Re: Intensity-Alpha textures on IR

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From: Angus Dorbie (dorbie++at++sgi.com)
Date: 03/10/2000 06:56:45

The artifacts are caused by the alpha subpixel mask. Basically the
transparency is using a subpixel screen door effect when you have a
multisample visual available. The more samples you have the more shades
can be represented by the screendoor effect. You see this quantizing
effect as bands.

With no multisamples the transparency uses blended alpha instead.

Look at the manual for pfTransparency.

You can force the high quality method by making the pfTransparency state
for the geometry in question PFTR_BLEND_ALPHA.

Cheers,ANgus.

Axel Volley wrote:
>
> Hi,
> 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 ?
>
> Alles wird gut !
>
> Axel
>
> --
> Axel Volley ~ Multigen-Paradigm Inc
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