CGAL users discussion list

[Andreas Fabri <>]

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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--
Andreas Fabri, PhD
Chief Officer, GeometryFactory
Editor, The CGAL Project

phone: +33.492.954.912    skype: andreas.fabri