CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

You can use the is_infinite triangulation member function to check is a 
cell is infinite.

The range [t.finite_cells_begin(),t.finite_cells_end ()] contains finite 
cells.

You can get all infinite cells using:

t.incident_cells ( t.infinite_vertex(), cell_output_iterator);
                
All these functions are documented on that page:

http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_3_ref/Class_Triangulation_3.html

Sebastien.

On 09/30/2012 05:16 PM, David Arken wrote:
> With the following typedefs:
>
> typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
> typedef CGAL::Regular_triangulation_euclidean_traits_3<K>   Traits;
> typedef Traits::RT                                          rWeight;
> typedef Traits::Bare_point                                  rPoint;
> typedef Traits::Weighted_point                              rWeighted_point;
> typedef CGAL::Regular_triangulation_3<Traits>                Rt;
>
> When I create a regular triangulation by insertion of points
> (.insert( point_list.begin(), point_list.end()) and then output the
> triangulation using "<<" to a std::ofstream, I see a extra vertex
> index in the cells. The points seem to be the input points. So if I
> filter all the tetrahedrons with this extra index, I was hoping to get
> the finite cells, but that does not seem to work.
>
> .number_of_finite_cells = 130949
> .number_of_cells = 140303
>
> I read the output of "<<" and I get 140303 tetrahedrons (as expected).
> Now I remove all tetrahedrons where there is this extra vertex and I
> only get 140281 tetrahedrons. Why this anomaly? What am I missing?
>
> A shorter version of my question: What is exactly the definition of
> infinite cells for a regular triangulation? Given all cells, how can i
> tell a cell is inifinite?
>
> Also: How do i enumerate the finite cells:
> (the following code gives compilation errors)
>
>      for( Finite_cells_iterator cit = rt.finite_cells_begin();
>              cit != rt.finite_cells_end();
>              ++cit)
>      {
>           for (int i=0; i<4; i++)
>            oFileT<<  cit->vertex(i)<<  " ";
>          // This does not work either: -->  oFileT<<  *cit;
>          oFileT<<  std::endl;
>      }
>
> Thanks,
> --Ram