_mevildan on 19 February 2012
What HappySquirrel is saying is correct.
I'm not sure saying DirectX is a wrapper language is correct at all. DirectX isn't even a language. It's just a collection of APIs.
Also assembly language is only really used on consoles for smaller high-frequency functions where a noticeable performance gain will be possible, or for things where no API call might exist (old school eg: enabling a vblank interrupt). I seriously doubt that any assembly is done on PCs anymore.
As for DX appearing on non-MS platforms... the API structure could easily be used on any other platform. It's just a matter of licensing and the fact that OpenGL has been an open standard for so long already that it is sufficient for developers on non-MS platforms..
