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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,192 @@ | ||
| import type { Point } from '@/internal-types'; | ||
|
|
||
| export class ANode { | ||
| x: number; | ||
| y: number; | ||
| g = Infinity; | ||
| h = 0; | ||
| f = Infinity; | ||
| parent: ANode | null = null; | ||
|
|
||
| constructor(x: number, y: number) { | ||
| this.x = x; | ||
| this.y = y; | ||
| } | ||
| } | ||
|
|
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| class PriorityQueue { | ||
| nodes: ANode[] = []; | ||
|
|
||
| enqueue(node: ANode) { | ||
| this.nodes.push(node); | ||
| this.nodes.sort((a, b) => a.f - b.f); | ||
| } | ||
|
|
||
| dequeue() { | ||
| return this.nodes.shift(); | ||
| } | ||
|
|
||
| includes(node: ANode) { | ||
| return this.nodes.some(n => n.x === node.x && n.y === node.y); | ||
| } | ||
| } | ||
|
|
||
| function heuristic(a: Point, b: Point) { | ||
| return Math.abs(a.x - b.x) + Math.abs(a.y - b.y); | ||
| } | ||
|
|
||
| export type Wall = { | ||
| minX: number; | ||
| maxX: number; | ||
| minY: number; | ||
| maxY: number; | ||
| }; | ||
|
|
||
| function getNeighbors( | ||
| node: ANode, | ||
| end: ANode, | ||
| walls: Wall[], | ||
| boundary: number | ||
| ) { | ||
| const neighbors = []; | ||
| const directions = [ | ||
| [1, 0], | ||
| [-1, 0], | ||
| [0, 1], | ||
| [0, -1], | ||
| // [1, 1], | ||
| // [-1, -1], | ||
| // [1, -1], | ||
| // [-1, 1], | ||
| ]; | ||
|
|
||
| for (const [dx, dy] of directions) { | ||
| const x = node.x + dx; | ||
| const y = node.y + dy; | ||
|
|
||
| if (Math.abs(x - end.x) > boundary || Math.abs(y - end.y) > boundary) { | ||
| continue; | ||
| } | ||
|
|
||
| const isWall = walls.some( | ||
| wall => | ||
| wall.minX <= x && x <= wall.maxX && wall.minY <= y && y <= wall.maxY | ||
| ); | ||
| if (isWall) { | ||
| continue; | ||
| } | ||
|
|
||
| const neighbor = new ANode(x, y); | ||
| neighbors.push(neighbor); | ||
| } | ||
|
|
||
| return neighbors; | ||
| } | ||
|
|
||
| export function aStar( | ||
| start: ANode, | ||
| end: ANode, | ||
| walls: Wall[], | ||
| boundary = 400 | ||
| ): Point[] { | ||
| const openSet = new PriorityQueue(); | ||
| const closedSet = new Set(); | ||
|
|
||
| start.g = 0; | ||
| start.h = heuristic(start, end); | ||
| start.f = start.h; | ||
| openSet.enqueue(start); | ||
|
|
||
| while (openSet.nodes.length > 0) { | ||
| const current = openSet.dequeue()!; | ||
|
|
||
| if (current.x === end.x && current.y === end.y) { | ||
| return reconstructPath(current); | ||
| } | ||
|
|
||
| closedSet.add(`${current.x},${current.y}`); | ||
|
|
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| const neighbors = getNeighbors(current, end, walls, boundary); | ||
| for (const neighbor of neighbors) { | ||
| const key = `${neighbor.x},${neighbor.y}`; | ||
|
|
||
| if (closedSet.has(key)) { | ||
| continue; | ||
| } | ||
|
|
||
| const tentativeG = | ||
| current.g + | ||
| (current.x !== neighbor.x && current.y !== neighbor.y ? Math.SQRT2 : 1); | ||
|
|
||
| if (tentativeG < neighbor.g) { | ||
| neighbor.parent = current; | ||
| neighbor.g = tentativeG; | ||
| neighbor.h = heuristic(neighbor, end); | ||
| neighbor.f = neighbor.g + neighbor.h; | ||
|
|
||
| if (!openSet.includes(neighbor)) { | ||
| openSet.enqueue(neighbor); | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| return []; | ||
| } | ||
|
|
||
| function reconstructPath(node: ANode | null): Point[] { | ||
| const path: ANode[] = []; | ||
| while (node) { | ||
| path.push(node); | ||
| node = node.parent; | ||
| } | ||
| return compressPath(path.reverse()); | ||
| } | ||
|
|
||
| function compressPath(nodes: ANode[]): Point[] { | ||
| if (nodes.length < 3) { | ||
| return nodes.map(node => ({ x: node.x, y: node.y })); | ||
| } | ||
|
|
||
| const compressed: Point[] = []; | ||
|
|
||
| let sx = nodes[0].x; | ||
| let sy = nodes[0].y; | ||
| let px = nodes[1].x; | ||
| let py = nodes[1].y; | ||
| let dx = px - sx; | ||
| let dy = py - sy; | ||
| let lx, ly, ldx, ldy, sq, i; | ||
|
|
||
| sq = Math.sqrt(dx * dx + dy * dy); | ||
| dx /= sq; | ||
| dy /= sq; | ||
|
|
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| compressed.push({ x: sx, y: sy }); | ||
|
|
||
| for (i = 2; i < nodes.length; i++) { | ||
| lx = px; | ||
| ly = py; | ||
|
|
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| ldx = dx; | ||
| ldy = dy; | ||
|
|
||
| px = nodes[i].x; | ||
| py = nodes[i].y; | ||
|
|
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| dx = px - lx; | ||
| dy = py - ly; | ||
|
|
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| sq = Math.sqrt(dx * dx + dy * dy); | ||
| dx /= sq; | ||
| dy /= sq; | ||
|
|
||
| if (dx !== ldx || dy !== ldy) { | ||
| compressed.push({ x: lx, y: ly }); | ||
| } | ||
| } | ||
|
|
||
| compressed.push({ x: px, y: py }); | ||
|
|
||
| return compressed; | ||
| } |
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