Does PS4 uses OpenGL or DirectX?
PS4 uses its own low level API and its own shader language.
Note: For most purposes this doesn’t matter to a UE4 user. We abstract away the platform details like the render hardware interface (RHI), and use .usf shaders that are cross-compiled to different platforms as necessary, so stuff ‘just works’ when run on other platforms.
Cheers,
Michael Noland