CGAL users discussion list

[Marius Kintel <>]

On 2013-10-30, at 12:41 PM, KeithSloan52 
<>
 wrote:
> 
> But I am still a bit confused because OpenSCAD seems to be making the same
> call to Convex_hull, but when viewing its output the facets look to be
> mostly 4 sided.
> 
Could it be that the 4-sided faces you see is an illusion due to CGAL 
providing separate edge information, which we use to render edges?

See CGAL/Nef_polyhedron_3.h:561, CGAL/Nef_3/SCN_external_structure.h and 
CGAL/Nef_3/SNC_simplify.h which could be responsible for this edge 
construction. The code is really hard to read and as far as I can see not 
documented, but perhaps someone here knows what's going on..

 -Marius