Mesa3D and OpenGL

Question

Wikipedia Article on Mesa 3D says -

Mesa 3D - An open source implementation of OpenGL.

But as I see SGI has the entire OpenGL implementation source available online at their website, how is OpenGL not open-source or what is the need of Mesa 3D?

Answer 1

The SGI reference implementation is incredibly outdated, I think it only implements 1.2.

Mesa is being worked on and supports newer versions of the OpenGL specification. Currently it implements OpenGL 2.1 and a few extensions from OpenGL 3/4.

Answer 2

OpenGL is not Open Source. The NVIDIA and ATI implementations of OpenGL are not Open Source, whatever MESA or SGI's implementation doesn't change the fact that not all OpenGL implementations are Open Source.

OpenGL is a Open Specification, made by a comitee inside the Khronos industrial group (the ARB).

Answer 3

Mesa contains hardware accelerated drivers for many chips and is constantly updated. I think that SGI reference implementation is software-only.

Answer 4

As well as the other answers posted here — that Mesa is an ongoing project that is substantially more current than the SGI implementation — the initial release of Mesa predates the SGI release by something like seven years.