Surface_mesh_approximation/vsa_class_interface_example.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
 
#include <CGAL/Variational_shape_approximation.h>
#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>
 
#include <iostream>
#include <fstream>
 
namespace VSA = CGAL::Surface_mesh_approximation;
 
typedef CGAL::Exact_predicates_inexact_constructions_kernel Kernel;
typedef CGAL::Surface_mesh<Kernel::Point_3> Mesh;
 
typedef boost::property_map<Mesh, boost::vertex_point_t>::type Vertex_point_map;
typedef CGAL::Variational_shape_approximation<Mesh, Vertex_point_map> Mesh_approximation;
 
// L21 error metric
typedef Mesh_approximation::Error_metric L21_metric;
 
int main(int argc, char** argv)
{
  const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/bear.off");
 
  // reads input surface triangle mesh
  Mesh mesh;
  if(!CGAL::Polygon_mesh_processing::IO::read_polygon_mesh(filename, mesh) ||
     !CGAL::is_triangle_mesh(mesh))
  {
    std::cerr << "Invalid input file." << std::endl;
    return EXIT_FAILURE;
  }
 
  Vertex_point_map vpmap = get(boost::vertex_point, const_cast<Mesh &>(mesh));
 
  // error metric and fitting function
  L21_metric error_metric(mesh, vpmap);
 
  // creates VSA algorithm instance
  Mesh_approximation approx(mesh, vpmap, error_metric);
 
  // seeds 100 random proxies
  approx.initialize_seeds(CGAL::parameters::seeding_method(VSA::RANDOM)
      .max_number_of_proxies(100));
 
  // runs 30 iterations
  approx.run(30);
 
  // adds 3 proxies to the one with the maximum fitting error,
  // running 5 iterations between each addition
  approx.add_to_furthest_proxies(3, 5);
 
  // runs 10 iterations
  approx.run(10);
 
  // teleports 2 proxies to tunnel out of local minima,
  // running 5 iterations between each teleport
  approx.teleport_proxies(2, 5);
 
  // runs 10 iterations
  approx.run(10);
 
  // extract approximated mesh with default parameters
  approx.extract_mesh(CGAL::parameters::default_values());
 
  // get approximated triangle soup
  std::vector<Kernel::Point_3> anchors;
  std::vector<std::array<std::size_t, 3> > triangles;
  approx.output(CGAL::parameters::anchors(std::back_inserter(anchors)).
    triangles(std::back_inserter(triangles)));
 
  return EXIT_SUCCESS;
}