Graphics Lab Assignment 1

// #pragma comment (lib,"glut32.lib")

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include <GL/glut.h>

#define BLACK 1, 1, 1

double angle_sun, angle_moon, angle_earth;

void display () {
    //clear the display
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glClearColor (BLACK, 0);
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode (GL_MODELVIEW);
    glLoadIdentity ();

    // defines a viewing transformation
    gluLookAt (.1, 0, 300, // eye
                0, 0, 0,   // lookat
                0, 0, 1);  // up


    // again select MODEL-VIEW
    glMatrixMode (GL_MODELVIEW);

    glColor3f (1, 0, 0);
    glPushMatrix (); {
        glTranslated (0, 0, 0);
        glRotatef (angle_sun, 1, 0, 0);

        glRotatef (90, 0, 1, 0);
        glutWireSphere (70,  // GLdouble radius
                        30,  // GLint slices
                        30); // GLint stacks

        glColor3f (0, 0, 1);
        glPushMatrix (); {
            glTranslated (0, 150, 0);
            glRotatef (angle_earth, 0, 0, 1);

            glRotatef (0, 1, 0, 0);
            glutWireSphere (40,  // GLdouble radius
                            18,  // GLint slices
                            18); // GLint stacks

            glColor3f (0, 0, 0);
            glPushMatrix (); {
                glTranslated (0, 100, 0);
                glRotatef (angle_moon, 0, 0, 1);

                glutWireSphere (25,  // GLdouble radius
                                18,  // GLint slices
                                18); // GLint stacks
            } glPopMatrix ();
        } glPopMatrix ();
    } glPopMatrix ();

    // ADD this line in the end --- if you use double buffer (i.e. GL_DOUBLE)
    glutSwapBuffers ();
}

void animate(){
    angle_sun += .1;
    angle_earth += .5;
    angle_moon += 2;
    glutPostRedisplay();
}

void init () {
    glClearColor (BLACK, 0);

    glMatrixMode (GL_PROJECTION); // load the projection matrix
    glLoadIdentity (); // initialize the matrix
    gluPerspective (70, 1, 0.1, 10000.0); // perspective parameters
}

int main (int argc, char **argv) {
    glutInit (&argc,argv);
    glutInitWindowSize (900, 700);
    glutInitWindowPosition (300, 200);
    glutInitDisplayMode (GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGB); // depth, double buffer, RGB color

    glutCreateWindow ("ID");
    init ();

    glEnable (GL_DEPTH_TEST); // enable depth testing
    glutDisplayFunc (display); // display callback function
    glutIdleFunc (animate); //what you want to do in the idle time (when no drawing is occuring)
    glutMainLoop (); // main loop of OpenGL

    return 0;
}