PrusaSlicer-NonPlainar/src/libslic3r/SlicesToTriangleMesh.cpp
2021-11-05 15:43:40 +01:00

138 lines
5 KiB
C++

#include <numeric>
#include "SlicesToTriangleMesh.hpp"
//#include "libslic3r/MTUtils.hpp"
#include "libslic3r/Execution/ExecutionTBB.hpp"
#include "libslic3r/ClipperUtils.hpp"
#include "libslic3r/Tesselate.hpp"
#include <tbb/parallel_for.h>
#include <tbb/parallel_reduce.h>
namespace Slic3r {
inline indexed_triangle_set wall_strip(const Polygon &poly,
double lower_z_mm,
double upper_z_mm)
{
indexed_triangle_set ret;
size_t startidx = ret.vertices.size();
size_t offs = poly.points.size();
ret.vertices.reserve(ret.vertices.size() + 2 *offs);
// The expression unscaled(p).cast<float>().eval() is important here
// as it ensures identical conversion of 2D scaled coordinates to float 3D
// to that used by the tesselation. This way, the duplicated vertices in the
// output mesh can be found with the == operator of the points.
// its_merge_vertices will then reliably remove the duplicates.
for (const Point &p : poly.points)
ret.vertices.emplace_back(to_3d(unscaled(p).cast<float>().eval(), float(lower_z_mm)));
for (const Point &p : poly.points)
ret.vertices.emplace_back(to_3d(unscaled(p).cast<float>().eval(), float(upper_z_mm)));
for (size_t i = startidx + 1; i < startidx + offs; ++i) {
ret.indices.emplace_back(i - 1, i, i + offs - 1);
ret.indices.emplace_back(i, i + offs, i + offs - 1);
}
ret.indices.emplace_back(startidx + offs - 1, startidx, startidx + 2 * offs - 1);
ret.indices.emplace_back(startidx, startidx + offs, startidx + 2 * offs - 1);
return ret;
}
// Same as walls() but with identical higher and lower polygons.
indexed_triangle_set inline straight_walls(const Polygon &plate,
double lo_z,
double hi_z)
{
return wall_strip(plate, lo_z, hi_z);
}
indexed_triangle_set inline straight_walls(const ExPolygon &plate,
double lo_z,
double hi_z)
{
indexed_triangle_set ret = straight_walls(plate.contour, lo_z, hi_z);
for (auto &h : plate.holes)
its_merge(ret, straight_walls(h, lo_z, hi_z));
return ret;
}
indexed_triangle_set inline straight_walls(const ExPolygons &slice,
double lo_z,
double hi_z)
{
indexed_triangle_set ret;
for (const ExPolygon &poly : slice)
its_merge(ret, straight_walls(poly, lo_z, hi_z));
return ret;
}
indexed_triangle_set slices_to_mesh(
const std::vector<ExPolygons> &slices,
double zmin,
const std::vector<float> & grid)
{
assert(slices.size() == grid.size());
using Layers = std::vector<indexed_triangle_set>;
Layers layers(slices.size());
size_t len = slices.size() - 1;
tbb::parallel_for(size_t(0), len, [&slices, &layers, &grid](size_t i) {
const ExPolygons &upper = slices[i + 1];
const ExPolygons &lower = slices[i];
// Small 0 area artefacts can be created by diff_ex, and the
// tesselation also can create 0 area triangles. These will be removed
// by its_remove_degenerate_faces.
ExPolygons free_top = diff_ex(lower, upper);
ExPolygons overhang = diff_ex(upper, lower);
its_merge(layers[i], triangulate_expolygons_3d(free_top, grid[i], NORMALS_UP));
its_merge(layers[i], triangulate_expolygons_3d(overhang, grid[i], NORMALS_DOWN));
its_merge(layers[i], straight_walls(upper, grid[i], grid[i + 1]));
});
auto merge_fn = []( const indexed_triangle_set &a, const indexed_triangle_set &b ) {
indexed_triangle_set res{a}; its_merge(res, b); return res;
};
auto ret = execution::reduce(ex_tbb, layers.begin(), layers.end(),
indexed_triangle_set{}, merge_fn);
its_merge(ret, triangulate_expolygons_3d(slices.front(), zmin, NORMALS_DOWN));
its_merge(ret, straight_walls(slices.front(), zmin, grid.front()));
its_merge(ret, triangulate_expolygons_3d(slices.back(), grid.back(), NORMALS_UP));
// FIXME: these repairs do not fix the mesh entirely. There will be cracks
// in the output. It is very hard to do the meshing in a way that does not
// leave errors.
its_merge_vertices(ret);
its_remove_degenerate_faces(ret);
its_compactify_vertices(ret);
return ret;
}
void slices_to_mesh(indexed_triangle_set & mesh,
const std::vector<ExPolygons> &slices,
double zmin,
double lh,
double ilh)
{
std::vector<float> grid(slices.size(), zmin + ilh);
for (size_t i = 1; i < grid.size(); ++i) grid[i] = grid[i - 1] + lh;
indexed_triangle_set cntr = slices_to_mesh(slices, zmin, grid);
its_merge(mesh, cntr);
}
} // namespace Slic3r