Vision

Vision (or line-of-sight) is the process by which tiles around the player are revealed.

The player also has a sight radius. By default, this sight radius is 8, but it can be increased to 10 with the Cateye trait. Additionally, some other effects can reveal a limited number of objects outside the player's sight radius.

Certain tiles (like walls) block the player's vision. The effects of these obstructions are calculated by a modification of Isaac Kuo's fast beam casting algorithm. The exact algorithm used by Doom RL is open-source as a part of FPC Valkyrie.