/*
 * attact.java
 *
 * Lorenz's strange attractor, found at
 * http://www.sat.t.u-tokyo.ac.jp/~hideyuki/java/attract.html
 *
 */

import java.awt.*;

public class Attract extends java.applet.Applet implements Runnable {
  Thread attract=null;
  double x, y, z;
 
  public void init() { 
    setBackground(Color.black); 
    setForeground(Color.white); 
    x=0; y=20; z=20;
  } 

  public void paint(Graphics g) {
    double xx, yy, zz; 
    xx=x+0.01*(-10*x+10*y);
    yy=y+0.01*(28*x-y-x*z);
    zz=z+0.01*(-8*z/3+x*y);
    g.drawLine((int)(x*10+250),(int)(-z*10+500),(int)(xx*10+250),(int)(-zz*10+500));
    x=xx; y=yy; z=zz;
  } 

/* public void update(Graphics g) {
     g.setColor(getBackground());
     g.fillRect(0, 0, width, height);
     g.setColor(getForeground());
     paint(g); 
   } 
*/ 

  public void update(Graphics g) {
    paint(g);
  } 

  public void start() {
    if (attract==null) {
      attract = new Thread(this);
      attract.start();
    }
  }

  public void stop() {
    if (attract!=null) {
      attract.stop();
      attract=null;
    }
  } 

  public void run() {
    while (true) {
      try {
        Thread.currentThread().sleep(10);
      } 
      catch (InterruptedException e) { 
        break;
      } 
      repaint();
    }
  }
}