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[Pádraig Ó Conbhuí <>]

Oh right, it works with std::map because it is "less than" comparable (ie the < operator works).

On Wed, May 18, 2016 at 11:44 AM, Andreas Fabri <> wrote:

It is in fact hashable, but the container then is not a std::map
but a boost::unordered_map

andreas

On 18/05/2016 12:39, Pádraig Ó Conbhuí wrote:

Hi Pratyush,

You can also use a std::map to store extra data, since Vertex_handle is
hashable. So something like

std::map<Polyhedron::Vertex_handle, double> my_values;
my_values[vertex_handle_i] = double_value;

could be the easiest solution, without having to play about with
changing the template parameters.

Cheers,
Paddy

On Wed, May 18, 2016 at 9:54 AM, Pratyush Pranav <

<mailto:>> wrote:

    Hi Sebastian,

    Thanks for pointing out the relevant material.

    Now, I try to write a basic code (a modification of one of the
    examples to have colour on the faces of the tetrahedron from the
    CGAL documentation), to be able to have some of my own items on the
    vertices, and also have access to point() on the vertex (this is
    what is giving me problems). Could you please help me with where I
    am going wrong? Below is the code.

    pratyush

    ————————————————————

    #include <CGAL/Simple_cartesian.h>
    #include <CGAL/Polyhedron_3.h>
    // A face type with a color member variable.

    typedef CGAL::Simple_cartesian<double>        Kernel;


    template <class Refs, class Traits>
    struct My_vertex : public CGAL::HalfedgeDS_vertex_base<Refs> {
             typedef typename Traits::Point_3 Point;
         double value;
             long index;
    };
    // An items type using my face.
    struct My_items : public CGAL::Polyhedron_items_3 {
         template <class Refs, class Traits>
         struct Vertex_wrapper {
             typedef My_vertex<Refs,Traits> Vertex;
         };
    };


    typedef Kernel::Point_3 Point_3;
    typedef CGAL::Polyhedron_3<Kernel,My_items>  Polyhedron;
    typedef Polyhedron::Halfedge_handle           Halfedge_handle;
    typedef Polyhedron::Vertex_handle           Vertex_handle;
    int main() {
         Point_3 p( 0.0, 0.0, 0.0);
         Point_3 q( 1.0, 0.0, 0.0);
         Point_3 r( 0.0, 1.0, 0.0);
         Point_3 s( 0.0, 0.0, 1.0);
         Polyhedron P;
         P.make_tetrahedron(p,q,r,s);
             Vertex_handle v = P.vertices_begin();
             //v->value = 3.14;
             v->index = 1;
             std::cerr<<v->point()<<" "<<v->index<<std::endl;
         return 0;
    }





     > On 17 May 2016, at 10:03, Sebastien Loriot (GeometryFactory)

    < <mailto:>> wrote:
     >
     > It is possible using a custom items traits (second template
    parameter).
     > The concept is documented here:
     > http://doc.cgal.org/latest/Polyhedron/classPolyhedronItems__3.html
     >
     > For an example see how ids are added to simplices in
    CGAL/Polyhedron_items_with_id_3.h
     >
     > Note that using the class Surface_mesh would allow you to do
    property assignment at run-time.
     >
     > http://doc.cgal.org/latest/Surface_mesh/
     >
     >
     > Best,
     >
     > Sebastien.
     >
     > On 05/15/2016 02:43 PM, Pratyush Pranav wrote:
     >> Hi,
     >>
     >> I would like to know if it is possible to derive a polyhedron_3
    in such a way that i can store a couple of extra information on the
    vertices (specifically each vertex should have two additional
    variables associated with it, one of a double type, and another one
    of long or int type).
     >>
     >> any leads would be great! thanks in advance!
     >>
     >> pratyush
     >>
     >
     >
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     >


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--
Andreas Fabri, PhD
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Editor, The CGAL Project

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