This is the Doom 3 GPL source code as it was released by id Software in late 2011. I prepared this source for release while I was an id employee, which is why this repository is present under my account. I am keeping it here as a reference due to the 400+ forks that were created out of it, but I am not doing any active development with it.
If you are looking for an updated and active Doom 3 GPL source tree, have a look at https://github.com/dhewm/dhewm3
Also note that the source code for Doom3 BFG edition was also released under GPL, and is significantly different from this codebase. You can get the original source release for Doom3 BFG here: https://github.com/id-Software/DOOM-3-BFG, and an active port tree here: https://github.com/RobertBeckebans/RBDOOM-3-BFG