import java.awt.*;

public class hw2 extends BufferedApplet
{
  long time0;

  boolean doUpDown = true;
  boolean doLR = true;
  boolean doScale = true;

   //define points to make things a little cleaner
   double origin[] = {0, 0, 0}; 
   double blf[] = {-1, -1, -1}; //(b)ottom-(l)eft-(f)ront
   double brf[] = { 1, -1, -1}; //(b)ottom-(r)ight-(f)ront
   double blb[] = {-1, -1,  1}; //(b)ottom-(l)eft-(b)ack
   double brb[] = { 1, -1,  1}; //(b)ottom-(l)eft-(b)ack
   double tlf[] = {-1,  1, -1}; //(t)op-(l)eft-(f)ront
   double trf[] = { 1,  1, -1}; //(t)op-(r)ight-(f)ront
   double tlb[] = {-1,  1,  1}; //(t)op-(l)eft-(b)ack
   double trb[] = { 1,  1,  1}; //(t)op-(l)eft-(b)ack

   //define how points fit together later in init()
   double tetra1[][];
   double tetra2[][];
   double hourglass[][][]; // = {dec1, dec2};

   double a[] = {0,0,0}, b[] = {0,0,0};
   int w, h, count = 0;
   double t = 0;

   //transformation matrix
   Matrix3D m;

  public void init() {
    super.init();

    //set up geometry
    initPyramids();

    time0 = System.currentTimeMillis(); //start the clock

    m = new Matrix3D();
  }

  public void render(Graphics g) {
    count = tick(); //set clock

    w = bounds().width;                         // FIND OUT HOW BIG THE APPLET WINDOW IS
    h = bounds().height;

    g.setColor(Color.white);                    // MAKE A CLEAR WHITE BACKGROUND
    g.fillRect(0,0,w,h);

    g.setColor(Color.black);                    // SET THE DRAWING COLOR TO BLACK

    animate();                                  // DO ANIMATION CALCULATIONS

    for (int i = 0 ; i < hourglass.length ; i++)   // LOOP THROUGH ALL THE SHAPES
    for (int j = 1 ; j < hourglass[i].length ; j++) { // LOOP THROUGH ALL THE LINES IN THE SHAPE
      m.transform(hourglass[i][j-1], a);                      // TRANSFORM BOTH ENDPOINTS OF LINE
      m.transform(hourglass[i][j  ], b);
      g.drawLine(x(a[0]), y(a[1]), x(b[0]), y(b[1]));    // DRAW ONE LINE ON THE SCREEN
    }

    animating = true;
  }

  void animate() {
    m.identity();

    //double theta = 0.25 * Math.cos(.1 * count);
    double theta = Math.PI/4;
    //double theta = 0.1*count;
    m.rotateY(theta);
    m.rotateX(-1*theta/2);

    double sz = 1.0;
    if (doScale) sz = 0.8*Math.abs(Math.sin(.1 * count)) + 0.2;
    m.scale(1.0, 1.0, sz);

    double tx = 0;
    double ty = 0; 
    if (doUpDown) ty = 0.6*Math.cos(.2 * count);
    double tz = 0;
    if (doLR) tz = 0.6*Math.sin(.1 * count);

    m.translate(tx, ty, tz);
  }

  //event handling
  public boolean keyDown(java.awt.Event evt, int key) {
    if (key == 32) //space
      doScale = !doScale;
    if (key == Event.UP || key == Event.DOWN) doUpDown = !doUpDown; 
    if (key == Event.LEFT || key == Event.RIGHT) doLR = !doLR;

    return true;
  }

  int x(double t) { return w/2 + (int)(t*w/4); } // CONVERT X COORDINATE TO SCREEN PIXELS
  int y(double t) { return h/2 - (int)(t*w/4); } // CONVERT Y COORDINATE TO SCREEN PIXELS

  private int tick() {
    long time = System.currentTimeMillis();

    double elapsed = (time - time0) / 1000.0;
    return (int)(30 * elapsed);
  }

  private void initPyramids() {
    tetra1 = new double[12][3];
    tetra1[0] = origin; tetra1[1] = blf; tetra1[2] = brf;
    tetra1[3] = origin; tetra1[4] = brf; tetra1[5] = brb;
    tetra1[6] = origin; tetra1[7] = brb; tetra1[8] = blb;
    tetra1[9] = origin; tetra1[10] = blb; tetra1[11] = blf;

    tetra2 = new double[12][3];
    tetra2[0] = origin; tetra2[1] = tlf; tetra2[2] = trf;
    tetra2[3] = origin; tetra2[4] = trf; tetra2[5] = trb;
    tetra2[6] = origin; tetra2[7] = trb; tetra2[8] = tlb;
    tetra2[9] = origin; tetra2[10] = tlb; tetra2[11] = tlf;

    hourglass = new double[2][12][3];
    hourglass[0] = tetra1;
    hourglass[1] = tetra2;
  }
}