Re: Perf 1.2 & Impact gfx

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Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Tue, 23 Jan 1996 15:27:53 +0100

What I think is happening is your background is black, your drawing
your transparent polygons which are then occluding your background
polygon because they write to the zbuffer. So you are blending
to black instead of your background polygon. The alpha = 0 works
because of the pfAlphaFunc settings. Try turning cull sorting on.

Rgds,
Angus.

On Jan 23, 9:36am, Shawn Soeder wrote:
> Subject: Perf 1.2 & Impact gfx
> Hello all,
>
> I am running a visual simulation on an Indigo2 High Impact (IRIX 5.3) using
> Performer 1.2. The program, basically a modified version of perfly, does not
> render blended alpha values correctly. I have a partially transparent layer
> on top of an opaque one, and only the areas where alpha = 1 or 0 is the
> transparency correct, and everywhere else no blending occurs (appears to be
> blended with black). This model and program behave correctly when run on RE
> graphics. The same problem also occurs when loading this model into the
> stock perfly.
>
> I suspect the problem has to do with Performer not knowing about Impact
> graphics. When I start the program, I get the following warning:
> > Performer Warning (2): Unable to determine graphics type 15. Default:
> VGXT using gfx
> > type mode = 0x4010003
>
> According to the brochures, the High Impact does support alpha blending. Do
> I need to change something so that Performer 1.2 recognizes Impact gfx?
>
> Shortly, I will start running this code on a Maximum Impact. Will this
> require further changes to recognize Max Impact gfx?
>
> Thanks for any help,
> Shawn Soeder
> shawn_soeder++at++grumman.com
>
>
>-- End of excerpt from Shawn Soeder

-- 
Angus Dorbie,
Silicon Graphics Ltd, UK
dorbie++at++reading.sgi.com

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