CGAL users discussion list

[Manuel Caroli <>]

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