Need for orientation

soup.cpp

#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Surface_mesh.h>
#include <CGAL/IO/polygon_soup_io.h>
#include <CGAL/Polygon_mesh_processing/orient_polygon_soup.h>
#include <CGAL/Polygon_mesh_processing/polygon_soup_to_polygon_mesh.h>

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

typedef CGAL::Exact_predicates_inexact_constructions_kernel     K;
typedef K::FT                                                   FT;
typedef K::Point_3                                              Point_3;

typedef CGAL::Surface_mesh<Point_3>                             Mesh;

typedef std::vector<std::size_t>                                CGAL_Polygon;

namespace PMP = CGAL::Polygon_mesh_processing;

int main(int, char**)
{
  // First, construct a polygon soup with some problems
  std::vector<Point_3> points;
  std::vector<CGAL_Polygon> polygons;

  CGAL::read_polygon_soup("triangulation.obj", points, polygons);
  std::cout << points.size() << "  "  << polygons.size() << std::endl;
  Mesh mesh;
  //PMP::orient_polygon_soup(points, polygons);
  PMP::polygon_soup_to_polygon_mesh(points, polygons, mesh);

  std::cout << "Mesh has " << num_vertices(mesh) << " vertices and " << num_faces(mesh) << " faces" << std::endl;


  return 0;
}