[vtkusers] Volume Opacity

[dsjen at cs.unc.edu]

Hello VTK Users,

I'm having trouble changing the opacity of a vtkVolume.  I'm creating 
a vtkPiecewiseFunction and adding the following points to the function 
with the following lines of code, where opacity is a the piecewise 
function:

	opacity.AddPoint(0, 0.0);
	opacity.AddPoint(255,0.0);

This should make the volume completely transparent after I set the 
opacity of the volume:

	...
	...
	property.SetScalarOpacity(opacity);
	...
	...
	actor.SetProperty(property);
	...
	...

If anyone has any suggestions, needs clarification, or can point me to 
any references, I'd be very grateful.  Also, just for reference, I'm 
using vtk4.0 on WindowsXP.

Thanks,
Dennis