Re: Intensity-Alpha textures on IR

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From: Allan Schaffer (allan++at++sgi.com)
Date: 03/09/2000 16:42:37


On Mar 10, 6:26pm, Axel Volley wrote:
> I encountered the following multisampling-related
> dithering artifacts by displaying an Intensity-Alpha texture
> on an Onyx2-IR:
>
> samples : visual : artifact
> -------------------------------------------
> 0 : 0x56 (db, Z23) : no artifacts
> 4 : 0x5a (db, Z23) : 4 shades of white
> 8 : 0x90 (db, Z23) : 8 shades of white
>
> Can anybody tell me how to fix the artifacts and what causes them ?

I might be misunderstanding the question but:

The quality of transparency depends on the transparency mode you
select, or if you don't make a selection, the default mode changes
depending on whether multisampling is on or off.

If multisampling is OFF then the only option available is the
PFTR_BLEND_ALPHA approach.

If multisampling is ON then you have a choice of
   - the PFTR_BLEND_ALPHA approach (slower, higher quality) or
   - the PFTR_MS_ALPHA approach (faster, lower quality). <--- DEFAULT

So you'll want to set this on your transparent geostates:
   pfGStateMode(gstate, PFSTATE_TRANSPARENCY, PFTR_HIGH_QUALITY);

Check the pfTransparency man page which explains this all a bit
better. :-)

Allan

-- 
Allan Schaffer                                            allan++at++sgi.com
Silicon Graphics                           http://reality.sgi.com/allan


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