谢尔宾斯基的分形三角形

import java.awt.Graphics;

import java.awt.Point;//时代Java公众号 - nowjava.com 提供


import javax.swing.JFrame;


public class Main extends JFrame {

  public static final int WINDOW_SIZE = 512;

  public static final int THRESHOLD = 10; // stopping criterion for recursion

  public static int P1_x, P1_y, P2_x, P2_y, P3_x, P3_y;


  public Main() {

    super("Sierpinski");


    setSize(WINDOW_SIZE, WINDOW_SIZE);
/** 来自 n o w j a v a . c o m - 时  代  Java**/

    // A simple triangle

    P1_x = (int) getSize().getWidth() / 2;

    ;

    P1_y = 40;

    P2_x = 20;

    P2_y = (int) getSize().getHeight() - 20;

    P3_x = (int) getSize().getWidth() - 20;

    P3_y = (int) getSize().getHeight() - 20;


    setVisible(true);


    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

  }


  // Compute the midpoint

  public Point getMiddle(Point p1, Point p2) {

    return new Point((int) (p1.getX() + p2.getX()) / 2, (int) (p1.getY() + p2.getY()) / 2);

  }


  public void paint(Graphics g) {

    super.paint(g);


    draw(new Point(P1_x, P1_y), new Point(P2_x, P2_y), new Point(P3_x, P3_y));

  }


  public void draw(Point p1, Point p2, Point p3) {

    // termination condition

    if (p1.distance(p2) < THRESHOLD && p1.distance(p3) < THRESHOLD && p2.distance(p3) < THRESHOLD)

      return; // stop recursion

    // draw the current triangle

    Graphics g = getGraphics();

    g.drawLine((int) p1.getX(), (int) p1.getY(), (int) p2.getX(), (int) p2.getY());

    g.drawLine((int) p2.getX(), (int) p2.getY(), (int) p3.getX(), (int) p3.getY());

    g.drawLine((int) p3.getX(), (int) p3.getY(), (int) p1.getX