Mesa is an OpenGL work-alike (similar to the relationship between LessTif and Motif). Mesa runs on a number of platforms, namely: Amiga, Apple Macintosh, NeXT, OS/2, MS-DOS, VMS, and Win32. Mesa can provide (in addition to its software renderers) basic hardware accelerated 3D support (e.g., 3Dfx Voodoo/VoodooRush/Voodoo2). It is open source, licensed under the GPL.