CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

IIRC, there is a plugin in the Polyhedron demo which is orienting
a soup of polygon.

Sebastien.

On 11/07/2012 08:36 AM, Guillaume Damiand wrote:
> Le 06/11/2012 18:18, johnzjq a écrit :
> > Is there any simpler solution to it, without knowing the global knowledge
> > about the polyhedron?
>
> Orientation is a global property.
> Indeed, you can build two objects having exactly a same local
> configuration but with two opposite orientations.
>
> To orient correctly a polyhedron, you can take a face with a given
> orientation, compute its normal, take a point in the face, translate it
> along the normal, and test if this point is inside or outside to the
> polyhedron (counting the number of intersections of a half-line starting
> from the point and the polyhedron).
> Depending on which orientation you want, you conclude if the initial
> orientation is correct or wrong; then you propagate the correct
> orientation to all the faces of the polyhedron.
>
> Guillaume
>
>
> > --
> > View this message in context:
> > http://cgal-discuss.949826.n4.nabble.com/orient-triangles-tp952874p4656161.html
> >
> > Sent from the cgal-discuss mailing list archive at Nabble.com.