/* * * Copyright (C) 2002 - 2005 Stephen F. Booth * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ import java.awt.Color; import java.awt.Point; import java.awt.Frame; import java.awt.Panel; import java.awt.Graphics; import java.awt.Polygon; import java.awt.Rectangle; import java.awt.event.MouseListener; import java.awt.event.MouseEvent; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; class ColorPoint { public Point p; public Color c; public ColorPoint(Point p, Color c) { this.p = p; this.c = c; } }; public class Sierpinski extends Panel implements MouseListener { public static void main(String[] args) { Frame frame = new Frame("Sierpinski's Gasket"); frame.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) {System.exit(0);} }); Sierpinski s = new Sierpinski(10000); frame.setSize(800, 800); frame.add(s); //frame.addMouseListener(s); frame.setVisible(true); } // ============================================================ Polygon mTriangle = null; ColorPoint [] mPoints = null; int mIterations = 0; int mCount = 0; public Sierpinski() { this(10000); } public Sierpinski(int iterations) { mIterations = iterations; addMouseListener(this); } private void init() { generate_triangle(); mPoints = new ColorPoint [mIterations]; while(mCount < mIterations) { generate_point(); } } private void destroy() { mTriangle = null; mPoints = null; mCount = 0; } public void mouseClicked(MouseEvent e) { destroy(); init(); repaint(); } public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} public void mousePressed(MouseEvent e) {} public void mouseReleased(MouseEvent e) {} public void paint(Graphics g) { Color restoreColor = g.getColor(); /* If we haven't inited, do so now */ /* Since initally the frame's size is (0,0), to do this from the constructor will cause an infinite loop */ if(mTriangle == null) init(); /* Fill the background with white and draw a black border */ Rectangle bounds = getBounds(); g.setColor(Color.WHITE); g.fillRect(bounds.x, bounds.y, bounds.width, bounds.height); g.setColor(Color.BLACK); g.drawRect(bounds.x + 1, bounds.y + 1, bounds.width - 2, bounds.height - 2); /* First draw our triangle that is the basis for the whole thing */ g.setColor(Color.BLACK); g.drawPolygon(mTriangle); /* Now draw the points */ for(int i = 0; i < mCount; ++i) { g.setColor(mPoints[i].c); g.drawLine(mPoints[i].p.x, mPoints[i].p.y, mPoints[i].p.x, mPoints[i].p.y); } g.setColor(restoreColor); } public void generate_triangle() { double x1, x2, x3; double y1, y2, y3; int width = getSize().width; int height = getSize().height; /* Generate three points */ x1 = width * Math.random(); x2 = width * Math.random(); x3 = width * Math.random(); y1 = height * Math.random(); y2 = height * Math.random(); y3 = height * Math.random(); /* Three points make a triangle iff the third point is not on * the line created by the first two points. */ /* y = mx + b, m = dy/dx, and b = y - mx */ /* We can calculate m and b from the two points on the line, * and use them to determine if the third point lies on the * line */ double m = (y2 - y1) / (x2 - x1); double b = y1 - m * x1; /* Determine if the third point is on the line */ /* Since we are using floating-point arithmetic, nothing will * match up exactly. Use a small delta to check for * equality - 0.001 or so */ double delta = 0.001; /* y = mx + b will rearrange in this case to |y - mx - b| < delta */ while(Math.abs(y3 - m * x3 + b) < delta) { x3 = width * Math.random(); y3 = height * Math.random(); } /* Now we have three points that form a triangle */ mTriangle = new Polygon(); mTriangle.addPoint((int) Math.floor(x1 + 0.5), (int) Math.floor(y1 + 0.5)); mTriangle.addPoint((int) Math.floor(x2 + 0.5), (int) Math.floor(y2 + 0.5)); mTriangle.addPoint((int) Math.floor(x3 + 0.5), (int) Math.floor(y3 + 0.5)); } public void generate_point() { double x, y; Color c; Point p; /* If this is the first iteration, generate a starting point */ if(mCount == 0) { int height = getSize().height; int width = getSize().width; /* Generate a point inside our original triangle */ do { x = width * Math.random(); y = height * Math.random(); } while(mTriangle.contains(x, y) == false); } /* Otherwise, use the previous point as our starter */ else { x = mPoints[mCount - 1].p.x; y = mPoints[mCount - 1].p.y; } /* Generate a number between 1 and 6 */ int roll = ((int) Math.floor(6 * Math.random())) + 1; double xcorner = 0, ycorner = 0; double newx = 0, newy = 0; double xdiff = 0, ydiff = 0; double xorigin = 0, yorigin = 0; switch(roll) { default: throw new RuntimeException(); //break; case 1: case 2: xcorner = mTriangle.xpoints[0]; ycorner = mTriangle.ypoints[0]; c = Color.RED; break; case 3: case 4: xcorner = mTriangle.xpoints[1]; ycorner = mTriangle.ypoints[1]; c = Color.GREEN; break; case 5: case 6: xcorner = mTriangle.xpoints[2]; ycorner = mTriangle.ypoints[2]; c = Color.BLUE; break; }; /* Calculate half the distance between the points */ xdiff = Math.abs(xcorner - x)/2; ydiff = Math.abs(ycorner - y)/2; /* Add the diffs to the lesser value */ xorigin = Math.min(xcorner, x); yorigin = Math.min(ycorner, y); newx = xorigin + xdiff; newy = yorigin + ydiff; p = new Point((int) Math.floor(newx + 0.5), (int) Math.floor(newy + 0.5)); mPoints[mCount++] = new ColorPoint(p, c); } };