RECURSION - Java Programming: From Problem Analysis to Program Design - page 895

COMPLETE PROGRAM LISTING
//*********************************************************
// Author: D.S. Malik
//
// Program: Drawing a Sierpinski Gasket
// Given the order of a Sierpinski Gasket, this program
// draws a Sierpinski Gasket of that order.
//*********************************************************

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

public class SierpinskiGasket extends JApplet
{

int level = 0;

public void init()
{

String levelStr = JOptionPane.showInputDialog
("Enter the recursion depth: ");

level = Integer.parseInt(levelStr);

}

public void paint(Graphics g)
{

Point pointOne = new Point(60, 160);
Point pointTwo = new Point(220, 160);
Point pointThree = new Point(140, 20);

drawSierpinski(g, level, pointOne, pointTwo,
pointThree);

}

private void drawSierpinski(Graphics g, int lev,
Point p1, Point p2, Point p3)

{

Point midP1P2;
Point midP2P3;
Point midP3P1;

1
3

if (lev > 0)
{

g.drawLine(p1.x, p1.y, p2.x, p2.y);
g.drawLine(p2.x, p2.y, p3.x, p3.y);
g.drawLine(p3.x, p3.y, p1.x, p1.y);

midP1P2 = midPoint(p1, p2);
midP2P3 = midPoint(p2, p3);
midP3P1 = midPoint(p3, p1);