OpenGL绘制环形渐变

 1 #include <math.h>
 2 
 3 #include <GL/glut.h>
 4 
 5 void init()
 6 {
 7     glClearColor(0.0, 0.0, 0.0, 0.0);
 8     glMatrixMode(GL_PROJECTION);
 9     gluOrtho2D(0.0, 600.0, 0.0, 600.0);
10 }
11 
12 void lineSegment()
13 {
14     glClear(GL_COLOR_BUFFER_BIT);
15     double r = 300.0;
16     glBegin(GL_POINTS);
17         for (int i=0; i<=600; ++i) for (int j=0; j<=600; ++j) {
18             double dis = sqrt((i-r)*(i-r)+(j-r)*(j-r));
19             double diff = fabs(dis-r);
20             double depth = 1 - diff / r;
21             depth *= depth;
22             depth *= depth;
23             depth *= depth;
24             glColor3f(1-depth, depth, depth);
25             glVertex2i(i, j);
26         }
27     glEnd();
28     glFlush();
29 }
30 
31 int main(int argc, char *argv[])
32 {
33     glutInit(&argc, argv);
34     glutInitDisplayMode(GLUT_RGB | GLUT_SINGLE);
35     glutInitWindowPosition(0, 0);
36     glutInitWindowSize(600, 600);
37     glutCreateWindow("OpenGL 3D View");
38     init();
39     glutDisplayFunc(lineSegment);
40     glutMainLoop();
41     return 0;
42 }