校园地图

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1.项目描述

  趁课余时间做了一个小作品,项目是校园地图,主要目的是练习Qt和一些基本的数据结构和算法。该项目的主要功能是从下拉列表中选择出发地和目的地,然后地图上可以显示路线。主要的显示方法是通过贴图来显示。时间久远才想起来整理,当时也是经历了一个星期的断断续续的修补,最后形成了一个比较完善的小地图软件。

2.基本思路

  01.首先需要构建路网(很重要),我首先写了一个该版本,然后把路网标记后保存。具体用来储存的数据结构是一个具有节点信息的结构体,然后借用C++的 vector (vector真的太好用了)来记录所有的路网节点。

 typedef struct road_dot{        int i;   // 该节点的id        int vistable; //该节点是否可访问        cv::Point self; //该节点在地图上的位置        std::vector<size_t> others_id;  // 保存与该节点相连的节点的id    }Road_node;

  下面是我用来标记路网并自动储存的模块:

/************************************************************************************************ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *   These under codes construct a tool to get the road nodes infomation                   * *   <2016-10-29><wuhui>                                                                   * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ void MainWindow::mousePressEvent(QMouseEvent *event){    if(0<x&&x<1480&&0<y&&y<800)  // if on the pic    {         Road_node new_node;         new_node.self = Point(x,y);         new_node.i = 200;  // not a pos         cv::circle(img,Point(x,y),6,cv::Scalar(255,0,255),-1);         qimg = Mat2QImage(img);         ui->pic->setPixmap(QPixmap::fromImage(qimg));         if(!first_node)         {start_node = new_node;start_set_flag = 1; first_node =2;pre_nodes_id = 0;}         for(int i = 0;i<point.size();i++)         {             if((abs(x-point[i].x) <10 )&& (abs(y-point[i].y)<10))  // if at pos               {                 new_node.i = i;                 qDebug()<<"this is pos "<<i;                 break;               }         }         road.push_back(new_node);// record this new node ;       for(int i = 0;i<road.size()-1;i++)       {           if((abs(x-road[i].self.x) <10 )&& (abs(y-road[i].self.y)<10))  // if at node           {  // yes               road.pop_back();  // drop this node               if(event->button() == Qt::LeftButton)   // if leftButton                {                   start_node = road[i];  // set start node                   start_set_flag = 1;                   pre_nodes_id = i;                }               else if(event->button() == Qt::RightButton)               {                   start_node = road[pre_nodes_id];   // this is start                   start_set_flag = 1;                   end_node = road[i];                   end_set_flag = 1;                   road[i].others_id.push_back(pre_nodes_id);                   road[pre_nodes_id].others_id.push_back(i);                    pre_nodes_id = i;               }               qDebug()<<"this node's others.size = "<<road[i].others_id.size();               break;            }           else if(i == road.size() - 2)           {  // no               if(!start_set_flag) // if have no start_node               {                   start_node = road[pre_nodes_id];                   start_set_flag = 1;               }               if(!end_set_flag)               {                   end_node = road[road.size()-1];                   end_set_flag = 1;               }               road[pre_nodes_id].others_id.push_back(road.size()-1);  // push now node               road[road.size()-1].others_id.push_back(pre_nodes_id);               qDebug()<<"this node's others.size = "<<road[road.size()-1].others_id.size();               pre_nodes_id = road.size()-1;               break;           }       }       if(end_set_flag && start_set_flag)       {           end_set_flag = 0;           start_set_flag = 0;           cv::line(img,start_node.self,end_node.self,cv::Scalar(0,0,0),3);           qimg = Mat2QImage(img);           ui->pic->setPixmap(QPixmap::fromImage(qimg)); // flush the pic       }     qDebug()<<"road.size"<<road.size();    }}  // :)

  该代码主要通过在地图上点击来标记,右键表示一个连续段的结束,每个节点会记录与之相连的其它节点的id号。结果示意图:(另外,地图图片是Google截图并精心修改而成)

  02.标记完了路网后就是设计一个找路算法了,想过深度或广度搜索,但是做过一个demo后觉得稍显复杂并且速度不理想,后来根据地图的形状设计了一个看似很low却很有效的算法:

    首先设立两个哨兵,一个在当前出发节点(哨兵A),另一个在下一个目标出发点(哨兵 B),下一个目标出发点由所有子节点中距离目的地最近的节点确定。

    当B所在的节点具有可走子节点(不是死胡同)并且还未达到目的地时,A走到B(所有走过的路压栈,方便后退),B继续探路,若走到死胡同就后退,走其他的最近子节点。

   该寻路算法如下:

    int start_id = ui->comboBox->currentIndex();  // get start and end node's id /    int end_id = ui->comboBox_2->currentIndex();    for(int i = 0;i<road.size();i++)    {        road[i].vistable = 0;  // set all nodes are visitable;    }  //  Road_node start_node_temp,end_node_temp;  // temp node    int road_start_i,road_end_i;    int road_start_i_temp,road_end_i_temp;    for(int i = 0;i<road.size();i++) // search which node is on the start/end point;    {        if(road[i].i == start_id)        {            qDebug()<<"start"<<i;            start_node = road[i];            road_start_i = i;  // get the id of start roadnode;            qDebug()<<"i = "<<start_node.i;        }        else if(road[i].i == end_id)        {            qDebug()<<"end"<<i;            end_node = road[i];            road_end_i = i;  // get the id of end roadnode;            qDebug()<<"i = "<<end_node.i;        }    }    /***********/    road_start_i_temp = road_start_i;    road_end_i_temp = road_start_i;   // start_node_temp = start_node;    //end_node_temp = start_node_temp;    std::vector<int> road_temp;    int pre_distance = 9000000;    while(road[road_end_i_temp].i!= end_id)    //for(int xx = 0;xx<10;xx++)    {        int useable_flag = 0;        for(int i = 0;i<road[road_end_i_temp].others_id.size();i++)   // if the current endpoint to have next point        {            if(road[road[road_end_i_temp].others_id[i]].vistable == 0)                useable_flag = 1;  // have useable point        }        if(useable_flag)   // have  useable next node        {           // start_node_temp = end_node_temp;            road_start_i_temp = road_end_i_temp;            road[road_start_i_temp].vistable = 1; // have visited it;            //start_node_temp.vistable = 1; // have visited it;            road_temp.push_back(road_start_i_temp);   // record the walked node            int temp_min_id;            for(int i = 0;i<road[road_start_i_temp].others_id.size();i++)  // find the min dis node   // int these next points            {                if(road[road[road_start_i_temp].others_id[i]].vistable == 0 )  // if this node have not visited;                {             int tempx,tempy;             tempx = (road[road[road_start_i_temp].others_id[i]].self.x- end_node.self.x)*(road[road[road_start_i_temp].others_id[i]].self.x - end_node.self.x);             tempy = (road[road[road_start_i_temp].others_id[i]].self.y- end_node.self.y)*(road[road[road_start_i_temp].others_id[i]].self.y - end_node.self.y);             if(pre_distance<(tempx+tempy))                {                 qDebug()<<"pre_distance = "<<pre_distance;                 qDebug()<<"now distance = "<<tempx+tempy;                  //  end_node_temp = road[road[road_start_i_temp].others_id[i-1]];                    road_end_i_temp = road[road_start_i_temp].others_id[temp_min_id];                }             else {                    //end_node_temp = road[start_node_temp.others_id[i]];                    road_end_i_temp = road[road_start_i_temp].others_id[i];                    temp_min_id = i;                    pre_distance = tempx+tempy;                   }                }            }            pre_distance = 9000000;        }   else // have no useable next node        {            road[road_end_i_temp].vistable = 1;          loop:    for(int i = 0;i<road[road_start_i_temp].others_id.size();i++)  // if have other useable nodes            {                if(road[road[road_start_i_temp].others_id[i]].vistable == 0)                    useable_flag = 1;  // have useable point            }            if(useable_flag)            {                int temp_min_id;                for(int i = 0;i<road[road_start_i_temp].others_id.size();i++)  // fine the min dis node                {                    if(road[road[road_start_i_temp].others_id[i]].vistable == 0 )  // if this node have not visited;                    {                 int tempx,tempy;                 tempx = (road[road[road_start_i_temp].others_id[i]].self.x- end_node.self.x)*(road[road[road_start_i_temp].others_id[i]].self.x - end_node.self.x);                 tempy = (road[road[road_start_i_temp].others_id[i]].self.y- end_node.self.y)*(road[road[road_start_i_temp].others_id[i]].self.y - end_node.self.y);                 if(pre_distance<(tempx+tempy))                    {                        //end_node_temp = road[road[road_start_i_temp].others_id[i-1]];                        road_end_i_temp = road[road_start_i_temp].others_id[temp_min_id];                    }                 else {                        //end_node_temp = road[start_node_temp.others_id[i]];                        road_end_i_temp = road[road_start_i_temp].others_id[i];                        temp_min_id = i;                        pre_distance = tempx+tempy;                       }                    }                }                pre_distance = 9000000;            }            else            {                road_temp.pop_back(); // drop this start_temp node                road_start_i_temp = road_temp[road_temp.size()-1];                goto loop;            }        }        /*    int pre_distance = 90000000;    for(int i = 0;i<start_node_temp.others_id.size();i++)  //    {     int tempx,tempy;     tempx = (road[start_node_temp.others_id[i]].self.x- end_node.self.x)*(road[start_node_temp.others_id[i]].self.x - end_node.self.x);     tempy = (road[start_node_temp.others_id[i]].self.y- end_node.self.y)*(road[start_node_temp.others_id[i]].self.y - end_node.self.y);     if(pre_distance<(tempx+tempy))        {            end_node_temp = road[start_node_temp.others_id[i-1]];        }     else {            end_node_temp = road[start_node_temp.others_id[i]];            pre_distance = tempx+tempy;           }    }    cv::line(img,start_node_temp.self,end_node_temp.self,cv::Scalar(0,0,0),3);    qimg = Mat2QImage(img);    ui->pic->setPixmap(QPixmap::fromImage(qimg)); // flush the pic    start_node_temp = end_node_temp;    xx++;*/   }    road_temp.push_back(road_end_i_temp);    for(int i = 0;i<road_temp.size()-1;i++)    {        cv::line(img,road[road_temp[i]].self,road[road_temp[i+1]].self,cv::Scalar(0,0,0),3);        qimg = Mat2QImage(img);        ui->pic->setPixmap(QPixmap::fromImage(qimg)); // flush the pic    }    qDebug()<<road_temp.size();}

  经过实验该算法还是很可靠的 ;) 

  效果图:

 

  另外鼠标悬停在某个地点时,还会展示该地点的图片信息(亲自把所有地点拍了一遍 ;)

 

 

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