"It is really just inertia that keeps us on OpenGL at this point. But it still works fine and we wouldn't get any huge benefits by making the switch, so I can't work up much enthusiasm for cleaning it out of our codebase," Carmack told BitGamer.

"Sure, if it was just a matter of the game code, we could quite quickly produce a DirectX PC executable, but all of our tool code has to share resources with the game renderer, and I wouldn't care to go over all of that for a dubious win."

Meanwhile, AMD rep Richard Huddy opined that "true" graphics innovation has been "driven" by Microsoft over the past decade.

"OpenGL has largely been tracking that, rather than coming up with new methods. Remember, the geometry shader, for example, which came in with Vista and DirectX 10, is wholly Microsoft's invention in the first place."

This statement won't make happy Mac users, who already "suffer" from a lack of games on their platform. To develop a game on Mac, the only API available is OpenGL, and Mac gamers (like me) are still waiting for more optimization. So please Apple and Khronos Group, do your best for improving this API before it's too late.

Source : http://www.tgdaily.com/software-features/54608-carmack-says-he-prefers-direct3d-to-opengl