CGAL users discussion list

["Shi Yan" <>]

hello guys,

i have some trouble with removing vertices from the half-edge data structure.

i have a geometry object, and i let it deform, however, when some
parts of the object move out of the scope, i will remove that part.

but i cannot find vertex remove function in CGAL.

i'm trying to use         P.erase_center_vertex() combining with
P.erase_facet(), but it doesn't work, because i always got access
violation, null halfedge handle errors.

here is what i did:

i first travel through all the vertices, and decide if some need to be
removed, and push them into a std::vector:

Vertex_iterator vIter=p.vertices_begin ();
  Vertex_iterator vIterEnd=p.vertices_end ();


  std::vector< Vertex_iterator> toBeRemoved;

  for(;vIter!=vIterEnd;++vIter)
  {

if needs to be removed:

                toBeRemoved.push_back(vIter);
  }


and then, i visit each entry of the std::vector and remove it from the
half-edge data

 if(toBeRemoved.size()>0)
  {
          std::vector< Vertex_iterator>::iterator rIter=toBeRemoved.begin();
          for(;rIter!=toBeRemoved.end();++rIter)
          {
                          p.erase_facet (   p.erase_center_vertex 
((*rIter)->halfedge()) );
        
          }

  }



i guess, the problem is, when some vertex is removed, some half-edge
handle becomes invalid. but i don't know how to do this in a better
way.

i think this is a very common problem, isn't it?

thank you so much.