Rob Jenkins (robj++at++quid.engr.sgi.com)
Thu, 30 Apr 1998 08:43:37 -0700
Patches would be the first thing I'd check. There were some regressions for EXP
and EXP2 fog on RE2 in the RE rollup patch 1702. Since then they were fixed in
patch 2038 which in turn has since been replaced by patch 2739. In short, make
sure you have the latest RE2 rollup patch installed:
Patch 2739: RealityEngine rollup #4 for IRIX 6.2
In practice I don't think 2739 has new fog fixes over 2038 so if you already
have 2038 at least then 2739 might not make any difference but you still ought
to have it for the other fixes in there.
You have a pretty big near:far clipping plane ratio, does the fog on RE2 get
better if you reduce that ? RE2 approximates the fog function in the screen
space rather than eye space so that ratio effects the fog resolutiuon spread
you get. If none of this helps then let me know, there's some other stuff we
can look into.
Cheers
Rob
On Apr 30, 8:57am, Steve Baker wrote:
> Subject: Fogging problems on RE2.
>
> Yes, I know this is a little off-topic, but I know
> a bunch of you clue-ful SGI types are listening and
> I didn't get any help from comp.graphics.api.opengl
> so here goes...
>
> I'm writing a simple GLUT/OpenGL program which runs
> quite nicely on an SGI ONYX Infinite Reality and on a
> Linux machine with Mesa and a 3Dfx Voodoo card.
>
> So far this is great.
>
> Now I try to run the same thing on an SGI ONYX RE2
> (IRIX 6.2) and the fog comes out WAY too dense.
>
> Here is the code to set up the fog:
>
> glEnable ( GL_FOG ) ;
> glHint ( GL_FOG_HINT, GL_NICEST ) ;
>
> static float fogcol [ 4 ] = { 0.3, 0.6, 1.0, 1.0 } ;
> glFogfv( GL_FOG_COLOR , fogcol ) ;
> glFogf ( GL_FOG_START , 0.0 ) ;
> glFogf ( GL_FOG_END , 50000.0 ) ;
> glFogf ( GL_FOG_DENSITY, 0.000005 ) ;
> glFogi ( GL_FOG_MODE , GL_EXP ) ;
>
> Near/far clip planes are 2.0 and 1000000.0.
>
> The scene is a regular grid of tristrips lying in the X/Z
> plane from the eye all the way out to somewhere beyond
> the far clip plane.
>
> Is there some lingering IrisGL-ness in the RE2's OpenGL
> that might be killing me here? Is there anything else I
> can do to make the RE2 fog look the same as it does on
> the other machines? Maybe there is some kind of patch I
> should have installed?
>
> HELP!
>
>
> Steve Baker (817)619-8776 (Vox/Vox-Mail)
> Raytheon Systems Inc. (817)619-4028 (Fax)
> Work: SBaker++at++link.com http://www.hti.com
> Home: SJBaker1++at++airmail.net http://web2.airmail.net/sjbaker1
>
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>-- End of excerpt from Steve Baker
--
________________________________________________________________
Rob Jenkins mailto:robj++at++sgi.com
Silicon Graphics, Mtn View, California, USA
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This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:57:19 PDT