The predecessor to OpenGL is SGI's proprietary IRIS GL. While OpenGL leaves window system operations to the native window system (for example, the X Window System or Windows NT), IRIS GL provides its own window management routines. OpenGL has a similar 3D rendering philosophy to IRIS GL, but OpenGL is a distinctly new interface. The OpenGL state machine is well defined and the OpenGL API has a cleaner design and regular name space. One of the most important changes in OpenGL from IRIS GL is the clean separation of renderer state from window state. In IRIS GL, the renderer and window state were coupled.
Locally running IRIS GL programs use virtualized, direct access rendering. In fact, most of the experience in supporting virtualized, direct access rendering for OpenGL was a result of experience with IRIS GL. The current IRIS GL direct rendering support actually uses the same support OpenGL uses.