CGAL users discussion list

[Olivier Devillers <>]

Dennis Endt a écrit :
> Hi Andreas,
>
> I read the manual for another time and it became clear how I can get a
> triangle of a facet. I think I understand how you define the geometry
> and how I can work with them.
>
> But I miss the edges of a triangle. Can I only read out the points?
>   

It must be clear that you do not "read the triangle" from the triangulation.
The triangle you get is constructed on the fly when you ask for it.

From the manual I get  (but you said that you looked at it ;-)


Triangle     t.triangle ( Face_handle f)     Returns the triangle formed 
by the three vertices of f.
Precondition:     The face is finite.
Segment     t.segment ( Face_handle f, int i)     Returns the line 
segment formed by the vertices ccw(i) and cw(i) of face f.
Precondition:     0 i 2. The vertices ccw(i) and cw(i) of f are finite.
Segment     t.segment ( Edge e)     Returns the line segment 
corresponding to edge e.
Precondition:     e is a finite edge
Segment     t.segment ( Edge_circulator ec)     Returns the line segment 
corresponding to edge *ec.
Precondition:     *ec is a finite edge.
Segment     t.segment ( Edge_iterator ei)     Returns the line segment 
corresponding to edge *ei.
Precondition:     *ei is a finite edge.
Point     t.circumcenter ( Face_handle f)     Compute the circumcenter 
of the face pointed to by f. This function is available only if the 
corresponding function is provided in the geometric traits.


thus you can get Segment corresponding to an edge (but this segment is 
constructed when you ask for it)
The only geometry stored in the trainagulation is a point for each 
finite vertex