Module pathfind 

Path finding over the map’s cells: the walkable regions and the A* pathfinder.

• regions gives every walkable cell the number of its connected region. A request between two regions fails at once, without a search.
• Pathfinder is the A* search, with a cost for each cell type (mode_costs).
• request checks a request as the original does, then searches.
• nearest_neighbour finds the allowed cell next to a cell that is nearest to a target.

The original solves paths on a worker thread, and a walker polls for the result. The port solves a path when it is requested; the walker still reads the result on its next update, so the timing is the same.

See Citizens for how citizens use it.

Structs

Pathfinder

The pathfinder: the map’s cells, the cost of each cell type, and the state of the A* search.

Constants

MAX_PATH

Longest path a search returns.

WALKABLE

Cell types a walker may enter (0–4, 9–11).

WATER

Water and blocking types (5–8): requests touching them skip the region check.

Functions

bit

The bit of a cell type in a type mask such as WALKABLE.

mode_costs

Per-type cost tables a mover selects (MoveTo) and whether the search may step diagonally.

nearest_neighbour

Of the 8 cells around cell whose type is in mask, the one nearest (squared cell distance) to toward; the first found wins ties (x outer, y inner).

regions

Label connected walkable cells in scan order, starting at 1 (0 = none).

request

Validate a request (both end types join the mask; without water types both ends must share a non-zero region), set the mask and search.

walkable

Whether a walker may enter a cell of this type (the test regions labels by).