Understanding Quake’s Fast Inverse Square Root
An article and research paper describe a fast, seemingly magical way to compute the inverse square root (1/sqrt(x)), used in the game Quake.
I’m no graphics expert, but appreciate why square roots are useful. The Pythagorean theorem computes distance between points, and dividing by distance helps normalize vectors. (Normalizing is often just a fancy term for division).
3D games like Quake …Mental Math Shortcuts
Swap two variables using XOR
Number Systems and Bases
A little diddy about binary file formats
Crowd Favorites
Math & Numbers
- Mental math shortcuts, adding 1-100
- Understanding exponents and the natural log
- Div, Curl, Flux, Gradient and other Vector Calculus topics
Programming & Web Development
- Site speedups with HTTP caching, gzip compression
- Understanding Rails, Web debugging, and Javascrtipt
- Swap bytes with XOR, byte order, unicode
