Polygon_mesh_processing/orient_polygon_soup_example.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>

#include <CGAL/Polyhedron_3.h>
#include <CGAL/Polyhedron_items_with_id_3.h>

#include <CGAL/Polygon_mesh_processing/orient_polygon_soup.h>
#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>
#include <CGAL/Polygon_mesh_processing/orientation.h>

#include <CGAL/IO/polygon_soup_io.h>

#include <fstream>
#include <iostream>
#include <string>
#include <vector>

typedef CGAL::Exact_predicates_inexact_constructions_kernel          K;
typedef CGAL::Polyhedron_3<K, CGAL::Polyhedron_items_with_id_3>      Polyhedron;

// Optional visitor for orientating a polygon soup to demonstrate usage for some functions.
// inherits from the default class as some functions are not overloaded
struct Visitor : public CGAL::Polygon_mesh_processing::Default_orientation_visitor
{
  void non_manifold_edge(std::size_t id1, std::size_t id2, std::size_t nb_poly)
  {
    std::cout << "The edge " << id1 << ", " << id2 << " is not manifold: " << nb_poly << " incident polygons." << std::endl;
  }
  void non_manifold_vertex(std::size_t id, std::size_t nb_cycles)
  {
     std::cout << "The vertex " << id << " is not manifold: "  << nb_cycles << " connected components of vertices in the link." << std::endl;
  }
  void duplicated_vertex(std::size_t v1, std::size_t v2)
  {
    std::cout << "The vertex " << v1 << " has been duplicated, its new id is " << v2 << "." << std::endl;
  }
  void vertex_id_in_polygon_replaced(std::size_t p_id, std::size_t i1, std::size_t i2)
  {
    std::cout << "In the polygon " << p_id << ", the index " << i1 << " has been replaced by " << i2 << "." << std::endl;
  }
  void polygon_orientation_reversed(std::size_t p_id)
  {
    std::cout << "The polygon " << p_id << " has been reversed." << std::endl;
  }
};

int main(int argc, char* argv[])
{
  const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/tet-shuffled.off");

  std::vector<K::Point_3> points;
  std::vector<std::vector<std::size_t> > polygons;

  if(!CGAL::IO::read_polygon_soup(filename, points, polygons) || points.empty())
  {
    std::cerr << "Cannot open file " << std::endl;
    return EXIT_FAILURE;
  }

  Visitor visitor;
  CGAL::Polygon_mesh_processing::orient_polygon_soup(points, polygons, CGAL::parameters::visitor(visitor));

  Polyhedron mesh;
  CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points, polygons, mesh);

  // Number the faces because 'orient_to_bound_a_volume' needs a face <--> index map
  int index = 0;
  for(Polyhedron::Face_iterator fb=mesh.facets_begin(), fe=mesh.facets_end(); fb!=fe; ++fb)
    fb->id() = index++;

  if(CGAL::is_closed(mesh))
    CGAL::Polygon_mesh_processing::orient_to_bound_a_volume(mesh);

  std::ofstream out("tet-oriented1.off");
  out.precision(17);
  out << mesh;
  out.close();

  CGAL::Polygon_mesh_processing::reverse_face_orientations(mesh);
  std::ofstream out2("tet-oriented2.off");
  out2.precision(17);
  out2 << mesh;
  out2.close();

  return EXIT_SUCCESS;
}