Polygon_mesh_processing/compute_normals_example_Polyhedron.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Polyhedron_3.h>
 
#include <CGAL/Polygon_mesh_processing/compute_normal.h>
#include <CGAL/Polygon_mesh_processing/IO/polygon_mesh_io.h>
// #include <CGAL/Unique_hash_map.h>
// #include <boost/unordered_map.hpp>
 
#include <boost/property_map/property_map.hpp>
 
#include <iostream>
#include <map>
#include <string>
 
typedef CGAL::Exact_predicates_inexact_constructions_kernel   K;
typedef K::Point_3                                            Point;
typedef K::Vector_3                                           Vector;
 
typedef CGAL::Polyhedron_3<K>                                 Mesh;
typedef boost::graph_traits<Mesh>::vertex_descriptor          vertex_descriptor;
typedef boost::graph_traits<Mesh>::face_descriptor            face_descriptor;
 
namespace PMP = CGAL::Polygon_mesh_processing;
 
int main(int argc, char* argv[])
{
  const std::string filename = (argc > 1) ? argv[1] : CGAL::data_file_path("meshes/eight.off");
 
  Mesh mesh;
  if(!PMP::IO::read_polygon_mesh(filename, mesh))
  {
    std::cerr << "Invalid input." << std::endl;
    return 1;
  }
 
  std::map<face_descriptor,Vector> fnormals;
  std::map<vertex_descriptor,Vector> vnormals;
  // Instead of std::map you may use std::unordered_map, boost::unordered_map
  // or CGAL::Unique_hash_map
  // CGAL::Unique_hash_map<face_descriptor,Vector> fnormals;
  // boost::unordered_map<vertex_descriptor,Vector> vnormals;
 
  PMP::compute_normals(mesh, boost::make_assoc_property_map(vnormals),
                             boost::make_assoc_property_map(fnormals));
 
  std::cout << "Face normals :" << std::endl;
  for(face_descriptor fd: faces(mesh))
    std::cout << fnormals[fd] << std::endl;
 
  std::cout << "Vertex normals :" << std::endl;
  for(vertex_descriptor vd: vertices(mesh))
    std::cout << vnormals[vd] << std::endl;
 
  return 0;
}