Off Topic: Mesa, opengl, glide, argh what is this jibberish!

[William Jensen <jensenb@charter.net>]

I'll confess right from the start I'm ignorant about this topic.  Some of the
words I read about are:

OpenGL
Direct3d
Mesa
Glide

Direct3d I pretty much get...it's MS's 3d implementation.  Can someone compare
and contrast what OpenGL, Mesa and Glide mean?  This is in specific regards
to Linux and xfree86 gaming.  I want to run Unreal Tournament on Linux but so
far the reading that I've done tells me the only cards supported for linux
gaming are the 3dfx voodoo cards.  Of course I have a tnt2 ultra (nvidia).

Also, how does the above discussion intermix itself with the release of
xfree86 4.0?  

If someone has a FAQ or a online article that explains these things, please
pass it on instead of a reply to this post.

Bill