CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Reading the documentation:

http://doc.cgal.org/latest/Polyhedron/classCGAL_1_1Polyhedron__3.html#a8edb13d0fb5748b20a8173bec85e7243

"Precondition:
    The size of both facets incident to h is at least four"

Since you are working on a triangulated surface, it does not work.

You should have a look at the edge simplification package:
http://doc.cgal.org/latest/Surface_mesh_simplification/index.html#Chapter_Triangulated_Surface_Mesh_Simplification

or directly use the internal function (which has no topology nor 
geometric tests):

#include <CGAL/Surface_mesh_simplification/halfedge_collapse_Polyhedron_3.h>
#include <CGAL/boost/graph/halfedge_graph_traits_Polyhedron_3.h>

CGAL::Surface_mesh_simplification::halfedge_collapse(hedge,poly);

Sebastien.

On 01/15/2014 03:38 AM, tang wrote:
> Dear all,
>
> I installed latest CGAL 4.3 and run the following code:
>
> void SimplifySurfaceMeshCGAL(Polyhedron *obj,double edgelengthmin)
> {
>         double minimum_edge_length = edgelengthmin*edgelengthmin;  // squared
>         double len;
> {std::ofstream log("update.off");log << *obj; } update.off
> <http://cgal-discuss.949826.n4.nabble.com/file/n4658645/update.off>
>         int count=0,n20=0;
>         while(1)
>         {
>                 int found=0;
>                 Halfedge_iterator eb0=obj->halfedges_begin() ;
>                 for( Polyhedron::Halfedge_iterator eb = 
> obj->halfedges_begin() ; eb !=
> obj->halfedges_end() ; ++ eb )
>                 {
>                         len=get_edge_length<Polyhedron>(eb);
>                         if(len<minimum_edge_length)
>                         {
>                                 *obj->join_vertex(eb);
>                                 eb=eb0 ;
>                                 if(found==0)found=1;
> count++;
> int n2=0;
> for (  Facet_iterator i = obj->facets_begin(); i != obj->facets_end(); ++i)
> {
>         Halfedge_facet_circulator j = i->facet_begin();
>         if((int)CGAL::circulator_size(j)==2)n2++;
> }
> if(n2>n20)
> {
>                 printf("%d %d\n",count,n2);
>                 n20=n2;
> {std::ofstream log("update1.off");log << *obj; } update1.off
> <http://cgal-discuss.949826.n4.nabble.com/file/n4658645/update1.off>
> exit(0);
> }
>                         }
>                         else
>                                 eb0=eb;
>                 }
>                 if(found==0)break;
>         }
> }
>
>
> I found that every time running the function "join_vertex", two degenerated
> facets (facets contains only two vertices) generated. Is it a bug of the
> function "join_vertex"? If not, how can I remove the degenerated facets?
>
> Thanks
>
>
>
> --
> View this message in context: 
> http://cgal-discuss.949826.n4.nabble.com/Bug-of-join-vertex-in-CGAL-tp4658645.html
> Sent from the cgal-discuss mailing list archive at Nabble.com.