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["Thomas Zangl - Home" <>]

Dear List!

I have a set of points and a set of faces which form a surface (can
also be a volume). 

I use the CGAL::Polyhedron_incremental_builder_3 to build a Polyhedron
out of those sets. After inserting all points and all facets I get an
assertion:

CGAL::Polyhedron_incremental_builder_3<HDS>::
lookup_halfedge(): input error: facet 2 shares a halfedge from vertex 86 to 
vertex 16 with facet 1.
CGAL error: assertion violation!
Expr: check_protocoll == 0
File: /home/TZi/CGAL-3.3/include/CGAL/Polyhedron_incremental_builder_3.h
Line: 198
Explanation:
Aborted (core dumped)

I know that facet 2 and facet 1 have a common edge. That is by
intention (the faces are from a triangulation). Is this a problem for
the incremental builder? 

This is my code:
 class Build_surface:public CGAL::Modifier_base<HalfedgeDS>
{
public:
  // this is an int, Point map
  IndexPointMap allPoints;
  // this is a container with a triple(int, int, int)
  // which holds the indices (see IndexPointMap) for each point of the
  // face
  FacesAsIndicesContainer allTriples;

  Build_surface(IndexPointMap& allPoints_,FacesAsIndicesContainer 
allTriples_):allPoints(allPoints_),allTriples(allTriples_){}

    void operator()( HalfedgeDS& hds)
    {
      CGAL::Polyhedron_incremental_builder_3<HalfedgeDS> B( hds, true); // 
verbose=False
      B.begin_surface( allPoints.size(), allTriples.size());
      typedef HalfedgeDS::Vertex Vertex;
      int count = 0;
      for(IndexPointMap::iterator 
p_it=allPoints.begin();p_it!=allPoints.end();++p_it)
      {
        cout << count << "-adding vertice: " << p_it->second << endl;
        B.add_vertex(p_it->second);
        count++;
      }
      count = 0;
      for(FacesAsIndicesContainer::iterator 
t_it=allTriples.begin();t_it!=allTriples.end();++t_it)
      {
        Point a = allPoints[t_it->first];
        Point b = allPoints[t_it->second];
        Point c = allPoints[t_it->third];
        Rt_Triangle tmp(a,b,c);
        if(tmp.is_degenerate()) continue;
        cout << count<<"-adding facet (idx): " << 
t_it->first<<"/"<<t_it->second<<"/"<<t_it->third << endl;
        cout << count<<"-adding facet (coords): " << a<<"/"<<b<<"/"<<c << 
endl;
        B.begin_facet();
          B.add_vertex_to_facet(t_it->first);
          B.add_vertex_to_facet(t_it->second);
          B.add_vertex_to_facet(t_it->third);
        B.end_facet();
        count++;
      }
      B.end_surface();
    }
};

This are the points which are mentioned by the error message:
(in front is the index)

16-adding vertice: 67.2414 67.2414 32.7586
27-adding vertice: 90.1561 90.1561 18.9655
11-adding vertice: 32.7586 67.2547 32.7586
86-adding vertice: 91.3793 68.9429 8.62069
88-adding vertice: 91.3793 79.5495 8.62069

0-adding facet (idx): 84/83/11
0-adding facet (coords): 8.62069 54.8008 8.62069/12.069 47.7297 
12.069/32.7586 67.2547 32.7586
1-adding facet (idx): 88/86/16
1-adding facet (coords): 91.3793 79.5495 8.62069/91.3793 68.9429 
8.62069/67.2414 67.2414 32.7586
2-adding facet (idx): 86/16/27
2-adding facet (coords): 91.3793 68.9429 8.62069/67.2414 67.2414 
32.7586/90.1561 90.1561 18.9655

In total there are 95 vertices and 267 faces.

Whats wrong? Please help :-) Thanks!

Best regards,
-- 
----------------------------------------------------------------
,yours Thomas Zangl, Bakk.rer.soc.oec. - 

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