Platform and OS Implementations

Mesa for DOS
A port of Mesa to the DOS platform.
http://www.geocities.com/CapeCanaveral/7992/

OpenGL Sample Implementation
SGI open-source OpenGL sample implementation.
http://oss.sgi.com/projects/ogl-sample/

OpenML - Open Media Library
Free, cross-platform programming environment for capturing, transporting, processing, displaying, and synchronizing digital media. Extensions to OpenGL, display control, device control and asynchronous communication between applications and hardware, and synchronization of media streams
http://www.khronos.org/openml/

Realtech DXGL Wrapper
Emulates DirectX API calls through OpenGL commands and other platform specific commands in order to run DirectX 8 applications on other platform than Windows.
http://www.realtech-vr.com/directx/

SciTech MGL
Open-source multi-latform interactive graphics library
http://www.scitechsoft.com/products/dev/mgl_home.html