Heretic2, etc.

The GL Library that comes with Heretic 2 doesn’t work, and Heavy Gear never works.

My X System seems to be setup perfectly, I have a Voodoo3 2000, Xfree86 4.0, Mandrake 7.1

I Have Mesa installed, but I keep getting washed about when it comes to installing GL, so I don’t know wheather it actually got installed or not. Could someone point me to the right place to download the correct GL?
(I can’t find it on the OpenGL page itself!)