[vtkusers] how to turn off lighting?

[Glen.Coates at csiro.au]

I'm writing an application which displays slices taken through a volume in 
3D.  I would like the slices to rendered with the same brightness 
irrespective of their relative orientation to the camera, unlike under the 
standard lighting model where brightness is inversely proportional to the 
angle between the slice and the view plane.

Is there some way of turning off lighting and having everything lit 
exactly the same all the time in 3D?

-- 
Cheers,
Glen