CGAL users discussion list

[Song Lin <>]

Now I have another problem:

For each point in "vector<Weighted_point> vwp" I used to build the
Alpha_shape_3, I tried to find the exact Vertex_handle in Alpha_shape_3
using "nearest_power_vertex()" but sometimes it doesn't find the vertex
I want. For example, sometimes nearest_power_vertex(point) returns a
vertex that point.x() not equal to vertex->point().x(). But I know there
should be one vertex that vertex->point().x() is exactly the same with
point.x().

I searched all of the points in "vector<Weighted_point> vwp" using
"nearest_power_vertex()". Some of the vertices were found several times
and some were never found. I have other information for the points and
what I want is each of the vertex was found once so I can put the
information into each vertex->info().


Can anyone help me about this problem?

Best regards,
Lin



在 2010-05-08六的 21:18 +0800，Song Lin写道： 
> I tried "nearest_power_vertex()" and it works. Thanks!
> 
> Lin
> 
> 
> 在 2010-05-08六的 13:17 +0200，Manuel Caroli写道：
> > Dear Song Lin,
> > 
> > you are computing the alpha shapes of a *regular* triangulation. Regular 
> > triangulations work with weighted points. The nearest vertex query is 
> > thus called nearest_power_vertex().
> > 
> > I see two possibilities: Either you use Delaunay triangulations instead 
> > of regular triangulations or you call nearest_power_vertex instead of 
> > nearest_vertex.
> > 
> > hope this helps
> > 
> > Manuel
> > 
> > On 08/05/10 09:30, Song Lin wrote:
> > > Hi,
> > >
> > > I was trying to use the function "dt.nearest_vertex(Point p)". And the
> > > class "Delaunay_triangulation_3" was needed.
> > >
> > > But I don't know how to integrate the class into my codes. The typedef
> > > part of my codes are:
> > >
> > > typedef CGAL::Exact_predicates_inexact_constructions_kernel Kk;
> > > typedef CGAL::Regular_triangulation_euclidean_traits_3<Kk>  Gt;
> > > typedef CGAL::Alpha_shape_vertex_base_3<Gt>  Vb_as;
> > > typedef CGAL::Triangulation_vertex_base_with_info_3<vertexinfo, Kk,
> > > Vb_as>  Vb;
> > > typedef CGAL::Alpha_shape_cell_base_3<Gt>  Cb_as;
> > > typedef CGAL::Triangulation_cell_base_with_info_3<cellinfo, Kk, Cb_as>
> > > Cb;
> > > typedef CGAL::Triangulation_data_structure_3<Vb,Cb>  Tds;
> > > typedef CGAL::Regular_triangulation_3<Gt,Tds>  Triangulation_3;
> > > typedef CGAL::Alpha_shape_3<Triangulation_3>  Alpha_shape_3;
> > >
> > >
> > > What should I do to use the function Alpha_shape_3.nearest_vertex() in
> > > my codes? Maybe it's naive but I was confused with the relationships
> > > between "traits","data_structures",and "kernels"..
> > >
> > > Best regards,
> > > Lin
> > >
> > 
> > 
> -- 
> Center of Computational and Systems Biology, 
> Institute of Biophysics, CAS.
> 15 Datun Road, Chaoyang District
> Beijing, 100101
> P.R.China
> 
> 
> 
-- 
Center of Computational and Systems Biology, 
Institute of Biophysics, CAS.
15 Datun Road, Chaoyang District
Beijing, 100101
P.R.China