CGAL users discussion list

[Laurent Rineau <>]

On Monday 25 June 2007 05:12:27 Lyndon Hill wrote:
> Hello,
>
> I am trying to load a 3D mesh from an OFF file using
> CGAL::scan_OFF(). The mesh has been generated by some
> simplification software.
>
> I get the following error:
>
> CGAL::Polyhedron_incremental_builder_3<HDS>::
> lookup_halfedge(): input error: facet 302 shares a
> halfedge from vertex 214 to vertex 213 with facet 300.
>
> I don't quite understand why two facets sharing a
> halfedge is a bad thing.

Two facets can share an edge. That is not a problem. What is a problem is two 
facets sharing an *half-edge*. It means that the two adjacent facets are not 
oriented correctly. If the two facets orientations were compatible, the two 
facets would have opposite half-edges, to represent the edge that they share.

You need to orient your mesh correctly.

-- 
Laurent Rineau
INRIA - Sophia Antipolis
BP 93, 2004 Route des Lucioles
06902 Sophia Antipolis Cedex FRANCE