#hexgrid

#Game coverage

#Shared design principles

• Pure and deterministic — every function is a mathematical operation on the grid: no I/O, no global state, no randomness. The same inputs always produce the same outputs on every backend.
• Zero dependencies — only moonbitlang/core; the binary heap and all algorithms are implemented from scratch.
• Caller-owned semantics — passability, terrain costs and transparency are caller-supplied functions; hexgrid imposes no game rules.

#Installation

moon add wbgxiaosu/hexgrid

import {
  "wbgxiaosu/hexgrid/hex",
  "wbgxiaosu/hexgrid/path",
  "wbgxiaosu/hexgrid/fov",
}

#Usage

///|
fn main raise {
  let start = @hex.Hex::make(0, 0)
  let goal = @hex.Hex::make(4, -2)
  // straight-line geometry
  println("distance: \{start.distance(goal)}") // 4
  // pathfinding around a wall on column q = 1
  fn passable(c : @hex.Hex) -> Bool {
    !(c.q == 1 && c.r != -1)
  }
  match @path.find_path(start, goal, passable, fn(_f, _t) { 1.0 }) {
    Some(steps) => println("detour: \{steps.length() - 1} steps") // 4
    None => println("unreachable")
  }
}

$ moon run cmd/main
distance 0;0 -> 4;-2 = 4
line 0;0 -> 4;-2: 0;0 1;0 2;-1 3;-1 4;-2
range 2 has 19 cells; ring 2 has 12
A* path (4 steps, detouring the wall): 0;0 -> 1;-1 -> 2;-1 -> 3;-1 -> 4;-2
visible cells (16): -2;0, -2;1, -2;2, -1;-1, -1;0, -1;1, -1;2, 0;-2, 0;-1, 0;0, 0;1, 0;2, 1;-2, 1;-1, 1;0, 2;-2

#Independent consumer example

$ cd examples/consumer && moon run .
consumer A* steps: 4
consumer fov cells: 19
consumer example OK

#Building and testing

moon check --deny-warn
moon test --deny-warn
moon run cmd/main
cd examples/consumer && moon run .

#Scope statement

#Ecosystem positioning

• Square-grid / general-graph pathfinding toolkits (e.g. moonpath, moonnavkit, moonbit-pathfinding) operate on 2D grids or abstract graphs; none provide axial/cube coordinates, ring/spiral generation, hex rotations or hex-specific line-of-sight.
• Procedural content generators (e.g. terrain) produce maps but define no grid topology.
• Tiled-map codecs (e.g. moonbit-pixelkit) parse map files without hex geometry math.

#Roadmap

• per-cell terrain layers on HexMap with falloff functions over multi-source Dijkstra maps;
• hex-rectangle iteration helpers and map transforms (rotation, reflection of whole maps);
• optional boolean-set operations on regions (union, intersection, subtraction).

#Acceptance

#License