CGAL users discussion list

[panayiotis foteinos <>]

Ok.

What I am trying to do (and surprisingly seems difficult) is to remove the 
triangles outside the PSLG given the CDT of the PSLG's convex hull, and THEN 
create the appropriate infinite triangles (deleting the old ones) and link 
them together correctly. "Appropriate" infinite triangles are these that are 
indicent to the PSLG's boundary segments.

Is this feasible?

Thanks,
Panagiotis Foteinos

On Friday 03 April 2009 16:30:23 Andreas Fabri wrote:
> 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.