This is a first step towards cleaning up the fog mess. The fog
parameter is added to the pixelshader compile args structure. That way
multiple pshaders are compiled for different fog settings, and the
pixel shader can remove the fog line if fog is not enabled. That way
we don't need special fog start and end settings, and this allows us
to implement EXP and EXP2 fog in the future too.
We cannot remove this because we still have to load the surface as
RGB. The shader may take care of setting the blue channel to 1.0 now,
but we still get the red and green channels loaded incorrectly if we
don't insert a blue channel before loading.
This allows us to drop the load time conversion and the clear
readback hack and replaces it with a color fixup in the fixed
function pipeline replacement.
Based on a patch by Stefan Dösinger. This is more flexible, and allows
the shader backend implementation to be simpler, since it doesn't have
to know about specific formats. The next patch makes use of this.
Note that minMipLookup and magLookup aren't particularly safe to use,
they're global arrays initialized from IWineD3DImpl_FillGLCaps(). The same
goes for the other global dynamic lookup tables.
Some stateblock parameters have to be compiled into the GL pixel
shader code, like lines for pixelformat fixups. This leads to problems
when applications switch those settings, requiring a recompilation of
the shader. This patch enables wined3d to have multiple GL shaders for
a D3D shader(pixel shaders only so far) to handle this more
efficiently.
This was suggested by Ivan quite a while ago, and we need it to better
handle conflicting texture format corrections and similar stateblock
value changes which until now required a recompilation of the entire
shader
A number of considerations contribute to this:
1) The shader backend knows best which shader(s) it needs. GLSL needs
both, arb only one
2) The shader backend may pass some parameters to the compilation
code(e.g. which pixel format fixup to use)
3) The structures used in (2) are different in vs and ps, so a
baseshader::Compile won't work
4) The structures in (2) are wined3d-private structures, so
having a public method in the vtable won't work(its a bad idea
anyway).