A星算法

没有采用二叉堆算法优化, 学习了几天终于搞除了一个demo, 这个列子如果点击按钮生成的方块大小不正确,可以先设置下预设调成相应的大小

只能上下左右走

 

using UnityEngine;

using System.Collections;

using System.Collections.Generic;

using System;



public class AStar

{



    public static PriorityQueue closedList;

    public static PriorityQueue openList;







    public static List<Node> FindPath(Node start, Node goal)

    {

        closedList = new PriorityQueue();

        openList = new PriorityQueue();                 //初始化OpenList

        openList.Push(start);                           //把开始节点放入OpenList中



        start.F = 0;

        start.G = 0;

        start.H = NodeCost(start, goal);



        start.SetH(start.H);

        start.SetF(start.F);

        start.SetG(start.G);





        Node node = null;

        List<Node> neighbours = null;

        Node neighbourNode = null;

        DateTime now = System.DateTime.Now;



        while (openList.Length != 0)

        {

            node = openList.First();



            //如果是终点,就返回一个列表list过去

            if (node.x == goal.x && node.y == goal.y)

            {

                Debug.Log("算法所消耗的时间: " + (System.DateTime.Now - now).TotalSeconds);

                return CalculatePath(node);

            }



            neighbours = new List<Node>();

            GridManager.Instance.GetNeighbours(node, neighbours);           //获取周围的格子加入列表中



            //遍历周围的方块

            for (int i = 0; i < neighbours.Count; i++)

            {

                neighbourNode = neighbours[i];



                float newCost = node.G + TraverseCost(node,neighbourNode);



                //相邻的方块如果以前的G值小于 这次计算的G值就忽略该格子

                if ((closedList.Contains(neighbourNode) || openList.Contains(neighbourNode)) && (neighbourNode.G <= newCost))

                {

                    continue;



                }else{

                    neighbourNode.G = newCost;

                    neighbourNode.parent = node;

                    neighbourNode.H = NodeCost(neighbourNode, goal);                                //这个格子离终点的估算

                    neighbourNode.F = neighbourNode.G + neighbourNode.H;

                    



                    //显示H F G的值

                    neighbourNode.SetH(neighbourNode.H);

                    neighbourNode.SetF(neighbourNode.F);

                    neighbourNode.SetG(neighbourNode.G);



                    

                    //如果方块不在开启列表中,就添加到开启列表中

                    if (!openList.Contains(neighbourNode))

                    {

                        openList.Push(neighbourNode);

                    }

                }

            }



            //把寻找的节点放入关闭列表中

            closedList.Push(node);

            openList.Remove(node);

            node.closeed = true;

        }



        Debug.Log("算法所消耗的时间: " + (System.DateTime.Now - now).TotalMilliseconds);



        if (node.x != goal.x && node.y != goal.y)

        {

            Debug.LogError("没有找到路径");

            return null;

        }



        Debug.Log("找到路径了");

        return CalculatePath(node);

    }



    /// <summary>

    /// 获取两个节点的距离(不计算障碍物)

    /// </summary>

    /// <param name="a">开始节点</param>

    /// <param name="b">结束节点</param>

    /// <returns>返回x +y 的距离</returns>

    private static int NodeCost(Node a, Node b)

    {

        int x = (int)Mathf.Abs(b.x - a.x);

        int y = (int)Mathf.Abs(b.y - a.y);

        return x + y;

    }



    /// <summary>

    /// 获取最终路径

    /// </summary>

    /// <param name="node"></param>

    /// <returns></returns>

    private static List<Node> CalculatePath(Node node)

    {

        List<Node> list = new List<Node>();



        while (node != null)

        {

            list.Add(node);

            node = node.parent;

        }

        list.Reverse();

        return list;

    }





    public static float TraverseCost(Node a,Node b) 

    {

        if (b.xiejia)

        {

            b.xiejia = false; 

            return a.G + 1.4f;

        }

        else 

        {

            return a.G + 1.0f;

        }

    }



}

 

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