[vtkusers] Bug in vtkPolygon ??

[Brad King]

de Boer Ingo wrote:
> Hi,
> 
> I am using VTK 4.4.0 release. This also happend in the versions before.
> 
> vtkPolygon.cxx: "$Revision: 1.104 $"
> 
> void vtkPolygon::ComputeNormal(vtkPoints *p, int numPts, vtkIdType *pts, double *n)
> 
> In this function, sometimes I have int numPts == 1 !! That is 
> why pts[1] equals -842150451 and I cannot get the correct point
> in line 92:
> 
> p->GetPoint(pts[1],v2);
> 
> And my application crashes. I tried something like:
> if ( numPts > 1 ) p->GetPoint(pts[1],v2);
> This works and my geometry looks good.
> But the loop afterwards
> for (i=0; i < numPts; i++) 
> {
> ...
> }
> uses v2 !!
> 
> Any ideas how I can avoid this ? Is this a bug ?
> There is nothing special in the geometry that I have!

The normal to a polygon in 3-D with less than 3 points is undefined. 
However, the method should be able to handle this and at least not 
crash.  Please submit this as a bug report at http://www.vtk.org/Bug.

Thanks,
-Brad