The ebuild has, since almost the dawn of time, carried the following message:
elog "Starting with 3369, the game supports render-to-texture. To enable"
elog "it, you will need the Nvidia drivers of at least version 7676 and"
elog "you should edit the following:"
The truth is it was a useful suggestion for about 0.5 seconds because everyone implemented render-to-texture in a hurry after Compiz was released. Any hardware that can run this at a tolerable framerate to begin with has all the required OpenGL 2.1 bits, not just Nvidia.
The advice below it about tweaking the ini file remains valid however, as that setting was never added to the UI.
Sorry for reporting the most trivial bug of the century so far. Better late than never though.
Thanks, this is useful. The default .ini files are part of the ut2004-data package. I am already midway through a massive cleanup of that and I don't want to force everyone to reinstall it twice so I'll patch the .ini files as part of that effort.