Simplified code by moving Nef creation outside

src/ifcgeom/kernels/cgal/CgalConversionFunctions.cpp

@@ -329,3 +329,28 @@ void IfcGeom::CgalKernel::remove_duplicate_points_from_loop(cgal_wire_t& polygon
     }
   }
 }
+
+CGAL::Nef_polyhedron_3<Kernel> IfcGeom::CgalKernel::create_nef_polyhedron(std::list<cgal_face_t> &face_list) {
+  
+  // Naive creation
+  CGAL::Polyhedron_3<Kernel> polyhedron = CGAL::Polyhedron_3<Kernel>();
+  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 << "Invalid polyhedron!" << std::endl;
+    std::ofstream fresult;
+    fresult.open("/Users/ken/Desktop/invalid.off");
+    fresult << old_polyhedron << std::endl;
+    fresult.close();
+  }
+  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 CGAL::Nef_polyhedron_3<Kernel>(polyhedron);
+}