随机绘制

 1 #include <windows.h>
 2 #include <gl/glew.h>
 3 #include <gl/glut.h>
 4 #include <cstdio>
 5 #include <cstdlib>
 6 #include <cmath>
 7 #include <time.h>
 8 #define STEP 1
 9 #define STEPNUMBER 500000
10 #define COLORSTEP 50
11 
12 void Init(void)
13 {
14     glClearColor(0.0, 0.0, 0.0, 0.0);
15     glMatrixMode(GL_PROJECTION);
16     glLoadIdentity();
17     gluOrtho2D(0.0, 800.0, 0.0, 600.0);
18 
19 }
20 
21 void lineSegment(void)
22 {
23     glClear(GL_COLOR_BUFFER_BIT);
24     int r;
25     int x = 400, y = 300;
26     float cr = 0, cg = 0, cb = 0;
27     srand(time(NULL));
28     for (int i = 0; i != STEPNUMBER; ++i) {
29         r = rand()%4;
30         switch (r) {
31         case 0: x = x - STEP; break;
32         case 1: x = x + STEP; break;
33         case 2: y = y - STEP; break;
34         case 3:    y = y + STEP; break;
35         default: break;
36         }
37 
38         if (i % (2 * COLORSTEP) == 0) ++cr;
39         if (i % (3 * COLORSTEP) == 0) ++cg;
40         if (i % (5 * COLORSTEP) == 0) ++cb;
41 
42         if (cg == 100 || cr == 100 || cb == 100)
43             cg = cr = cb = 0;
44         if (x > 0 && x < 800 && y > 0 && y < 600) {
45             glColor3f(cr/100,cg/100,cb/100);
46             glBegin(GL_POINTS);
47             glVertex2i(y, x);
48             glEnd();
49         }
50         else {
51             x = 400;
52             y = 300;
53         }
54     }
55     glFlush();
56 }
57 
58 int main(int argc, char* argv[])
59 {
60     glutInit(&argc, argv);
61     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);   
62     glutInitWindowPosition(50, 100);
63     glutInitWindowSize(800, 600);
64     glutCreateWindow("An Example OpenGL Program");
65     Init();
66     glutDisplayFunc(lineSegment);
67     glutMainLoop();
68     return 0;
69 }