Doom 3 source code

The Doom 3 source code, also formally referred to as the id Tech 4 source code, was released under the GPLv3 license by id Software on November 22, 2011, roughly seven years after the game's release.

Until late 2011, the id Tech team focused on, and after finishing the game, began preparation of 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" algorithm for stencil shadow rendering, thus preventing infringement on a patent held by. After this issue was settled, the source was released via GitHub on November 22 by.