[vtkusers] Keeping normals with vtkClipPolyData

[Mathieu Coursolle]

Hi VTK users,

I am using vtkClipPolyData to clip a vtkPolyData with a box, so that  
the part of the polydata which
is outside of the box is not visible.

My polydata has some specific normals, which I want to keep for the  
clipped result.

However, the resulting polydata does not seem to have any normals. Is  
there a way to keep the normals
for the part of the polydata that is kept?

Thanks!

Mathieu