Hitbox radius in doom actually means square side length

[IgeNiaI]

Pages 270 to 272 display enemy hitboxes as circles, but in game they are actually squares. Though hitbox size property is still called "radius" in code.

[BenMcLean]

This does make a significant difference to the game's rules and I agree it would be best for the book to reflect this.

In the Wolfenstein 3-D re-creation I've been working on, I needed a better way to handle collision detection for pickups so I copied the idea of this square hitbox behavior from Doom.