#include <vgl.h>
static int year =0, day =0;void init(void)
{glClearColor(0.0,0.0,1.0,0.0);  //清除背景底色glShadeModel(GL_FLAT);
}
void display(void)
{glClear(GL_COLOR_BUFFER_BIT);glColor3f(0.5,0.5,0.5);         //相当于画笔glPushMatrix();                 glRotatef((GLfloat)year, 0.0, 1.0, 0.0);glutWireSphere(1,30,24);        //sun: radius  longtitude  latitudeglPopMatrix();                  glPushMatrix();glRotatef((GLfloat)year,-1,1,0);glTranslatef(3.0, 0.0, 0.0); glTranslatef(0.0, 3.0, 0.0); glRotatef((GLfloat)day, -1.0, 1.0, 0.0);glutWireSphere(0.3,10,8);glPopMatrix();glPushMatrix();glRotatef((GLfloat)year,1,1,0);glTranslatef(2.0,0.0,0.0); glTranslatef(0.0,-2.0,0.0); glRotatef((GLfloat)day,1,1,0);glutWireSphere(0.3,10,8);glPopMatrix();glutSwapBuffers();
}void reshape(int w,int h)
{glViewport(0,0,(GLsizei)w,(GLsizei)h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(60,(GLfloat)w/(GLfloat)h,1.0,20.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();gluLookAt(0.0,0.0,6.0,0.0,0.0,0.0,0.0,1.0,0.0 );
}
void keyboard(unsigned char key, int x,int y)
{switch(key){case 'd':  day = (day+10) %360;glutPostRedisplay();break;case 'D':  day = (day-10) %360;glutPostRedisplay();break;case 'y':  year = (year+5) %360;glutPostRedisplay();break;case 'Y':  year = (year-5) %360;glutPostRedisplay();break;default:break;}
}
int main(int argc, char** argv)
{glutInit(&argc,argv);glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);glutInitWindowSize(400,400);glutInitWindowPosition(200,200);glutCreateWindow(argv[0]);init();glutDisplayFunc(display);glutReshapeFunc(reshape);glutKeyboardFunc(keyboard);glutMainLoop();return 0;
}

2.说出结果