CGAL users discussion list

["Laurent Rineau (GeometryFactory)" <>]

On Thursday 14 May 2009 15:53:33 Monique Teillaud wrote:
> A 3D triangulation is a decomposition of the space into 3D cells
> (tetrahedra). 3D cells _are_ actually consistently oriented.
> (see the user manuals of chapters 3d traingulation and 3d triangulation
> data structure)

Nizar is talking about *facets* of a 3D triangulation. Facets of a 3D 
triangulation are not stored in the data-structure. Only the vertices and the 
cells of the triangulation are stored, and facets are implicit. The cells of 
the triangulation are consistently oriented, and for that reason it is 
possible to consistently orient two facets incident to the same edge, but 
that 
is not strait-forward.

-- 
Laurent Rineau, PhD
Engineer at GeometryFactory
http://www.geometryfactory.com/