a星寻路

关于A星寻路的介绍我就不多说了，网上到处都有，具体实现也各有写法，但大致还是一样的，下面是使用C++实现的源码，不足之处还望指出以便共同学习！

//
//  CAstar.h
//  Astar
//
//  Created by xujw on 15/4/9.
//  Copyright (c) 2015年 xujw. All rights reserved.
//
/*
    F:路径评分 = g+h
    G:走一格格子的花销
    H:当前格子到目标格子的估算花销

    上下左右走一格花销为10，斜着走一格花销为14，以方便计算
    即格子宽高为10 对角线为14
 */
#ifndef __Astar__CAstar__
#define __Astar__CAstar__

#include <stdio.h>
#include <vector>
#include <iostream>
using namespace std;
//地图最大值
#define MAX_X 10
#define MAX_Y 10

enum class AType
{
    ATYPE_UNKNOWN,
    ATYPE_CLOSED,
    ATYPE_OPENED,
    ATYPE_BARRIER   //障碍
};

class APoint
{
public:
    APoint();
    ~APoint();
    int x;
    int y;
    AType type;   //类型:障碍、开放列表、关闭列表
    int f;  //f = g+h
    int g;
    int h;
    APoint *parent;
    bool operator == (const APoint& po)
    {
        if (x == po.x && y == po.y)
        {
            return true;
        }
        return false;
    }

};

class CAstar
{
    vector<APoint*> _openList;      //开放列表
    vector<APoint*> _closeList;     //关闭列表
    vector<APoint*> _neighbourList; //周边节点
    APoint* _endPoint;
    APoint* _curPoint;
    vector< vector<APoint*> > _allPoints;
public:
    CAstar();
    ~CAstar();
    APoint* findWay(APoint* beginPoint,APoint* endPoint,vector< vector<APoint*> >& allPoints);
//    APoint* findWay(int beginX,int beginY,int endX,int endY);
private:
    int getF(APoint *point);
    int getH(APoint *point);
    vector<APoint*> getNeighboringPoint(APoint* point);
};
#endif /* defined(__Astar__CAstar__) */

//
//  CAstar.cpp
//  Astar
//
//  Created by xujw on 15/4/9.
//  Copyright (c) 2015年 xujw. All rights reserved.
//
//  上下左右走一格花销为10，斜着走一格花销为14，以方便计算
//  即格子宽高为10 对角线为14
#include "CAstar.h"

//自定义排序函数
bool mySort(const APoint* p1,const APoint* p2)
{
    return p1->f < p2->f;
}

APoint::APoint():x(0)
                ,y(0)
                ,h(0)
                ,f(0)
                ,g(0)
                ,parent(nullptr)
                ,type(AType::ATYPE_UNKNOWN)
{
}
APoint::~APoint()
{
}


#pragma mark------CAstar-------

CAstar::CAstar():_endPoint(nullptr)
                ,_curPoint(nullptr)
{
}

CAstar::~CAstar()
{
    _openList.clear();
    _closeList.clear();
    _neighbourList.clear();
    _allPoints.clear();
}

APoint* CAstar::findWay(APoint *beginPoint, APoint *endPoint,vector< vector<APoint*> >& allPoints)
{
    //传递地图
    _allPoints = allPoints;

    _endPoint = endPoint;

    if (_endPoint->type == AType::ATYPE_BARRIER)
    {
        cout<<"终点是障碍"<<endl;
        return nullptr;
    }
    if (*_endPoint == *beginPoint)
    {
        cout<<"起始点相同"<<endl;
        return nullptr;
    }

    _openList.push_back(beginPoint);
    beginPoint->type = AType::ATYPE_OPENED;
    beginPoint->f = getF(beginPoint);
    //---------
    do
    {
        //获取最小值的节点
        _curPoint = _openList[0];
        _openList.erase(_openList.begin());
        _curPoint->type = AType::ATYPE_CLOSED;
        _closeList.push_back(_curPoint);

        if (*_curPoint == *_endPoint)
        {
            cout<<"have find way"<<endl;
            return _curPoint;
        }
        //获取相邻的节点
        vector<APoint*> neVec = getNeighboringPoint(_curPoint);
        for (int i = 0; i<neVec.size(); i++)
        {
            auto tmpoint = neVec[i];
            if (tmpoint->type == AType::ATYPE_CLOSED)
            {
                continue;
            }
            //是否在开放列表里
            if (tmpoint->type != AType::ATYPE_OPENED)
            {
                tmpoint->parent = _curPoint;
                tmpoint->g = _curPoint->g + 10;
                //计算H值
                tmpoint->h = getH(tmpoint);
                //添加到开放列表里
                _openList.push_back(tmpoint);
                tmpoint->type = AType::ATYPE_OPENED;
            }
            else
            {
                //已经在开放列表里
                if (tmpoint->h < _curPoint->h)
                {
                    tmpoint->parent = _curPoint;
                    tmpoint->g = _curPoint->g + 10;
                }
            }
        }
        //排序 F值最小的排在前面
        sort(_openList.begin(), _openList.end(), mySort);

    } while (_openList.size()>0);


    cout<<"---can not find way---"<<endl;

    return nullptr;
}

//APoint* CAstar::findWay(int beginX, int beginY, int endX, int endY)
//{
//    
//    
//    return nullptr;
//}

int CAstar::getF(APoint *point)
{
    return (point->g + getH(point));
}
int CAstar::getH(APoint *point)
{
    //曼哈顿城市街区估算法
    return (abs(_endPoint->y - point->y) + abs(_endPoint->x - point->x))*10;
}

vector<APoint*> CAstar::getNeighboringPoint(APoint *point)
{
    _neighbourList.clear();
//    cout<<"nei size:"<<_neighbourList.size()<<endl;
    if (point->x < MAX_X-1)
    {
        if (_allPoints[point->x+1][point->y]->type != AType::ATYPE_BARRIER)
        {
            _neighbourList.push_back(_allPoints[point->x+1][point->y]);
        }
    }
    if (point->x >0)
    {
        if (_allPoints[point->x-1][point->y]->type != AType::ATYPE_BARRIER)
        {
            _neighbourList.push_back(_allPoints[point->x-1][point->y]);
        }
    }
    if (point->y < MAX_Y-1)
    {
        if (_allPoints[point->x][point->y+1]->type != AType::ATYPE_BARRIER)
        {
            _neighbourList.push_back(_allPoints[point->x][point->y+1]);
        }
    }
    if (point->y >0)
    {
        if (_allPoints[point->x][point->y-1]->type != AType::ATYPE_BARRIER)
        {
            _neighbourList.push_back(_allPoints[point->x][point->y-1]);
        }
    }

    return _neighbourList;
}

下面是测试代码：

//
//  main.cpp
//  Astar
//
//  Created by xujw on 15/4/9.
//  Copyright (c) 2015年 xujw. All rights reserved.
//

#include <iostream>
#include "CAstar.h"

void printMap(char map[MAX_X][MAX_Y],int width,int height)
{
    for (int i = 0; i<width; i++)
    {
        for (int j = 0; j<height; j++)
        {
            printf("%c\t",map[i][j]);
        }
        printf("\n");
    }
}

int main(int argc, const char * argv[]) {

    cout<<"---map---"<<endl;
    //初始化地图矩阵 0代表障碍
    char mapdata[MAX_X][MAX_Y] =
    {
        {'1','0','0','1','0','1','1','1','1','1'},
        {'1','1','1','1','0','1','1','1','1','1'},
        {'0','0','0','1','0','1','1','1','1','1'},
        {'1','0','0','1','0','1','1','1','1','0'},
        {'1','1','1','1','0','1','1','1','1','1'},
        {'1','1','0','0','1','1','1','1','1','1'},
        {'1','1','1','1','1','1','1','1','1','1'},
        {'1','0','0','1','1','1','1','1','1','1'},
        {'1','1','0','0','1','1','1','1','1','1'},
        {'1','0','1','1','1','1','1','1','1','1'},
    };

    printMap(mapdata, MAX_X, MAX_Y);
    //创建地图
    vector< vector<APoint*> > map;
    for (int i = 0; i<MAX_X; i++)
    {
        vector<APoint*> tmp;
        for (int j = 0; j<MAX_Y; j++)
        {
            APoint *point = new APoint();
            point->x = i;
            point->y = j;
            if (mapdata[i][j]=='0')
            {
                point->type = AType::ATYPE_BARRIER;
            }
            tmp.push_back(point);
        }
        map.push_back(tmp);
    }

    //开始寻路
    auto star = new CAstar();
    auto point = star->findWay(map[0][0], map[9][9], map);

    if (!point)
    {
        return 0;
    }

    cout<<"---下面是路径点(倒序)---"<<endl;

    while (point)
    {
        mapdata[point->x][point->y] = '*';
        cout<<point->x<<","<<point->y<<endl;
        point = point->parent;
    }
    cout<<"---打印路径---"<<endl;
    printMap(mapdata, MAX_X, MAX_Y);

    //-------------释放内存----------
    delete star;

    for (int i = 0; i<MAX_X; i++)
    {
        for (int j = 10; j<MAX_Y; j++)
        {
            delete map[i][j];
            map[i][j] = nullptr;
        }
    }
    return 0;
}

运行截图：

源码下载(使用Xcode可以直接运行):https://github.com/sky068/AStarSearch