CGAL users discussion list

["Thomas Zangl - Home" <>]

Am Wed, 18 Jul 2007 16:15:05 +0200, schrieb "Peter Hachenberger" 
<>:

Hi!

>How do you extract the vertices from a triangle? I'm not completely sure
>how our triangulation works, but I would assume that the vertices of a
>facet should be oriented consistently if you triangulate an orientable
>surface.

I extract them like this:

  Rt_Facet_iterator fIt = t.facets_begin();
  Rt_Facet_iterator fEnd = t.facets_end();
  if ( fIt == fEnd ) { std::cout << "no faces found" << std::endl ;}
  else {
    while(fIt != fEnd) {
      Rt_Cell_handle cell = fIt->first;
      // this is the index of the facet's opposite vertex
      int faceIndex = fIt->second;
      // "info" is a simple int which holds an index, assigned
      // upon insertion into the triangulation.
      // bascially its just 0, 1, 2, 3, 4, 5 ... 
      int a = cell->vertex((faceIndex+1) % 4)->info();
      int b = cell->vertex((faceIndex+2) % 4)->info();
      int c = cell->vertex((faceIndex+3) % 4)->info();
      
      // I then test here if the triangle is useful for later
      // processing..
      if (isUseFull) {
        intTriple faceOfIndices(a,b,c);
        complex.push_back(faceOfIndices);
      }  
  }
  
So I end up with a vector of intTriple (which hold the indices of the
points forming each facet in the vector). And I have another vector
where I have a mapping index -> point which I need later for building
the Polyhedron. 
Nothing special :-)

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

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