02->交互式图形学--用glut库实现Sierpinski镂垫

1 在三角形内随机选择一个初始点p(x, y)
2 随机选择三角形顶点之一
3 计算p和随机选择顶点之间的中点q
4 将q对应位置用相应标记在图形中显示出来
5 用这个中点q代替原来的p
6 转到步骤2，直到取得一定数量的点

 1 #include <glut.h>
 2 #include <stdlib.h>
 3 #include <vector>
 4 using namespace std;
 5 
 6 class Point2d {
 7 public:
 8     GLfloat x = 0.0f;
 9     GLfloat y = 0.0f;
10     Point2d(const GLfloat &a, const GLfloat &b) : x(a), y(b) {}
11     Point2d() {}
12 };
13 
14 Point2d triVer[3];  // 初始三角形顶点
15 
16                     // 计算两点连线的中点
17 Point2d halfScale(const Point2d &a, const Point2d &b) {
18     Point2d res;
19     res.x = (a.x + b.x) / 2.0;
20     res.y = (a.y + b.y) / 2.0;
21     return res;
22 }
23 
24 void SierpinskiDisp() {
25 
26     // 设置初始三角形顶点
27     triVer[0] = Point2d(-0.8f, -0.8f);
28     triVer[1] = Point2d(0.0f, 0.8f);
29     triVer[2] = Point2d(0.8f, -0.8f);
30 
31     vector<Point2d> points(5000);
32 
33     // 取三角形一条中位线的中点做为初始三角形内的点
34     Point2d u, v, p;
35     u = halfScale(triVer[0], triVer[1]);
36     v = halfScale(triVer[0], triVer[2]);
37     p = halfScale(u, v);
38     points[0].x = p.x;
39     points[0].y = p.y;
40 
41     for (int i = 1; i < 5000; i++) {
42         int j = rand() % 3;
43         p = halfScale(points[i - 1], triVer[j]);
44         points[i] = p;
45     }
46     glClearColor(0.5, 0.5, 0.5, 1.0);
47     glClear(GL_COLOR_BUFFER_BIT);
48 
49     // 画三角形顶点
50     glColor3f(1.0f, 0.0f, 0.0f);
51     glPointSize(6.0f);
52     glBegin(GL_POINTS);
53     for (int i = 0; i < 3; i++) {
54         glVertex2f(triVer[i].x, triVer[i].y);
55     }
56     glEnd();
57 
58     // 画随机生成的5000个点
59     glColor3f(1.0f, 1.0f, 0.0f);
60     glPointSize(3.0f);
61     glBegin(GL_POINTS);
62     for (int i = 0; i < 5000; i++) {
63         glVertex2f(points[i].x, points[i].y);
64     }
65     glEnd();
66     glFlush();
67 }
68 
69 int main(int argc, char *argv[]) {
70     glutInit(&argc, argv);
71     glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
72     glutInitWindowPosition(100, 100);
73     glutInitWindowSize(600, 600);
74     glutCreateWindow("Sierpinski镂垫");
75     glutDisplayFunc(&SierpinskiDisp);
76     glutMainLoop();
77 }