CGAL users discussion list

[Richard Southern <>]

Hi there,

<This is my first posting, so apologies if I'm not giving you all the 
necessary info.
I'm using CGAL 3.3.1 on 32 & 64 bit Linux platforms, gcc 4.1.2 mostly.>

I've got a problem with a mesh that I am modifying using a custom 
geometric operation (not covered
by the split / fill_hole type operations provided in Polyhedron_3). 
Basically I would like to remove
a subset of faces and replace them with an alternative triangulation 
without having to rebuild the
entire mesh from scratch.

For this, the best thing appears to be to firstly use 
Polyhedron_3::erase_facet to get rid of facets to
be replaced, and thereafter to use the Polyhedron_incremental_builder_3 
with ABSOLUTE_INDEXING
to create new facets and vertices to fill the hole.

Unfortunately I see no obvious way to get the integer index of a vertex 
in the original mesh from a
Vertex_handle, so there is no way that new faces will be stitched 
together consistently.

Interestingly there is a function which appears to do the opposite:
/"Vertex_handle / / B.vertex ( std::size_t i) / returns handle for the 
vertex of index /i/, or /Vertex_handle/ if there is no /i/-th vertex."

So:
- Is there a way to get the integer index of a vertex in a mesh that has 
already been constructed given a
 Vertex_handle?

- Is this approach going to work in general?

- Is there a better way to do it?

Thanks a bunch,
- Richard