CGAL users discussion list

[Manuel Caroli <>]

Dear Angelo,

first of all: it would have been nice to mention that the discussion 
you're referring to dates back to October 2007 ;-)


 wrote:
> I'm dealing with the same problem but I didn't get the methond Andreas has 
> proposed.
> What's the thing about checking in a set<Vertex_handle>?
For each cell incident to your vertex v, you visit all three incident 
edges. Thus you would output each edge several times (once from each 
incident cell), which you probably don't want to do...

> So far I've managed to retrieve the incident cells but I'm wondering how I 
> can visit the edges.
> the vertex v is fixed but how can I determine the other vertices?
> I understood that I can get the edges providing the indices of the 
vertices (0,1,2,3)

Assume we consider cell c.
You get the index of v by v_ind = c->index(v).
So the three edges you get from c are the triples
        (c, v_ind, ((v_ind+i)%4) )
with i\in {1,2,3}

> how can I get these indices from a vertex handle?
In general: use the Cell_handle::index(int) method as shown above.
>
The idea of the std::set<Vertex_handle> is to store the respective 
vertex c->vertex((v_ind+i)%4) in the set and before returning an edge, 
check whether the second vertex of that edge is contained in the set 
(which means you have this edge already)

> Thanks for your help
Please ask again if I wasn't clear enough...

Best

Manuel