GL_FUNC_ADD

OpenGL Development
#1

Howdy.

I’m doing some simple blending.

According to the Red Book, the valid operands for glBlendEquation() are GL_FUNC_ADD, GL_FUNC_SUBTRACT, GL_FUNC_REVERSE_SUBTRACT, GL_MIN, GL_MAX.

As such I would expect to find all those constants defined in GL11.

However, GL_FUNC_ADD, GL_FUNC_SUBTRACT, and GL_FUNC_REVERSE_SUBTRACT are all found in ARBImaging. GL_FUNC_ADD of course is the most commonly used blend operand.

Can you explain to me why these constants live in ARBImaging and not GL11?

Am I somehow smoking crack and not realizing it?!

Thanks!

#2

Heh, nevermind.

I see that it is indeed part of the ARBImaging extension. Funny I never realized that before. Under C++ there is was never any indication that it was an optional part of the language, although I did finally find mention of it in the Red Book.