Posted by Joseph J. Strout on January 21, 2004 at 15:44:59:
At 6:05 PM -0500 1/21/04, Frank C. wrote:>>Extensions to what? You're not proposing that we need new Quesa
>>APIs for dealing with this, are you?
>
>Maybe I'm misunderstanding the whole 3DMF/QD3D philosophy but I
>thought it was standard practice to add extensions to the format to
>cater to specific renderers, and that those attributes are simply
>ignored if a renderer doesn't support them.But it's Quesa philosophy to be binary compatible with QD3D.
Extensions to enable the current (broken!) behavior would be fine,
but by default, code that works with QD3D should work with Quesa.>I'm suggesting that perhaps Quesa's default interactive renderer
>could use some extensions to keep up with the times, (or in this
>case keep up with QD3D) though I suppose it could just as easily be
>done in a plug-in renderer.Hmm... I guess I'm still confused then. If you're talking about code
within Quesa's IR, then these would be extensions to what, exactly?
Our own IR doesn't need new Quesa APIs to change its behavior, so
maybe you're talking about OpenGL extensions or some such?>The texture and fog are rendered at the same time, so the current
>blend mode affects both. You could blend fog in a separate pass (and
>many games do, especially for volumetric effects) but that would
>incur a performance hit.Hmm. So you're saying, OpenGL simply doesn't have any way to say "do
this with the textures" and "do that for the fog." It's just one
setting, and it affects both. Yuck. Is there no way around that
short of a separate rendering pass?>There may be a way to keep the QD3D behaviour and make it work in
>fog using vendor extensions, register combiners, or destination
>alpha, but I'm just not sure - these aren't standard across hardware
>so it'll be messy and may not work at all on some hardware (if it's
>possible). I'm not up to speed with Vertex/Pixel shaders, but I
>suppose anything is possible with those, but with even less hardware
>compatibility...Ugh. OpenGL -- who came up with this junk? :)
I suppose then we might have to go with a separate pass for the fog.
We already need multiple passes when translucent objects are
involved, as I understand it. Maybe one more won't slow things down
too much.--
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