I don't like that I have to do this because the posFixup is in all
vertex programs, so its at the same position and could be loaded
globally. Unfortunately, there are only 256 env parameters usually,
which makes it impossible for any shader to use c256, even if it does
not use indirect addressing, and so we can't claim 256 constant
support.
I find it helpful for debugging to have this controlled at a central place,
without having to disable the entire GL extension or manually find all the
places where GL_SUPPORT(NV_VERTEX_PROGRAM2_OPTION) controls clipplane use. It
is useful for debugging the emulation code on NV cards and for debugging mac
driver issues.
b2f09fd20421d0a5e179b42332ca63bc5ac17d8a accidentally got the
device->vs_clipping check wrong. The FFP replacement should emulate
clipping if GL can't do this natively with vertex shaders, not the
other way. Also don't emulate clipping if we're using fixed function
vertex processing because (a) clipping is always supported by GL in
this case, and (b), fragment.texcoord[7] is undefined. (Or in the
worst case set to something bad by the app).
If the needed constants are available, we can support all vs_2_0 and ps_2_0
requirements with the plain ARB extensions. We cannot however, run SM 2.0a or
SM 2.0b.
ps 1.x constants are clamped to [-1;1], constants in >= 2.0 pshaders
are not. This means we have to reload constants when switching between
those shader types in ARB. In GLSL this is not a concern because
constants are tied to program objects and are reloaded on a shader
change anyway.
This patch tries to find a free texture coordinate to load up to 4 clip
coordinates into the pixel shader, and uses KIL to throw away fragments
that are cut by a clipplane. If no free texture coordinate is found,
clipping is not done. If more than 4 clipplanes are used, only the first
4 are actually enabled. That should be pretty rare though.
Using GL_NV_vertex_program2_option so far. If we're really desparate we can
handle some cases without the extension by using a custom varying and texkill
in the fragment program.
This gives a small performance improvement. Don't enable NVfp for it though,
because the NVfp penalty is bigger than the gain from this patch. But if NVfp
is enabled anyway, make use of it.
This reverts patch ba35760f9fd5fd90a0fa34077862f04513d1ab16.
The original patch did not achive its goal, because CMP is a macro that is
expanded to SLT, SGE, MUL, MAD, at least on nvidia hardware. To make matters
worse, it uses a temporary register, and the assembler usually is not clever
enough to find a free temporary from the shader code. If we generate the code
outselves we can pick one of our temps for this job.
Many 2.0 and 3.0 shaders end with a "mov oC0, rx". If sRGB writing is enabled,
the ARB backend writes to a TMP_COLOR temporary, and at the end of the shader
writes the sRGB corrected color to result.color. If oC0 is not partially
rewritten after the mov, we can ignore the mov, not declare TMP_COLOR at all,
and just use the rx register as input for the sRGB correction code. This saves
a temporary and an instruction.
