/* Another pre-Mandelbrot classic, this one found by W. Sierpinski around 
 * World War I. It is generated by dividing a triangle into four congruent 
 * smaller triangles, doing the same to each of them, and so on, even 
 * unto infinity (in our case, 'max'). 
 * If you think of the interior triangles as "holes", they occupy more and 
 * more of the total area, while the "solid" portion becomes hopelessly 
 * fragile.
 * C.A. Bertulani, 07/21/2000
*/

import java.awt.*;
import java.applet.*;

public class Sierpin extends Applet {

  public void Sierplot(Graphics g)   /* plot method */
  {
    int i,max;
    double x, y, r;
    double a1,a2,a3,b1,b2,b3;
    max=80000;    /* maximum number of iterations */
	// set width, height and positions within gasket
    a1=20;
    b1=360;
    a2=320;    
    b2=360;    
    a3=170;
    b3=100;
	// starting point - center
    x = 180.;        
    y = 150.;
	// graphics
    setBackground(Color.black);   
    g.setColor(Color.yellow);
	// draw the gasket
    for(i=1 ; i<=max ; i++)              
    {
      r  = Math.random();   /* generate random number in interval (0-1) */
      if (r <= 0.3333)
      {
         x = 0.5*(x + a1);
         y = 0.5*(y + b1);
      }
      else if(r > 0.3333 && r <= 0.6666)
      {
         x = 0.5*(x + a2);
         y = 0.5*(y + b2);
      }   
      else 
      {
         x = 0.5*(x + a3);
         y = 0.5*(y + b3);
      }
	  // Draws a line, using the current color, between the points (x1, y1) 
	  // and (x2, y2) in this graphics context's coordinate system.
	  // Here it just draws a point
      g.drawLine((int)x,(int)y,(int)x,(int)y); 
   }
  }

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