orient_soup_plus_plus.cpp

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

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

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Surface_mesh<K::Point_3> Mesh;

int main(int argc, char* argv[])
{;
  std::ifstream input(argv[1]);

  if (!input)
  {
    std::cerr << "Cannot open file " << std::endl;
    return 1;
  }

  std::vector<K::Point_3> points;
  std::vector< std::vector<std::size_t> > polygons;
  if (!CGAL::read_OFF(input, points, polygons))
  {
    std::cerr << "Error parsing the OFF file " << std::endl;
    return 1;
  }

  // merge duplicated points (useful to also stitch uncorrectly oriented patches)
  const std::size_t nb_points = points.size();
  std::vector<std::size_t> point_index(nb_points, 0);
  std::map<K::Point_3, std::size_t> point_to_id;
  std::vector<K::Point_3> unique_points;
  unique_points.reserve(nb_points);
  
  for (std::size_t i=0; i<nb_points; ++i)
  {
    std::size_t id =
      point_to_id.insert( std::make_pair(points[i], unique_points.size()) ).first->second;
    if ( id == unique_points.size() )
      unique_points.push_back( points[i] );
    point_index[i]=id;
  }

  if (unique_points.size() != nb_points)
  {
    typedef std::vector<std::size_t> Polygon;
    BOOST_FOREACH(Polygon& p, polygons)
    {
      BOOST_FOREACH(std::size_t& id, p)
        id = point_index[id];
    }
    points.swap(unique_points);
  }

  CGAL::Polygon_mesh_processing::orient_polygon_soup(points, polygons);

  Mesh mesh;
  CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points, polygons, mesh);

  if (CGAL::is_closed(mesh) && (!CGAL::Polygon_mesh_processing::is_outward_oriented(mesh)))
    CGAL::Polygon_mesh_processing::reverse_face_orientations(mesh);


  std::ofstream out("oriented.off");
  out << std::setprecision(17) << mesh;
  out.close();

  return 0;
}