How to split a Polyhedron mesh into a set of diferent Polyhedron having signed faces?

Question

So here we have a Polyhedron mesh with signed faces. But how to put that signed faces into a new Polyhedron mesh? To smplify: say we loaded a 100 faces mesh, we want to pick 50 random faces from it and put them into a new mesh. How one can do it in CGAL?

Answer 1

There is the following undocumented function in CGAL/Polygon_mesh_processing/connected_components.h:

CGAL::internal::corefinement::extract_connected_components(
  const Polyhedron& P,
  const Adjacency_criterium& adjacent,
  Output_iterator out);

Adjacency_criterium is a function object like the following:

struct AC_example{
  bool
  operator()(Polyhedron::Halfedge_handle h) const
  {
    bool incident_faces_in_the_same_component = .... ;
    return incident_faces_in_the_same_component;
  }
};

It must return true for all but the patch border halfedges.

Output_iterator is an output iterator of Polyhedron

In CGAL 4.10, the function moved into CGAL/internal/corefinemnt/connected_components.h. A nicer and more generic function is on its way and should be published in an upcoming release.