This is a story about Doom 3's source code and how beautiful it is. Yes, beautiful. Allow me to explain.
After releasing my video game Dyad I took a little break. I read some books and watched some movies I'd put off for too long. I was working on the European version of Dyad, but that time was mostly waiting for feedback from Sony quality assurance, so I had a lot of free time. After loafing around for a month or so I started to seriously consider what I was going to do next. I wanted to extract the reusable/engine-y parts of Dyad for a new project.
When I originally started working on Dyad there was a very clean, pretty functional game engine I created from an accumulation of years of working on other projects. By the end of Dyad I had a hideous mess.
In the final six weeks of Dyad development I added over 13k lines of code. MainMenu.cc ballooned to 24,501 lines. The once-beautiful source code was a mess riddled with #ifdefs, gratuitous function pointers, ugly inline SIMD and asm code—I learned a new term: "code entropy." I searched the internet for other projects that I could use to learn how to organize hundreds of thousands of lines of code. After looking through several large game engines I was pretty discouraged; the Dyad source code wasn't actually that bad compared to everything else out there!
Unsatisfied, I continued looking, and found a very nice analysis of id Software's Doom 3 source code by the computer expert Fabien Sanglard.
Read more: Kotaku