CGAL users discussion list

[Dominik Szczerba <>]

Thank you, this is very useful.

Still one question though: what is ci->neighbor(i) supposed to return
if a cell does not have a neighbor i? I tried testing against NULL,
but it does not seem to be the case. I also tried
ci->has_neighbor(ci->neighbor(i) but this seems to always return true.

Thanks for any hints,
Dominik

On Thu, Feb 9, 2012 at 11:18 AM, Laurent Rineau (GeometryFactory)
<>
 wrote:
> Le jeudi 09 février 2012 11:03:38 Dominik Szczerba a écrit :
>> Hi,
>>
>> I am generating a tet mesh directly from a segmented medical image
>> more or less like
>>
>> C3t3 c3t3 = CGAL::make_mesh_3<C3t3>(domain, criteria);
>> const Tr& tr = c3t3.triangulation();
>>
>> I am then converting it to another required representation more or less
>> like:
>>
>>    for( Finite_vertices_iterator vit = tr.finite_vertices_begin();
>>    vit != tr.finite_vertices_end();
>>    ++vit)
>>    {
>> // get vertices
>>    }
>>
>>    for( Cell_iterator cit = c3t3.cells_begin() ;
>>    cit != c3t3.cells_end() ;
>>    ++cit )
>>    {
>> // get cells
>>    }
>>
>> Now my question is: is there also cell connectivity (which cell has
>> which neighbours) available in c3t3 after the mesh has been created?
>> By "available" I mean that this information be already available for
>> quick extraction, I do NOT mean its dedicated (lengthy) computation
>> afterwards.
>
> Sure.
>
> c3t3.triangulation() is a full CGAL triangulation.
>
> Given a Cell_handle, or any cell iterator, let's call it 'ci', you can call:
>
>   ci->neighbor(i) // for i in {0, 1, 2, 3}
>
> See the documentation of the Cell type here:
>
>  http://www.cgal.org/Manual/latest/doc_html/cgal_manual/TriangulationDS_3_ref/Concept_TriangulationDSCellBase_3.html
>
> Here is the corresponding short link:
>
>  http://bit.ly/wGwmY3
>
> --
> Laurent Rineau, PhD
> R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
> Release Manager of the CGAL Project       http://www.cgal.org/
>
>
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-- 
Dominik