// The copyright of this program is reserved by “N”L.
/* 
Turtle Graphics : Sierpinski‹Èü
*/ 

/* <applet code="Ex061014a.class" width=420 height=420> </applet> */

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Ex061014a extends JApplet implements ActionListener{
	dTurtle t;
	boolean flag=false;
	double length;
	double theta=0.0;
	int order;
	JComboBox cb1;
	String cbl1[]={"n=1","n=2","n=3","n=4","n=5","n=6","n=7","n=8"};	
	public void init(){
		Container cp = getContentPane();
		JPanel pl = new JPanel();
		pl.setBackground(Color.black);
		t = new dTurtle();
    pl.setLayout(null);
    cb1 = new JComboBox(cbl1);
    cb1.setBounds(0,0,60,20);
    cb1.setSelectedIndex(0);
    cb1.addActionListener(this);
		pl.add(cb1);		
		cp.add(pl);
	}
	
	public void actionPerformed(ActionEvent event){
		order = cb1.getSelectedIndex()+1;
		length = 400.0/(Math.pow(2.0,order)-1)/(1.0+Math.cos(Math.PI/4.0));
		t.setColor(Color.yellow);
		t.setPos(10.0,10.0);
		t.setAng(0.0);
		flag=true;
		repaint();
	}
	
	public void paint(Graphics g){
		super.paint(g);
		if(flag==true)
			Sierpin(order,length,g);
	}
	
 	void Sierpin(int n,double len,Graphics g) {
  	if (n==0) {
    	t.turn(-90);
    }else{
    	Sierpin(n-1,len,g);
    	t.move(len,g);
    	Sierpin(n-1,len,g);
    	t.turn(135);
    	t.move(len,g);
    	t.turn(135);
    	Sierpin(n-1,len,g);
    	t.move(len,g);
    	Sierpin(n-1,len,g);
    }	
  }	
	
}