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[Evan Behar <>]

I am loading the model from an OBJ file--first I read in the vertices and facets from the OBJ file and then I am constructing the polyhedron using those values. I add the vertices all at once and then construct the facets using the vertex indices, so I am almost certainly reusing the vertices. The modifier code is below:

class Build_polyhedron : public CGAL::Modifier_base<Polyhedron::HalfedgeDS> {

  public:

    Build_polyhedron() {}

    void operator()(Polyhedron::HalfedgeDS& hds) {

      CGAL::Polyhedron_incremental_builder_3<Polyhedron::HalfedgeDS> builder(hds,true);

    

      const std::vector<Point>& vertices = OBJReader::vertices;

      const std::vector<std::vector<int> >& facets = OBJReader::facets;

      builder.begin_surface(vertices.size(),facets.size());

      // add vertices

      for (int i=0;i<vertices.size();i++) {

        builder.add_vertex(vertices[i]);

      }   

      // add facets

      for (int i=0;i<facets.size();i++) {

        builder.begin_facet();

        for (int j=0;j<facets[i].size();j++) {

          builder.add_vertex_to_facet(facets[i][j]);

        }

        Halfedge_handle h = builder.end_facet();

        std::cout << "Validating...\n";

        if (h->opposite()->facet() != Facet_handle()) {

          std::cout << "Opposite halfedge's facet not invalid!\n";

        }   

      }   

      builder.end_surface();

    }

};

On Wed, Mar 6, 2013 at 12:37 AM, Sebastien Loriot (GeometryFactory) <> wrote:

Can you give more information like the modifier you wrote for example?

A common mistake is not reusing the vertices. If you add two vertices
with the same coordinates, they will be consider as different.

Sebastien.

On 03/06/2013 05:51 AM, Evan Behar wrote:

I have constructed a Polyhedron_3, /P/, using the

Polyhedron_incremental_builder_3, and I am running into the problem that
none of the halfedges in the structure are being associated with any
opposite halfedges that have been previously constructed.

After construction, retrieving a Halfedge_handle /h/ from /P /and
calling /h->opposite()->facet()/ always results in an invalid Facet_handle.

Is this expected behavior from Polyhedron_incremental_builder_3? Do I
have to stitch the facets together manually?

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