I just read about that extension and thought “damn, that´s what you need”!
But when i check the extension string, this extension does not show up! On a Geforce 4200 with 45.23 drivers.
Why? I could really use that extension. Which cards do support it?
I always thought this extension is quite old and should be implemented in all cards, but certainly i am wrong.
I am disappointed.
BlendFuncSeparate is a part of the core (maybe the imaging subset, not sure).
this extension is not hardware accelerated on gf4 ti, I tried it too and this was the sad result. I worked around it with using opacity weighted colors and blend func GL_ONE, GL_ONE_MINUS_SRC_ALPHA (I need the color values blended, but the alpha values added, for rendering my cloud impostor textures with destination alpha).