In this devlog, I want to share how a simple and familiar algorithm — Flood fill — helped me massively speed up pathfinding in my game.
Why Bother?
Imagine you have a big map filled with obstacles: houses, walls, trees, etc. When a creature wants to move from point A to point B, the game needs to figure out if it’s even possible to get there.
Running a full pathfinding algorithm every time — even when there's clearly no path — wastes time and resources. So I decided to precalculate which areas are actually connected and only allow pathfinding when it makes sense.
The Idea: Divide the Map into isolated zones
Every time the player places an unwalkable structure (like a wall) on a tile, the game runs a Flood fill algorithm from each walkable side of that tile.
The algorithm explores all reachable walkable tiles connected to that side and tries to form a new isolated zone.
You can think of it like pouring paint from each side of the blocked tile — each "puddle" becomes its own zone.
As a result, instead of running expensive pathfinding calculations, creatures in the game now simply check whether their destination tile is in the same zone they’re currently in.
If it is — go ahead and search for a path.
If it’s not — no need to try: there's clearly no way to get there!
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