CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

I don't know how you get these numbers but they are incorrect.
The program joint indicates 8 finite vertices, 34 facets (16 are
finite) and 17 cells (5 are finite).

Sebastien.


#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Triangulation_3.h>
#include <iostream>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Triangulation_3<K> T3;

int main(){
  T3 t;
  t.insert(K::Point_3(0,0,0));
  t.insert(K::Point_3(1,0,0));
  t.insert(K::Point_3(0,1,0));
  t.insert(K::Point_3(0,0,1));
  t.insert(K::Point_3(2,0,0));
  t.insert(K::Point_3(3,0,0));
  t.insert(K::Point_3(2,1,0));
  t.insert(K::Point_3(2,0,1));

  std::cout << "V" << t.number_of_vertices() << std::endl;
  std::cout << "F" << t.number_of_facets() << std::endl;
  std::cout << "C" << t.number_of_cells() << std::endl;

  std::list<T3::Cell_handle> icells;
  t.incident_cells(t.infinite_vertex(),std::back_inserter(icells));
  std::cout << "IIV" << icells.size() << std::endl;

}



On 08/10/2011 06:49 PM, henrikz wrote:
> Hello,
>
> I have also come across a peculiarity regarding the infinite_vertex, which I
> am hoping you might be able to clear up for me.
>
> Similar to the other posts, in my case it seems that not all connected
> components of a Tetmesh are connected with the infinite vertex.
>
> I create my Tetmesh using the incremental builder (for details see below),
> as a simple example I created 2 Tets which are simply translates of
> eachother:
>
>   Vertices
>   8
>   0 0 0 0
>   1 0 0 0
>   0 1 0 0
>   0 0 1 0
>   2 0 0 0
>   3 0 0 0
>   2 1 0 0
>   2 0 1 0
>   Tetrahedra
>   2
>   1 2 3 4
>   5 6 7 8
>
> now the outputting the number of elements yield the following:
>
>   #vertices: 8
>   #edges   : 20
>   #faces   : 20
>   #cells   : 10
>
> while the number of vertices seems ok, the rest seems odd!?
>
> Furthermore, outputting the number of /incident_cells/ to the
> /infinite_vertex/ yields:
>
>   #cells incident to inf vertex = 4
>
> The "problem" occurred to me when trying to visualize the outer surface
> mesh(es) (of a multi-component tetmesh) using incidence with the infinite
> vertex...
>
> Can someone please tell me if this is the wanted functionality and/or if I
> am simply using the Triangulation/Builder wrong?
>
>
> Many thanks,
> Henrik
>
> The used data structure:
> /typedef CGAL::Exact_predicates_inexact_constructions_kernel    TM_K;
> typedef TVB_with_index<TM_K>                                    TM_VB;
> typedef TCB_with_index<TM_K>                                    TM_CB;
> typedef CGAL::Triangulation_data_structure_3<  TM_VB, TM_CB>     TM_TDS;
> typedef CGAL::Triangulation_3&lt;TM_K, TM_TDS&gt;
> TetMeshT3;
> typedef Triangulation_3_with_indices<TetMeshT3>                 TetMeshCGAL;
> typedef CGAL::Triangulation_incremental_builder_3<TetMeshCGAL>
> TetMeshCGALIncrementalBuilder;/
>
>
>
>
>
> --
> View this message in context: 
> http://cgal-discuss.949826.n4.nabble.com/Infinite-vertex-in-Triangulations-tp1015702p3733540.html
> Sent from the cgal-discuss mailing list archive at Nabble.com.