CGAL users discussion list

["Juan Pablo Carbajal" <>]

Andreas,
Yes, I have read the documentation.
The problem is - sorry for my newbiness - that I thought that with
those iterators I could do as follow

typedef CGAL::Alpha_shape_2<Delaunay> Alpha_shape;

Alpha_shape::Alpha_shape_vertices_iterator  it = 
A.alpha_shape_vertices_begin();

x = (*it).point().x();
y = (*it).point().y();

where A is an Alpha_shape_2 created from a list of Point_2.

This doesn't compile. The error says that it has no member "point".

I was trying to read more on Vertex_handle but I cannot find
documentation and the header file is a little too much for my C++
level.

Thanks again,

JPi


On Sun, Oct 5, 2008 at 2:07 PM, Andreas Fabri
<>
 wrote:
> Juan Pablo Carbajal wrote:
>>
>> Dear all,
>> I am new to CGAL and I am trying to obtain the 2D alpha shape of a set
>> of points (in the plane, of course).
>> Everything is working ok but I just cannot figure out how to get the
>> list of vertices of the boundary of the alpha shape.
>> I have checked the discussions about alpha shapes boundaries in the
>> archive of the list but I could not find the solution there.
>> Is there something like
>> Alpha_shape_3::get_alpha_shape_vertices
>>  for Alpha_shape_2?
>>
>> Thanks
>>
>> JPi
>
> Hi Juan Pablo,
>
> There is no iterator that allows you to follow the border, if that
> is what you are looking for.
>
> However, the alpha shape class provides iterators for enumerating
> the vertices and edges
>
> http://www.cgal.org/Manual/3.3/doc_html/cgal_manual/Alpha_shapes_2_ref/Class_Alpha_shape_2.html#Cross_link_anchor_995
>
> best regards,
>
> andreas
> --
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-- 
JuanPi
"You can know the name of a bird in all the languages of the world,
but when you're finished, you'll know absolutely nothing whatever
about the bird... So let's look at the bird and see what it's doing --
that's what counts. I learned very early the difference between
knowing the name of something and knowing something."
Richard Feynman - What Do You Care What Other People Think