3.6.2 编程实例－河南地图绘制
程序有关介绍请参考图书3.6.1节内容
程序运行结果如下图：
1 #include <iostream> 2 #include <fstream> 3 #include<vector> 4 #include <GL/glut.h> 5 using namespace std; 6 7 class MapPoint 8 { 9 public: 10 double longitude; 11 double latitude; 12 }; 13 class Polygon 14 { 15 public: 16 vector<MapPoint> points; //多边形的顶点序列 17 }; 18 vector<Polygon*> polys; //多边形集合 19 vector<Polygon*> ReadMapData(char* filename) 20 { 21 int PointCount; 22 vector<Polygon*> polygons; 23 ifstream fs(filename); 24 while(fs.eof()!=true) 25 { 26 Polygon* poly=new Polygon; 27 fs>>PointCount; 28 cout<<PointCount<<endl; 29 for(int i=0;i<PointCount;i++) 30 { 31 MapPoint p; 32 fs>>p.longitude>>p.latitude; 33 poly->points.push_back(p); 34 } 35 polygons.push_back(poly); 36 37 } 38 return polygons; 39 } 40 void display(void) 41 { 42 glClear (GL_COLOR_BUFFER_BIT); 43 //用蓝色色绘制各省边界 44 glColor3f (0.0, 0.0, 1.0); 45 glPolygonMode(GL_BACK, GL_LINE); 46 for(int i=0;i<polys.size();i++) 47 { 48 vector<MapPoint> points=polys[i]->points; 49 glBegin(GL_LINE_STRIP); 50 for(int j=0;j<points.size();j++) 51 { 52 glVertex3f (points[j].longitude, points[j].latitude, 0.0); 53 } 54 glEnd(); 55 } 56 glFlush(); 57 } 58 void init (void) 59 { 60 //设置背景颜色 61 glClearColor (1.0, 1.0, 1.0, 0.0); 62 //初始化观察值 63 glMatrixMode(GL_PROJECTION); //将矩阵模式设为投影 64 glLoadIdentity(); //对矩阵进行单位化 65 glOrtho(110.0, 118.0, 30.0, 38.0, -1.0, 1.0); //构造平行投影矩阵 66 } 67 int main(int argc, char** argv) 68 { 69 //数据文件请到http://files.cnblogs.com/opengl/HenanCounty.rar下载放到D盘根目录下并解压 70 char* filename="D:/HenanCounty.txt"; 71 72 polys=ReadMapData(filename); 73 glutInit(&argc, argv); 74 glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); //单缓存和RGB 75 glutInitWindowSize (500, 500); 76 glutInitWindowPosition (100, 100); 77 glutCreateWindow ("地图绘制"); 78 init (); 79 glutDisplayFunc(display); //显示回调函数 80 glutMainLoop(); 81 return 0; 82 }
附上本实验的VC++工程代码（VC++2008），已含地图数据文件,放在工程文件夹中，与上述程序路径不一样。
