CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 06/10/2013 01:04 AM, schrodingersnewcat wrote:
> Okay, I've done that and it does indeed come back telling me there are
> degenerate triangles.
>
> First a note.  I had to use this snippet instead of what you posted as
> CGAL::orientation was giving me an error.
Strange...

> for (Polyhedron::Facet_iterator fit=polyhedron.facets_begin();
>                         fit!=polyhedron.facets_end();
>                         ++fit)
>         {
>                 if ( CGAL::collinear(
>                                 fit->halfedge()->vertex()->point(),
>                                 fit->halfedge()->next()->vertex()->point(),
>                                 
> fit->halfedge()->opposite()->vertex()->point() ) )
>                 {
>                         std::cout<<  "degenerate triangle\n";
>                 }
>         }
>
> So, now my question is how do I repair a polyhedron that has developed this
> pathology and how does it occur in the first place?
>
> As I said before I'm using a kernel with an exact number type.  In fact it
> is interchangeable with CGAL::Exact_predicates_exact_constructions_kernel.
> I just wanted to specify the number and kernel type manually.
>
> The polyhedrons I'm using are the result of boolean operations using Nef
> polyhedrons.  Each is converted from a Nef polyhedron a few steps before I
> create the AABB trees.
Try calling join_facet on the 0-length edges:

http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Polyhedron_ref/Class_Polyhedron_3.html#Function_Halfedge_handle_join_facet6_Halfedge_handle_h9;

Sebastien.

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