text: #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>                                 Polyhedron;
  typedef boost::graph_traits<Polyhedron>::vertex_descriptor    vertex_descriptor;
  typedef boost::graph_traits<Polyhedron>::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");
  
    Polyhedron 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;
  }
  