On November 23, 2011 id Software supported its own tradition and published the source code of its previous engine.
This time, it's time idTech4 , which was used in Prey, in Quake 4 and, of course, in Doom 3. In just a few hours more than 400 forks of the repository on GitHub were created, people began to explore the internal mechanisms of the game or port it to other platforms. I also decided to participate and created a Intel version for Mac OS X , which John Carmack kindly advertised .
From the point of view of cleanliness and comments, this is the best release of the id Software code since the code base Doom iPhone (which was released later, and therefore commented better). I highly recommend that everyone learn this engine, collect it and experiment.
Here are my notes about what I understood. As usual, I cleaned them, I hope they save someone a couple of hours and encourage someone to study the code to improve their programming skills.