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[Nico Kruithof <>]

Hi Gilles,

The surface should be orientable. The first triangle and the quadrilangle have inconsistent orientation (both have the edge from 0 to 1). The following order for the facets will probably work (not tested):

0 1 2

5 4 3

1 0 3 4

2 1 4 5

0 2 5 3

If you apply the right hand rule, all normals will point outward.

Bests,

Nico

On Sat, Nov 21, 2009 at 9:24 AM, Gilles <> wrote:

Hello CGALer,

(Sorry) I'm still a newbee in CGAL and I have this following problem :

Trying to build a simple prism (with a triangle base) and I get this error when
I try to build a facet sharing points with another one :

lookup_halfedge(): input error: facet 2 shares a halfedge from vertex 0 to
vertex 1 with facet 0.

My code is :

...

B.begin_surface(6,3,0);
               //upper vertices
               B.add_vertex( Point_3(-1,0,0));
               B.add_vertex( Point_3(1,0,0));
               B.add_vertex( Point_3(0,1,0));

               //lower vertices
               B.add_vertex( Point_3(-1,0,-1));
               B.add_vertex( Point_3(1,0,-1));
               B.add_vertex( Point_3(0,1,-1));

               //upper-facet
               B.begin_facet();
                   B.add_vertex_to_facet(0);
                   B.add_vertex_to_facet(1);
                   B.add_vertex_to_facet(2);
               B.end_facet();

               //bottom-facet
               B.begin_facet();
                   B.add_vertex_to_facet(3);
                   B.add_vertex_to_facet(4);
                   B.add_vertex_to_facet(5);
               B.end_facet();

               // side-facet 1 of 3  (doing this make problem)
               B.begin_facet();
                   B.add_vertex_to_facet(0);
                   B.add_vertex_to_facet(1);
                   B.add_vertex_to_facet(4);
                   B.add_vertex_to_facet(3);
               B.end_facet();
B.end_surface();
...

What's wrong ?


Gilles

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