csmooth in geomview

[Dennis Roseman <roseman at dimension4.math.uiowa.edu>]

I use the new version of the 4dviewer using csmooth shading to look  
at some of my examples.  My question does not really involve the  
4dviewer.

For example, dump.75.4off as is found in /work1/roseman/May93.

This shading is based on the "w-coordinate".

I rotate the object in geomview--not changing the projection--just  
using the "r" mode of geomview.  I should not expect to see the color  
of a point change, am I correct?  (The color of a vertex is  
determined by the fourth coordinate.)

But it does.  One can see this most easily by turning the edges on so  
that one can more easily track a given point and also make sure it is  
not being occluded.  What seems to happen is that the color one sees  
at a given point depends on the obliquness of the angle of the  
surface with respect to the camera position.  (This is most notable  
for extreem angles)

Why is this?  Is this expected behavior?  (It is not expected from  
the algorithm, since the rotations do not change the "w-coordinate"  
of a point.)  


If this is not expected behavior of cshading, is the problem due to  
software or hardware?