[Mesa3d-dev] Bug in SI-GLU: invalid call to glMapGrid2f()

[Diego S. C. <Die...@ep...>]

Hi,

First of all thanks for the great work you have put on Mesa!

I've been using the SI-GLU for some time with Mesa-3.4.1 and I have come
across what I think is a bug in the NURBS renderer of the SI GLU. In
some cases it generates invalid calls to glMapGrid2f(), with a value of
vn or un of zero. Since the SI GLU is being integrated in Mesa I think
this is relevant here. I have submitted this to the SI mailing list but
that appears to be almost abondoned. Since the SI GLU is being
integrated in Mesa this might be the place to report it. Hope this is
the correct mailing list.

Below is a copy of the message I sent to the SI mailing list at
ogl...@os..., with a test program as well as a very simple
patch that I think fixes the problem (as far as I could test, but my
knowledge of the GLU implementation is very limited).

Best regards,

	Diego

--

Hi there,

Sorry for sending this bug report to this mailing lits instead of
reporting it via bugzilla but I have been unable to get a password from
the bugzilla system (mail sent with password never arrived).

The bug is that the GLU nurbs renderer sometimes places invalid calls to
glMapGrid2f() with parameters 'un' and/or 'vn' of 0.

I have traced the bug to main/gfx/lib/glu/libnurbs/internals/slicer.cc
and I think I have fixed it in the patch which I attach.

The nurbs_revol.c program attached demonstrates the problem. Note that
it occurs only when using the GLU_NURBS_RENDERER, not with the
GLU_NURBS_TESSELLATOR (as it does not use GL evaluators).

If any help is needed you can contact me at my e-mail address (I'm not
member of this mailing list).

Best regards,

	Diego Santa Cruz

PS: I have tried the bug and it occurs on Irix machines (with the
shipped GLU) as well as Linux/i386 ones (with the SI-GLU compiled by
me).
-- 
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Diego Santa Cruz                         mailto:Die...@ep...
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