[Dri-devel] Voodoo3 gamma tables

[Jamie G. <gu...@bl...>]

System: ABIT BP-6 dual Celeron/466
GPU: 3dfx Voodoo3 3000, PCI, 16MB
OS: Stock Red Hat 7.1 (XFree 4.1)

Most everything works great out of the box.  Quake3 runs smooth
(30-40fps is plenty for me), and gears churns out about 500 fps.

But good old Quake2 is just too dark.

So, I tried the SSTH3_xGAMMA (x=R,G,B) environment variable Glide hack.
I found the code that does the gamma table loading in

/usr/src/redhat/BUILD/XFree86-4.1.0/Glide3/h3/minihwc/linhwc.c.dri

(from the XFree86 SRPM)

The function is hwcGammaTable(), which ends up living in
  /usr/lib/glide3/libglide3-v3.so
It looks like it has mmapped access to the 3dfx regsiter
space and sets the gamma tables via address/offset poking.

I know it *works*, because I can see the whole screen go darker or
lighter depending on the SST* env. settings, but only for a
split-second, then it reverts to whatever it was before.

I tried debugging a copy of gears, and I found that the gamma
tables get reset in this code path in libglut,

  glutMainLoop()
  interruptibleXNextEvent()
  XFlush(__glutDisplay)

The reset happens right at the XFlush(), so its as if the X Server
is setting the gamma tables back to default values.  All the SST*
processing of course happens in the client app.

So what I'm looking to do is track down where in the X server
this might be happening, and I'm not sure where to look.

Any pointers?

Thanks,
-Jamie

p.s.
I realize SSTH3_* is a hack, and Quake2 is probably slightly
broken since it can't properly set brightness, but this 
is a fun little hack project to see if I can get it working.