Method process_extrusion

src/ifcgeom/kernels/cgal/CgalKernel.cpp:995–1187

}

bool CgalKernel::process_extrusion(const cgal_face_t& bottom_face, taxonomy::direction3::ptr direction, double height, cgal_shape_t& shape) {

	bool has_inner_bounds = !bottom_face.inner.empty();

	std::list<cgal_wire_t> faces_to_extrude;
	std::set<std::pair<size_t, size_t>> internal_edges;

	// CGAL::Cartesian_converter<CGAL::Epeck, CGAL::Simple_cartesian<double>> C;

	if (has_inner_bounds) {
		CGAL::Polygon_with_holes_2<Kernel_> pwh;
		CGAL::Aff_transformation_3<Kernel_> place;
		// @todo check for segment intersections, analogous to other places.
		// they are caught now below after triangulation.
		face_to_poly_with_holes(bottom_face, pwh, place);
		CGAL::Polygon_triangulation_decomposition_2<Kernel_> decompositor;
		std::list<CGAL::Polygon_2<Kernel_>> decom_polies;
		decompositor(pwh, std::back_inserter(decom_polies));

		int n_vertices = 0;
		std::map<Kernel_::Point_2, size_t> point_map;
		for (auto& p : decom_polies) {
			for (auto it = p.vertices_begin(); it != p.vertices_end(); ++it) {
				point_map.insert({ *it, point_map.size() });
				++n_vertices;
			}
		}

		std::map<std::pair<size_t, size_t>, std::pair<size_t, size_t>> external_edges;

		size_t i = 0;
		for (auto& p : decom_polies) {
			// this is always 3 given the usage of Polygon_triangulation_decomposition_2
			size_t n = std::distance(p.vertices_begin(), p.vertices_end());
			for (size_t j = 0; j < n; ++j) {
				auto k = (j + 1) % n;
				auto& p0 = *(p.vertices_begin() + j);
				auto& p1 = *(p.vertices_begin() + k);
				auto i0 = point_map.find(p0)->second;
				auto i1 = point_map.find(p1)->second;
				if (i0 > i1) {
					std::swap(i0, i1);
				}
				auto p = external_edges.insert({ { i0, i1 }, { i, j} });
				if (!p.second) {
					// Mark as internal before erasure in external
					// This is {i,j} at the time the edge use was inserted.
					internal_edges.insert(p.first->second);
					// not inserted, remove
					external_edges.erase(p.first);

					// @nb note the difference here in indices, {i0, i1} is point indices in
					// point_map. i is index in faces_to_extrude, j is segment index in wire.
					internal_edges.insert({ i, j });
				}
			}
			i++;
		}