title: Access the faces and vertex of 2d Apollonius diagram CGAL- Weighted Voronoi diagram
body: <p>When I try using the following code to access the faces and vertices of Apollonius Voronoi Diagram (Reference : <a href="https://stackoverflow.com/questions/18274584/cgal-2d-apollonius-diagram-for-weighted-voronoi-how-to-generate-and-get-the-fa">CGAL 2D APOLLONIUS diagram for Weighted Voronoi - How to generate and get the faces and vertices?</a>)</p>
  
  <pre><code>for(A_Bounded_faces_iterator f = VDA.bounded_faces_begin(); f != VDA.bounded_faces_end(); f++)
      {
  
          A_Ccb_halfedge_circulator ec_start = (f)-&gt;ccb();
          A_Ccb_halfedge_circulator ec = ec_start;
          poly.clear();
          do {
              x = ((A_Halfedge_handle)ec)-&gt;source()-&gt;point().x();
              y = ((A_Halfedge_handle)ec)-&gt;source()-&gt;point().y();
              poly.push_back(QPointF(x,y));
          } while ( ++ec != ec_start );        
          List_Poly.push_back(poly);
      }
  </code></pre>
  
  <p>I get the following error</p>
  
  <pre><code>**terminate called after throwing an instance of 'CGAL::Assertion_exception'
    what():  CGAL ERROR: assertion violation!
  Expr: incircle(f, p) == NEGATIVE
  File: /usr/include/CGAL/Apollonius_graph_2.h
  Line: 1050**
  </code></pre>
  
  <p>I dont know why the assertion is getting violated. Please can you help me as I need to access the faces and vertices of apollonius diagram for my problem. Is there any other way i can access the faces and vertices of apollonius diagram.</p>