Another Alpha Texture Question

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Scott A. Friedman (friedman++at++ucla.edu)
Fri, 13 Feb 1998 15:12:48 -0800


Hi,

I have been trying to use pfString using a textured font. The GeoStates
on the font set Transparency to

     pfGStateMode(gs, PFSTATE_TRANSPARENCY, PFTR_ON | PFTR_NO_OCCLUDE);
     pfGStateMode(gs, PFSTATE_ALPHAFUNC, PFAF_GREATER);
     pfGStateVal(gs, PFSTATE_ALPHAREF, 4.0f / 255.0f);

The rendered text looks fine unless there is some opaqe geometry behind
it. When this happens the text disappears behind the more distant opaqe
geometry.

Resetting the transparency on the text to just PFTR_BLEND_ALPHA works
correctly but the edges of the characters have a banding effect when
rendered over the opaqe geometry. In both cases (with and without
NO_OCCLUDE) the text looks fine against the background - no banding,
frosting whatever you want to call it.

The channel is set to perform sorting so shouldn't textures with alpha
be rendered after the opaqe geometry? Even with NO_OCCLUDE this should
work but it doesn't.

Any suggestions on what I am not doing right here?

Thanks,
Scott

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