OpenGL 实现模拟太阳系运动

#include <gl/glut.h>

static int year = 0, day = 0;
static int sun = 0;

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

void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);

glPushMatrix();

glRotatef((GLfloat)sun, 0.0, 1.0, 0.0);
glutWireSphere(1.0, 20, 16);
glRotatef((GLfloat)year, 0.0, 1.0, 0.0);
glTranslatef(2.0, 0.0, 0.0);
glRotatef((GLfloat) day, 0.0, 1.0, 0.0);
glutWireSphere(0.2, 10, 8);

glPopMatrix();

glutSwapBuffers();
}

void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);

glLoadIdentity();
gluPerspective(60.0, (GLfloat)w / (GLfloat)h, 1.0, 20.0);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
}

void keyboard(unsigned char key, int x, int y)
{
switch (key)
{

case 'd':
day = (day + 10) % 360;
sun = (sun + 1) % 360;
glutPostRedisplay();
break;

case 'D':
day = (day - 10) % 360;
sun = (sun + 1) % 360;
glutPostRedisplay();
break;

case 'y':
year = (year + 5) % 360;
sun = (sun + 1) % 360;
glutPostRedisplay();
break;

case 'Y':
year = (year - 5) % 360;
sun = (sun + 1) % 360;
glutPostRedisplay();
break;

default:
break;
}
}

int main(int argc, char **argv)
{
glutInit(&argc, argv);
glutInitWindowSize(500, 500);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);

init();

glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMainLoop();

return 0;
}