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Re: [cgal-discuss] Alpha_shape with user info


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  • From: "Sebastien Loriot (GeometryFactory)" <>
  • To:
  • Subject: Re: [cgal-discuss] Alpha_shape with user info
  • Date: Fri, 09 Dec 2011 15:58:10 +0100

Note that the alpha shape has this constructor:

Alpha_shape_3<Dt> A ( Dt& dt, FT alpha = 0, Mode m = REGULARIZED);
Build an alpha shape of mode m from the triangulation dt. Be
careful that this operation destroy the triangulation.



You can first insert your points in the triangulation and then construct the alpha shape from the triangulation.

Note that the vertex type of the TDS should be:
CGAL::Alpha_shape_vertex_base_3<Traits,Vb> where Vb is the triangulation
with info vertex type.


See here how to insert points and info:
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Triangulation_3/Chapter_main.html#Subsection_38.5.3

Alpha_shape_3 reference page:
http://www.cgal.org/Manual/latest/doc_html/cgal_manual/Alpha_shapes_3_ref/Class_Alpha_shape_3.html

Sebastien.

Farhad Bazyari wrote:
Hello,

Sorry this might be a very newbie question.
I'm looking for a simple example that constructs an alpha_shape and assigns
user info (a pointer in this case) to each vertix.
Something similar to example 38.5.2

This arrangement doesn't compile:

typedef CGAL::Exact_predicates_inexact_constructions_kernel Gt;

typedef CGAL::Triangulation_vertex_base_with_info_3<CGAL::Color, Gt>
Vb;
typedef CGAL::Alpha_shape_cell_base_3<Gt> Fb;
typedef CGAL::Triangulation_data_structure_3<Vb,Fb> Tds;
typedef CGAL::Delaunay_triangulation_3<Gt,Tds> Triangulation_3;
typedef CGAL::Alpha_shape_3<Triangulation_3> Alpha_shape_3;

typedef Gt::Point_3 Point;
typedef Alpha_shape_3::Alpha_iterator Alpha_iterator;

Many thanks,
Farhad

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