CGAL users discussion list

[Andreas Fabri <>]

Hi Priyank,

You have to initialize the plane yourself. The Polyhedron only provides the 
storage.

andreas

Priyank Jain wrote:
> I am always getting a degenerate plane, when I try to find out the plane 
> from the given half-edge in Polyhedron data structure. Any guesses why ???
>
> for(Halfedge_iterator hedge_it = model.halfedges_begin() ; hedge_it !=
> model.halfedges_end(); hedge_it++)
> {
> // proceed for boundary edges
> if( hedge_it->is_border() == false) // boundary(hedge_it)
> continue;
>
> // find x_proj by:
> // "projecting_distance" perpendicular to "hedge_it" from the midpoint
> of hedge_it
> // in the plane of the model at hedge_it
> // Finding the midpoint: midPt
> Point_3& point1 = hedge_it->vertex()->point();
> Point_3& point2 = hedge_it->opposite()->vertex()->point();
> Point_3& midPt = midpoint(point1, point2);
>
> Plane& plane = hedge_it->opposite()->face()->plane(); //opposite
> half-edge since this gives the plane of the model at that edge
> Vector3& direction = plane.orthogonal_vector();
>
> //debugging purposes
> Point_3 pt = plane.point();
> bool waste = false;
> waste = plane.is_degenerate();
>
> //Vertex_3 x_proj = hedge_it.project(midpoint, projecting_distance);
> Point_3& x_proj = midPt + (direction * projecting_distance);
> }
>
> waste (degenerate plane) always becomes true, why ? I tried different 
> values
> of
> vertices, but still..
>
> Polyhedron model is made up of:
> Point_3 p( 1.0, 0.0, 0.0);
> Point_3 q( 0.0, 1.0, 0.0);
> Point_3 r( 0.0, 0.0, 0.0);
> model.make_triangle(p, q, r);
>
> Can someone please help me with this?
>
> Thanks