CGAL users discussion list

[Guillaume Damiand <>]

Le 06/06/2014 13:12, Pranav a écrit :
> On reading  User Manual <http://doc.cgal.org/latest/HalfedgeDS/index.html>  ,
> I find that each edge is decomposed into two half edges with opposite
> orientations.
> In combinatorial maps, only the edges which are shared between faces have 2
> darts associated with them and remaining edges have only one dart as shown
> in the  Figure 24.2
> <http://doc.cgal.org/latest/Combinatorial_map/index.html#fig__figexemplecombimaps>
> (left figure).
>
> I have been assuming a dart to be equivalent to a half edge, but then Half
> edge representation of this 2D object(Figure 24.2) will be different from
> that using Combinatorial maps?

In 2D, dart=hald_edge. For objects with boundary, there are different 
possibilities to manage the boundaries: mark darts belonging to boundary 
(as in HDS package) or do not represent these darts (as in CMap).

However in your previous email you speak about set of tetrahedra, thus 
you are in 3D, right ?
In this case, dart!=half_edge. Indeed in 3D an edge can be composed by 
any number of darts (twice the number of volumes incident to the edge).



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