[vtkusers] transparency based on distance from viewport?

[Alex Chekholko]

Hi all,

I wrote a small program which displays a 3-D volume using a
vtkRenderer and allows me to adjust the opacity of the voxels based on
their intensity.

Now I have a piece of binary data that I would like to visualize in
the same way.

Is there a way to adjust the opacity of the voxels based on their
distance from the viewport?  Is there a better way that I'm not
thinking of?

Thanks,
Alex