[vtkusers] Define the Z dimension of a Frustum ?

[Francesco Ferro]

Hello,

I'm currently playing with vtkRendereAreaPicker class and in particualar 
with ::DefineFrustum.

I wanted to see the shape of my frustum so I used vtkFrusutmSource (I 
saw the piece of code on this mailling list, thx to the person who 
posted that..) to display the Frustum polydata...
It works perfectly. However there is something wierd... Depending the 
size of the frustum.. the Z dimension is not always the same !?

for example with a 60x60 (relatively big) frustum square the Z dimension 
of thegenerated frustum it's maybe 20
and with a smaller one (15x15) the Z dimension of thegenerated frustum 
it's maybe 60 ...

So I was wondering if there was a possibility to Crop or Cut or Define 
the Z dim of the generated frustum ?

(vtkAreaPicker (where the frustum is computed) but I can't find where 
the dim are set.. )

Thank's in advance,
F.F