Both DirectX and OpenGL are collections of application programming interfaces (APIs) used for handling multimedia information in a computer. They are the two most common APIs used today for video cards.
DirectX is created by Microsoft to allow multimedia related hardware, such as GPU, to communicate with the Windows system. OpenGL is the open source version that can be used on many operating system including Mac OS.
The decision to use DirectX or OpenGL APIs to program is dependent on operating system of the target machine.
Unreal Engine 4 was first launched using DirectX11. Following the announcement that DirectX 12 ships with Windows 10, Unreal has created a DirectX 12 branch from the 4.4 version to allow developers ...