CGAL users discussion list

[Asher Kamiraze <>]

Thank you Sebastien

I finally did that and it seems to work:

  Alpha_shape_2(Dt& dt, NT alpha = 0, Mode m = REGULARIZED)

      :_alpha(alpha), _mode(m), 

      use_vertex_cache(false), use_edge_cache(false)

  {

      Dt::swap(dt);

      if (dimension() == 2)

      {

          // Compute the associated _interval_face_map

          initialize_interval_face_map();

          // Compute the associated _interval_edge_map

          initialize_interval_edge_map();

          // Compute the associated _interval_vertex_map

          initialize_interval_vertex_map();

          // merge the two maps

          initialize_alpha_spectrum();

      }

  }

Thank you for your help.

Regards,

Asher

2011/5/19 Sebastien Loriot (GeometryFactory) <sloriot.ml@gmail.com>

Asher Kamiraze wrote:

OK. May this simple hack inspired from the 3D version will work?

That's what I did too.


S.

 Alpha_shape_2(Dt& dt, NT alpha = 0, Mode m = REGULARIZED)
   :_alpha(alpha), _mode(m),     use_vertex_cache(false), use_facet_cache(false)
   {
     Dt::swap(dt);
     if (dimension() == 2) initialize_alpha();
   }

Regards,

Asher

2011/5/19 Mariette Yvinec < <mailto:>>

   I see ...
   In 3D you may construct  the Alpha_shape from the Triangulation
   so that you can enter your vertices wih their info
   in the triangulation and then build the Alpha_shape from the
   triangulation.

   In 2D, such a constructor does not seem to exist.
   Obviously, we should add it.

   Regards,
   Mariette


   Le 19/05/11 15:52, Asher Kamiraze a écrit :

   Hi,

   2011/5/19 Mariette Yvinec <

   <mailto:>>

       push_back should be private too.


   Yes, that's what I thought.
   
       If you use push_back,
        the triangulation will be updated but not the alpha_shapes...

       I don't see any problem in what you propose.


   Since I can use neither push_back nor insert, how can I attach
   info to a vertex?
   If it is a triangulation, I add a point and get the returned
   vertex, then attach the info on it. With alpha shapes, I have to
   give as input a range of points, and do not know how to attach
   info of the resulting vertices.

   Regards,

   Asher



       Le 19/05/11 12:46, Asher Kamiraze a écrit :

           Hi all,

           Is there a way to build an alpha_shape_2 with info?
           Something similar to a triangulation with info.
           I have also noticed that insert() is private in
           alpha_shape_2, but, push_back is not. Isn't it a problem?

           Here is what I am trying to do:


              typedef
           CGAL::Exact_predicates_exact_constructions_kernel                                  K;

              struct vertex_info { Point point3d; };
              struct face_info {};

              typedef
           CGAL::Triangulation_vertex_base_with_info_2<vertex_info,K>
                        Vb_2;
              typedef
           CGAL::Constrained_triangulation_face_base_with_info_2<face_info,K>
                Fb_2;

              typedef CGAL::Alpha_shape_vertex_base_2<K, Vb_2> Vb;
              typedef CGAL::Alpha_shape_face_base_2<K, Fb_2>  Fb;

              typedef CGAL::Triangulation_data_structure_2<Vb,Fb>                                    TDS_2;
              typedef CGAL::Delaunay_triangulation_2<K  , TDS_2>                                         DT_2;

              typedef CGAL::Alpha_shape_2<DT_2> Alpha_shape_2;


                      Alpha_shape_2 alpha_shape(0.5);
                      // How to insert points in alpha_shape with
           attached info?

           Hope you could help

           Best regards

           Asher


       --         Mariette Yvinec
       Geometrica project team
       INRIA  Sophia-Antipolis




       --         You are currently subscribed to cgal-discuss.
       To unsubscribe or access the archives, go to
       https://lists-sop.inria.fr/wws/info/cgal-discuss

   --     Mariette Yvinec
   Geometrica project team
   INRIA  Sophia-Antipolis  

--
You are currently subscribed to cgal-discuss.
To unsubscribe or access the archives, go to
https://lists-sop.inria.fr/wws/info/cgal-discuss