CGAL users discussion list

[Noel Warren <>]

Hi Sebastien

I actually use CGAL wrapped in ruby.  You can checkout my repo at (https://github.com/noelwarr/rgal).  Let me know if you want any licenses put anywhere.  (I do know about the cgal-bindings project but I couldn't get my head around swig.)

Because it is a pain to compile the whole RGAL repo I have put together a little cpp file and nef file that fails to create a nef from one of the volumes.  The interesting thing is that even though the same volume fails, it throws a different error.  The cpp file complains about a segmentation fault whereas my ruby wrapped code produces...

CGAL ERROR: assertion violation! (RuntimeError)

Expr: cet->get_index() == ce->twin()->get_index()

File: /usr/local/include/CGAL/Nef_3/SNC_external_structure.h

Line: 1169

Even wierder is the fact that if I don't regularize the nef, the cpp code produces a result but my ruby code continues to fail.

Let me know if you need something else.

2013/3/11 Sebastien Loriot (GeometryFactory) <>

Dear Noel,

could you please provide a complete compilable example showing the problem?

Thanks,

Sebastien.

On 03/07/2013 01:13 PM, Noel Warren wrote:

I have a function that splits Nefs into smaller nefs from the shells of
the volumes.  I am doing it using an undocumented Nef constructor.  In
the majority of cases it works a charm but ocasionally it fails.  I have
attatched a nef that fails (infact it only has one volume so should
return an Array of length 1 containing a Nef) when trying to split.

Here is a code snippet

vector<Nef_polyhedron_3> nefs;
Nef_polyhedron_3::Volume_const_iterator vi = ++N.volumes_begin();
Nef_polyhedron_3::Shell_entry_const_iterator si;
CGAL_forall_volumes(vi,N) {
if(vi->mark()) {
Nef_polyhedron_3::Shell_entry_const_iterator si;
CGAL_forall_shells_of(si, vi) {
Nef_polyhedron_3::SFace_const_handle sfch(si);
Nef_polyhedron_3 O(N,sfch);
nefs.push_back(O);
}
}
}

Here is the error...

CGAL ERROR: assertion violation! (RuntimeError)
Expr: itl != it->second.end()
File: /usr/local/include/CGAL/Nef_3/SNC_external_structure.h
Line: 1102

If I shouldn't be using this Nef constructor, how should I go about
"splitting" a nef into smaller ones.  Thanks in advance for your time.

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