[vtkusers] clipping question

[Langer, Stephen A. (Fed)]

Hi --

When using vtkTableBasedClipDataSet to apply two more more clipping planes to a grid, I'm seeing incorrect results along the line where the planes meet.  I've attached a simple program that demonstrates the problem and a screenshot of the output.   The program generates a vtkRectilinearGrid and pipes it through vtkTableBasedClipDataSet with its clip function set to two perpendicular planes.  The result should have a concave right angle, but diagonal facets appear instead.
 
I've tried using vtkClipDataSet instead, but it just gives different wrong answers, although it does work correctly when the clipping planes lie exactly along a row of nodes in the grid.  vtkTableBasedClipDataSet draws diagonal facets across cells in that case.

What am I doing wrong?  

Thanks.

  -- Steve 

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