CGAL users discussion list

[Andreas Fabri <>]

The infinite vertex is SYMBOLIC, that is you shouldn't take its point
and evaluate geometric predicates with it

andreas



panayiotis foteinos wrote:
> Thank you.
>
> There is something else I do not quite understand. Could you explain how I can 
> orient an infinite triangle? 
>
> Why the predicate orientation(infinite_vertex()->point(), Point(0,0), 
> Point(0,6)) gives -1 (CLOCKWISE), but the test 
> orientation(infinite_vertex()->point(), Point(1,0), Point(0,6)) gives 1 
> (COUNTERCLOCKWISE) ?
>
> Regards,
> Panagiotis Foteinos
>
> On Friday 03 April 2009 03:39:47 Olivier Devillers wrote:
> > panayiotis foteinos a écrit :
> > > -----> is this because the resulting mesh does not triangulate the convex
> > > hull
> > yes
> >
> > (see the source of is_valid in Triuangulation_2.h)
> >
> >
> > either you only use the is_valid of the tds  (do not check orientation
> > of triangles)
> > either you rewrite your own is_valid keeping the geometric check only
> > fot finite triangles.