OpenGL “太阳、地球和月亮”天体运动动画 例子  

#include <GL/glut.h>
#include <stdio.h>
#include <time.h>

// 太阳、地球和月亮
// 假设每个月都是12天
// 一年12个月，共是360天
static int day = 200; // day的变化：从0到359

double CalFrequency()
{
static int count;
static double save;
static clock_t last, current;
double timegap;

++count;
if( count <= 50 )
return save;
count = 0;
last = current;
current = clock();
timegap = (current-last)/(double)CLK_TCK;
save = 50.0/timegap;
return save;
}

void myDisplay(void)
{
double FPS = CalFrequency();
printf("FPS = %f\n", FPS);

glEnable(GL_DEPTH_TEST);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(75, 1, 1, 400000000);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0, -200000000, 200000000, 0, 0, 0, 0, 0, 1);

// 绘制红色的“太阳”
glColor3f(1.0f, 0.0f, 0.0f);
glutSolidSphere(69600000, 20, 20);
// 绘制蓝色的“地球”
glColor3f(0.0f, 0.0f, 1.0f);
glRotatef(day/360.0*360.0, 0.0f, 0.0f, -1.0f);
glTranslatef(150000000, 0.0f, 0.0f);
glutSolidSphere(15945000, 20, 20);
// 绘制黄色的“月亮”
glColor3f(1.0f, 1.0f, 0.0f);
glRotatef(day/30.0*360.0 - day/360.0*360.0, 0.0f, 0.0f, -1.0f);
glTranslatef(38000000, 0.0f, 0.0f);
glutSolidSphere(4345000, 20, 20);

glFlush();
glutSwapBuffers();
}

void myIdle(void)
{
++day;
if( day >= 360 )
day = 0;
myDisplay();
}

int main(int argc, char *argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowPosition(100, 100);
glutInitWindowSize(400, 400);
glutCreateWindow("太阳，地球和月亮");
glutDisplayFunc(&myDisplay);
glutIdleFunc(&myIdle);
glutMainLoop();
return 0;
}