A星寻路，在Unity上用C#代码实现。

A星寻路原理：

略，网上可搜到

通过理解A星寻路的原理可以设计出以下流程图：

流程图通过processon制作

Unity C#脚本实现代码：

各个坐标节点为单独的gameObject，并自带脚本：

using UnityEngine;
using System.Collections;

public class AStarNodeSC : MonoBehaviour {

    public bool obstacle=false;
    public float CostG=0;
    public float CostH=0;
    public float CostF
    {
        get
        {
            return this.CostG + this.CostH;
        }
    }

    public GameObject previousNode=null;




    // Use this for initialization
    void Start () {

    }

    // Update is called once per frame
    void Update () {




    }
}

场景控制脚本，各个成员，包括根据流程图写出的寻路方法：

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;

public class AStarNew : MonoBehaviour {

    public Ray AStarRay;
    public RaycastHit AStarHit;
    public RaycastHit AStarHit2;

    public float CostG;
    public float CostH;

    public GameObject AStarNode;

    public GameObject start;
    public static GameObject end;
    public int SDflag=0;
    public float timespan=0;

    public static List OpenList=new List();
    public static List ClostList=new List();

    public static GameObject minnode;
    public static List adjpoints = new List ();
    public static GameObject routestart;
    public static int minnodeint;

    public GameObject AStarSearch(float x1,float y1,float x2,float y2,GameObject currentnode){

        adjpoints.Add (new Vector3 (x1, y1 - 1,1f));
        adjpoints.Add (new Vector3 (x1, y1 + 1,1f));
        adjpoints.Add (new Vector3 (x1 + 1, y1 - 1,1f));
        adjpoints.Add (new Vector3 (x1 + 1, y1,1f));
        adjpoints.Add (new Vector3 (x1 + 1, y1 + 1,1f));
        adjpoints.Add (new Vector3 (x1 - 1, y1 - 1,1f));
        adjpoints.Add (new Vector3 (x1 - 1, y1,1f));
        adjpoints.Add (new Vector3 (x1 - 1, y1 + 1,1f));

        foreach (Vector3 temp in adjpoints) {

            if (Physics.Linecast (new Vector3(temp.x,temp.y,-10), temp, out AStarHit2)) { //if the node is within the map

                if (ClostList.Contains(AStarHit2.transform.gameObject)) {
                    continue;
                }

                if (AStarHit2.transform.gameObject.GetComponent ().obstacle) {
                    continue;
                }

                if (OpenList.Contains (AStarHit2.transform.gameObject)) {

                    this.CostG=Mathf.Abs (AStarHit2.transform.position.x - currentnode.transform.position.x) + Mathf.Abs (AStarHit2.transform.position.y - currentnode.transform.position.y);

                    if (this.CostG <= 1.1f&&this.CostG>=0.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 10f;
                    }

                    if (this.CostG<=2.1f&&this.CostG>=1.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 14f;
                    }

                    if (AStarHit2.transform.gameObject.GetComponent ().CostG > this.CostG) {
                        AStarHit2.transform.gameObject.GetComponent ().previousNode = currentnode;
                        AStarHit2.transform.gameObject.GetComponent ().CostG = this.CostG;
                    }
                    continue;
                }


                if (!OpenList.Contains (AStarHit2.transform.gameObject) && !ClostList.Contains (AStarHit2.transform.gameObject)) {

                    this.CostG=Mathf.Abs (AStarHit2.transform.position.x - currentnode.transform.position.x) + Mathf.Abs (AStarHit2.transform.position.y - currentnode.transform.position.y);

                    if (this.CostG <= 1.1f&&this.CostG>=0.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 10f;
                    }

                    if (this.CostG<=2.1f&&this.CostG>=1.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 14f;
                    }

                    AStarHit2.transform.gameObject.GetComponent ().previousNode = currentnode;
                    AStarHit2.transform.gameObject.GetComponent ().CostG = this.CostG;
                    AStarHit2.transform.gameObject.GetComponent ().CostH = Mathf.Abs (AStarHit2.transform.position.x - x2) + Mathf.Abs (AStarHit2.transform.position.y - y2);

                    if (AStarHit2.transform.gameObject.GetComponent ().CostH >= -0.00001&&AStarHit2.transform.gameObject.GetComponent ().CostH <= 0.00001) {
                        return AStarHit2.transform.gameObject;
                    }

                    OpenList.Add (AStarHit2.transform.gameObject);
                    AStarHit2.transform.gameObject.GetComponent().material.color=Color.yellow;
                    continue;
                }
            }

            else{
                continue;
            }


        }

        adjpoints.RemoveRange (0, adjpoints.Count);

        OpenList.Remove (currentnode);
        ClostList.Add (currentnode);
        currentnode.GetComponent ().material.color = Color.gray;

        if (OpenList.Count == 0) {
            return null;
        }


        minnode = OpenList [0]; 
        minnodeint = 0;
        for(int i=0;i
            if (minnode.GetComponent ().CostF > OpenList[i].GetComponent ().CostF) {
                minnode = OpenList[i];
                minnodeint=i;
            }
        }
        return OpenList [minnodeint];
    }

场景控制脚本，在Start里对场景进行初始设置，以及在Update内通过鼠标设置障碍，起始点，终点并调用寻路方法：

    void Start () {

        int column = 50;
        int line = 50;

        for(int i=0;i
            for(int j=0;j
                GameObject aStarNodeClOne=Instantiate(AStarNode,new Vector2(i,j),AStarNode.transform.rotation)as GameObject;
            }
        }

        Camera.main.transform.position = new Vector3 (column/2, line/2,-15);
    }

    // Update is called once per frame
    void Update () {

        if (Input.GetMouseButton (0) && SDflag == 0){
            AStarRay= Camera.main.ScreenPointToRay (Input.mousePosition);
            if(Physics.Raycast (AStarRay, out AStarHit, 1000.3f)){ 
                AStarHit.transform.gameObject.GetComponent ().material.color = Color.red;
                AStarHit.transform.gameObject.GetComponent ().obstacle = true;
            }
        }

        if (Input.GetMouseButton (1) && SDflag == 0) {
            AStarRay = Camera.main.ScreenPointToRay (Input.mousePosition);
            if (Physics.Raycast (AStarRay, out AStarHit, 1000.3f)) { 
                print ("hit");
                SDflag = 1;
                start = AStarHit.transform.gameObject;
                AStarHit.transform.gameObject.GetComponent ().material.color = Color.blue;
            }
        }

        if(SDflag==1){
            timespan+=Time.deltaTime;
        }

        if (Input.GetMouseButton (1) && SDflag == 1 && timespan > 1) {
            AStarRay = Camera.main.ScreenPointToRay (Input.mousePosition);
            if (Physics.Raycast (AStarRay, out AStarHit, 1000.3f)) {    
                print ("hit");
                timespan = 0;
                SDflag = 2;
                end = AStarHit.transform.gameObject;
                AStarHit.transform.gameObject.GetComponent ().material.color = Color.yellow;
            }
        }

        if (SDflag == 2) {

            start.GetComponent().CostH=Mathf.Abs (start.transform.position.x-end.transform.position.x) + Mathf.Abs (start.transform.position.y-end.transform.position.y);
            OpenList.Add(start);
            routestart=AStarSearch(start.transform.position.x,start.transform.position.y,end.transform.position.x,end.transform.position.y,start);

            for(int i=0;routestart.GetComponent().CostH>=0.1f;i++)
            {
                routestart=AStarSearch(routestart.transform.position.x,routestart.transform.position.y,end.transform.position.x,end.transform.position.y,routestart);
            }
            SDflag=3;

            for(int i=0;routestart.GetComponent().previousNode!=null;i++){
                routestart.transform.gameObject.GetComponent().material.color=Color.green;
                routestart=routestart.GetComponent().previousNode;
            }
        }
    }
}

结合Unity Linecast方法与A星寻路算法做出以下效果，红色点为障碍物，灰色表示在关闭列表内，黄色在开放列表内，绿色为最捷路径：

除了利用for循环调用寻路方法，也可以将此方法改为递归，但是在节点数过多时会出现堆栈溢出异常：

    public GameObject AStarSearch(float x1,float y1,float x2,float y2,GameObject currentnode){

        adjpoints.Add (new Vector3 (x1, y1 - 1,1f));
        adjpoints.Add (new Vector3 (x1, y1 + 1,1f));
        adjpoints.Add (new Vector3 (x1 + 1, y1 - 1,1f));
        adjpoints.Add (new Vector3 (x1 + 1, y1,1f));
        adjpoints.Add (new Vector3 (x1 + 1, y1 + 1,1f));
        adjpoints.Add (new Vector3 (x1 - 1, y1 - 1,1f));
        adjpoints.Add (new Vector3 (x1 - 1, y1,1f));
        adjpoints.Add (new Vector3 (x1 - 1, y1 + 1,1f));

        foreach (Vector3 temp in adjpoints) {

            if(!Physics.Linecast (new Vector3(temp.x,temp.y,-10), temp, out AStarHit2)){
                continue;
            }

            if (Physics.Linecast (new Vector3(temp.x,temp.y,-10), temp, out AStarHit2)) { //if the node is within the map

                if (ClostList.Contains(AStarHit2.transform.gameObject)) {
                    continue;
                }

                if (AStarHit2.transform.gameObject.GetComponent ().obstacle) {
                    continue;
                }

                if (OpenList.Contains (AStarHit2.transform.gameObject)) {

                    this.CostG=Mathf.Abs (AStarHit2.transform.position.x - currentnode.transform.position.x) + Mathf.Abs (AStarHit2.transform.position.y - currentnode.transform.position.y);

                    if (this.CostG <= 1.1f&&this.CostG>=0.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 10f;
                    }

                    if (this.CostG<=2.1f&&this.CostG>=1.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 14f;
                    }

                    if (AStarHit2.transform.gameObject.GetComponent ().CostG > this.CostG) {
                        AStarHit2.transform.gameObject.GetComponent ().previousNode = currentnode;
                        AStarHit2.transform.gameObject.GetComponent ().CostG = this.CostG;
                    }
                    continue;
                }


                if (!OpenList.Contains (AStarHit2.transform.gameObject) && !ClostList.Contains (AStarHit2.transform.gameObject)) {

                    this.CostG=Mathf.Abs (AStarHit2.transform.position.x - currentnode.transform.position.x) + Mathf.Abs (AStarHit2.transform.position.y - currentnode.transform.position.y);

                    if (this.CostG <= 1.1f&&this.CostG>=0.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 10f;
                    }

                    if (this.CostG<=2.1f&&this.CostG>=1.9f) {
                        this.CostG = currentnode.GetComponent ().CostG + 14f;
                    }

                    AStarHit2.transform.gameObject.GetComponent ().previousNode = currentnode;
                    AStarHit2.transform.gameObject.GetComponent ().CostG = this.CostG;
                    AStarHit2.transform.gameObject.GetComponent ().CostH = Mathf.Abs (AStarHit2.transform.position.x - x2) + Mathf.Abs (AStarHit2.transform.position.y - y2);

                    if (AStarHit2.transform.gameObject.GetComponent ().CostH >= -0.00001&&AStarHit2.transform.gameObject.GetComponent ().CostH <= 0.00001) {
                        return AStarHit2.transform.gameObject;
                    }


                    OpenList.Add (AStarHit2.transform.gameObject);
                    continue;
                }
            }
        }

        adjpoints.RemoveRange (0, adjpoints.Count);

        OpenList.Remove (currentnode);
        ClostList.Add (currentnode);

        if (OpenList.Count == 0) {
            return null;
        }


        minnode = OpenList [0]; //not sure
        minnodeint = 0;
        for(int i=0;i
            if (minnode.GetComponent ().CostF > OpenList[i].GetComponent ().CostF) {
                minnode = OpenList[i];
                minnodeint=i;
            }
        }
        return AStarSearch (OpenList[minnodeint].transform.position.x, OpenList[minnodeint].transform.position.y, end.transform.position.x, end.transform.position.y, OpenList[minnodeint]);
    }

另外，以上代码虽然实现了A星寻路的思想但是不够优化，在节点数超过10000时搜寻速度不甚理想，因此只为展示思路。