Re: Hidden3d Bug Fix

[Daniel J S. <dan...@ie...>]

I placed another hidden3d line bug fix on SourceForge, [1727198] Hidden lines: 
Degenerate polygons creating problems.  This is the source of the inside/outside 
line problem.  Current CVS tries to make something meaningful for a plane 
equation out of two points and consequently would get the frontfacing setting 
wrong and the orientation wrong messing up the cover test.  The patch is a real 
short one.

OK, summary:

1) The alternative line removal algorithm patch fixes the bits and pieces 
problem reported by Thomas.

2) The degenerate polygon patch fixes the red/green (inside/outside) problem 
also reported by Thomas.

3) There still remains an issue with touching polygons facing different 
directions (one front, one back) not being able to resolve which edge color 
should be shown.  This rarely occurs except in that figure 8 tube demo.  Not 
sure this can be fixed without adding a little more info about where the edge 
originates from.

4) There still remains an issue with the seam showing for a 360 degree object 
such as the glass or the globe.  I suspect the problem is that the different 
vertices are a source of problem even though these vertices come out to be 
exactly the same.  Could use V_EQUAL() to check for duplicate vertices, but eh 
save that for a rainy day.

Dan