[vtkusers] How to set colors of surface coresponding to surface normal direction?

[XViz]

Hello VTK community,

I've got a structured grid and I visualizate it using vtkGridSynchronizedTemplates3D and then with vtkPolyDataMapper. But I need to colorize it depending on surface normal direction: for example if normal points down - it is blue, if it points up - it is red, in middle case - it is green. Maybe I can do it with vtkExtractVectorComponents and its method GetVzComponent(), but I don't know how to clip this filter with my iso-surface and mapper. 
Maybe there is better way to do it?

Thank you!
  
  
XViz, D_E at ukr.net 
2007-11-07