CGAL编程实现点集的Delaunay三角剖分和Voronoi图

转自： http://blog.csdn.net/jinzhilong580231/article/details/6746533

//使用CGAL编程实现点集的Delaunay三角剖分，voronoi图
//如果对Delaunay算法本身关注，请参考CGAL对Delaunay三角剖分的实现，CGAL对Delaunay三角剖分的实现是增量算法（Incremental）
//本程序的重点在于对CGAL中Delaunay数据结构的访问，请参考函数points_triangulation()。初次使用CGAL，不妥之处请多指正，谢谢。

//SudoLeo 2010/7/20
//CGAL required, GLUT required

 

 

 //使用CGAL编程实现点集的Delaunay三角剖分，voronoi图
 //如果对Delaunay算法本身关注，请参考CGAL对Delaunay三角剖分的实现，CGAL对Delaunay三角剖分的实现是增量算法（Incremental）
 //本程序的重点在于对CGAL中Delaunay数据结构的访问，请参考函数points_triangulation()

 //SudoLeo 2010/7/20
 //CGAL required, GLUT required

 #include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
 #include <CGAL/Triangulation_euclidean_traits_xy_3.h>
 #include <CGAL/Delaunay_triangulation_2.h>
 #include <GL/glut.h>
 #include <iostream>
 #include <cmath>

 typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
 typedef CGAL::Delaunay_triangulation_2<K> Delaunay;
 typedef Delaunay::Vertex_handle Vertex_handle;

 typedef K::Point_2 Point;

 std::vector<Point> vertices;

 int global_w, global_h;
 int tri_state = 0;

 void points_draw()
 {
 glClear(GL_COLOR_BUFFER_BIT);
 glPushMatrix();

 std::vector <Point>::iterator iter;
 glColor3f( 1.0, 1.0, 1.0 );
 glPointSize(5);
 glBegin(GL_POINTS);
 for( iter = vertices.begin(); iter != vertices.end(); iter++ )
 glVertex2i( iter->hx(), iter->hy() );
 glEnd();

 glPopMatrix();
 glutSwapBuffers();
 }

 void points_add_point( int x, int y )
 {
 vertices.push_back( Point( x, global_h-y ) );
 }


 void points_clear()
 {
 glClear(GL_COLOR_BUFFER_BIT);
 glPushMatrix();
 glPopMatrix();
 glutSwapBuffers();

 vertices.clear();
 tri_state = 0;
 }

 void read_file()//从文件中读入点集数据，调试时所使用
 {
 FILE* f;
 f = freopen( "data.txt", "r", stdin );

 int a,b;
 while(std::cin>>a >> b)
 {
 vertices.push_back( Point( a, b ) );
 }

 fclose(f);
 }

 void points_triangulation()
 {
 Delaunay dt;//Delaunay数据结构，代表当前数据的一个且仅有一个的三角剖分，详情请参考CGAL_manual

 dt.insert(vertices.begin(), vertices.end());//输入数据

 points_draw();//points_draw()函数中已经调用一次glutSwapBuffers()，本函数再一次调用glutSwapBuffers()
 //在一帧的绘制中两次调用glutSwapBuffers()，虽对本例无影响，但存在一些问题，这不是本文的重点，可暂且忽略之

 glPushMatrix();

 Delaunay::Finite_faces_iterator fit;//遍历Delaunay的所有面（有限面），将每个面的边画出来
 glColor3f( 0.0, 0.0, 1.0 );
 for( fit = dt.finite_faces_begin(); fit != dt.finite_faces_end(); fit ++)
 {
 glBegin(GL_LINE_LOOP);
 glVertex2i( fit->vertex(0)->point().hx(), fit->vertex(0)->point().hy() );
 glVertex2i( fit->vertex(1)->point().hx(), fit->vertex(1)->point().hy() );
 glVertex2i( fit->vertex(2)->point().hx(), fit->vertex(2)->point().hy() );
 glEnd();
 }//完成Delaunay三角剖分的绘制，Delaunay图

 Delaunay::Edge_iterator eit;//遍历Delaunay的所有边，绘制Delaunay图的对偶图，即Voronoi图

 glEnable( GL_LINE_STIPPLE );//使用点画模式，即使用虚线来绘制Voronoi图
 glLineStipple( 1, 0x3333 );
 glColor3f( 0.0, 1.0, 0.0 );

 for( eit = dt.edges_begin(); eit != dt.edges_end(); eit ++)
 {
 CGAL::Object o = dt.dual(eit);//边eit在其对偶图中所对应的边

 if (CGAL::object_cast<K::Segment_2>(&o)) //如果这条边是线段，则绘制线段
 {
 glBegin(GL_LINES);
 glVertex2i( CGAL::object_cast<K::Segment_2>(&o)->source().hx(), CGAL::object_cast<K::Segment_2>(&o)->source().hy() );
 glVertex2i( CGAL::object_cast<K::Segment_2>(&o)->target().hx(), CGAL::object_cast<K::Segment_2>(&o)->target().hy() );
 glEnd();
 }
 else if (CGAL::object_cast<K::Ray_2>(&o))//如果这条边是射线，则绘制射线
 {
 glBegin(GL_LINES);
 glVertex2i( CGAL::object_cast<K::Ray_2>(&o)->source().hx(), CGAL::object_cast<K::Ray_2>(&o)->source().hy() );
 glVertex2i( CGAL::object_cast<K::Ray_2>(&o)->point(1).hx(), CGAL::object_cast<K::Ray_2>(&o)->point(1).hy() );
 glEnd();
 }
 }
 glDisable( GL_LINE_STIPPLE );//关闭点画模式

 glPopMatrix();
 glutSwapBuffers();

 tri_state = 1;//完成三角剖分，置状态为1
 }

 void display(void)
 {
 }

 void init(void)
 {
 glClearColor (0.0, 0.0, 0.0, 0.0);
 glShadeModel (GL_FLAT);

 }

 void reshape(int w, int h)
 {
 global_w = w;
 global_h = h;
 points_clear();

 glViewport (0, 0, w, h);
 glMatrixMode(GL_PROJECTION);
 glLoadIdentity();

 glOrtho(0, w, 0, h, -1.0, 1.0);
 glMatrixMode(GL_MODELVIEW);
 glLoadIdentity();
 }

 void mouse(int button, int state, int x, int y)
 {
 if ( button == GLUT_LEFT_BUTTON && state == GLUT_UP )
 {
 if( tri_state == 1 ) points_clear();
 else
 {
 points_add_point(x,y);
 //read_file();
 points_draw();
 }
 }
 if ( button == GLUT_RIGHT_BUTTON && state == GLUT_UP )
 {
 if( tri_state == 1 ) points_clear();
 else points_triangulation();
 }
 }

 void keyboard(unsigned char key, int x, int y)
 {
 switch (key) {
 case 27:
 exit(0);
 break;
 }
 }

 int main(int argc, char** argv)
 {
 glutInit(&argc, argv);
 glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
 glutInitWindowSize (800, 600);
 glutInitWindowPosition (100, 100);
 glutCreateWindow (argv[0]);
 init ();
 glutDisplayFunc(display);
 glutReshapeFunc(reshape);
 glutMouseFunc(mouse);
 glutKeyboardFunc(keyboard);
 glutMainLoop();
 return 0;
 }