Michael Jones (mtj++at++babar)
Wed, 19 Apr 1995 07:59:01 -0700
--- Forwarded mail from "Angus Henderson" <angus++at++death.reading.sgi.com>
From: "Angus Henderson" <angus++at++death.reading.sgi.com>
Date: Wed, 19 Apr 1995 09:06:48 +0100
To: "Michael Jones" <mtj>
> :
> : Very small changes in the z buffer range can be a big difference, it is
> :worth trying.
>
> I'll just add that changes to the near-clip distance are much more
> important than changes in the far clip distance.
>
I'l just add that if you are going to get anywhere with fog on a "deep" scene
you have to have active near/far planes and often active fog parameters as
well.
When you are close to the ground you need a "near" near-plane but you can't see
far (hopefully) so you can have a near far-plane as well. When you are up high
you can push the near plane out to give you lots of relsolution for distant fog
on the horizon.
If you want to get close to an object high up in the scene you have a
problem....
Then you need to draw the object with different nea far planes to the rest of
the world. If this object is an aircraft and it flies off into the haze you
have even more problems because it won't fog the same as the world. You can fix
that by playing tunes on fog values although if someone who knows about fog
microcode could suggest how performer could handle all this for us mortals that
would be nice.
...here's one I can't solve... I fire a missile from my ownship and it leaves a
contrail from the near plane to a (fogged) explosion tens of kilometers away.
I remember on old fashioned IRIS 3000's you could set the near-plane clipping
to 0.0 I'd like that so my contrails never ever clipped nearby as that makes
them look crap.
fog eh... clipping eh ?
ANGUs
---End of forwarded mail from "Angus Henderson" <angus++at++death.reading.sgi.com>
--Be seeing you, Phone:415.390.1455 Fax:415.965.2658 M/S:8U-590 Michael T. Jones Silicon Graphics, Advanced Graphics Division mtj++at++sgi.com 2011 N. Shoreline Blvd., Mtn. View, CA 94039-7311
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