/* Class Fold immitates a strip of paper being folded and unfolded

so that all folds are 90 degrees.

Shown in the hardcover version of Jurassic Park.

Nice fractal



Written by Michael Mandel



	Last change:  MM    4 Mar 2000    7:14 pm

 */





import java.awt.*;

import java.lang.*;



public class Fold extends java.applet.Applet implements Runnable{

    private int REPS;

    private int LINESTART;



    private static final int NORTH = 0;

    private static final int EAST = 1;

    private static final int SOUTH = 2;

    private static final int WEST = 3;

    private static final int LEFT = -1;

    private static final int RIGHT = 1;



    private int lineLength, lineCount = 1;

    private int[] array, newArray;

    private int startX, startY, width, height;



    private Image doubleBuffer;

    private boolean dbChanged = true;



    public void init()

    {

		array = new int[0];

		newArray = new int[1];



		REPS = Integer.parseInt(getParameter("reps"));

		LINESTART = Integer.parseInt(getParameter("lineStart"));
		
		new Thread(this).start();

    }
    
    public void run()
    {
    		for(int x = 0; x < REPS; x ++)
			{
		   	iterate();
		   	repaint();
	  	   	try{Thread.sleep(1000);} catch(Exception ignored){};
			}
	  }



    public void iterate()

    {
    	int x;



		for(x = 0; x < array.length; x++)

			    if(array[x] == LEFT || array[x] == RIGHT)

			    	newArray[x] = array[x];



		newArray[x] = RIGHT;



		x = 1;

		while(x <= array.length)

		{

		    if(array[array.length - x] == RIGHT)

				newArray[array.length + x] = LEFT;

		    else if(array[array.length - x] == LEFT)

				newArray[array.length + x] = RIGHT;

		    x++;

		}



		array = new int[newArray.length];

		for(x = 0; x < array.length; x++)

		    array[x] = newArray[x];

		newArray = new int[array.length * 2 + 1];

	

		lineLength = LINESTART / lineCount;

		lineCount++;

	

		dbChanged = true;

    }



    private void getDimensions()

    {

		int count, direction = NORTH;

		int x= 0, y = -lineLength, minX = 0, minY = -lineLength, maxX = 0, maxY = 0;

	

	   for (count = 0; count < array.length; count++)

		{

		    direction = (direction + array[count] + 4) % 4;

	

		    switch ( direction )

		    {

				case NORTH :

					y -= lineLength;

				    break;

				case SOUTH :

					y += lineLength;

				    break;

				case EAST :

					x += lineLength;

				    break;

				case WEST :

					x -= lineLength;

				    break;

				default :

				    break;

		    }

	

		    if(x > maxX)

				maxX = x;

		    if(y > maxY)

				maxY = y;

		    if(x < minX)

				minX = x;

		    if(y < minY)

				minY = y;

		}

	

		height = maxY - minY + 40;

		width = maxX - minX + 20;

		startX = 10 - minX;

		startY = 30 - minY;

	

		doubleBuffer = createImage(width, height);

    }



    public void drawToDB()

    {

		getDimensions();

	

		Graphics g = doubleBuffer.getGraphics();

	
		int count;

		int direction = NORTH;

		int x, y;



		x = startX;

		y = startY;



		g.fillRect(startX - 3, startY - 3, 6, 6);



		g.drawLine(x, y, x, y - lineLength);

		y -= lineLength;



		for (count = 0; count < array.length; count++)

		{

		    direction = (direction + array[count] + 4) % 4;

	

		    switch ( direction )

		    {

			case NORTH :

				g.drawLine(x, y, x, y - lineLength);

				y -= lineLength;

			    break;

			case SOUTH :

				g.drawLine(x, y, x, y + lineLength);

				y += lineLength;

			    break;

			case EAST :

				g.drawLine(x, y, x + lineLength, y);

				x += lineLength;

			    break;

			case WEST :

				g.drawLine(x, y, x - lineLength, y);

				x -= lineLength;

			    break;

	

			default :

			    break;

		    }

		}

		dbChanged = false;

    }



    public void paint(Graphics g)

    {

    	if(dbChanged)

	    drawToDB();

		g.drawImage(doubleBuffer, 0, 0, this);

    }

}