>::max();
for(size_t l = lidx; l < rpts.size(); ++l) {
thr();
double d = distfn(rpts[l], rpts[uidx]);
if(d < distmin) { lidx = l; distmin = d; }
}
// Set up lnextidx to be ahead of lidx in cyclic mode
lnextidx = lidx + 1;
if(lnextidx == rpts.size()) lnextidx = offs;
// This will be the flip switch to toggle between upper and lower triangle
// creation mode
enum class Proceed {
UPPER, // A segment from the upper polygon and one vertex from the lower
LOWER // A segment from the lower polygon and one vertex from the upper
} proceed = Proceed::UPPER;
// Flags to help evaluating loop termination.
bool ustarted = false, lstarted = false;
// The variables for the fitness values, one for the actual and one for the
// previous.
double current_fit = 0, prev_fit = 0;
// Every triangle of the wall has two edges connecting the upper plate with
// the lower plate. From the length of these two edges and the zdiff we
// can calculate the momentary squared offset distance at a particular
// position on the wall. The average of the differences from the reference
// (squared) offset distance will give us the driving fitness value.
const double offsdiff2 = std::pow(offset_difference_mm, 2);
const double zdiff2 = std::pow(upper_z_mm - lower_z_mm, 2);
// Mark the current vertex iterator positions. If the iterators return to
// the same position, the loop can be terminated.
size_t uendidx = uidx, lendidx = lidx;
do { thr(); // check throw if canceled
prev_fit = current_fit;
switch(proceed) { // proceed depending on the current state
case Proceed::UPPER:
if(!ustarted || uidx != uendidx) { // there are vertices remaining
// Get the 3D vertices in order
const Vec3d& p_up1 = rpts[uidx];
const Vec3d& p_low = rpts[lidx];
const Vec3d& p_up2 = rpts[unextidx];
// Calculate fitness: the average of the two connecting edges
double a = offsdiff2 - (distfn(p_up1, p_low) - zdiff2);
double b = offsdiff2 - (distfn(p_up2, p_low) - zdiff2);
current_fit = (std::abs(a) + std::abs(b)) / 2;
if(current_fit > prev_fit) { // fit is worse than previously
proceed = Proceed::LOWER;
} else { // good to go, create the triangle
inverted
? ind.emplace_back(int(unextidx), int(lidx), int(uidx))
: ind.emplace_back(int(uidx), int(lidx), int(unextidx));
// Increment the iterators, rotate if necessary
++uidx; ++unextidx;
if(unextidx == offs) unextidx = 0;
if(uidx == offs) uidx = 0;
ustarted = true; // mark the movement of the iterators
// so that the comparison to uendidx can be made correctly
}
} else proceed = Proceed::LOWER;
break;
case Proceed::LOWER:
// Mode with lower segment, upper vertex. Same structure:
if(!lstarted || lidx != lendidx) {
const Vec3d& p_low1 = rpts[lidx];
const Vec3d& p_low2 = rpts[lnextidx];
const Vec3d& p_up = rpts[uidx];
double a = offsdiff2 - (distfn(p_up, p_low1) - zdiff2);
double b = offsdiff2 - (distfn(p_up, p_low2) - zdiff2);
current_fit = (std::abs(a) + std::abs(b)) / 2;
if(current_fit > prev_fit) {
proceed = Proceed::UPPER;
} else {
inverted
? ind.emplace_back(int(uidx), int(lnextidx), int(lidx))
: ind.emplace_back(int(lidx), int(lnextidx), int(uidx));
++lidx; ++lnextidx;
if(lnextidx == rpts.size()) lnextidx = offs;
if(lidx == rpts.size()) lidx = offs;
lstarted = true;
}
} else proceed = Proceed::UPPER;
break;
} // end of switch
} while(!ustarted || !lstarted || uidx != uendidx || lidx != lendidx);
return ret;
}
/// Offsetting with clipper and smoothing the edges into a curvature.
void offset(ExPolygon& sh, coord_t distance) {
using ClipperLib::ClipperOffset;
using ClipperLib::jtRound;
using ClipperLib::etClosedPolygon;
using ClipperLib::Paths;
using ClipperLib::Path;
auto&& ctour = Slic3rMultiPoint_to_ClipperPath(sh.contour);
auto&& holes = Slic3rMultiPoints_to_ClipperPaths(sh.holes);
// If the input is not at least a triangle, we can not do this algorithm
if(ctour.size() < 3 ||
std::any_of(holes.begin(), holes.end(),
[](const Path& p) { return p.size() < 3; })
) {
BOOST_LOG_TRIVIAL(error) << "Invalid geometry for offsetting!";
return;
}
ClipperOffset offs;
offs.ArcTolerance = scaled<double>(0.01);
Paths result;
offs.AddPath(ctour, jtRound, etClosedPolygon);
offs.AddPaths(holes, jtRound, etClosedPolygon);
offs.Execute(result, static_cast<double>(distance));
// Offsetting reverts the orientation and also removes the last vertex
// so boost will not have a closed polygon.
bool found_the_contour = false;
sh.holes.clear();
for(auto& r : result) {
if(ClipperLib::Orientation(r)) {
// We don't like if the offsetting generates more than one contour
// but throwing would be an overkill. Instead, we should warn the
// caller about the inability to create correct geometries
if(!found_the_contour) {
auto rr = ClipperPath_to_Slic3rPolygon(r);
sh.contour.points.swap(rr.points);
found_the_contour = true;
} else {
BOOST_LOG_TRIVIAL(warning)
<< "Warning: offsetting result is invalid!";
}
} else {
// TODO If there are multiple contours we can't be sure which hole
// belongs to the first contour. (But in this case the situation is
// bad enough to let it go...)
sh.holes.emplace_back(ClipperPath_to_Slic3rPolygon(r));
}
}
}
/// Unification of polygons (with clipper) preserving holes as well.
ExPolygons unify(const ExPolygons& shapes) {
using ClipperLib::ptSubject;
ExPolygons retv;
bool closed = true;
bool valid = true;
ClipperLib::Clipper clipper;
for(auto& path : shapes) {
auto clipperpath = Slic3rMultiPoint_to_ClipperPath(path.contour);
if(!clipperpath.empty())
valid &= clipper.AddPath(clipperpath, ptSubject, closed);
auto clipperholes = Slic3rMultiPoints_to_ClipperPaths(path.holes);
for(auto& hole : clipperholes) {
if(!hole.empty())
valid &= clipper.AddPath(hole, ptSubject, closed);
}
}
if(!valid) BOOST_LOG_TRIVIAL(warning) << "Unification of invalid shapes!";
ClipperLib::PolyTree result;
clipper.Execute(ClipperLib::ctUnion, result, ClipperLib::pftNonZero);
retv.reserve(static_cast<size_t>(result.Total()));
// Now we will recursively traverse the polygon tree and serialize it
// into an ExPolygon with holes. The polygon tree has the clipper-ish
// PolyTree structure which alternates its nodes as contours and holes
// A "declaration" of function for traversing leafs which are holes
std::function<void(ClipperLib::PolyNode*, ExPolygon&)> processHole;
// Process polygon which calls processHoles which than calls processPoly
// again until no leafs are left.
auto processPoly = [&retv, &processHole](ClipperLib::PolyNode *pptr) {
ExPolygon poly;
poly.contour.points = ClipperPath_to_Slic3rPolygon(pptr->Contour);
for(auto h : pptr->Childs) { processHole(h, poly); }
retv.push_back(poly);
};
// Body of the processHole function
processHole = [&processPoly](ClipperLib::PolyNode *pptr, ExPolygon& poly)
{
poly.holes.emplace_back();
poly.holes.back().points = ClipperPath_to_Slic3rPolygon(pptr->Contour);
for(auto c : pptr->Childs) processPoly(c);
};
// Wrapper for traversing.
auto traverse = [&processPoly] (ClipperLib::PolyNode *node)
{
for(auto ch : node->Childs) {
processPoly(ch);
}
};
// Here is the actual traverse
traverse(&result);
return retv;
}
/// This method will create a rounded edge around a flat polygon in 3d space.
/// 'base_plate' parameter is the target plate.
/// 'radius' is the radius of the edges.
/// 'degrees' is tells how much of a circle should be created as the rounding.
/// It should be in degrees, not radians.
/// 'ceilheight_mm' is the Z coordinate of the flat polygon in 3D space.
/// 'dir' Is the direction of the round edges: inward or outward
/// 'thr' Throws if a cancel signal was received
/// 'last_offset' An auxiliary output variable to save the last offsetted
/// version of 'base_plate'
/// 'last_height' An auxiliary output to save the last z coordinate of the
/// offsetted base_plate. In other words, where the rounded edges end.
Contour3D round_edges(const ExPolygon& base_plate,
double radius_mm,
double degrees,
double ceilheight_mm,
bool dir,
ThrowOnCancel thr,
ExPolygon& last_offset, double& last_height)
{
auto ob = base_plate;
auto ob_prev = ob;
double wh = ceilheight_mm, wh_prev = wh;
Contour3D curvedwalls;
int steps = 30;
double stepx = radius_mm / steps;
coord_t s = dir? 1 : -1;
degrees = std::fmod(degrees, 180);
// we use sin for x distance because we interpret the angle starting from
// PI/2
int tos = degrees < 90?
int(radius_mm*std::cos(degrees * PI / 180 - PI/2) / stepx) : steps;
for(int i = 1; i <= tos; ++i) {
thr();
ob = base_plate;
double r2 = radius_mm * radius_mm;
double xx = i*stepx;
double x2 = xx*xx;
double stepy = std::sqrt(r2 - x2);
offset(ob, s * scaled(xx));
wh = ceilheight_mm - radius_mm + stepy;
Contour3D pwalls;
double prev_x = xx - (i - 1) * stepx;
pwalls = walls(ob.contour, ob_prev.contour, wh, wh_prev, s*prev_x, thr);
curvedwalls.merge(pwalls);
ob_prev = ob;
wh_prev = wh;
}
if(degrees > 90) {
double tox = radius_mm - radius_mm*std::cos(degrees * PI / 180 - PI/2);
int tos = int(tox / stepx);
for(int i = 1; i <= tos; ++i) {
thr();
ob = base_plate;
double r2 = radius_mm * radius_mm;
double xx = radius_mm - i*stepx;
double x2 = xx*xx;
double stepy = std::sqrt(r2 - x2);
offset(ob, s * scaled(xx));
wh = ceilheight_mm - radius_mm - stepy;
Contour3D pwalls;
double prev_x = xx - radius_mm + (i - 1)*stepx;
pwalls =
walls(ob_prev.contour, ob.contour, wh_prev, wh, s*prev_x, thr);
curvedwalls.merge(pwalls);
ob_prev = ob;
wh_prev = wh;
}
}
last_offset = std::move(ob);
last_height = wh;
return curvedwalls;
}
inline Point centroid(Points& pp) {
Point c;
switch(pp.size()) {
case 0: break;
case 1: c = pp.front(); break;
case 2: c = (pp[0] + pp[1]) / 2; break;
default: {
auto MAX = std::numeric_limits<Point::coord_type>::max();
auto MIN = std::numeric_limits<Point::coord_type>::min();
Point min = {MAX, MAX}, max = {MIN, MIN};
for(auto& p : pp) {
if(p(0) < min(0)) min(0) = p(0);
if(p(1) < min(1)) min(1) = p(1);
if(p(0) > max(0)) max(0) = p(0);
if(p(1) > max(1)) max(1) = p(1);
}
c(0) = min(0) + (max(0) - min(0)) / 2;
c(1) = min(1) + (max(1) - min(1)) / 2;
// TODO: fails for non convex cluster
// c = std::accumulate(pp.begin(), pp.end(), Point{0, 0});
// x(c) /= coord_t(pp.size()); y(c) /= coord_t(pp.size());
break;
}
}
return c;
}
inline Point centroid(const ExPolygon& poly) {
return poly.contour.centroid();
}
/// A fake concave hull that is constructed by connecting separate shapes
/// with explicit bridges. Bridges are generated from each shape's centroid
/// to the center of the "scene" which is the centroid calculated from the shape
/// centroids (a star is created...)
ExPolygons concave_hull(const ExPolygons& polys, double max_dist_mm = 50,
ThrowOnCancel throw_on_cancel = [](){})
{
namespace bgi = boost::geometry::index;
using SpatElement = std::pair<BoundingBox, unsigned>;
using SpatIndex = bgi::rtree< SpatElement, bgi::rstar<16, 4> >;
if(polys.empty()) return ExPolygons();
ExPolygons punion = unify(polys); // could be redundant
if(punion.size() == 1) return punion;
// We get the centroids of all the islands in the 2D slice
Points centroids; centroids.reserve(punion.size());
std::transform(punion.begin(), punion.end(), std::back_inserter(centroids),
[](const ExPolygon& poly) { return centroid(poly); });
SpatIndex boxindex; unsigned idx = 0;
std::for_each(punion.begin(), punion.end(),
[&boxindex, &idx](const ExPolygon& expo) {
BoundingBox bb(expo);
boxindex.insert(std::make_pair(bb, idx++));
});
// Centroid of the centroids of islands. This is where the additional
// connector sticks are routed.
Point cc = centroid(centroids);
punion.reserve(punion.size() + centroids.size());
idx = 0;
std::transform(centroids.begin(), centroids.end(),
std::back_inserter(punion),
[&punion, &boxindex, cc, max_dist_mm, &idx, throw_on_cancel]
(const Point& c)
{
throw_on_cancel();
double dx = x(c) - x(cc), dy = y(c) - y(cc);
double l = std::sqrt(dx * dx + dy * dy);
double nx = dx / l, ny = dy / l;
double max_dist = scaled<double>(max_dist_mm);
ExPolygon& expo = punion[idx++];
BoundingBox querybb(expo);
querybb.offset(max_dist);
std::vector<SpatElement> result;
boxindex.query(bgi::intersects(querybb), std::back_inserter(result));
if(result.size() <= 1) return ExPolygon();
ExPolygon r;
auto& ctour = r.contour.points;
ctour.reserve(3);
ctour.emplace_back(cc);
Point d(scaled(nx), scaled(ny));
ctour.emplace_back(c + Point( -y(d), x(d) ));
ctour.emplace_back(c + Point( y(d), -x(d) ));
offset(r, scaled(1.));
return r;
});
// This is unavoidable...
punion = unify(punion);
return punion;
}
void base_plate(const TriangleMesh &mesh, ExPolygons &output, float h,
float layerh, ThrowOnCancel thrfn)
{
TriangleMesh m = mesh;
m.require_shared_vertices(); // TriangleMeshSlicer needs this
TriangleMeshSlicer slicer(&m);
auto bb = mesh.bounding_box();
float gnd = float(bb.min(Z));
std::vector<float> heights = {float(bb.min(Z))};
for(float hi = gnd + layerh; hi <= gnd + h; hi += layerh)
heights.emplace_back(hi);
std::vector<ExPolygons> out; out.reserve(size_t(std::ceil(h/layerh)));
slicer.slice(heights, 0.f, &out, thrfn);
size_t count = 0; for(auto& o : out) count += o.size();
// Now we have to unify all slice layers which can be an expensive operation
// so we will try to simplify the polygons
ExPolygons tmp; tmp.reserve(count);
for(ExPolygons& o : out)
for(ExPolygon& e : o) {
auto&& exss = e.simplify(scaled<double>(0.1));
for(ExPolygon& ep : exss) tmp.emplace_back(std::move(ep));
}
ExPolygons utmp = unify(tmp);
for(auto& o : utmp) {
auto&& smp = o.simplify(scaled<double>(0.1));
output.insert(output.end(), smp.begin(), smp.end());
}
}
Contour3D create_base_pool(const ExPolygons &ground_layer,
const PoolConfig& cfg = PoolConfig())
{
// for debugging:
// Benchmark bench;
// bench.start();
double mergedist = 2*(1.8*cfg.min_wall_thickness_mm + 4*cfg.edge_radius_mm)+
cfg.max_merge_distance_mm;
// Here we get the base polygon from which the pad has to be generated.
// We create an artificial concave hull from this polygon and that will
// serve as the bottom plate of the pad. We will offset this concave hull
// and then offset back the result with clipper with rounding edges ON. This
// trick will create a nice rounded pad shape.
ExPolygons concavehs = concave_hull(ground_layer, mergedist, cfg.throw_on_cancel);
const double thickness = cfg.min_wall_thickness_mm;
const double wingheight = cfg.min_wall_height_mm;
const double fullheight = wingheight + thickness;
const double slope = cfg.wall_slope;
const double wingdist = wingheight / std::tan(slope);
const double bottom_offs = (thickness + wingheight) / std::tan(slope);
// scaled values
const coord_t s_thickness = scaled(thickness);
const coord_t s_eradius = scaled(cfg.edge_radius_mm);
const coord_t s_safety_dist = 2*s_eradius + coord_t(0.8*s_thickness);
const coord_t s_wingdist = scaled(wingdist);
const coord_t s_bottom_offs = scaled(bottom_offs);
auto& thrcl = cfg.throw_on_cancel;
Contour3D pool;
for(ExPolygon& concaveh : concavehs) {
if(concaveh.contour.points.empty()) return pool;
// Get rid of any holes in the concave hull output.
concaveh.holes.clear();
// Here lies the trick that does the smoothing only with clipper offset
// calls. The offset is configured to round edges. Inner edges will
// be rounded because we offset twice: ones to get the outer (top) plate
// and again to get the inner (bottom) plate
auto outer_base = concaveh;
outer_base.holes.clear();
offset(outer_base, s_safety_dist + s_wingdist + s_thickness);
ExPolygon bottom_poly = outer_base;
bottom_poly.holes.clear();
offset(bottom_poly, -s_bottom_offs);
// Punching a hole in the top plate for the cavity
ExPolygon top_poly;
ExPolygon middle_base;
ExPolygon inner_base;
top_poly.contour = outer_base.contour;
if(wingheight > 0) {
inner_base = outer_base;
offset(inner_base, -(s_thickness + s_wingdist + s_eradius));
middle_base = outer_base;
offset(middle_base, -s_thickness);
top_poly.holes.emplace_back(middle_base.contour);
auto& tph = top_poly.holes.back().points;
std::reverse(tph.begin(), tph.end());
}
ExPolygon ob = outer_base; double wh = 0;
// now we will calculate the angle or portion of the circle from
// pi/2 that will connect perfectly with the bottom plate.
// this is a tangent point calculation problem and the equation can
// be found for example here:
// http://www.ambrsoft.com/TrigoCalc/Circles2/CirclePoint/CirclePointDistance.htm
// the y coordinate would be:
// y = cy + (r^2*py - r*px*sqrt(px^2 + py^2 - r^2) / (px^2 + py^2)
// where px and py are the coordinates of the point outside the circle
// cx and cy are the circle center, r is the radius
// We place the circle center to (0, 0) in the calculation the make
// things easier.
// to get the angle we use arcsin function and subtract 90 degrees then
// flip the sign to get the right input to the round_edge function.
double r = cfg.edge_radius_mm;
double cy = 0;
double cx = 0;
double px = thickness + wingdist;
double py = r - fullheight;
double pxcx = px - cx;
double pycy = py - cy;
double b_2 = pxcx*pxcx + pycy*pycy;
double r_2 = r*r;
double D = std::sqrt(b_2 - r_2);
double vy = (r_2*pycy - r*pxcx*D) / b_2;
double phi = -(std::asin(vy/r) * 180 / PI - 90);
// Generate the smoothed edge geometry
if(s_eradius > 0) pool.merge(round_edges(ob,
r,
phi,
0, // z position of the input plane
true,
thrcl,
ob, wh));
// Now that we have the rounded edge connecting the top plate with
// the outer side walls, we can generate and merge the sidewall geometry
pool.merge(walls(ob.contour, bottom_poly.contour, wh, -fullheight,
bottom_offs, thrcl));
if(wingheight > 0) {
// Generate the smoothed edge geometry
wh = 0;
if(s_eradius) pool.merge(round_edges(middle_base,
r,
phi - 90, // from tangent lines
0, // z position of the input plane
false,
thrcl,
ob, wh));
// Next is the cavity walls connecting to the top plate's
// artificially created hole.
pool.merge(walls(inner_base.contour, ob.contour, -wingheight,
wh, -wingdist, thrcl));
}
// Now we need to triangulate the top and bottom plates as well as the
// cavity bottom plate which is the same as the bottom plate but it is
// elevated by the thickness.
pool.merge(triangulate_expolygon_3d(top_poly));
pool.merge(triangulate_expolygon_3d(bottom_poly, -fullheight, true));
if(wingheight > 0)
pool.merge(triangulate_expolygon_3d(inner_base, -wingheight));
}
return pool;
}
void create_base_pool(const ExPolygons &ground_layer, TriangleMesh& out,
const PoolConfig& cfg)
{
// For debugging:
// bench.stop();
// std::cout << "Pad creation time: " << bench.getElapsedSec() << std::endl;
// std::fstream fout("pad_debug.obj", std::fstream::out);
// if(fout.good()) pool.to_obj(fout);
out.merge(mesh(create_base_pool(ground_layer, cfg)));
}
}
}