[Mesa-dev] updating tex combine for frag program

[Dave Airlie]

On Tue, Feb 7, 2012 at 10:09 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 02/07/2012 12:08 PM, Dave Airlie wrote:
>>
>> Hi guys,
>>
>> Is there any reason we need to update tex combiner state if we are
>> using shaders?
>>
>> can we drop update_tex_combine updates to only the case where we don't
>> have a fragment shader/program unless its from the FF shader?
>
>
> I don't recall when update_tex_combine happens.  Does it happen at draw-time
> or state change-time?  If it happens at state change-time, the state will
> need to get updated when program 0 gets bound.  Otherwise something like the
> following would break:
>
>        glUseProgram(my_prog);
>        glTexEnvi(GL_TEXTURE_2D, GL_TEXTURE_ENV_MODE,
>                GL_DECAL);
>        glUseProgram(0);
>        glDrawArrays(...);


IT happens in update_texture_state which happens on _NEW_TEXTURE, so
it should be fine, since with the maintain fixed function stuff we
update the program on _NEW_TEXTURE.

Dave.