Re: Questions RE> Performer

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John Rohlf (jrohlf++at++tubes)
Mon, 10 Jan 94 10:55:28 -0800

>| 3. Intesity Alpha textures
>| ==============================
>| In multigen -- works ok (i.e. using the whole intensity range)
>|
>| In perfromer -- does not work correctly ( look ditherd )
>
>You are not seeing dithering, but color quantization.
>For full speed texturing, Performer uses 16bit texels.
>
> RGB textures: (R,G,B) (5bits, 6bits, 5bits)
> RGBA textures: (R,G,B,A) (4bits, 4bits, 4bits, 4bits)
>
>If you call pfTexFormat(tex, PFTEX_INTERNAL_FORMAT, TX_RGBA8),
>you'll get 32bit texels, but pixel-fill will run at half speed
>for those textures.

        The "dithered" look may be a result of using screen-door
transparency which Performer uses on multisample-capable Onyxes.
In this case you will only get a maximum of 16 transparency levels
rather than 256 but performance will be much better. If you want smooth
transparency you have to use the PFTR_HIGH_QUALITY token.

>| 4. Textures sometimes vanishes for short while:
>| ================================================
>| This is probably the strangest problem. If you drive a long a textured
>| road. On certain spotsparts of the road dissappears.
>|
>| My customer has installed a MCO option aswell as a normal screen. If we
>| run the application using MCO and three channels, the texure can
>| dissappear in one of the cannels but not in the others.
>
>Strange. Maybe someone else has an idea.

        An older IRIX release had a bug where a specific mipmap level would
drop out. What release are you running?

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