import java.awt.*;
import java.util.Enumeration;
import jds.Deque;
import jds.collection.LinkedList;
import jds.collection.IndexedDeque;
import jds.util.CloseQuit;

class Line {
	Line (Point s, Point e) { start = s; stop = e; }
	public Point start, stop;

	public void draw (Graphics g) 
		{ g.drawLine(start.x, start.y, stop.x, stop.y); }
}

class Snowflake extends Frame {
	public static void main (String [ ] args) {
		Snowflake world = new Snowflake(); world.show(); world.run(); 
	}

	public Snowflake () 
		{ setTitle("Fractal Snowflake"); setSize(400, 400); 
		addWindowListener(new CloseQuit());
		}

	public void run () {
			// insert first lines into snowflake
		Point a = new Point(50, 140);
		Point b = new Point(350, 140);
		Point c = new Point(200, 360);
		lines.addFirst(new Line(a, b));
		lines.addFirst(new Line(b, c));
		lines.addFirst(new Line(c, a));
			// now make the snowflake
		while (! lines.isEmpty()) {
			Line lne = (Line) lines.getFirst();
			lines.removeFirst();
			processLine (lne);
			try { Thread.sleep(100); } catch(Exception e) { }
			repaint();
		}
	}

	private void processLine (Line lne) {
			// first compute line lengths
		int dx = (lne.stop.x - lne.start.x)/3;
		int dy = (lne.stop.y - lne.start.y)/3;
		if ((dx * dx + dy * dy) < 10) {
			done.addFirst(lne); // line is too small
		} else {
			Point a = new Point (lne.start.x + dx, lne.start.y+dy);
			Point b = new Point (lne.start.x + 3*dx/2 + dy, 
					lne.start.y + 3*dy/2 - dx);
			Point c = new Point (lne.start.x+2*dx, lne.start.y+2*dy);
			lines.addFirst(new Line(lne.start, a));
			lines.addFirst(new Line(a, b));
			lines.addFirst(new Line(b, c));
			lines.addFirst(new Line(c, lne.stop));
		}
	}

	public void paint (Graphics g) {
		Enumeration e = lines.elements();
		while (e.hasMoreElements()) {
			Line lne = (Line) e.nextElement();
			lne.draw(g);
		}
		e = done.elements();
		while (e.hasMoreElements()) {
			Line lne = (Line) e.nextElement();
			lne.draw(g);
		}
	}

	private Deque lines = new IndexedDeque();
	private Deque done = new IndexedDeque();
}