[PATCH 3/5] wined3d: Remove ARB_/EXT_TEXTURE_ENV_ADD.

[Matteo Bruni]

2015-02-25 9:42 GMT+01:00 Henri Verbeet <hverbeet at gmail.com>:
> On 24 February 2015 at 13:38, Matteo Bruni <mbruni at codeweavers.com> wrote:
>> Unused.
>> ---
> But they should be used by ffp_fragment_get_caps(), since set_tex_op()
> uses that functionality.

It's not all that clear and nice. set_tex_op() really depends on
GL_(ARB|EXT)_texture_env_combine, since it's always setting
GL_TEXTURE_ENV_MODE to GL_COMBINE (or GL_COMBINE4_NV) and using its
knobs to set the texture color or alpha operation state (and those
include the ADD setting for the COMBINE pname).
There is actually no instance of GL_TEXTURE_ENV_MODE being set to
GL_ADD in wined3d, which is the only addition in the
GL_ARB_texture_env_add spec.

So TEXTURE_ENV_ADD is really unused AFAICS. We do always depend on
GL_(ARB|EXT)_texture_env_combine and we're not exposing that
dependency correctly. I'm not sure I want to spend much time on fixing
that or introducing a fallback for the case where those extensions are
missing. Maybe I should just add an early-exit branch in set_tex_op
for the no *_texture_env_combine case, handling only the few settings
supported in unextended OpenGL (which are MODULATE, SELECTARG1 and
SELECTARG2 I think) and update ffp_fragment_get_caps() accordingly.