CGAL users discussion list

[Andreas Fabri <>]

Hello,

When you have facets with more than three vertices they must be
coplanar, which might not be given if their coordinates are doubles.
The solution is to either make them coplanar, or to triangulate
the faces.

best regards,

andreas





 wrote:
> Hello,
>
> I am very new to CGAL, and I am wondering if it is possible to do
> solid/solid intersections. 
>
> It is funny to see that infact, I have the same question as Cedric
> Le Maitre (he sent a mail today)...
>
> More precisely, I have two solids described by two closed Polyhedra
> (using 3 and 4 nodes faces).
>
> I would like to get the Polyhedra that represents the difference between
> the two solids.
>
> I tried using the Nef_polyhedron_3 classes :
>
> 1- construct two Polyhedron
> 2- construct the Nef_polyhedron from the 2 polyhedron
> 3- intersect the 2 Nef_polyhedron
> 4- convert the result back to a Polyhedron
>
> When I construct the nef associated with one of the Polyhedrons, I
> get the following error :
>
> CGAL error: assertion violation!
> Expr: pe_prev->facet()->plane().
> has_on(pe_prev->opposite()->vertex()->point())
> File: ./cgal_build/CGAL-3.2.1/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h
> Line: 151
>
> I had a look in this file, but the error is not so obvious, at least for
> a 'CGAL-beginner' like me.
>
>
> Could anyone guide me, and tell me if such operation is available in
> CGAL, and if yes, how to achieve it ? Any help would be greatly
> appreciated.
>
>
> Best Regards,
>
> Frederic.