spacewalk

The geometry instrument for operations conducted on a lattice — board games, tactics games, and tile maps: cells, directions, distance, sight, regions, and routes. Pieces, terrain, players, and the game clock remain under the command of your application.

Quick start

[dependencies]
spacewalk = "0.1"

use spacewalk::{Adjacency, FullGrid, Grid, Movement, Sq};

let grid = FullGrid::square(8, 8, Adjacency::Four);
let mud = [Sq::new(3, 3), Sq::new(3, 4)];

let movement = Movement::cell_cost(&grid, |cell| {
    Some(if mud.contains(&cell) { 30 } else { 10 })
});

let route = grid
    .path_between(Sq::new(0, 0), Sq::new(7, 7), &movement)
    .expect("the route should be open");

assert_eq!(route.len(), 14);
assert_eq!(route.cells(&grid).count(), 15); // the start is included

Why

• One vocabulary, three boards. Code written against the Grid trait runs on a stored cell set (FullGrid), an arithmetic rectangle (RectGrid), or a borrowed region (SubGrid) without a change of course.
• Any shape. Square, hex, disc, and tile-map hex rectangles ship as constructors; a custom Coord implementation opens anything else, including three-dimensional boards.
• Directed movement costs. A step's cost belongs to the cell entered and the direction of arrival — rivers, conveyors, and ledges just work. A*, budget-bounded Dijkstra, and reverse reachability search the graph with deterministic tie-breaking.
• Sight and regions come back as boards. Range, ring, component, and field-of-view queries return a SubGrid, so the thing you highlight is also the thing you path over.
• Integer pathfinding, reproducible replays. Floats exist only in the screen-layout layer; no float ever reaches a cost, metric, or step table.

Requirements and features

• Rust 1.88 or newer, edition 2024.
• #![no_std] with alloc; one runtime dependency (hashbrown).
• serde feature: serialization for the plain-data types and CellMap. Grids rebuild from their cells; serialize coordinates, never indices.
• Safety caps bound untrusted map files: MAX_CELLS is 2²⁴ cells and MAX_SIGHT is 64. Panicking constructors have try_ counterparts.

More examples and documentation

• API documentation — rustdoc is the manual: the Grid vocabulary, cost models, metrics, index identity, and layouts.
• tests/ — public-API missions: square tactics, checkers, hex capture, three-dimensional chess, field of view, directed threats, save/load, and robustness at hostile numeric limits.
• CHANGELOG
• Issue tracker

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Banner image: “Astronaut Walks in Space,” credited to the U.S. Information Agency; source via Artvee.