Dave Akers (dla)
Tue, 29 Feb 2000 17:04:48 -0800
Just to clarify what Sean said this morning.. The dithering you're
experiencing actually doesn't have to do with alpha storage in the
framebuffer. Volumizer doesn't even need alpha in the framebuffer, because
it uses only the source alpha in blending calculations. Dithering occurs
because you're not getting high-enough bit-depth in R,G,B.
On the O2 your problem is related to the framebuffer configuration. Try
running the "xscreen" configuration program, and then selecting "32x32" as
your framebuffer format. This gives you 32-bit front AND back buffers..
which you need for double buffered 8-8-8-8 visuals to be supported. The
dithering problem should go away.. let me know if it doesn't.
Your Octane is most likely an SI with only one rasterization engine. In
this case if you're running in 1280x1024 mode the best double-buffered
visual you'll be able to get is 5-5-5 for R,G,B.. and hence dithering
results because your textures are higher quality.. So in this case, you
have two options.. a) switch to single-buffered mode, and you'll get
deeper visuals. b) as Sean suggested, decrease the screen resolution to
1024x768 using 'setmon' and you _should_ be able to get 8-8-8 and
double-buffered.
To confirm that this is what's going on, could you send me the results
of glxinfo and /usr/gfx/gfxinfo on your Octane? Thanks..
Dave
On Tue, 29 Feb 2000, Mark Davey wrote:
> Hi...
>
> Ok.. I would like to thank everyone for responding to my previous e-mail
> concerning the problems I have been having with our new octane. I did
> initially think that the problem was due to me remotely logging on to an
> Onyx and running the Volumizer demos from there. However, I have
> discovered that ALL graphics on the Octane are dithered, not just those
> generated when remotely logging on to a different machine. Surely the
> Octane can produce 24 bit colour? We also have the same problem with the
> O2 machines here but up until now I havent given it much attention.
>
> I know that this question now is no longer directly relevant to
> Volumizer but does anyone have any ideas. The problem is not a
> client-server one and so VizServer is not the answer.
>
> Regards
> Mark
>
> --
> From: Mark Davey
> Dept. of Medical Physics, UCL.
>
> TEL: +44 (0)171 915 1673.
> FAX: +44 (0)171 837 9279.
>
> Institute of Laryngology and Otology,
> 330 Gray's Inn Road,
> London.
> WC1X 8GE.
>
>
>
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