Doom 3, legendary classical game from id software, has been “stripped” by the makers. All of its arranging code can be seen.
Doom 3 source code can be released with GNU Public License (GPL) open source license and free to be downloaded by anyone wanted it. Surely this code is not included its game content.
The released code made possible for developer or developer community possible to process it into playable game. The similar thing once was done for Quake 3 source code.
Doom 3 firstly appeared in the market on August 2004 through Activision. That game had been available in Windows, Linux, Mac, and Xbox platform.
Get Doom 3 source code in Github
Story of the lost code
One interesting fact, Doom 3 code released to public isn’t included one method named ‘Carmack’s Reverse’. This method was found by John Carmack, id founder, to get shading in playing display.
The story was, in Doom 3 developing phase, Carmack found (and published) a shading application process known as Carmack’s Reverse term. Out of Carmack knowing, the method in fact had been patented in 1999 by Creative Labs with ‘Depth Fail’ name.
Although both of them developed separately, method used by Carmack considered to violate Creative patent. Carmack gave in and tried new method to outsmart it, so he won’t be considered violating law. Unfortunately, the new method made Doom 3 run slower so id Software opted to wear Carmack’s Reverse or Depth Fail and paid license to Creative Labs.
“it showed how patent system is so stupid. To outsmart it, I just need to add four code row and change two,” said Carmack in his Twitter account. (via Toms Hardware)