82 lines
2.1 KiB
TypeScript
82 lines
2.1 KiB
TypeScript
import type { Position } from '@dflike/shared';
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import type { GameMap } from './GameMap.js';
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interface Node {
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x: number;
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y: number;
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g: number;
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h: number;
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f: number;
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parent: Node | null;
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}
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function heuristic(a: Position, b: Position): number {
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return Math.abs(a.x - b.x) + Math.abs(a.y - b.y);
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}
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const NEIGHBORS = [
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{ dx: 0, dy: -1 },
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{ dx: 0, dy: 1 },
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{ dx: -1, dy: 0 },
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{ dx: 1, dy: 0 },
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];
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export function findPath(map: GameMap, start: Position, goal: Position): Position[] | null {
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if (start.x === goal.x && start.y === goal.y) return [];
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const open: Node[] = [];
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const closed = new Set<string>();
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const key = (x: number, y: number) => `${x},${y}`;
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const startNode: Node = {
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x: start.x, y: start.y,
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g: 0, h: heuristic(start, goal), f: heuristic(start, goal),
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parent: null,
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};
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open.push(startNode);
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while (open.length > 0) {
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// Find lowest f
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let bestIdx = 0;
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for (let i = 1; i < open.length; i++) {
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if (open[i].f < open[bestIdx].f) bestIdx = i;
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}
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const current = open.splice(bestIdx, 1)[0];
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if (current.x === goal.x && current.y === goal.y) {
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// Reconstruct path (excluding start)
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const path: Position[] = [];
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let node: Node | null = current;
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while (node && !(node.x === start.x && node.y === start.y)) {
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path.push({ x: node.x, y: node.y });
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node = node.parent;
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}
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return path.reverse();
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}
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closed.add(key(current.x, current.y));
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for (const { dx, dy } of NEIGHBORS) {
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const nx = current.x + dx;
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const ny = current.y + dy;
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if (!map.isWalkable(nx, ny) || closed.has(key(nx, ny))) continue;
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const g = current.g + 1;
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const h = heuristic({ x: nx, y: ny }, goal);
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const existing = open.find(n => n.x === nx && n.y === ny);
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if (existing) {
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if (g < existing.g) {
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existing.g = g;
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existing.f = g + h;
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existing.parent = current;
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}
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} else {
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open.push({ x: nx, y: ny, g, h, f: g + h, parent: current });
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}
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}
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}
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return null; // No path found
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}
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