import java.awt.*;
import java.awt.event.*;

public class c03_koch extends java.applet.Applet {
  double r = 0.29;
  int n = 5;
  Graph graph;
  Controls controls;

  class Graph extends Canvas {
    public void paint(Graphics g)
    {
      koch(g, 1, 30, 190, 30+300, 190);
    }

    private void koch(Graphics g, int level, double x1, double y1, double x2, double y2)
    {
      if (level < n) {
        double nx = (2*x1+x2)/3;
        double ny = (2*y1+y2)/3;
        koch(g, level+1, x1, y1, nx, ny);
        double ox = nx;
        double oy = ny;
        nx = (x1+x2)/2 - r*(y1-y2);
        ny = (y1+y2)/2 + r*(x1-x2);
        koch(g, level+1, ox, oy, nx, ny);
        ox = nx; oy = ny;
        nx = (x1+2*x2)/3;
        ny = (y1+2*y2)/3;
        koch(g, level+1, ox, oy, nx, ny);
        koch(g, level+1, nx, ny, x2, y2);
      } else {
        g.drawLine((int)x1, (int)y1, (int)x2, (int)y2);
      }
    }
  }

  class Controls extends Container {
    private TextField tr;
    private TextField tn;
    private Button redraw;

    public Controls()
    {
      setLayout(new FlowLayout());
      add(new Label("r =", Label.RIGHT));
      add(tr = new TextField(""+r, 6));
      add(new Label("n =", Label.RIGHT));
      add(tn = new TextField(""+n, 6));
      add(redraw = new Button("Redraw"));
      redraw.addActionListener(
        new ActionListener() {
          public void actionPerformed(ActionEvent e) {
            try {
              r = Double.valueOf(tr.getText()).doubleValue();
              n = Integer.parseInt(tn.getText());
            } catch (NumberFormatException nfx) {
            }
            c03_koch.this.graph.repaint();
          }
        }
      );
    }
  }

  public void init()
  {
    setLayout(new BorderLayout());
    add(controls = new Controls(), BorderLayout.SOUTH);
    add(graph = new Graph(), BorderLayout.CENTER);
  }
}