CGAL users discussion list

[Laurent Provot <>]

Hello David,

If I have well understood your piece of code you want to remove all the
incident facets of a vertex (represented by an halfedge v) and if this
creates an isolated vertex it gets automatically removed as well.

But isn't it simpler to use the P.erase_center_vertex(...) on your
exterior vertices ? I guess it gives the same result, doesn't it ?

Laurent


Le Wed, 23 May 2007 15:30:24 +0200,
David Coeurjolly 
<>
 a écrit :

> Dear all,
> 
> I've to admit that I'm a brand new CGAL user for a couple of weeks and
> my questions may be stupid. My problem is quite simple: cut a
> polyhedron with an oriented plane.
> 
> It is quite easy to tag  the vertices ('exterior/interior') and to
> create the new halfedges/vertices for intersection points
> (edge/plane). But I have troubles to "remove" the exterior vertices.
> 
> More precisely, I've pushed in a list<Halfedge_handle>, an halfedge
> handle per exterior vertex (called list_exterior_handles) obtained
> during the exterior vertex scan step. My idea was to use
> P.erase_facet() as follows:
> 
> Halfedge_around_vertex_circulator circ;
> for( list<Halfedge_handle>::iterator v =
> list_exterior_handles.begin(); v != list_exterior_handles.end() ;
> ++v){ 
>       circ = (*v)->vertex_begin();
>       unsigned int deg = (*v)->vertex()->degree();
>       for (unsigned int i=0; i< deg; i++)
>           if (not circ->is_border()) P.erase_facet(circ);
>       circ++;
> }     
> 
> But this does not work..... I obtain segfaults due to the
> dereferencing of a NULL pointer in the (*v)->vertex()->degree()
> computation.
> 
> Do you have any idea of what's going on ? By the way, my choice of the
> erase_facet operation may not be not good.. Any other suggestion ?
> 
> Thanks in advance, regards,
> david
> 
>