Doom 3 source code

The Doom 3 source code, or formally id Tech 4 source code, was released under the GPL V3 license by id Software on November 22, 2011, roughly 7 years after the game itself.

Until late 2011 the id Software tech team focused on Rage, and after finishing the game started preparing the Doom 3 source code for release. The preparations included John Carmack adding four new lines of code and editing another two to replace the so-called 'Carmack's reverse' functionality, thus preventing infringement on a Creative Labs' 3D shading technique patent. After the issue was settled, the source was released via GitHub on November 22 by Timothee Besset.