111 lines
3.8 KiB
TypeScript
111 lines
3.8 KiB
TypeScript
///<reference path="./PriorityQueueNode.ts" />
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module es {
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/**
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* 计算路径给定的IAstarGraph和开始/目标位置
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*/
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export class AStarPathfinder {
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/**
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* 尽可能从开始到目标找到一条路径。如果没有找到路径，则返回null。
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* @param graph
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* @param start
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* @param goal
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*/
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public static search<T>(graph: IAstarGraph<T>, start: T, goal: T) {
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let foundPath = false;
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let cameFrom = new Map<T, T>();
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cameFrom.set(start, start);
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let costSoFar = new Map<T, number>();
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let frontier = new PriorityQueue<AStarNode<T>>(1000);
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frontier.enqueue(new AStarNode<T>(start), 0);
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costSoFar.set(start, 0);
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while (frontier.count > 0) {
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let current = frontier.dequeue();
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if (current.data instanceof Vector2 && goal instanceof Vector2 && current.data.equals(goal)) {
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foundPath = true;
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break;
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} else if (current.data == goal){
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foundPath = true;
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break;
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}
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graph.getNeighbors(current.data).forEach(next => {
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let newCost = costSoFar.get(current.data) + graph.cost(current.data, next);
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if (!this.hasKey(costSoFar, next) || newCost < costSoFar.get(next)) {
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costSoFar.set(next, newCost);
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let priority = newCost + graph.heuristic(next, goal);
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frontier.enqueue(new AStarNode<T>(next), priority);
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cameFrom.set(next, current.data);
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}
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});
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}
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return foundPath ? this.recontructPath(cameFrom, start, goal) : null;
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}
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/**
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* 从cameFrom字典重新构造路径
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* @param cameFrom
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* @param start
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* @param goal
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*/
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public static recontructPath<T>(cameFrom: Map<T, T>, start: T, goal: T): T[] {
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let path = [];
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let current = goal;
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path.push(goal);
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while (current != start) {
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current = this.getKey(cameFrom, current);
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path.push(current);
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}
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path.reverse();
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return path;
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}
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private static hasKey<T>(map: Map<T, number>, compareKey: T) {
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let iterator = map.keys();
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let r: IteratorResult<T>;
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while (r = iterator.next() , !r.done) {
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if (r.value instanceof Vector2 && compareKey instanceof Vector2 && r.value.equals(compareKey))
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return true;
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else if (r.value == compareKey)
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return true;
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}
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return false;
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}
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private static getKey<T>(map: Map<T, T>, compareKey: T) {
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let iterator = map.keys();
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let valueIterator = map.values();
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let r: IteratorResult<T>;
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let v: IteratorResult<T>;
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while (r = iterator.next(), v = valueIterator.next(), !r.done) {
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if (r.value instanceof Vector2 && compareKey instanceof Vector2 && r.value.equals(compareKey))
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return v.value;
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else if (r.value == compareKey)
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return v.value;
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}
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return null;
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}
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}
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/**
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* 使用PriorityQueue需要的额外字段将原始数据封装在一个小类中
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*/
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class AStarNode<T> extends PriorityQueueNode {
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public data: T;
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constructor(data: T) {
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super();
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this.data = data;
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}
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}
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}
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