RE: [GD-Windows] Direct3D 8.0 texture stage states

[Jon W. <hp...@mi...>]

Thanks all. The surprising thing is that what I'm doing is almost exactly
the same thing as mentioned in the examples: add a modulate(current,diffuse)
as the third stage. The other surprising thing is that this works fine on
OpenGL (and, in fact, you can enable a large number of general combiners on
a GF2 in OpenGL). We're using very current drivers (but we're targeting back
to version 28.xx, 'cause that's what Dell shipped for one whole YEAR).

Multi-passing really isn't much of an option for us. We're already REALLY
tied for CPU, as we assumed hardware transform a long time ago, but the mass
market still is stuck in the SuperSavage and i845 era. We also have a
physics/networking system which requires a fixed update rate, leaving
precious little CPU for graphics on min-spec hardware. If there were
something like LockArraysEXT() to magically re-use transformed data for
multi-passing, maybe it could be made to work, but something like
ProcessVertices() doesn't let use re-use the card-specific set-up (texture
interpolation values, etc).

Perhaps it gets confused by the LERP triadic in the second stage (which uses
TEXTURE|REPLICATE_ALPHA for ARG0). Or perhaps I'm not setting alpha in all
three stages (but I think I am). I'll investigate some more, and ask our
NVIDIA person. Thanks for the pointers, everyone!

Cheers,

				/ h+


-----Original Message-----
From: gam...@li...
[mailto:gam...@li...]On Behalf Of
Daniel Vogel
Sent: Wednesday, March 03, 2004 2:02 AM
To: gam...@li...
Subject: RE: [GD-Windows] Direct3D 8.0 texture stage states


Jon, you're best off contacting NVIDIA devrel about the issue as there are
only a handful 3 stage setups that work on GeForce 1/2 class hardware. Tom's
blog <http://tomsdxfaq.blogspot.com/> has a little blurb on the issue.

-- Daniel, Epic Games Inc.

> -----Original Message-----
> From: gam...@li...
> [mailto:gam...@li...] On
> Behalf Of Jon Watte
> Sent: Tuesday, March 02, 2004 9:19 PM
> To: gam...@li...
> Subject: [GD-Windows] Direct3D 8.0 texture stage states
>
>
> We're porting an OpenGL renderer to Direct3D 8.0.
>
> The documentation in concordance with the device caps for a
> GeForce2 claim
> that you can configure up to 8 texture stage states, but you
> can only bind
> two textures. We have a specific texturing set-up that in
> OpenGL looks like
> this:
>
> Texture0 \
>           LERP \
> Texture1 /      MODULATE -> done
>        Diffuse /
>
> This uses 2 texture environments on OpenGL, but it appears
> that DirectX 8
> for fixed-function hardware cannot route two textures to one
> texture stage
> state. Thus, we want to use three stage states, in the following
> configuration:
>
> Texture0 \
>           SELECT1 \
>                    LERP \
>          Texture1 /      MODULATE -> done
>                 Diffuse /
>
> We can get the first two stages to work fine, but as soon as
> we turn on the
> third stage, the operations from the first two stages
> disappear, and we get
> solid-white diffuse lit geometry. Note that we get that, even
> if we choose
> SELECTARG1 for the operation for the third stage state (i e
> stage state
> index 2).
>
> We are disabling the stage state with index 3, just to make
> sure that we've
> gotten nothing wrong. However, no matter what we do, we can't
> make this
> work. We've tried both debug and release DirectX 9.0b runtime (can't
> downgrade on the development machines to try with 8.0 proper).
>
> Right now, we're feeling pretty glum. Any ideas?
>
> Cheers,
>
> 			/ h+
>
>
>
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