CGAL users discussion list

[Paul Neugebauer <>]

I tried this:

typedef CGAL::Voronoi_diagram_2<SDG2,SDG2_AT2,SDG2_AP2>                VD;

typedef CGAL::Polygon_2<Alg_kernel>             Alg_polygon_2;
typedef Alg_polygon_2::Point_2                          Alg_point_2;
typedef Alg_polygon_2::Segment_2                    Alg_segment_2;

VD vd;
Alg_segment_2   seg(Alg_point_2(7,20), Alg_point_2(50,44));

Edge_iterator edit = vd.edges_begin();
for ( ; edit != vd.edges_end(); ++edit)
{
   bool intersect ;
   intersect = do_intersect(seg, *edit);
   ...
}

But get an error, because *edit is not a possible value for the 
intersect routine. The problem is similar to my other one here: 
https://lists-sop.inria.fr/wws/arc/cgal-discuss/2008-04/msg00239.html

I don't know how to extract the Segment from the voronoi edge iterator. 
This is a comprehension problem for me.
Maybe there is someone who can explaine me this.

Thank you.
Paul

Ashwin Nanjappa schrieb:
>  wrote:
> > @~ash
> > Thank you for the reply. Which is the right routine for computing the 
> > intersection? This one:
> >
> > CGAL::intersection ( Type1<Kernel> obj1, Type2<Kernel> obj2)
> >
> > is just for the types: Line_2, Segment_2,...
> >
> > Which routine can I use for the voronoi edges ?
>
> See:
> <http://www.cgal.org/Manual/3.3.1/doc_html/cgal_manual/Kernel_23_ref/Function_intersection.html> 
>
>
> You can intersect a Iso_rectangle_2 with a Segment_2. A Voronoi edge 
> is a Segment_2. You could form a Iso_rectangle_2 around your polygon 
> and intersect it with Segment_2 to get the intersection point. Then 
> check if this point lies on the polygon by using its bounded_side() 
> function.
>
> ~ash