Hollow Polygon Drawing Algorithm

[djennin at RELAY.NSWC.NAVY.MIL]

    In reference to Issue 11 in the IRIS Universe, in the article 
'The Hidden Charms of Z-Buffer', pp. 34 - 37, a person in my group 
is having difficulty implementing the hollow polygon algorithm.  
It appears that the entire sphere is always visible, instead of 
what is shown in Figures 5 and 6.  She is using RGB mode, with the 
z comparison reversed (as discussed on p. 32, i.e., 
'lsetdepth(0x7fffff, 0x000000)'), and Gouraud (default) shading.  
Has anyone successfully implemented this, and if so, what does your 
initialization look like (are we just forgetting to set some parameter)?
We have tried several ways to get this to work, but it always appears 
the same.  Thanks.


David Jennings
Naval Surface Warfare Center
djennin at relay.nswc.navy.mil