Yes but Carmack also said that he now prefers D3D[1] and that difference between OpenGl and D3d does not really matter: "It’s interesting how little of the technology cares what API you’re using and what generation of the technology you’re on. You’ve got a small handful of files that care about what API they’re on, and millions of lines of code that are agnostic to the platform that they’re on." [2]