Open Graphics Library (OpenGL)

SGI originally developed a graphics library called IrisGL for their high-end 3D hardware. They made some clever changes to make it work on any platform and renamed it OpenGL. Very recently SGI relaxed their restrictions for licensing and also released conformance tests for OpenGL. OpenGL abstracts 3D operations such as projections, lighting, rendering, texturing, matrix operations, etc, making it very easy for developers to produce high quality 3D applications.