[Bug 14762] Max Payne 2: sepia tone filter issues (high PPE)

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=14762





--- Comment #15 from Stefan Dösinger <stefandoesinger at gmx.at>  2008-11-02 17:14:19 ---
You could try to implement a coordinate correction like this, but it is pretty
tricky. Here are a few rules that have to be implemented:

1) No vertex or pixel shader: Correct the coords in the texture matrix
2) vertex shader, but no pixel shader: Correct the coords in the vertex shader
3) Pixel shader, vertex shader yes or no: Correct the coords in the pixel
shader

(1) and (2) are needed because without a pixel shader there is no other option
to fix the coordinates. OK, you may get away with it if a fixed function
pipeline replacement is active, e.g. GL_ATI_fragment_shader, or
GL_ARB_fragment_program, but this would be kinda ugly.

(3) is needed because pixel shaders can do arbitrary calculations in the
texture coords before they sample the texture

Now the ugly part is that this adds many dependencies across different states.
It ties pixel, vertex, texture, texture matrix states all together, although
the are mostly independent right now. The performance implications would be not
so good.

The other bad aspect is that the coordinate correction needs at least 2 single
float uniforms per sampler, which are supposed to be available to the
application. (even hardcoding the values into the shader won't help - the
driver needs a uniform for this)

I think the best is to close this bug as WONTFIX and ignore the issue. It only
occurs on one card type, the GeForce 5 series. All other cards either have
native NP2 texture support, or the driver emulates it in hardware if we stick
to the texture rectangle limitations.

I really hate to do that - my credo is that everything that works on Windows
should work on Wine, with the same hardware, at the same feature level and the
same performance. But this is one of the corner cases we can't fix.


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