#include "SLABasePool.hpp" #include "SLABoilerPlate.hpp" #include "boost/log/trivial.hpp" #include "SLABoostAdapter.hpp" #include "ClipperUtils.hpp" #include "Tesselate.hpp" // For debugging: //#include //#include //#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& rfaces = 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()); rfaces.reserve(2*upoints.size() + 2*lpoints.size()); const double sf = SCALING_FACTOR; for(auto& p : upoints) rpts.emplace_back(p.x()*sf, p.y()*sf, upper_z_mm); for(auto& p : lpoints) rpts.emplace_back(p.x()*sf, p.y()*sf, 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::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[size_t(uidx)]; const Vec3d& p_low = rpts[size_t(lidx)]; const Vec3d& p_up2 = rpts[size_t(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? rfaces.emplace_back(unextidx, lidx, uidx) : rfaces.emplace_back(uidx, lidx, 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[size_t(lidx)]; const Vec3d& p_low2 = rpts[size_t(lnextidx)]; const Vec3d& p_up = rpts[size_t(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? rfaces.emplace_back(uidx, lnextidx, lidx) : rfaces.emplace_back(lidx, lnextidx, 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 = 0.01*mm(1); Paths result; offs.AddPath(ctour, jtRound, etClosedPolygon); offs.AddPaths(holes, jtRound, etClosedPolygon); offs.Execute(result, static_cast(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(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 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; } /// Only a debug function to generate top and bottom plates from a 2D shape. /// It is not used in the algorithm directly. inline Contour3D roofs(const ExPolygon& poly, coord_t z_distance) { auto lower = triangulate_expolygon_3d(poly); auto upper = triangulate_expolygon_3d(poly, z_distance*SCALING_FACTOR, true); Contour3D ret; ret.merge(lower); ret.merge(upper); return ret; } /// 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*mm(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*mm(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; } /// Generating the concave part of the 3D pool with the bottom plate and the /// side walls. Contour3D inner_bed(const ExPolygon& poly, double depth_mm, double begin_h_mm = 0) { Contour3D bottom; Pointf3s triangles = triangulate_expolygon_3d(poly, -depth_mm + begin_h_mm); bottom.merge(triangles); coord_t depth = mm(depth_mm); coord_t begin_h = mm(begin_h_mm); auto lines = poly.lines(); // Generate outer walls auto fp = [](const Point& p, Point::coord_type z) { return unscale(x(p), y(p), z); }; for(auto& l : lines) { auto s = coord_t(bottom.points.size()); bottom.points.emplace_back(fp(l.a, -depth + begin_h)); bottom.points.emplace_back(fp(l.b, -depth + begin_h)); bottom.points.emplace_back(fp(l.a, begin_h)); bottom.points.emplace_back(fp(l.b, begin_h)); bottom.indices.emplace_back(s + 3, s + 1, s); bottom.indices.emplace_back(s + 2, s + 3, s); } return bottom; } 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::max(); auto MIN = std::numeric_limits::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; 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 = mm(max_dist_mm); ExPolygon& expo = punion[idx++]; BoundingBox querybb(expo); querybb.offset(max_dist); std::vector 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(coord_t(mm(1)*nx), coord_t(mm(1)*ny)); ctour.emplace_back(c + Point( -y(d), x(d) )); ctour.emplace_back(c + Point( y(d), -x(d) )); offset(r, mm(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; TriangleMeshSlicer slicer(&m); auto bb = mesh.bounding_box(); float gnd = float(bb.min(Z)); std::vector heights = {float(bb.min(Z))}; for(float hi = gnd + layerh; hi <= gnd + h; hi += layerh) heights.emplace_back(hi); std::vector out; out.reserve(size_t(std::ceil(h/layerh))); slicer.slice(heights, &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(0.1/SCALING_FACTOR); for(ExPolygon& ep : exss) tmp.emplace_back(std::move(ep)); } ExPolygons utmp = unify(tmp); for(auto& o : utmp) { auto&& smp = o.simplify(0.1/SCALING_FACTOR); output.insert(output.end(), smp.begin(), smp.end()); } } void create_base_pool(const ExPolygons &ground_layer, TriangleMesh& out, const PoolConfig& cfg) { // 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 tilt = PI/4; const double wingdist = wingheight / std::tan(tilt); // scaled values const coord_t s_thickness = mm(thickness); const coord_t s_eradius = mm(cfg.edge_radius_mm); const coord_t s_safety_dist = 2*s_eradius + coord_t(0.8*s_thickness); const coord_t s_wingdist = mm(wingdist); auto& thrcl = cfg.throw_on_cancel; Contour3D pool; for(ExPolygon& concaveh : concavehs) { if(concaveh.contour.points.empty()) return; // Get rid of any holes in the concave hull output. concaveh.holes.clear(); // Here lies the trick that does the smooting 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); auto inner_base = outer_base; offset(inner_base, -(s_thickness + s_wingdist)); // Punching a hole in the top plate for the cavity ExPolygon top_poly; ExPolygon middle_base; top_poly.contour = outer_base.contour; if(wingheight > 0) { 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 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 connencting the top plate with // the outer side walls, we can generate and merge the sidewall geometry pool.merge(walls(ob.contour, inner_base.contour, wh, -fullheight, (s_thickness + s_wingdist) * SCALING_FACTOR, thrcl)); if(wingheight > 0) { // Generate the smoothed edge geometry 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, -s_safety_dist * SCALING_FACTOR, 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(inner_base, -fullheight, true)); if(wingheight > 0) pool.merge(triangulate_expolygon_3d(inner_base, -wingheight)); } // 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(pool)); } } }