These libraries are used by the 3dfx DRI module (lib/modules/dri/tdfx_dri.so) 
to provide 3d hardware accelerated OpenGL for 3dfx Voodoo3/4/5/Banshee cards.  
This does not support applications requiring the Glide library.

WWW: http://people.freebsd.org/~anholt/dri/
- Eric Anholt
anholt@FreeBSD.org