Looks like source engine for mac in newly released steam still uses dx9 to opengl translation and it’s not native opengl game.
it doesn’t really matter if it works, but still it’s direct x
valve’s dev: I wrote the native OpenGL module for Source Mac. It presents a DX9 compatible interface to the engine, engine calls me, I call GL, dots appear.
rbarris: On Mac Source, all of the source code has been compiled native. Specific modules have been replaced with ones that can drive OS X API’s, like graphics and sound. All the OpenGL code lives in a little lib called “shaderapidx9″ which is shorthand for “the shading subsystem that can run on dx9-class hardware”. That’s sort of the grand central station for graphics API traffic coming out of the engine and down into the OS&driver.