CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

The only way to do it for now I think is to use the Delaunay
triangulation.
Note that it will take more time to compute than the other function.
(I'll add a todo for adding this in a future release)

Build the triangulation following this example:
http://doc.cgal.org/latest/Triangulation_3/index.html#Triangulation_3UsingtheBoostTransformIterator

Then something like this should work (not tested):

struct Chull_indices
{
  void operator()(Delaunay::Vertex_handle vh) const
  {
      m_indices.push_back(vh->info());
  }

  std::vector<std::size_t> m_indices;
};

Chull_indices chull_indices;

T.adjacent_vertices(T.infinite_vertex(),
                    boost::make_function_output_iterator(chull_indices)
);

for( std::size_t i : chull_indices.m_indices)
  std::cout << i << std::endl;

Sebastien.

On 10/24/2013 04:12 PM, Nuno Pessanha Santos wrote:
> Hi,
>
> Thanks Sebastien for your  answer.
>
> I only need the index of the points, example:
>
> Original Point Cloud:
> point 1
> point 2
> point 3
> point 4
>
> Convex Hull:
> point 3
> point 4
>
> I want to read the 3 and 4, to make them correspond in my further
> processing.
>
> Thanks.
>
> Nuno Pessanha Santos
>
>
>
>
>  > Date: Thu, 24 Oct 2013 07:11:37 +0200
>  > From: 
>
>  > To: 
>
>  > Subject: Re: [cgal-discuss] Convex_hull_3 - CGAL
>  >
>  > On 10/24/2013 05:31 AM, Nuno Pessanha Santos wrote:
>  > > Hi,
>  > >
>  > > I am starting to use CGAL, and maybe this is a stupid question but I
>  > > need some help.
>  > >
>  > > When you use the function "CGAL::convex_hull_3(points.begin(),
>  > > points.end(), Polyhedron_3 poly);" you obtain the polyhedron poly.
>  > >
>  > > How can I read the obtained vertices or the points index that are
>  > > contained in the convex hull? I see so many examples but none of them
>  > > could help me in my task.
>  >
>  > Is the following what you are looking for?
>  >
>  > Polyhedron_3 poly;
>  > CGAL::convex_hull_3(points.begin(), points.end(), poly);
>  > std::vector<Point_3> chull_points(poly.points_begin(),
> poly.points_end());
>  >
>  >
>  > Sebastien
>  >
>  > >
>  > > Thanks
>  > >
>  > > Nuno Pessanha Santos
>  > >
>  > >
>  >
>  >
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