#642368 libgl1-mesa-dri: Issues with OpenGL point size

Package:
libgl1-mesa-dri
Source:
mesa
Description:
free implementation of the OpenGL API -- DRI modules
Submitter:
Sylvain Beucler
Date:
2011-12-04 15:45:11 UTC
Severity:
normal
#642368#5
Date:
2011-09-21 23:05:18 UTC
From:
To:
Hi,

When testing Guus' excellent tutorial:
http://en.wikibooks.org/wiki/OpenGL_Programming/Scientific_OpenGL_Tutorial_01
we spotted a few issues in the software and radeon renderers linked to
the point size feature in OpenGL.

Attached is a sample program.  You can press F1/F2/F3 to switch
between lines/dots/point-sprites rendering, what interests us here are
dots and point-sprites.

- Under Radeon, all modes get color artifacts (memory-corruption-like
  colors are displayed instead of a shade of blue).

- Dots are not working with LIBGL_ALWAYS_SOFTWARE=1: variable dots
  size instead of fixed size (it seems to use gl_Position.x as point
  size).  Point sprites seem to have a similar issue.

- Dots are showned properly on an IntelGPU+Ubuntu environment, and
  under windows with radeon 9600, making me suggest the problem lies
  in the OpenGL implementation rather than in the code.

Dots and point-sprites are not common in games, but more in scientific
applications.

Cheers!
#642368#10
Date:
2011-12-04 15:32:35 UTC
From:
To:
You should probably take this up on the mesa-dev@lists.freedesktop.org
list, where the radeon developers will have a better chance of figuring
this out.

Cheers,
Julien