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[pwr00 <>]

Hi! 
I'm trying to use the polygon reduction functionality in CGAL. I have
managed to do this when using the cow.off file that I found in the source.
But when I try to reduce my own polygon data I don't get any reduced
polygons. Is there any restrictions on what the polygon data must look like?
My polygon data are planes (open meshes) and I construct the polyhedron by
doing this:

template< class HDS >
class PolyhedronBuilder :
      public CGAL::Modifier_base< HDS >
{
public:

   PolyhedronBuilder( std::vector< wlib::Double >& rCoords, std::vector<
wlib::Int >& rTris ) :
      m_rCoords( rCoords ),
      m_rTris( rTris )
   {
   }

   void operator()( HDS& rHds)
   {
      typedef typename HDS::Vertex   Vertex;
      typedef typename Vertex::Point Point;

      // create a cgal incremental builder
      CGAL::Polyhedron_incremental_builder_3< HDS > oIncrementalBuilder(
rHds, true );
      oIncrementalBuilder.begin_surface( m_rCoords.size() / 3,
m_rTris.size() / 3 );

      // add the polyhedron vertices
      for( wlib::Int nIndex = 0; nIndex < m_rCoords.size(); nIndex += 3 )
      {
         oIncrementalBuilder.add_vertex( Point( m_rCoords[ nIndex + 0 ],
m_rCoords[ nIndex + 1 ], m_rCoords[ nIndex + 2 ] ) );
      }

      // add the polyhedron triangles
      for( wlib::Int nIndex = 0; nIndex < m_rTris.size(); nIndex += 3 )
      {
         oIncrementalBuilder.begin_facet();
         oIncrementalBuilder.add_vertex_to_facet( m_rTris[ nIndex + 0 ] );
         oIncrementalBuilder.add_vertex_to_facet( m_rTris[ nIndex + 1 ] );
         oIncrementalBuilder.add_vertex_to_facet( m_rTris[ nIndex + 2 ] );
         oIncrementalBuilder.end_facet();
      }
      // finish up the surface
      oIncrementalBuilder.end_surface();
   }
private:
   std::vector< wlib::Double >& m_rCoords;
   std::vector< wlib::Int >& m_rTris;

};


This is how I perform the reduction:

   //CGAL::Surface_mesh_simplification::Count_stop_predicate< Polyhedron3 >
oStop( 1 );
   CGAL::Surface_mesh_simplification::Count_ratio_stop_predicate<
Polyhedron3 > oStop( 0.5 );
   //CGAL::Surface_mesh_simplification::LindstromTurk_cost< Polyhedron3 >
oStop;

   wlib::Int nNumRemovedEdges =
CGAL::Surface_mesh_simplification::edge_collapse(
         m_oPolyhedron3,
         oStop,
         CGAL::vertex_index_map( boost::get( CGAL::vertex_external_index,
m_oPolyhedron3 ) ).edge_index_map( boost::get( CGAL::edge_external_index,
m_oPolyhedron3 ) ) );






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