初步了解了一些寻路算法后，本以为dijstra是比较合适的寻路算法，今天仔细看了关于A星寻路算法的教程和视频后，我认为A星寻路算法很适合战棋游戏。由于我的项目是仿照小小合金的玩法，所以是只需要上下左右寻路的正方形格子地图。
A星寻路的原理和教程我就不班门弄斧了，百度前几个都是大神写的。对着前辈的教程，我简单修改了一部分代码后做了一个简单的demo，又花了一个晚上将跑通的demo的脚本移植到项目了，在博客里就只贴出demo里的脚本了，作为我的学习记录。
其中有一部分不是很懂，写的注释（理解）可能是错的，以后有时间会重新学习和修改的。
Point类，存储着每一个点的各种属性，父点、F、G、H值，x、z坐标
public class Point {
public Point ParentPoint { get; set; }
public float F { get; set; }
public float G { get; set; }
public float H { get; set; }
public int X { get; set; }
public int Z { get; set; }
public bool IsObstacle { get; set; }
public Point(int x, int z, Point parent = null)
{
this.X = x;
this.Z = z;
this.ParentPoint = parent;
}
public void UpdateParent(Point parent,float g)
{
this.ParentPoint = parent;
this.G = g;
F = G + H;
}
}
AStar类，根据需要能得到移动路径点列表、移动所需要的步数、障碍物（不能走的格子）
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class AStar : MonoBehaviour {
private const int mapWith = 5;
private const int mapHeight = 5;
private Point[,] map;
Point start;
Point end;
public GameObject player;
List<Point> pointList = new List<Point>();
Vector3 targetPos;
int step;
void Update () {
if (pointList.Count == 0)
return;
Move();
}
void InitPath(int row,int column)
{
map = new Point[row, column];
InitMap();
start = map[0, 0];//起始坐标
end = map[1, 2];//目标点坐标
FindPath(start, end);
SetPathByParent(start, end);
}
//移动方法
void Move()
{
for (int i = pointList.Count; i > 0; i--)
{
Vector3 pointPos = new Vector3(pointList[i - 1].X, player.transform.position.y, pointList[i - 1].Z);
if (player.transform.position == pointPos)
{
pointList.Remove(pointList[i - 1]);
break;
}
if (i == pointList.Count)
{
targetPos = pointPos;
break;
}
}
player.transform.position = Vector3.MoveTowards(player.transform.position, targetPos, 1 * Time.deltaTime);
}
//将通过父点，将路径点添加进列表
private void SetPathByParent(Point start, Point end)
{
Point temp = end;
pointList.Add(temp);
while (true)
{
if (temp.ParentPoint == null)
break;
temp = temp.ParentPoint;
step++;
pointList.Add(temp);
}
Debug.Log(step);
}
//点过滤方法，关闭列表里存在的点——其本身，在周围能走的点列表里移除该点
private void PointsFilter(List<Point> src, List<Point> closeList)
{
foreach (Point p in closeList)
{
if (src.IndexOf(p) > -1)
{
src.Remove(p);
}
}
}
//初始化格子坐标和属性
private void InitMap()
{
for (int x = 0; x < mapWith; x++)
{
for (int z = 0; z < mapHeight; z++)
{
map[x, z] = new Point(x, z);
}
}
//设置某点为障碍物
map[0, 1].IsObstacle = true;
}
//寻找路径方法，传入起始点和结束点，
private void FindPath(Point start, Point end)
{
//声明开启列表和结束列表，将起始点添加进开启列表
List<Point> openList = new List<Point>();
List<Point> closeList = new List<Point>();
openList.Add(start);
//如果开启列表数量不为0
while (openList.Count > 0)
{
//找到开启列表里最小F值的点，将该点移除开启列表，添加进关闭列表
Point point = FindMinFOfPoint(openList);
openList.Remove(point);
closeList.Add(point);
//得到该点的周围的点，并将关闭列表里最小F值的点从中移除
List<Point> surroundPoints = GetSurroundPoints(point);
PointsFilter(surroundPoints, closeList);
//遍历周围能走的点列表，第一次循环结束后，开启列表里最小F值的点为所以周围的点的父点，并且周围的点都添加进了开启列表
foreach (Point surroundPoint in surroundPoints)
{
//如果周围的点在开启列表里，计算当前遍历到的周围的点的G值
if (openList.IndexOf(surroundPoint) > -1)
{
float nowG = CalcG(surroundPoint, point);
if (nowG < surroundPoint.G)
{
surroundPoint.UpdateParent(point, nowG);
}
}
//不在开启列表里，将当前点设为周围能走的点的父点，计算周围点的F、H、G值，将其添加进开启列表
else
{
surroundPoint.ParentPoint = point;
CalcF(surroundPoint, end);
openList.Add(surroundPoint);
}
}
//如果开启列表为空，跳出循环
if (openList.IndexOf(end) > -1)
{
break;
}
}
}
//得到周围点方法
private List<Point> GetSurroundPoints(Point point)
{
//默认点有四个方向，上下左右四个点，由地图大小判断四个点是否存在
Point up = null, down = null, left = null, right = null;
//Point lu = null, ru = null, ld = null, rd = null;
if (point.Z < mapHeight - 1)
{
up = map[point.X, point.Z + 1];
}
if (point.Z > 0)
{
down = map[point.X, point.Z - 1];
}
if (point.X > 0)
{
left = map[point.X - 1, point.Z];
}
if (point.X < mapWith - 1)
{
right = map[point.X + 1, point.Z];
}
//判断上下左右点是否为障碍物点，返回存储能走的点的list
List<Point> list = new List<Point>();
if (down != null && down.IsObstacle == false)
{
list.Add(down);
}
if (up != null && up.IsObstacle == false)
{
list.Add(up);
}
if (left != null && left.IsObstacle == false)
{
list.Add(left);
}
if (right != null && right.IsObstacle == false)
{
list.Add(right);
}
return list;
}
//在开启列表里寻找最小F值的点，并返回该点
private Point FindMinFOfPoint(List<Point> openList)
{
//初始化f值为最大值，遍历开启列表，判断开启列表里F值最小的点，即为最合适的点
float f = float.MaxValue;
Point temp = null;
foreach (Point p in openList)
{
if (p.F < f)
{
temp = p;
f = p.F;
}
}
return temp;
}
//返回由父点计算得到的当前点的G值
private float CalcG(Point now, Point parent)
{
return Vector2.Distance(new Vector2(now.X, now.Z), new Vector2(parent.X, parent.Z))+parent.G;
}
//计算F值，传入当前点和结束点
private void CalcF(Point now,Point end)
{
//得到当前点和结束点的x、z两坐标值之差的绝对值之和为h值，g初始化为0
float h = Mathf.Abs(end.X-now.X) + Mathf.Abs(end.Z-now.Z);
float g = 0;
//如果当前点没有父点，说明为起始点，g值为0
if (now.ParentPoint == null)
g = 0;
//如果有父点，则计算当前点到父点的距离加上父点的g值就为当前点的g值
else
g = Vector2.Distance(new Vector2(now.X, now.Z), new Vector2(now.ParentPoint.X, now.ParentPoint.Z))+ now.ParentPoint.G;
float f = g + h;
now.F = f;
now.G = g;
now.H = h;
}
}
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