记录一个下午撸的A星寻路算法

大致思路主要围绕open表和close表可能的路径点先放到open列表里面(如果该点已经存在于close则跳过，如果改点已经存在与open中，则判断和值是否更小，如果是则更新)open列表里面和值最小的转移到close里面去，直到最终到达终点，再遍历前寄得到所有路径点。（8方向不会对角线穿墙）

//曼哈顿估价法function manhattan(point, endPoint) {    return Math.abs(point.x - endPoint.x) + Math.abs(point.y - endPoint.y);}/** *  * @param {Number} row 行 * @param {Number} col 列 */var aStar = function (row, col) {    if (row <= 0 || col <= 0) {        console.error('error query');        return;    }    //初始化棋盘    this._list = [];    this._row = row;    this._col = col;    for (var i = 0; i < row; i++) {        this._list[i] = [];        for (var j = 0; j < col; j++) {            this._list[i][j] = 1;        }    }};/** * 添加障碍物 */aStar.prototype.addObstacle = function (points) {    if (typeof points.length !== 'undefined') {        for (var i = 0; i < points.length; i++) {            var point = points[i];            this._list[point.x][point.y] = 0;        }    } else {        this._list[points.x][points.y] = 0;    }};/** * 获得路径(direction!==4则按8方向计算路径) */aStar.prototype.getRoute = function (startPoint, endPoint, direction) {    if (!this._list[startPoint.x][startPoint.y] || !this._list[endPoint.x][endPoint.y]) {        console.error('起点或终点不能是障碍物');        return [];    }    if (startPoint.x == endPoint.x && startPoint.y == endPoint.y) {        console.error('起点和终点不能相同');        return [];    }    this._openList = [];    //一个记录下所有被考虑来寻找最短路径的方块    this._closeList = {};   //一个记录下不会再被考虑的方块    //将节点添加到open列表中去    var head = null;    var node = this._createNode(head, startPoint, endPoint);    this._addNodeToOpenList(node);    return this._getRoute(endPoint, direction);};aStar.prototype._getRoute = function (endPoint, direction) {    //获得open列表中最小和值的节点    var list = this._getOpenMin();    if (list.length === 0) {        return [];    }    for (var i = 0; i < list.length; i++) {        var e = list[i];        var index = e.index;        var node = e.node;        if (node.data.H === 0/** 已经是终点*/) {            var route = [];            while (node.head) {                route.splice(0, 0, node.point);                node = node.head;            }            route.splice(0, 0, node.point);            return route;        }        //添加到close列表中去        this._addOpenToCloseList(index, node);        //遍历邻居点        /**         * 如果p在closed列表中：不管它。         * 如果p不在open列表中：添加它然后计算出它的和值。         * 如果p已经在open列表中：当我们使用当前生成的路径到达那里时，检查F 和值是否更小。如果是，更新它的和值和它的前继。         */        this._getNeighbor(node.point, function (point) {            if (this._list[point.x][point.y]/** 不是障碍物*/ && !this._closeList[point.x + ',' + point.y]/** 不在close表里面*/) {                var n = this._createNode(node, point, endPoint);                this._addNodeToOpenList(n);            }        }, direction);    }    return this._getRoute(endPoint, direction);};/** * 寻找周围的节点 *  * @param {any} point 基础点 * @param {any} cb 回掉 * @param {bool} d 8方向还是4方向，默认8 8方向 *  */aStar.prototype._getNeighbor = function (point, cb, d) {    var xMin = point.x > 0 ? (point.x - 1) : 0;    var xMax = (point.x < this._col - 1) ? (point.x + 1) : point.x;    var yMin = point.y > 0 ? (point.y - 1) : 0;    var yMax = (point.y < this._row - 1) ? (point.y + 1) : point.y;    for (var i = xMin; i <= xMax; i++) {        for (var j = yMin; j <= yMax; j++) {            if (d === 4) {                //4方向                if ((i !== point.x && j === point.y) || (i === point.x && j !== point.y)) {                    cb.call(this, { x: i, y: j });                }            } else {                if (this._judgeAcross(point, { x: i, y: j })) {                    //8方向                    if (i !== point.x || j !== point.y) {                        cb.call(this, { x: i, y: j });                    }                }            }        }    }};/** * 主要用于8方向时判断路径是否穿墙了 */aStar.prototype._judgeAcross = function (p1, p2) {    if (p1.x !== p2.x && p1.y !== p2.y) {        if (this._list[p1.x][p2.y] === 0 && this._list[p2.x][p1.y] === 0) {            return false;        }    }    return true;};/** * 将open列表里面的节点添加到close里面去，同时从open中删除 */aStar.prototype._addOpenToCloseList = function (index, node) {    var k = node.point.x + ',' + node.point.y;    this._closeList[k] = node;    this._openList.splice(index, 1);};/** * 添加节点到open列表 */aStar.prototype._addNodeToOpenList = function (node) {    for (var i = this._openList.length - 1; i >= 0; i--) {        var n = this._openList[i];        if (n.point.x === node.point.x && n.point.y === node.point.y) {            if (n.data.F < node.data.F) {                return;            }            this._openList.splice(i, 1);            break;        }    }    this._openList.push(node);};aStar.prototype._createNode = function (head, point, endPoint) {    var addG = 1;    if (head && head.x !== point.x && head.y !== point.y) {        addG = 1.414213562373095;    }    var G = head ? head.data.G + 1 : 0;    var H = manhattan(point, endPoint);    return {        head: head,        data: {            F: G + H,            G: G,            H: H        },        point: point    };};aStar.prototype._getOpenMin = function () {    var min = [];    var minF = 0;    for (var i = this._openList.length - 1; i >= 0; i--) {        var element = this._openList[i];        if (!minF) {            minF = element.data.F;        }        if (element.data.F === minF) {            min.push({ index: i, node: element });        } else if (element.data.F < minF) {            minF = element.data.F;            min = [{ index: i, node: element }];        }    }    return min;};var a = new aStar(30, 30);a.addObstacle({ x: 0, y: 1 });a.addObstacle({ x: 2, y: 0 });a.addObstacle({ x: 2, y: 1 });a.addObstacle({ x: 2, y: 2 });a.addObstacle({ x: 1, y: 3 });a.addObstacle({ x: 10, y: 20 });a.addObstacle({ x: 14, y: 13 });a.addObstacle({ x: 14, y: 14 });a.addObstacle({ x: 14, y: 15 });a.addObstacle({ x: 14, y: 16 });console.time('a');var route = a.getRoute({ x: 0, y: 0 }, { x: 20, y: 15 });console.timeEnd('a');for (var i = 0; i < route.length; i++) {    var p = route[i];    a._list[p.x][p.y] = '@';}for (var i = 0; i < a._list.length; i++) {    console.log(a._list[i].toString());}