[vtkusers] Clip volume data

[Weiguang Guan]

Hello,

I have a volume data of vtkImageData type, and would like to do volume 
rendering of a portion of it, specified by a vtkBoxWidget. The box 
widget is rotation enabled so that the region of interest may not align 
with x-y-z axes. I hesitate to use vtkClipVolume because it would change 
the data to unstructured gird data and the fast texture-mapping based 
volume rendering couldn't be used. Can someone suggest a better solution 
for what I want to do? Thanks.

Best,
Weiguang