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[johnzjq <>]

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;
}
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