Weirdly beautiful. Wonderful bit of game history exploring why the code for the 1993 game Doom uses a slightly wrong value for pi (the programmer recalls that he misremembered the 10th digit), and a bizarre exploration of what happens to the gameplay when you deliberately change pi to different values.

We all know that the value of pi is a constant with a particular immutable value. Anyone who has done any graphical programming also knows that visual rendering relies not just on pi but trigonometry more broadly as well as other mathematical techniques. If we look into the source code of the first person shooter Doom we find that the value of pi used in the game is wrong. In this talk I will explore what happens when we subtly and not so subtly break math in the source.

Doom is a well known classic first person shooter game with source code released under the GPL in 1999. In this talk I will begin by exploring what happens to the game when we make the value of pi even more wrong. What about when we change other trigonometric functions and constants to incorrect values? How will our familiar understanding and ability to traverse this virtual world change when we do this. Are there any interesting gaming possibilities with non-Euclidean geometries? A brief segway will cover some optimization tricks made to enable the game to run well on hardware available at the time. At the end I will provide a link to other games and public source code repositories that also use an incorrect value of pi. Pointers will also be provided to allow the audience to compile their own incorrect math version of the game.

—Non-Euclidean Doom: what happens to a game when pi is not 3.14159…