The biggest advantage of OpenGL has across platformability, which can run on many operating systems (UNIX, Linux, Windows, etc.). But DirectX can only run on the Windows platform. However, most PCs in the world have Windows, so DirectX's dependence on Windows has not brought too much trouble. On the contrary, DirectX is because it is Mircosoft research and development, so its optimization work is better than OpenGL on the Windows platform.
Compared with OpenGL, DirectXGraphics keeps close to the system low-level, which is more flexible to machine devices. In addition, Windows also has a set of graphics interfaces - GUI, which is mainly based on DirectXGraphics in normal Win32 applications. But for ordinary Win32 applications, it has been more than enough. There are many small games on the market to develop directly with GUI, but these games can only be 2D.
