Hi All
OpenGL and DirectX are libraries are used with many well known language like ( Visula C, Java , PHP as well ) to make 3D games.
http://en.wikipedia.org/wiki/OpenGL http://www.opengl.org http://en.wikipedia.org/wiki/Directx http://www.microsoft.com/windows/directx
Also used in modelling and simulation of in defence projects like making 3D model of enamy locations and its weapons