[vtkusers] recent vtkClipDataSet can give non-tets?

[Mathieu Malaterre]

Adrian Umpleby wrote:
> Hi all,
> 
> I've been using vtkClipDataSet with version 4.2 of vtk to cut off a 
> hexahedral mesh at a scalar value of zero. This gives all tets (though 
> some of them are very thin slivers on the cut surface, which I have to 
> deal with before continuing), just as the (latest) documentation says:
> 
> "vtkClipDataSet will triangulate all types of 3D cells (i.e., create 
> tetrahedra). This is true even if the cell is not actually cut. This is 
> necessary to preserve compatibility across face neighbors..."
> 
> 
> However, I've recently been using it on some upgraded Linux boxes which 
> have version 4.4 of vtk, and now I find a whole load of wedges coming 
> out of vtkClipDataSet!
> 
> Is this the way vtkClipDataSet is supposed to behave now? Is there a way 
> to choose to switch it back to tets? (Couldn't see anything in member 
> list.)

That's correct. Try to clip a tetra, you'll realize that there are a 
bunch of possibilties for the clip to return a wedge. So yes wedge is 
the general output of clip ( vtkClipDataSet even return wedges with two 
edges collapsed (=tetra), but vtkGeometryFilter handles those 'fake' 
tetras).

What is your problem ?

HTH
Mathieu