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[Josip Dzolonga <>]

Hi Andreas,

I corrected myself in my latest reply, but that did not solve the problem.

Josip

On Sun, Nov 15, 2009 at 9:07 PM, Andreas Fabri <> wrote:

Hi Josip,

You shouldn't expect that ++vit works correctly after that you called
T.remove(vit).

You better write this

for(Finite_vertices_iterator vit = T.finite_vertices_begin();

                vit != T.finite_vertices_end();) {

                if(seen.find(vit->point()) != seen.end()) {
                    seen.erase(vit->point());

                    Vertex_handle vh = vit;
                    ++vit;
                    T.remove(vh);
                    break;
                }
          }


Note that the same would be true for a std::list.

andreas

Josip Dzolonga wrote:

Hi Nico,

I thought of that, but at no point I am reusing old cell handles/vertex handles. I thought that while removing them, I might be causing the problem - but even if I change to code to the following, the problems remains

while(!seen.empty()) {
         for(Finite_vertices_iterator vit = T.finite_vertices_begin();
               vit != T.finite_vertices_end(); ++vit) {
               if(seen.find(vit->point()) != seen.end()) {
                   seen.erase(vit->point());
                   T.remove(vit);
                   break;
               }
         }
}

That is, I am iterating again over all vertices.

Thanks,
Josip

On Sun, Nov 15, 2009 at 8:42 PM, Nico Kruithof < <mailto:>> wrote:

   Hi Josip,

   The assertion says that the vertex is not contained in the Cell.
   When you remove vertices, cells get removed and added when
   re-triangulating. Internally, CGAL will reuse the memory of deleted
   cells for the new cells. This might be the reason you are getting
   the assertion.
   -- Nico


   On Sun, Nov 15, 2009 at 6:26 PM, Josip Dzolonga <

   <mailto:>> wrote:

       Hello everyone,

       I am trying to remove some certain points from the Delaunay
       triangulation. I had some problems even before, and got some
       advice from here, but the problem still pertains. The
       problematic code follows

       for(Finite_vertices_iterator vit = T.finite_vertices_begin();
                   vit != T.finite_vertices_end(); ++vit) {
                   if(seen.find(vit->point()) != seen.end()) {
                       seen.erase(vit->point());
                       T.remove(vit);
                  }
       }

       Where seen is of type std::set<Point> and has been already
       filled. Later on when I try to use the triangulation, I get the
       following error

       CGAL error: assertion violation!
       Expr: v == V[3]
       File: /usr/include/CGAL/Triangulation_ds_cell_base_3.h
       Line: 98
       terminate called after throwing an instance of 'std::logic_error'
         what():  basic_string::_S_construct NULL not valid
       Aborted

       Which comes from the function  int index(const Vertex_handle&
       v). I can not remove the same vertex twice, since I am iterating
       over the finite vertices and this is the only place where vertex
       removal is taking place. Any ideas would be highly appreciated!

       Best,
       Josip

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