Heat_method_3/heat_method.cpp

#include <CGAL/Simple_cartesian.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/Heat_method_3/Surface_mesh_geodesic_distances_3.h>
#include <CGAL/IO/Color_ramp.h>
#include <CGAL/boost/graph/IO/PLY.h>
#include <iostream>
#include <fstream>
 
typedef CGAL::Simple_cartesian<double>                       Kernel;
typedef Kernel::Point_3                                      Point_3;
typedef CGAL::Surface_mesh<Point_3>                          Triangle_mesh;
 
typedef boost::graph_traits<Triangle_mesh>::vertex_descriptor vertex_descriptor;
typedef Triangle_mesh::Property_map<vertex_descriptor,double> Vertex_distance_map;
typedef Triangle_mesh::Property_map<vertex_descriptor,CGAL::IO::Color> Vertex_color_map;
 
int main(int argc, char* argv[])
{
  const std::filesystem::path filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/elephant.off");
 
  Triangle_mesh tm;
  if(!CGAL::IO::read_polygon_mesh(filename, tm) ||
     CGAL::is_empty(tm) || !CGAL::is_triangle_mesh(tm))
  {
    std::cerr << "Invalid input file." << std::endl;
    return EXIT_FAILURE;
  }
 
  //property map for the distance values to the source set
  Vertex_distance_map vertex_distance = tm.add_property_map<vertex_descriptor, double>("v:distance", 0).first;
 
  vertex_descriptor source = *(vertices(tm).first);
 
  CGAL::Heat_method_3::estimate_geodesic_distances(tm, vertex_distance, source) ;
 
  double sdistance = 0;
  std::cout << "Source vertex " << source << " at: " << tm.point(source) << std::endl;
 
  Vertex_color_map vertex_color = tm.add_property_map<vertex_descriptor, CGAL::IO::Color>("v:color", CGAL::IO::Color()).first;
  for(vertex_descriptor vd : vertices(tm))
  {
    double d = get(vertex_distance, vd);
   sdistance = (std::max)(sdistance,d);
  }
 
  CGAL::IO::Color_ramp ramp;
  ramp.build_thermal();
  for(vertex_descriptor vd : vertices(tm))
  {
    double d = get(vertex_distance, vd);
    put(vertex_color,vd, ramp.interpolate(d/sdistance));
  }
  std::ofstream out("out.ply");
  CGAL::IO::write_PLY(out, tm );
 
  return 0;
}