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

public class SnowFlake extends Applet
 { private int side = 400;
   private int order = 6;

   public void init()
    {  order = Integer.valueOf(getParameter("order")).intValue();
       if(order < 1) order = 1;
       if(order > 6) order = 6;
       resize(side, side);
    }

   private void snow(Graphics g, int n)
    { double x1=0.0, y1=0, x2=0.5, y2=Math.sqrt(3.0)/2, x3=1, y3=0;
      sline(g, x1, y1, x2, y2, n);
      sline(g, x2, y2, x3, y3, n); /* curve has three sections */
      sline(g, x3, y3, x1, y1, n); /* 1st order curve is a triangle */
    }

   private void sline(Graphics g,
		      double x1, double y1, double x5, double y5, int n)
    { if(n > 1) /* break line ((x1,y1).(x5,y5)) into 4 segments */
       { double x2, y2, x3, y3, x4, y4;
	 x2=(2*x1+  x5)/3; y2=(2*y1+  y5)/3;
	 x4=(  x1+2*x5)/3; y4=(  y1+2*y5)/3;
	 double sixty = Math.PI / 3;
	 x3=x2+(x2-x1)*Math.cos(sixty)-(y2-y1)*Math.sin(sixty);
	 y3=y2+(x2-x1)*Math.sin(sixty)+(y2-y1)*Math.cos(sixty);
	 sline(g, x1,y1, x2,y2, n-1);
	 sline(g, x2,y2, x3,y3, n-1); /* the kink out */
	 sline(g, x3,y3, x4,y4, n-1);
	 sline(g, x4,y4, x5,y5, n-1);
       }else /* n == 0 */
       { int s2 = Math.round(5*side/6);
	 double root3by2 = Math.sqrt(3.0)/2;
	 g.drawLine( 5+(int)Math.round(x1*s2),
		5+(int)Math.round((root3by2-y1)*s2),
		     5+(int)Math.round(x5*s2),
		5+(int)Math.round((root3by2-y5)*s2) );
    }  }

   public void paint(Graphics g)                  // redraw the applet
    { g.drawRect(0, 0, side-1, side-1);
      g.drawString("L.Allison, Computer Science, Monash University.  order="
                   + Integer.toString(order), 1, side-2);
      snow(g, order);
    }

   public boolean mouseUp(Event e, int x, int y)  // mouse click
    { if( x > side/2 ) order += 1; else order -= 1;
      if( order > 9 ) order = 9;
      if( order < 1 ) order = 1;
      repaint();
      return true;
    }
 }

/* L.Allison, Department of Computer Science, Monash University */