int     eyeX = 0, eyeY = 15, eyeZ = 60,
        lookAtX = 0, lookAtY = 0, lookAtZ = -20,
        upX = 0, upY = 1,  upZ = 0;

int speed = 1;
int refreshmil = 250;

void timer(int value){
    glutPostRedisplay();
    glutTimerFunc(refreshmil, timer, 0);
}

void setCamera(int eyeX, int eyeY, int eyeZ, int lookAtX, int lookAtY, int lookAtZ, int upX, int upY, int upZ){
    gluLookAt(eyeX, eyeY, eyeZ, lookAtX, lookAtY, lookAtZ, upX, upY, upZ);
}

void init()
{
    GLfloat light_amb[] = { 1, 1, 1, 0 };
    glEnable(GL_DEPTH_TEST);
    glShadeModel(GL_SMOOTH);
    glLightfv(GL_LIGHT0, GL_AMBIENT, light_amb);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glShadeModel(GL_SMOOTH);
    glEnable(GL_COLOR_MATERIAL);
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}

void moveCamera(unsigned char key, int x, int y) {
    switch (key) {
        case 119: //W move camera forward
            lookAtZ--;
            eyeZ--;
            break;
        case 115: //S move camera back
            lookAtZ++;
            eyeZ++;
            break;
        case 97: //A move camera left
            lookAtX--;
            eyeX--;
            break;
        case 100: //D move camera right
            lookAtX++;
            eyeX++;
            break;
        case 113: //Q move camera down
            lookAtY--;
            eyeY--;
            break;
        case 101: //E move camera up
            lookAtY++;
            eyeY++;
            break;
        case 122: //tilt up
            lookAtY++;
            break;
        case 120: //tilt down
            lookAtY--;
            break;
        case 99:
            lookAtX--;
            break; //tilt left
        case 118:
            lookAtX++;
            break; //tilt right
        case 32: //press space bar to exit program
            exit(0);
            break;
    }
}

int rotateVal = 0;

void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glLineWidth(1.0);
    glClearColor(0.678, 0.847, 0.902, 0);
    glLoadIdentity();
    glutKeyboardFunc(moveCamera);

    setCamera(eyeX, eyeY, eyeZ, lookAtX, lookAtY, lookAtZ, upX, upY, upZ);

    glFlush();
}

void reshape(int w, int h)
{
    glViewport(0, 0, (GLsizei)w, (GLsizei) h);
    glMatrixMode(GL_PROJECTION);
    glFrustum(-1.0, 1.0, -1.0, 1.0, 1, 400.0);
    glMatrixMode(GL_MODELVIEW);
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(900, 700);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("blank");


    init();

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    glColor3f(0, 1, 0);
    glutDisplayFunc(display);

    glutReshapeFunc(reshape);
    glutTimerFunc(10, timer, 0);
    // glutFullScreen();
    glutMainLoop();
    return 0;
}