gistfile1.java

import java.awt.*;
import java.awt.geom.*;
import java.util.Stack;
import javax.swing.*;

// キモい再帰的なツリーを描くプログラム
public class drawtree extends JPanel
{
	private static final int DEGREE = 12;
	private static final int BRUNCH_LENGTH = 40;
	private static final int DRAW_LEVEL = 8;

	public static void main(String[] args)
	{
		drawtree dt = new drawtree();

		JFrame jf = new JFrame();
		jf.setSize(200, 200);
		jf.setVisible(true);
		jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		jf.setLayout(new BorderLayout());
		jf.add(dt, BorderLayout.CENTER);
	}

	public drawtree()
	{
		this.currentDegree = 90;
		this.positionStack = new Stack<Point2D>();
		positionStack.push(new Point2D.Double(100, 150));
	}

	private int currentDegree;
	private Stack<Point2D> positionStack;

	public void drawtree(Graphics g, int n)
	{
		if(n == 0)
		{
			// 何もしない
		}
		else
		{
			left();
			forward(g, n);
			drawtree(g, n-1);
			back(n);
			right();

			right();
			forward(g, n);
			drawtree(g, n-1);
			back(n);
			left();
		}
	}

	public void left()
	{
		this.currentDegree -= DEGREE;
	}

	public void right()
	{
		this.currentDegree += DEGREE;
	}

	public void forward(Graphics g, int n)
	{
		int brunchLength = BRUNCH_LENGTH - ((DRAW_LEVEL - n) * 2);

		Graphics2D g2d = (Graphics2D)g;
		Point2D currentPosition = (Point2D)positionStack.peek();

		// debug
		//System.out.println("CURRENT:" + currentPosition.getX() + "," + currentPosition.getY());

		Point2D moveTo = null;
		if(currentDegree <= 90)
		{
			double moveX = Math.sin((90 - (currentDegree - DEGREE)) / 180.0) * brunchLength;
			double moveY = Math.sin((currentDegree - DEGREE) / 180.0) * brunchLength;
			moveTo = new Point2D.Double(currentPosition.getX() - moveX, currentPosition.getY() - moveY);
		}
		else
		{
			int targetDegree = 180 - currentDegree;
			double moveX = Math.sin((90 - (targetDegree - DEGREE)) / 180.0) * brunchLength;
			double moveY = Math.sin((targetDegree - DEGREE) / 180.0) * brunchLength;
			moveTo = new Point2D.Double(currentPosition.getX() + moveX, currentPosition.getY() - moveY);
		}

		// debug
		//System.out.println("MOVE:" + moveTo.getX() + "," + moveTo.getY());

		g.setColor(Color.black);
		Line2D.Double line2d = new Line2D.Double(currentPosition.getX(), currentPosition.getY(), moveTo.getX(), moveTo.getY());
		g2d.draw(line2d);

		positionStack.push(moveTo);
	}

	public void back(int n)
	{
		positionStack.pop();
	}

	public void paint(Graphics g)
	{
		drawtree(g, DRAW_LEVEL);
	}
}