Barnsley fern
Barnsley fern is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
A Barnsley fern is a fractal named after British mathematician Michael Barnsley and can be created using an iterated function system (IFS).
The task: create this fractal fern, using the following transformations:
- ƒ1 (chosen 1% of the time)
xn + 1 = 0 yn + 1 = 0.16 yn
- ƒ2 (chosen 85% of the time)
xn + 1 = 0.85 xn + 0.04 yn yn + 1 = −0.04 xn + 0.85 yn + 1.6
- ƒ3 (chosen 7% of the time)
xn + 1 = 0.2 xn − 0.26 yn yn + 1 = 0.23 xn + 0.22 yn + 1.6
- ƒ4 (chosen 7% of the time)
xn + 1 = −0.15 xn + 0.28 yn yn + 1 = 0.26 xn + 0.24 yn + 0.44.
Starting position: x = 0, y = 0
<lang java>import java.awt.*; import java.awt.image.BufferedImage; import javax.swing.*;
public class BarnsleyFern extends JPanel {
BufferedImage img;
public BarnsleyFern() { final int dim = 640; setPreferredSize(new Dimension(dim, dim)); setBackground(Color.white); img = new BufferedImage(dim, dim, BufferedImage.TYPE_INT_ARGB); createFern(dim, dim); }
void createFern(int w, int h) { double x = 0; double y = 0;
for (int i = 0; i < 200_000; i++) { double tmpx, tmpy; double r = Math.random();
if (r <= 0.01) { tmpx = 0; tmpy = 0.16 * y; } else if (r <= 0.08) { tmpx = 0.2 * x - 0.26 * y; tmpy = 0.23 * x + 0.22 * y + 1.6; } else if (r <= 0.15) { tmpx = -0.15 * x + 0.28 * y; tmpy = 0.26 * x + 0.24 * y + 0.44; } else { tmpx = 0.85 * x + 0.04 * y; tmpy = -0.04 * x + 0.85 * y + 1.6; } x = tmpx; y = tmpy;
img.setRGB((int) Math.round(w / 2 + x * w / 11), (int) Math.round(h - y * h / 11), 0xFF32CD32); } }
@Override public void paintComponent(Graphics gg) { super.paintComponent(gg); Graphics2D g = (Graphics2D) gg; g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g.drawImage(img, 0, 0, null); }
public static void main(String[] args) { SwingUtilities.invokeLater(() -> { JFrame f = new JFrame(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setTitle("Barnsley Fern"); f.setResizable(false); f.add(new BarnsleyFern(), BorderLayout.CENTER); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); }); }
}</lang>
zkl
Uses the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl
<lang zkl>fcn barnsleyFern(){
w,h:=640,640; bitmap:=PPM(w+1,h+1,0xFF|FF|FF); // White background
x,y, nx,ny:=0.0, 0.0, 0.0, 0.0; do(0d100_000){ r:=(0).random(100); // [0..100)% if (r<= 1) nx,ny= 0, 0.16*y; else if(r<= 8) nx,ny= 0.2*x - 0.26*y, 0.23*x + 0.22*y + 1.6; else if(r<=15) nx,ny=-0.15*x + 0.28*y, 0.26*x + 0.24*y + 0.44; else nx,ny= 0.85*x + 0.04*y, -0.04*x + 0.85*y + 1.6; x,y=nx,ny; bitmap[w/2 + x*60, y*60] = 0x00|FF|00; // Green dot } bitmap.writeJPGFile("barnsleyFern.jpg");
}();</lang>
- Output:
http://www.zenkinetic.com/Images/RosettaCode/barnsleyFern.jpg