feat: add kruskal maze generator

PROJECT_DESCRIPTION.md

@@ -36,7 +36,7 @@ npm run build
 | Need | Algorithm(s) | Module | Example |
 | ---- | ------------ | ------ | ------- |
 | Grid pathfinding | `astar`, `dijkstra`, `jumpPointSearch`, `computeFlowField`, `buildNavMesh`, `findNavMeshPath`, `manhattanDistance`, `gridFromString` | `pathfinding/astar.ts`, `pathfinding/dijkstra.ts`, `pathfinding/jumpPointSearch.ts`, `pathfinding/flowField.ts`, `pathfinding/navMesh.ts` | `examples/astar.ts`, `examples/flowField.ts`, `examples/navMesh.ts` |
-| Procedural textures & terrain | `perlin`, `perlin3D`, `simplex2D`, `simplex3D`, `worley`, `worleySample`, `waveFunctionCollapse`, `cellularAutomataCave`, `poissonDiskSampling`, `computeVoronoiDiagram`, `diamondSquare`, `generateLSystem`, `generateBspDungeon`, `generateRecursiveMaze`, `generatePrimMaze` | `procedural/*.ts` | `examples/simplex.ts`, `examples/worley.ts`, `examples/waveFunctionCollapse.ts`, `examples/cellularAutomata.ts`, `examples/poissonDisk.ts`, `examples/voronoi.ts`, `examples/diamondSquare.ts`, `examples/lSystem.ts`, `examples/dungeonBsp.ts`, `examples/mazeRecursive.ts`, `examples/mazePrim.ts` |
+| Procedural textures & terrain | `perlin`, `perlin3D`, `simplex2D`, `simplex3D`, `worley`, `worleySample`, `waveFunctionCollapse`, `cellularAutomataCave`, `poissonDiskSampling`, `computeVoronoiDiagram`, `diamondSquare`, `generateLSystem`, `generateBspDungeon`, `generateRecursiveMaze`, `generatePrimMaze`, `generateKruskalMaze` | `procedural/*.ts` | `examples/simplex.ts`, `examples/worley.ts`, `examples/waveFunctionCollapse.ts`, `examples/cellularAutomata.ts`, `examples/poissonDisk.ts`, `examples/voronoi.ts`, `examples/diamondSquare.ts`, `examples/lSystem.ts`, `examples/dungeonBsp.ts`, `examples/mazeRecursive.ts`, `examples/mazePrim.ts`, `examples/mazeKruskal.ts` |
 | Spatial queries & collision | `Quadtree`, `aabbCollision`, `aabbIntersection`, `satCollision`, `circleRayIntersection`, `sweptAABB` | `spatial/*.ts` | `examples/sat.ts` |
 | Web performance & UI throttling | `debounce`, `throttle`, `LRUCache`, `memoize`, `deduplicateRequest`, `clearRequestDedup`, `calculateVirtualRange` | `util/*.ts` | `examples/requestDedup.ts`, `examples/virtualScroll.ts` |
 | Text & search | `fuzzySearch`, `fuzzyScore`, `Trie`, `binarySearch`, `levenshteinDistance` | `search/*.ts` | `examples/search.ts` |

README.md

@@ -25,7 +25,7 @@ CDN usage:
 | Goal | Algorithms | Import From | Example |
 | ---- | ---------- | ----------- | ------- |
 | Pathfinding & navigation | `astar`, `dijkstra`, `jumpPointSearch`, `computeFlowField`, `buildNavMesh`, `findNavMeshPath`, `manhattanDistance`, `gridFromString` | `pathfinding/astar.ts`, `pathfinding/dijkstra.ts`, `pathfinding/jumpPointSearch.ts`, `pathfinding/flowField.ts`, `pathfinding/navMesh.ts` | `examples/astar.ts`, `examples/flowField.ts`, `examples/navMesh.ts` |
-| Procedural generation | `perlin`, `perlin3D`, `simplex2D`, `simplex3D`, `worley`, `worleySample`, `waveFunctionCollapse`, `cellularAutomataCave`, `poissonDiskSampling`, `computeVoronoiDiagram`, `diamondSquare`, `generateLSystem`, `generateBspDungeon`, `generateRecursiveMaze`, `generatePrimMaze` | `procedural/*.ts` | `examples/simplex.ts`, `examples/worley.ts`, `examples/waveFunctionCollapse.ts`, `examples/cellularAutomata.ts`, `examples/poissonDisk.ts`, `examples/voronoi.ts`, `examples/diamondSquare.ts`, `examples/lSystem.ts`, `examples/dungeonBsp.ts`, `examples/mazeRecursive.ts`, `examples/mazePrim.ts` |
+| Procedural generation | `perlin`, `perlin3D`, `simplex2D`, `simplex3D`, `worley`, `worleySample`, `waveFunctionCollapse`, `cellularAutomataCave`, `poissonDiskSampling`, `computeVoronoiDiagram`, `diamondSquare`, `generateLSystem`, `generateBspDungeon`, `generateRecursiveMaze`, `generatePrimMaze`, `generateKruskalMaze` | `procedural/*.ts` | `examples/simplex.ts`, `examples/worley.ts`, `examples/waveFunctionCollapse.ts`, `examples/cellularAutomata.ts`, `examples/poissonDisk.ts`, `examples/voronoi.ts`, `examples/diamondSquare.ts`, `examples/lSystem.ts`, `examples/dungeonBsp.ts`, `examples/mazeRecursive.ts`, `examples/mazePrim.ts`, `examples/mazeKruskal.ts` |
 | Spatial queries & collision | `Quadtree`, `aabbCollision`, `aabbIntersection`, `satCollision`, `circleRayIntersection`, `sweptAABB` | `spatial/*.ts` | `examples/sat.ts` |
 | AI behaviours & crowds | `seek`, `flee`, `arrive`, `pursue`, `wander`, `updateBoids`, `BehaviorTree`, `rvoStep` | `ai/steering.ts`, `ai/boids.ts`, `ai/behaviorTree.ts`, `ai/rvo.ts` | `examples/steering.ts`, `examples/boids.ts`, `examples/rvo.ts` |
 | Web performance & UI | `debounce`, `throttle`, `LRUCache`, `memoize`, `deduplicateRequest`, `clearRequestDedup`, `calculateVirtualRange` | `util/*.ts` | `examples/requestDedup.ts`, `examples/virtualScroll.ts` |
@@ -52,7 +52,7 @@ npm run size        # Enforce bundle size budget
 - Milestone 0.2 next targets crowd-flow integrations (RVO + flow fields) and behaviour-tree decorators for richer AI control.
 - Milestone 0.4 plans a procedural + gameplay systems toolkit (Wave Function Collapse, dungeon suite, L-systems, game loop, camera, particles, inventory, combat, save/load, and more).
 
-Examples live under `examples/` and can be executed with `tsx`/`ts-node` or compiled for the browser. See `examples/astar.ts`, `examples/flowField.ts`, `examples/navMesh.ts`, `examples/cellularAutomata.ts`, `examples/poissonDisk.ts`, `examples/voronoi.ts`, `examples/diamondSquare.ts`, `examples/lSystem.ts`, `examples/dungeonBsp.ts`, `examples/mazeRecursive.ts`, `examples/mazePrim.ts`, `examples/steering.ts`, `examples/boids.ts`, `examples/requestDedup.ts`, `examples/search.ts`, `examples/graph.ts`, `examples/geometry.ts`, `examples/visual.ts`, `examples/sat.ts`, `examples/simplex.ts`, and `examples/worley.ts` for quick starts. The `examples` registry exported from `src/index.ts` provides a typed index you can traverse programmatically.
+Examples live under `examples/` and can be executed with `tsx`/`ts-node` or compiled for the browser. See `examples/astar.ts`, `examples/flowField.ts`, `examples/navMesh.ts`, `examples/cellularAutomata.ts`, `examples/poissonDisk.ts`, `examples/voronoi.ts`, `examples/diamondSquare.ts`, `examples/lSystem.ts`, `examples/dungeonBsp.ts`, `examples/mazeRecursive.ts`, `examples/mazePrim.ts`, `examples/mazeKruskal.ts`, `examples/steering.ts`, `examples/boids.ts`, `examples/requestDedup.ts`, `examples/search.ts`, `examples/graph.ts`, `examples/geometry.ts`, `examples/visual.ts`, `examples/sat.ts`, `examples/simplex.ts`, and `examples/worley.ts` for quick starts. The `examples` registry exported from `src/index.ts` provides a typed index you can traverse programmatically.
 
 ## Contributing
 1. Fork the repository.

docs/index.d.ts

@@ -54,6 +54,7 @@ export const examples: {
     readonly generateBspDungeon: 'examples/dungeonBsp.ts';
     readonly generateRecursiveMaze: 'examples/mazeRecursive.ts';
     readonly generatePrimMaze: 'examples/mazePrim.ts';
+    readonly generateKruskalMaze: 'examples/mazeKruskal.ts';
   };
   readonly spatial: {
     readonly Quadtree: 'examples/sat.ts';
@@ -619,6 +620,14 @@ export function generateRecursiveMaze(options: MazeOptions): MazeResult;
  */
 export function generatePrimMaze(options: MazeOptions): MazeResult;
 
+/**
+ * Generates a maze using Kruskal's algorithm with disjoint sets.
+ * Use for: evenly distributed corridors with minimal bias.
+ * Performance: O(width × height log cells).
+ * Import: procedural/maze.ts
+ */
+export function generateKruskalMaze(options: MazeOptions): MazeResult;
+
 /**
  * Simplex noise generator for smooth gradients without directional artifacts.
  * Use for: large terrain synthesis, animated textures, volumetric noise.

examples/mazeKruskal.ts

@@ -0,0 +1,11 @@
+import { generateKruskalMaze } from '../src/index.js';
+
+const { grid, start, end } = generateKruskalMaze({
+  width: 21,
+  height: 21,
+  seed: 777,
+});
+
+console.log('Start:', start);
+console.log('End:', end);
+console.log('Sample row:', grid[10]?.join(''));

src/index.ts

@@ -50,6 +50,7 @@ export const examples = {
     generateBspDungeon: 'examples/dungeonBsp.ts',
     generateRecursiveMaze: 'examples/mazeRecursive.ts',
     generatePrimMaze: 'examples/mazePrim.ts',
+    generateKruskalMaze: 'examples/mazeKruskal.ts',
   },
   spatial: {
     Quadtree: 'examples/sat.ts',
@@ -290,6 +291,13 @@ export { generateRecursiveMaze } from './procedural/maze.js';
  */
 export { generatePrimMaze } from './procedural/maze.js';
 
+/**
+ * Kruskal's maze generator for evenly distributed layouts.
+ *
+ * Example file: examples/mazeKruskal.ts
+ */
+export { generateKruskalMaze } from './procedural/maze.js';
+
 // ============================================================================
 // 🎯 SPATIAL & COLLISION
 // ============================================================================

src/procedural/maze.ts

@@ -44,11 +44,7 @@ export function generateRecursiveMaze({
 
     const next = neighbours.find((candidate) => isWall(candidate, grid));
     if (next) {
-      const mid = {
-        x: current.x + (next.x - current.x) / 2,
-        y: current.y + (next.y - current.y) / 2,
-      };
-      carveCell(grid, mid);
+      carveCorridorBetween(grid, current, next);
       carveCell(grid, next);
       stack.push(next);
     } else {
@@ -65,7 +61,7 @@ export function generateRecursiveMaze({
 
 /**
  * Generates a maze using randomized Prim's algorithm.
- * Useful for: maze layouts with different structural characteristics than DFS.
+ * Useful for: mazes with branching corridors differing from DFS results.
  */
 export function generatePrimMaze({
   width,
@@ -99,6 +95,7 @@ export function generatePrimMaze({
     if (!neighbour) {
       continue;
     }
+
     carveCorridorBetween(grid, cell, neighbour);
     carveCell(grid, cell);
     addFrontierCells(cell, grid, frontier);
@@ -110,6 +107,70 @@ export function generatePrimMaze({
   return { grid, start, end };
 }
 
+/**
+ * Generates a maze using Kruskal's algorithm with a disjoint-set structure.
+ * Useful for: evenly distributed mazes with minimal bias.
+ */
+export function generateKruskalMaze({
+  width,
+  height,
+  seed = Date.now(),
+}: MazeOptions): MazeResult {
+  validateDimensions(width, height);
+
+  const grid = Array.from({ length: height }, () => Array<number>(width).fill(WALL));
+  const random = createLinearCongruentialGenerator(seed);
+
+  const cells: Cell[] = [];
+  const indexMap = new Map<string, number>();
+  let idx = 0;
+  for (let y = 1; y < height; y += 2) {
+    for (let x = 1; x < width; x += 2) {
+      cells.push({ x, y });
+      indexMap.set(cellKey(x, y), idx);
+      idx += 1;
+      carveCell(grid, { x, y });
+    }
+  }
+
+  const dsu = createDisjointSet(cells.length);
+  const edges: Array<{ a: Cell; b: Cell }> = [];
+
+  for (const cell of cells) {
+    const neighbours: Array<[number, number]> = [
+      [2, 0],
+      [0, 2],
+    ];
+    for (const [dx, dy] of neighbours) {
+      const nx = cell.x + dx;
+      const ny = cell.y + dy;
+      if (nx < width && ny < height) {
+        edges.push({ a: cell, b: { x: nx, y: ny } });
+      }
+    }
+  }
+
+  shuffle(edges, random);
+
+  for (const edge of edges) {
+    const aIndex = indexMap.get(cellKey(edge.a.x, edge.a.y));
+    const bIndex = indexMap.get(cellKey(edge.b.x, edge.b.y));
+    if (aIndex === undefined || bIndex === undefined) {
+      continue;
+    }
+    if (findSet(dsu, aIndex) !== findSet(dsu, bIndex)) {
+      unionSet(dsu, aIndex, bIndex);
+      carveCorridorBetween(grid, edge.a, edge.b);
+    }
+  }
+
+  const start: Cell = { x: 1, y: 1 };
+  const end = findFarthestCell(start, grid);
+  carveCell(grid, end);
+
+  return { grid, start, end };
+}
+
 function validateDimensions(width: number, height: number): void {
   if (!Number.isInteger(width) || !Number.isInteger(height)) {
     throw new Error('width and height must be integers.');
@@ -204,3 +265,47 @@ function findFarthestCell(start: Cell, grid: number[][]): Cell {
   }
   return farthest;
 }
+
+function cellKey(x: number, y: number): string {
+  return `${x}:${y}`;
+}
+
+function shuffle<T>(items: T[], random: () => number): void {
+  for (let i = items.length - 1; i > 0; i -= 1) {
+    const j = Math.floor(random() * (i + 1));
+    [items[i], items[j]] = [items[j], items[i]];
+  }
+}
+
+function createDisjointSet(size: number): Int32Array {
+  const parent = new Int32Array(size);
+  for (let i = 0; i < size; i += 1) {
+    parent[i] = -1;
+  }
+  return parent;
+}
+
+function findSet(parent: Int32Array, index: number): number {
+  if (parent[index] < 0) {
+    return index;
+  }
+  parent[index] = findSet(parent, parent[index]);
+  return parent[index];
+}
+
+function unionSet(parent: Int32Array, a: number, b: number): void {
+  const rootA = findSet(parent, a);
+  const rootB = findSet(parent, b);
+  if (rootA === rootB) {
+    return;
+  }
+  const sizeA = -parent[rootA];
+  const sizeB = -parent[rootB];
+  if (sizeA >= sizeB) {
+    parent[rootA] -= sizeB;
+    parent[rootB] = rootA;
+  } else {
+    parent[rootB] -= sizeA;
+    parent[rootA] = rootB;
+  }
+}

tests/index.test.ts

@@ -16,6 +16,7 @@ describe('package entry point', () => {
     expect(examples.procedural.generateBspDungeon).toBe('examples/dungeonBsp.ts');
     expect(examples.procedural.generateRecursiveMaze).toBe('examples/mazeRecursive.ts');
     expect(examples.procedural.generatePrimMaze).toBe('examples/mazePrim.ts');
+    expect(examples.procedural.generateKruskalMaze).toBe('examples/mazeKruskal.ts');
     expect(examples.search.Trie).toBe('examples/search.ts');
     expect(examples.pathfinding.buildNavMesh).toBe('examples/navMesh.ts');
   });
@@ -62,6 +63,7 @@ describe('package entry point', () => {
       | 'generateBspDungeon'
       | 'generateRecursiveMaze'
       | 'generatePrimMaze'
+      | 'generateKruskalMaze'
     >();
   });
 });

tests/mazeKruskal.test.ts

@@ -0,0 +1,24 @@
+import { describe, expect, it } from 'vitest';
+
+import { generateKruskalMaze } from '../src/index.js';
+
+describe('generateKruskalMaze', () => {
+  it('is deterministic for identical seeds', () => {
+    const options = { width: 21, height: 21, seed: 404 } as const;
+    const a = generateKruskalMaze(options);
+    const b = generateKruskalMaze(options);
+
+    expect(a.grid).toEqual(b.grid);
+    expect(a.start).toEqual(b.start);
+    expect(a.end).toEqual(b.end);
+  });
+
+  it('produces a maze fully enclosed by walls', () => {
+    const { grid } = generateKruskalMaze({ width: 17, height: 17, seed: 99 });
+    expect(grid[0].every((cell) => cell === 1)).toBe(true);
+    expect(grid[grid.length - 1].every((cell) => cell === 1)).toBe(true);
+    expect(grid.every((row) => row[0] === 1 && row[row.length - 1] === 1)).toBe(true);
+    const walkable = grid.flat().filter((cell) => cell === 0).length;
+    expect(walkable).toBeGreaterThan(0);
+  });
+});