Orkuncakilkaya
07e5a20c0e
Grid.* operates on the Map tilemap (Map.size/Map.row): a cell is passable unless
it is out of bounds or holds the caller's `wall` tile (a char code, e.g. '#'), so
any impassable glyph works. Everything is integer and deterministic.
- Grid.line(x0,y0,x1,y1) -> []Cell Bresenham line cells (LOS/raycast base)
- Grid.blocked(x,y,wall) -> bool the shared passability test
- Grid.line_of_sight(x0,y0,x1,y1,wall) unobstructed straight line?
- Grid.flood(x,y,wall) -> []Cell 4-connected reachable region (BFS)
- Grid.a_star(x0,y0,x1,y1,wall) -> []Cell shortest 4-connected path (A*,
Manhattan heuristic), empty if unreachable
The engine (runtime/native/grid.ludic, ~150 lines of Ludic, C-free) is spliced
into a game via core.ludic since it reads the tilemap runtime; returned Cell
slices are ordinary Ludic slices (`len` / `[i]`; each cell has `.x` `.y`).
Pathfinding lives under Grid rather than a `Path` namespace — that name is
already the filesystem-paths library (#10).
Verified against Python references: a 1500-case fuzzer over random maps agrees
exactly on A* path length (optimal, == BFS), flood-fill count, and line-of-sight.
examples/library/grid.ludic asserts the behaviour and is wired into `x test`
(now 61 passed); docs: a Grid section + 5 per-symbol pages, inventory/coverage
green. Seed reseeded; the C-free bootstrap fixpoint holds.
Scope: this lands the Grid.*/pathfinding half of #24. The ECS Query.* helpers
(count/first, and nearest/within which want a runtime spatial index) remain the
tracked follow-up the issue calls out as blocked.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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| id | name | category | kind | tokens | sig | tip | order | ns | member |
|---|---|---|---|---|---|---|---|---|---|
| grid-a_star | Grid.a_star | grid | namespace-method | Grid.a_star | Grid.a_star(x0, y0, x1, y1, wall) -> []Cell | The shortest 4-connected path between two cells (A*), or an empty list. | 5 | Grid | a_star |
Returns the shortest path from (x0, y0) to (x1, y1) over passable (non-wall) cells, 4-connected with uniform step cost, as a Cell slice from start to goal inclusive — an A* search with a Manhattan heuristic. Empty if the goal is unreachable (or start/goal is a wall). (Named under Grid rather than Path, which is the filesystem-paths library.)
Parameters:
x0,y0— the start cellx1,y1— the goal cellwall— the impassable tile char, e.g.'#'
program Demo {
handler H phase Update {
let path = Grid.a_star(1, 1, 20, 12, '#')
if len(path) > 0 { print(len(path)) }
}
}