[vtkusers] (minor) problem to display UnstructuredGrid

[laurent.paul at club-internet.fr]

Hi users,

I've got a problem to display UnstructuredGrid.
Datas come from vtkClipVolume which output UnstructuredGrid. So I use vtkUnstructuredGridVolumeRayCastMapper from VTK CVS version.
Before doing this, I tried a basic, read and display an unstructuredGrid in a window.
It doesn't work (neither Tcl nor C++)!

If I use the pipe:
reader->mapper->renderer
I've got a warning at run-time: 
Warning: In C:\lib\VTK44\VTKCVS\VTK\VolumeRendering\vtkUnstructuredGridBunykRayCastFunction.cxx, line 657
vtkUnstructuredGridBunykRayCastFunction (03450048): Input contains more than tetrahedra - only tetrahedra are supported

So I use vtkDataSetTriangleFilter:
reader->TriangleFilter->mapper->renderer
I've got multiple errors at run-time:
ERROR: In C:\lib\VTK44\VTKCVS\VTK\VolumeRendering\vtkUnstructuredGridBunykRayCastFunction.cxx, line 634
vtkUnstructuredGridBunykRayCastFunction (03450048): Degenerate topology - cell face used more than twice
However, I can see datas!

That's not a big problem since I can display UnstructuredGrid with vtkUnstructuredGridVolumeZSweepMapper and vtkProjectedTetrahedraMapper (with vtkDataSetTriangleFilter).
I'd just want to understand why!

Thanks,

Laurent.