This extension is a subset of GL_NV_half_float that defines support
for the stream format(same constant), but doesn't define texture
formats or immediate mode entrypoints.
GL_ARB_shader_texture is supported on dx9 ATI cards(and probably dx10
ones too). For Nvidia cards I included a fallback to normal texld.
GL_EXT_gpu_shader4 supports similar texture*Grad GLSL functions, just
with an EXT prefix instead of ARB. For dx9 NV cards we'd have to use
GL_NV_fragment_program2, which supports a texldd equivalent on those
cards.
Some drivers apparently need private constants, or don't have an efficient
immval packing. For example, MacOS seems to need 1 float for each different
relative addressing offset. fglrx has the same issue, although it is more
efficient in general
Previously this worked on most drivers because the 16 + 4 reserved int and
bool constants kept the problem hidden. Now that we are more aggressive with
uniforms we have to keep free room for some drivers.
This allows better defining of driver desc fixups without adding extra if
lines for each card.
For starters, there's a fixup for the advertised GLSL constants in ATI cards.
fglrx advertises 512 GLSL uniforms instead of the supported 1024(means 128
instead of 256 vec4's). This bug was confirmed by ATI.
Right now we assume that the extension is there but this isn't always
the case. The next patch in this series will add a
non-WGL_ARB_pixel_format codepath to help VirtualBox and others.
This prevents fallout from the GL_EXT_fog_coord emulation. glEnable
and glDisable calls other than those that change GL_FOG are not
hooked. The glEnableWINE and glDisableWINE functions can be used to
add other hooks too if ever needed.
Stefan Dösinger