CGAL users discussion list

[Sebastien Loriot <>]

If you just need the direction, it is given by the intersection of
the line or the ray with the bounding box (at least if the bounding box 
contains all voronoi vertices in its interior), which is a segment.

Le mer 27 juin 2007 15:51, Kuan a écrit :
> Hi Sebastien,
> thank you very much, it seems good!
> And i have one more question, if i use CGAL::Vronoi diagram 2, how can i get
> these CGAL::Ray_2?
> Because in that class, i can only get Halfedge, which only has a marker to
> define whether it's infinite. Because i also want to do someting with these
> directions.
> greeting
> Kuan
> 
> 2007/6/27, Sebastien Loriot 
> <>:
> >
> > Le mer 27 juin 2007 14:43, Kuan a écrit:
> > > Hi all,
> > > I have a question about the Voronor diagram.
> > > I created a Voronor diagram in 2D from input points. And it will of
> > course
> > > have some infinite edges. But now i want to restrict the diagram in a
> > quad
> > > area. So how can i get the direction of the infinite edges, so i can
> > > calculate the intersect point of the edge and the quad area boundary.
> > >
> > > greeting
> > > Kuan
> > Hi,
> >
> > You can do something like this.
> >
> > typedef CGAL::Ray_2<KernelCD>
> > Ray;
> > typedef
> > CGAL::Line_2<KernelCD>                                            Line;
> > typedef CGAL::Segment_2<KernelCD>
> > Segment;
> > typedef
> > std::list<Ray>                                                    RayList;
> > typedef std::list<Line>
> > LineList;
> > typedef
> > std::list<Segment>                                                
> > SegmentList;
> > typedef CGAL::Iso_rectangle_2<KernelCD>
> > Rectangle;
> >
> > struct Voronoi_recup {  //class using stream to get the voronoi diagram
> >   RayList quR;
> >   LineList quL;
> >   SegmentList quS;
> >
> >   Voronoi_recup() {}
> >
> >   void operator<<(const Ray p){quR.insert(quR.begin(),p);}
> >   void operator<<(const Line p){quL.insert(quL.begin(),p);}
> >   void operator<<(const Segment p){quS.insert(quS.begin(),p);}
> >
> > };
> >
> > //Convert objects into drawable segments
> > template<class iterator,class lst>
> > void cast_into_seg(const iterator first,const iterator end,const
> > Rectangle& bbox,lst& Seglist){
> >   for (iterator it=first;it!=end;++it){
> >     CGAL::Object obj_cgal = CGAL::intersection(*it,bbox);
> >     Segment s;
> >     if (CGAL::assign(s, obj_cgal))
> >       Seglist.push_back(s);
> >   }
> > }
> >
> >
> > int main(){
> >
> > CGAL::Delaunay_triangulation_2<KernelCD> de;
> > Voronoi_recup v_recup = Voronoi_recup();
> >
> >
> > //add your points here
> >
> >
> > dt.draw_dual(v_recup);
> >
> > cast_into_seg(v_recup.quR.begin(),v_recup.quR.end(),bbox_cgal,SL);//cast
> > rays into segments in bbox
> > cast_into_seg(v_recup.quL.begin(),v_recup.quL.end(),bbox_cgal,SL);//cast
> > lines into segments in bbox
> > cast_into_seg(v_recup.quS.begin(),v_recup.quS.end(),bbox_cgal,SL);//cast
> > lines into segments in bbox
> >
> > }
> >
> >
> > --
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> > 2004 route des Lucioles, BP 93
> > 06902 Sophia-Antipolis FRANCE
> > Phone: 33 (0)4 92 38 79 73
> > ,
> >  http://www-sop.inria.fr/geometrica
> >
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-- 
INRIA Sophia-Antipolis - Geometrica 
2004 route des Lucioles, BP 93
06902 Sophia-Antipolis FRANCE
Phone: 33 (0)4 92 38 79 73 
,
 http://www-sop.inria.fr/geometrica