Re: [Mesa3d-dev] GL_EXT_vertex_weighting (was EXT_texture_env discussion)

[Olivier M. <Oli...@cy...>]

Hello,

I found two serious bugs in the GLU tesselator. I reported these bugs on
the sourceforge bug tracking system. They are easy to reproduce on linux
using gtklookat-0.8.2 (which uses libvrml97-0.8.2) and loading the two
VRML files I mention in the bug report.

I tested these two VRML files on my G3 with MacLookAt which relies on
the same libvrml97 library but uses Apple OpenGL and they both worked
nicely.

Both gtklookat and libvrml97 (as well as MacLookAt) are available from
http://www.openvrml.org/projects/ with complete source code.

One bug is very annoying since it makes GLU crash (SEGFAULT probably due
to a memory leak while attempting to free memory). The other bug causes
reversing the order of vertices in some non convex faces when the normal
is negative, which makes that the wrong side of the face is rendered
(typically the top face of a non-convex VRML Extrusion is drawn properly
while the bottom face is drawn on the wrong side).

I tryed to get into the GLU code to understand the problem, but it seems
not so easy for me. I think you Gareth are the author of that code and
you may help me fixing that problem if you can reproduce the bug (any
hint greatly appreciated).

Best,

-Olivier