[D3D9 Only] Returns the adapter index that the user should pass into CreateDevice to set up D3D9 in such a way that it can go full screen exclusive on the HMD. Returns -1 if there was an error.
See Implementation
[D3D9 Only] Returns the adapter index that the user should pass into CreateDevice to set up D3D9 in such a way that it can go full screen exclusive on the HMD. Returns -1 if there was an error.