Taken directly from the DOTA2 source tree, the translation layer supports limited subset of D3D 9.0c, bytecode-level HLSL to GLSL translator, and some SM3 support. It will require some tinkering to get it to compile, and there is some hardcoded Source-specific stuff included.
Valve declared back in 2012 that OpenGL is indeed faster than DX11 even on windows - http://www.extremetech.com/gam... "The Valve Linux Team breaks it down on their shiny new blog: With an Nvidia GTX 680, Intel i7-3930k, and 32GB of RAM, Windows 7 and DirectX, Left 4 Dead 2 maxes out at 270.6 fps. With the same hardware, but different software — Ubuntu 12.04 and OpenGL — L4D2 scores 315 fps, almost 20% faster than Windows". The Dota2 community has grown so huge that tinkering these APIs won`t be any hurdle. Albeit,i personally feel that Values is essentially trying to bring back some of the old Russians/Chinese Dota Teams,who have yet not made any appearance in D2 because of the high graphics requirement in D2 compared to D1. All of this may change when Blizzard introduces their own D2.
Parkinson's Law: Work expands to fill the time alloted it.