CGAL users discussion list

[shusen liu <>]

Thanks very much for all the detailed answers!!!

I still have another question related to voronoi diagram in CGAL. Is
there a standard way to do 3D voronoi diagram in CGAL right now? In
the document there is no 3D voronoi diagram section but CGAL claim to
have 3D voronoi diagram support all the time.

Any suggestion for doing 3D voronoi diagram in CGAL?

Thanks very much for reading this!

Regards,
Shusen

On Thu, Apr 22, 2010 at 7:00 AM, Vu, Khuong 
<>
 wrote:
> Hi Shusen,
>
>
>
> Please see me answer below. Generally speaking, the dual of a Voronoi 
> diagram is the Delaunay, and vice versa. Please email me if you want the 
> specific code to convert.
> ________________________________________
> From: shusen liu 
> []
> Sent: Wednesday, April 21, 2010 3:17 PM
> To: 
> 
> Subject: [cgal-discuss] Question about method of dealing with the unbounded 
> half-edge in  Voronoi_diagram_2
>
> Hi everyone,
>
> I've been search on the solution for this problem for a while. Seems
> it has been asked several times on this mailing list. But I still
> didn't find a working solution.
>
> The problem we have is, when using the Voronoi_diagram_2 adapter to
> calculate voronoi diagram within a certain region(a quad for example),
> in order to get the correct face we need to clip the unbounded face
> with the boundary of this region.
>
> it has been discussed in several thread:
> One solution is in here :
> https://lists-sop.inria.fr/sympa/arc/cgal-discuss/2007-06/msg00229.html
> but it require you to use dual of Delaunay_triangulation_2 in stead of
> voronoi_diagram_2
>
> Since you can't(or I don't know how) convert unbounded half-edge into
> Ray_2, the reasonable solution would be calculate the direction by
> yourself using the sites position. But this also turn out to be
> difficult to do.
>
>
>
> -> please see 
> https://lists-sop.inria.fr/sympa/arc/cgal-discuss/2010-04/msg00127.html for 
> the solution.
>
>
> There are two possible way to access the two sites related to the
> edge. One is using left() and right() method for half-edge
> structure.But when I test this method, right and left didn't return
> the defining site along the edge (the vertex returned seems like the
> geometrical on the "left" or "right" of the edge, not the sites define
> the edge)
>
> -> please see the third example for the details. 
> http://www.cgal.org/Manual/3.2/doc_html/cgal_manual/Segment_Delaunay_graph_2/Chapter_main.html#Section_26.5
>
> I'm sure it works.
>
> The other one is call the half-edge's dual method, this is what
> confuse me alot. I have no idea what the returned "Delaunay_edge" is.
> There is no document tell you what the structure is.
>
> typedef Delaunay_graph::Edge    Delaunay_edge;  // I don't know where
> Delaunay_graph is come from....
>
> When you goto the its
> documets:http://www.cgal.org/Manual/last/doc_html/cgal_manual/Voronoi_diagram_2_ref/Concept_DelaunayGraph_2.html#Cross_link_anchor_1403
>
> It seems to have a structure like this, but the Face_handle to
> Triangulation_ds_face_base_2 and a int index CAN ONLY decide ONE
> vertex, HOW COULD I GET THE OTHER ONE?
>
> typedef std::pair<Face_handle,int>  Edge;
>
> I use /// 
> c_halfedge->dual().first->vertex(c_halfedge->dual().second)->point()
>  to get the point
>
> Could anyone give me some hint on how to get the points data from the
> Delaunay_graph::Edge ?
>
> -> there is no way to compute the vertex coordinate from the Delaunay 
> graph. You have to either convert the Delaunay into Voronoi then retrive 
> the data. This works perfectly for Voronoi/Delaunay graph of points. 
> However, there is a bug in diagram of segments. Please email me if you need 
> anything else.
>
>
>
> Best Regards,
> Shusen
>
> PhD student at University of Utah
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://lists-sop.inria.fr/wws/info/cgal-discuss
>