Constrained_triangulation_3/conforming_constrained_Delaunay_triangulation_3.cpp

Simple example demonstrating the usage of the Constrained_triangulation_3 package.

Simple example demonstrating the usage of the Constrained_triangulation_3 package.

It constructs a 3D constrained Delaunay triangulation from a polygon mesh.

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/IO/polygon_mesh_io.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/make_conforming_constrained_Delaunay_triangulation_3.h>
#include <CGAL/IO/write_MEDIT.h>
 
#include <cassert>
 
using K = CGAL::Exact_predicates_inexact_constructions_kernel;
 
int main(int argc, char* argv[])
{
  auto filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/mpi.off");
 
  CGAL::Surface_mesh<K::Point_3> mesh;
  if(!CGAL::IO::read_polygon_mesh(filename, mesh)) {
    std::cerr << "Error: cannot read file " << filename << std::endl;
    return EXIT_FAILURE;
  }
 
  std::cout << "Read " << mesh.number_of_vertices() << " vertices and "
            << mesh.number_of_faces() << " faces" << std::endl;
 
  auto ccdt = CGAL::make_conforming_constrained_Delaunay_triangulation_3(mesh);
 
  std::cout << "Number of vertices in the CDT: "
            << ccdt.triangulation().number_of_vertices() << '\n';
  std::cout << "Number of constrained facets in the CDT: "
            << ccdt.number_of_constrained_facets() << '\n';
 
  std::ofstream ofs(argc > 2 ? argv[2] : "out.mesh");
  ofs.precision(17);
  CGAL::IO::write_MEDIT(ofs, ccdt);
 
  auto tr = std::move(ccdt).triangulation();
  // Now `tr` is a valid `CGAL::Triangulation_3` object that can be used for further processing.
  // and the triangulation of `ccdt` is empty.
  std::cout << "Number of vertices in the triangulation `tr`: "
            << tr.number_of_vertices() << '\n';
  std::cout << "Number of vertices in `ccdt`: "
            << ccdt.triangulation().number_of_vertices() << '\n';
  assert(ccdt.triangulation().number_of_vertices() == 0);
 
  return EXIT_SUCCESS;
}