CGAL users discussion list

[Miltiadis Koutsokeras <>]

I'm experiencing some strange behavior while using an std::vector of 
CGAL::Polyhedron_3<Traits>::Vertex  pointers.
While iterating through the container I watermark every element is 
labeled with the value -1 or 1 and its 1-ring neighbors with value 2. In 
every iteration labeling only the vertices that have a label equal to 
zero, because a vertex can be a neighbor of a
previous thus it's already labeled with 2. The strange thing is that I 
encounter vertices labeled with 1 or -1, although before the iteration 
all vertices labels are initialized with zeros. In the example code 
below I specify the condition that breaks. Can someone
please give me any tip about CGAL::Polyhedron_3<Traits>::Vertex pointers 
and why this behavior happens?

Code:
      /**
       * Embeds the watermark to the primitive.
       */
       void embedWatermark(SpatialPrimitive& v, WatermarkPrimitive 
watermark)
       {
#ifdef _DEBUG
           assert(v.m_label == 0);
#endif

           typedef typename SpatialPrimitive VertexType;
           typedef typename 
VertexType::Halfedge_around_vertex_circulator Circ;
           typedef typename VertexType::Vertex_handle Vertex_handle;

           std::size_t neighbors_num = 0;

           // loop through neighbors
           Circ c = v.vertex_begin();
           Circ end = c;
           Vertex_handle neighbor;

           CGAL_For_all(c, end)
           {
               neighbor = c->opposite()->vertex();
               neighbors_num++;
               neighbor->m_label = 2;
           }

#ifdef _DEBUG
           assert(neighbors_num == v.vertex_degree());
#endif
           v.m_label = watermark;
       }



    /**
   * Watermarks a list of vertices usign a list of watermark samples.
   * @param chosen_verts List of vertices to watermark.
   * @param watermark_samples List of watermark samples.
   */
   void watermarkVertices(std::vector<Vertex *> chosen_verts, 
std::vector<short> watermark_samples)
   {
#ifdef _DEBUG
       unsigned int chosen_vertices_size = chosen_verts.size(),
                       watermark_samples_size = watermark_samples.size();
       assert(chosen_vertices_size == watermark_samples_size);
#endif
       std::vector<Vertex *>::iterator vertex_it = chosen_verts.begin();
       std::vector<Vertex *>::const_iterator vertex_end = 
chosen_verts.end();
       std::vector<short>::iterator sample_it = watermark_samples.begin();

       for(; vertex_it != vertex_end; ++vertex_it, ++sample_it)
       {
#ifdef _DEBUG
           *// this assertion fails after some iterations
           assert(((*vertex_it)->m_label == 0) || 
((*vertex_it)->m_label == 2));*
#endif
           if((*vertex_it)->m_label == 0)
           {
               embedWatermark(*(*vertex_it), *sample_it);
           }
       }
   }

--
Koutsokeras Miltiadis

Computational Intelligence Laboratory (http://www.iit.demokritos.gr/cil/)
Institute of Informatics and Telecommunications
National Center for Scientific Research "Demokritos"
P.O. BOX   60228
GR-153 10 Agia Paraskevi, Athens, Greece.