mirror of https://github.com/vitalif/openscad
141 lines
4.5 KiB
C++
141 lines
4.5 KiB
C++
#include "Polygon2d-CGAL.h"
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#include "polyset.h"
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#include "printutils.h"
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#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
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#include <CGAL/Constrained_Delaunay_triangulation_2.h>
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#include <CGAL/Triangulation_face_base_with_info_2.h>
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#include <CGAL/Polygon_2.h>
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#include <iostream>
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#include <boost/foreach.hpp>
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namespace Polygon2DCGAL {
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struct FaceInfo
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{
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FaceInfo() : nesting_level(42) {}
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int nesting_level;
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bool in_domain() { return nesting_level%2 == 1; }
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};
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typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
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typedef CGAL::Triangulation_vertex_base_2<K> Vb;
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typedef CGAL::Triangulation_face_base_with_info_2<FaceInfo,K> Fbb;
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typedef CGAL::Constrained_triangulation_face_base_2<K,Fbb> Fb;
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typedef CGAL::Triangulation_data_structure_2<Vb,Fb> TDS;
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typedef CGAL::Exact_predicates_tag Itag;
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typedef CGAL::Constrained_Delaunay_triangulation_2<K, TDS, Itag> CDT;
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typedef CDT::Point Point;
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typedef CGAL::Polygon_2<K> Polygon_2;
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void
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mark_domains(CDT &ct,
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CDT::Face_handle start,
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int index,
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std::list<CDT::Edge> &border)
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{
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if (start->info().nesting_level != -1) return;
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std::list<CDT::Face_handle> queue;
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queue.push_back(start);
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while (!queue.empty()) {
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CDT::Face_handle fh = queue.front();
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queue.pop_front();
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if (fh->info().nesting_level == -1) {
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fh->info().nesting_level = index;
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for (int i = 0; i < 3; i++) {
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CDT::Edge e(fh,i);
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CDT::Face_handle n = fh->neighbor(i);
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if (n->info().nesting_level == -1) {
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if (ct.is_constrained(e)) border.push_back(e);
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else queue.push_back(n);
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}
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}
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}
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}
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}
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// Explore set of facets connected with non constrained edges,
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// and attribute to each such set a nesting level.
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// We start from facets incident to the infinite vertex, with a nesting
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// level of 0. Then we recursively consider the non-explored facets incident
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// to constrained edges bounding the former set and increase the nesting level by 1.
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// Facets in the domain are those with an odd nesting level.
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void
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mark_domains(CDT &cdt)
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{
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for(CDT::All_faces_iterator it = cdt.all_faces_begin(); it != cdt.all_faces_end(); ++it) {
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it->info().nesting_level = -1;
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}
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int index = 0;
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std::list<CDT::Edge> border;
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mark_domains(cdt, cdt.infinite_face(), index++, border);
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while (!border.empty()) {
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CDT::Edge e = border.front();
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border.pop_front();
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CDT::Face_handle n = e.first->neighbor(e.second);
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if (n->info().nesting_level == -1) {
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mark_domains(cdt, n, e.first->info().nesting_level+1, border);
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}
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}
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}
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}
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#define OPENSCAD_CGAL_ERROR_BEGIN \
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CGAL::Failure_behaviour old_behaviour = CGAL::set_error_behaviour(CGAL::THROW_EXCEPTION); \
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try {
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#define OPENSCAD_CGAL_ERROR_END(errorstr, onerror) \
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} \
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catch (const CGAL::Precondition_exception &e) { \
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PRINTB(errorstr ": %s", e.what()); \
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CGAL::set_error_behaviour(old_behaviour); \
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onerror; \
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} \
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CGAL::set_error_behaviour(old_behaviour);
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/*!
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Triangulates this polygon2d and returns a 2D PolySet.
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*/
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PolySet *Polygon2d::tessellate() const
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{
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PRINTDB("Polygon2d::tessellate(): %d outlines", this->outlines().size());
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PolySet *polyset = new PolySet(*this);
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Polygon2DCGAL::CDT cdt; // Uses a constrained Delaunay triangulator.
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OPENSCAD_CGAL_ERROR_BEGIN;
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// Adds all vertices, and add all contours as constraints.
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BOOST_FOREACH(const Outline2d &outline, this->outlines()) {
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// Start with last point
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Polygon2DCGAL::CDT::Vertex_handle prev = cdt.insert(Polygon2DCGAL::Point(outline.vertices[outline.vertices.size()-1][0], outline.vertices[outline.vertices.size()-1][1]));
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BOOST_FOREACH(const Vector2d &v, outline.vertices) {
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Polygon2DCGAL::CDT::Vertex_handle curr = cdt.insert(Polygon2DCGAL::Point(v[0], v[1]));
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if (prev != curr) { // Ignore duplicate vertices
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cdt.insert_constraint(prev, curr);
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prev = curr;
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}
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}
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}
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OPENSCAD_CGAL_ERROR_END("CGAL error in Polygon2d::tesselate()", return NULL);
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// To extract triangles which is part of our polygon, we need to filter away
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// triangles inside holes.
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mark_domains(cdt);
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for (Polygon2DCGAL::CDT::Finite_faces_iterator fit=cdt.finite_faces_begin();
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fit!=cdt.finite_faces_end();++fit) {
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if (fit->info().in_domain()) {
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polyset->append_poly();
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for (int i=0;i<3;i++) polyset->append_vertex(fit->vertex(i)->point()[0],
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fit->vertex(i)->point()[1],
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0);
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}
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}
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return polyset;
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}
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