CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

Hello,

Which version of CGAL are you using?

Using CGAL-3.7-beta1 the color stays into the facet.
I added the following assertion at the end of the code and it runs
without error.

CGAL_assertion( P.facets_begin()->color==CGAL::RED );

S.

johnzjq wrote:
> Dear All,
>
> I am using Polyhedron_incremental_builder_3 to build a HDS extended by face
> color.
>
> Everything goes well from begin_surface to end_surface (I had verified the
> color information of the facets during this process). However, when the step
> jumps out of the delegate() function, I found the face color in the
> polyhedron became invalid!
>
> How to solve it? Please help.
>
> John
>
> Attached code:
>
> #include <CGAL/Simple_cartesian.h>
> #include <CGAL/Polyhedron_incremental_builder_3.h>
> #include <CGAL/Polyhedron_3.h>
>
> template <class Refs>
> struct My_face : public CGAL::HalfedgeDS_face_base<Refs>{
>         CGAL::Color color;
>         My_face(){}
>         My_face(CGAL::Color c) : color(c){}
> };
> struct My_items : public CGAL::Polyhedron_items_3{
>         template<class Refs,class Traits>
>         struct Face_wrapper{
>                 typedef My_face<Refs> Face;
>         };
> }; 
>
> template <class HDS>
> class Build_triangle : public CGAL::Modifier_base<HDS> {
> public:
>         typedef typename HDS::Vertex::Point Point;
>         typedef typename HDS::Face_handle Face_handle;
>         Build_triangle() {}
>         void operator()( HDS& hds) {
>                 // Postcondition: ‘hds’ is a valid polyhedral surface.
>                 CGAL::Polyhedron_incremental_builder_3<HDS> B( hds, true);
>                 B.begin_surface( 3, 1, 6);
>                 B.add_vertex( Point( 0, 0, 0));
>                 B.add_vertex( Point( 1, 0, 0));
>                 B.add_vertex( Point( 0, 1, 0));
>                 Face_handle f = B.begin_facet();
>                 f->color = CGAL::RED;
>                 B.add_vertex_to_facet( 0);
>                 B.add_vertex_to_facet( 1);
>                 B.add_vertex_to_facet( 2);
>                 B.end_facet();
>                 B.end_surface();
>         }
> };
> typedef CGAL::Simple_cartesian<double> Kernel;
> typedef CGAL::Polyhedron_3<Kernel,My_items> Polyhedron;
> typedef Polyhedron::HalfedgeDS HalfedgeDS;
>
> int main()
> {
> Polyhedron P;
> Build_triangle<HalfedgeDS> triangle;
> P.delegate( triangle);
> //here the color is gone!
> CGAL_assertion( P.is_triangle( P.halfedges_begin()));
> return 0;
> }