CGAL users discussion list

[Pierre Alliez <>]

hi Peter,

I think the preferred way to go is to combine atomic operations
such as edge collapses. What is missing in the current polyhedron
is a function

        bool is_collapsible(Halfedge_handle he)

but this type of function has been implemented by Fernando in the
mesh simplification package.

Fernando, would it be possible to move this function from the
mesh simplification component to the polyehdron itself? we could
also start listing some other atomic operations which would make
sense to add.

Pierre


Peter Schröder a écrit :
> What's the best way to remove a facet from a polyhedron_3? In my case I 
> actually have a simplicial 2-manifold with boundary (arbitrary genus) if 
> that makes a difference. I don't want to punch a hole. what I want is to 
> "coalesce" the three boundary vertices of a given triangle into a single 
> vertex (this will additionally remove [at least?] 3 other triangles; the 
> "flaps") and consolidate all the surrounding edges correctly.
>
> Basically I have need for a mesh cleanup operation in which I remove all 
> zero area triangles without changing the genus of the surface (and, yes, 
> the zero area triangle could be on the boundary, but the generic case is 
> for it to be someplace in the interior of the mesh).
>
> I looked at some of the operations for polyhedron_3, but none appears to 
> be a direct match. One possibility is to do two consecutive edge 
> contractions. Is that the preferred way to go about this, given the 
> primitives available?
>
> peter