Z-Buffer, fog, and post processing

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Jude Anthony (jude++at++p3.enzian.com)
Thu, 19 Sep 1996 17:02:11 EST

I'm working on a simulation involving large databases and terrain.
For reference, our clipping planes are about 20 nautical miles apart
(some 37,000+ meters). Unfortunately, all the data doesn't fit
between the clipping planes, so when we move from one end of the
terrain to the other, mountains appear to extrude themselves from
an invisible play-doh press.

We would like to have the mountains appear gradually out of haze. We
tried to implement this using fog, but the linear fog near and far
ranges don't do what you would expect them to do (nor what the man
pages say they should do). I'm interested in examining the Z-buffer
after each draw frame and blending the color of far-off pixels with
the sky color, thus implementing a nice haze effect.

I tried the man pages, but I can't find any reference to Z-buffer,
let alone reading a Z-buffer. Nor is there anything intuitive for
changing the color of a single pixel. Anybody know where I can find
some example code for this kind of effect?

We're using an Onyx with IR2.

Thanks,
Jude Anthony
jude++at++p3.enzian.com
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