CGAL users discussion list

[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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