IfcOpenShell/src/ifcgeom/kernels/cgal/CgalConversionFunctions.cpp

#include "CgalKernel.h"

bool IfcGeom::CgalKernel::convert_wire_to_face(const cgal_wire_t& wire, cgal_face_t& face) {
  face.outer = wire;
  return true;
}

void IfcGeom::CgalKernel::remove_duplicate_points_from_loop(cgal_wire_t& polygon) {
  std::set<cgal_point_t> points;
  for (int i = 0; i < polygon.size(); ++i) {
    if (points.count(polygon[i])) {
      polygon.erase(polygon.begin()+i);
      --i;
    } else points.insert(polygon[i]);
  }
}

CGAL::Polyhedron_3<Kernel> IfcGeom::CgalKernel::create_polyhedron(std::list<cgal_face_t> &face_list) {
  
  // Naive creation
  CGAL::Polyhedron_3<Kernel> polyhedron;
  PolyhedronBuilder builder(&face_list);
  polyhedron.delegate(builder);
  
  // Stitch edges
  //  std::cout << "Before: " << polyhedron.size_of_vertices() << " vertices and " << polyhedron.size_of_facets() << " facets" << std::endl;
  CGAL::Polygon_mesh_processing::stitch_borders(polyhedron);
  if (!polyhedron.is_valid()) {
    std::cout << "create_polyhedron: Polyhedron not valid!" << std::endl;
    //    std::ofstream fresult;
    //    fresult.open("/Users/ken/Desktop/invalid.off");
    //    fresult << polyhedron << std::endl;
    //    fresult.close();
    return CGAL::Polyhedron_3<Kernel>();
  } if (polyhedron.is_closed()) {
    if (!CGAL::Polygon_mesh_processing::is_outward_oriented(polyhedron)) {
      CGAL::Polygon_mesh_processing::reverse_face_orientations(polyhedron);
    }
  }
  
  //  std::cout << "After: " << polyhedron.size_of_vertices() << " vertices and " << polyhedron.size_of_facets() << " facets" << std::endl;
  
  return polyhedron;
}

CGAL::Polyhedron_3<Kernel> IfcGeom::CgalKernel::create_polyhedron(CGAL::Nef_polyhedron_3<Kernel> &nef_polyhedron) {
  if (nef_polyhedron.is_simple()) {
    CGAL::Polyhedron_3<Kernel> polyhedron;
    nef_polyhedron.convert_to_polyhedron(polyhedron);
    return polyhedron;
  } else {
    std::cout << "Nef polyhedron not simple: cannot create polyhedron!" << std::endl;
    return CGAL::Polyhedron_3<Kernel>();
  }
}

CGAL::Nef_polyhedron_3<Kernel> IfcGeom::CgalKernel::create_nef_polyhedron(std::list<cgal_face_t> &face_list) {
  CGAL::Polyhedron_3<Kernel> polyhedron = create_polyhedron(face_list);
  return CGAL::Nef_polyhedron_3<Kernel>(polyhedron);
}

CGAL::Nef_polyhedron_3<Kernel> IfcGeom::CgalKernel::create_nef_polyhedron(CGAL::Polyhedron_3<Kernel> &polyhedron) {
  if (polyhedron.is_valid()) {
    CGAL::Polygon_mesh_processing::triangulate_faces(polyhedron);
    return CGAL::Nef_polyhedron_3<Kernel>(polyhedron);
  } else {
    std::cout << "Polyhedron not valid: cannot create Nef polyhedron!" << std::endl;
    return CGAL::Nef_polyhedron_3<Kernel>();
  }
}