// lines.java
// source for program to iterate trough an l-system

import java.awt.*;
import java.applet.*;
import java.lang.*;

public class Lines2 extends Applet
{
  static final int MAXLINES = 6;
  static final int MAXITERATIONS = 3;
  static final int SNAP = 32;
  static final int TOP = 32;
  static final int BOTTOM = 336;
  static final int LEFT = 32;
  static final int RIGHT = 336;
  private int mode;
  private int iterations;
  private Point lastpoint = new Point(0,0);
  private Point firstpoint = new Point(0,0);
  private String lsys;
  private String good;
  private double ang;
  private double distance;

  public Lines2()
  {
    mode = 0;
    ang = Math.E;
    lsys = "";
  }

  public void get_template(Graphics g)
  {
    int loop, loop2;
    Point temp = new Point(0,0);
    Point temp2 = new Point(0,0);
    double angle = 0;
    int x = firstpoint.x;
    int y = firstpoint.y;

    g.setFont(new Font("TimesRoman", Font.PLAIN, 14));
    g.drawString("Click to draw template." + lsys, 5, 15);
    g.drawRect(LEFT,TOP,RIGHT-LEFT,BOTTOM-TOP);
    for (loop = LEFT + SNAP; loop < RIGHT; loop += SNAP)
      for (loop2 = TOP + SNAP; loop2 < BOTTOM; loop2 += SNAP)
        g.drawLine(loop, loop2, loop, loop2);
    for (loop = 0; loop < lsys.length(); loop++)
    {
      if (lsys.charAt(loop) == 'r')
        angle -= Math.PI/2;
      if (lsys.charAt(loop) == 'l')
        angle += Math.PI/2;
      if (lsys.charAt(loop) == 'd')
      {
        g.drawLine(x, y, (int)(x + Math.cos(angle) * SNAP), (int)(y - Math.sin(angle) * SNAP));
        x += (int)(Math.cos(angle) * SNAP);
        y -= (int)(Math.sin(angle) * SNAP);
      }
    }
  }

  public void draw_lsys(Graphics g)
  {
    int loop;
    double angle = 0;
    int x = firstpoint.x;
    int y = firstpoint.y;

    g.drawString(lsys,  5, 15);
    for (loop = 0; loop < lsys.length(); loop++)
    {
      if (lsys.charAt(loop) == 'r')
        angle -= Math.PI/2;
      if (lsys.charAt(loop) == 'l')
        angle += Math.PI/2;
      if (lsys.charAt(loop) == 'd')
      {
        g.drawLine(x, y, (int)(x + Math.cos(angle)*SNAP/Math.pow(distance, iterations)), (int)(y - Math.sin(angle)*SNAP/Math.pow(distance, iterations)));
        x += (int)(Math.cos(angle) * SNAP / Math.pow(distance, iterations));
        y -= (int)(Math.sin(angle) * SNAP / Math.pow(distance, iterations));
      }
    }
  }

  public boolean mouseDown(Event event, int x, int y)
  {
    if (mode == 0 && x >= LEFT+SNAP && x < RIGHT && y > TOP+SNAP && y < BOTTOM)
    {
      addpoint(x, y);
      repaint();
    }
    else if (mode == 0)
    {
      iterations = 0;
      mode = 1;
      good = lsys;
    }
    else if (mode == 1)
    {
      if (iterations < MAXITERATIONS)
      {
        iterations++;
        iterate();
        distance = (lastpoint.x - firstpoint.x) / SNAP;
      }
      repaint();
    }
    return true;
  }

  public void addpoint(int x, int y)
  {
    int ydiff;
    int xdiff;
    int loop;

    if (x % SNAP > SNAP / 2)
      x += SNAP - x % SNAP;
    else
      x -= x % SNAP;
    if (y % SNAP > SNAP / 2)
      y += SNAP - y % SNAP;
    else
      y -= y % SNAP;
    xdiff = x - lastpoint.x;
    ydiff = y - lastpoint.y;
    if (ang == Math.E)
    {
      firstpoint.move(x,y);
      lastpoint.move(x,y);
      ang = 0;
    }
    else
    {
      if (Math.abs(xdiff) > Math.abs(ydiff))
      {
        ydiff = 0;
        y = lastpoint.y;
        if (xdiff > 0)
        {
          if (ang != 0) 
            if (ang > Math.PI)
              lsys += 'l'; 
            else
              lsys += 'r';
          ang = 0;
        }
        else
        {
          if (ang != Math.PI)
            if (ang > Math.PI)
              lsys += 'r';
            else
              lsys += 'l';
          ang = Math.PI;
        }
        for (loop = 0; loop < Math.abs(xdiff) / SNAP; loop++)
          lsys += 'd';
      }
      else
      {
        xdiff = 0;
        x = lastpoint.x;
        if (ydiff > 0)
        {
          if (ang != 3 * Math.PI / 2)
            if (ang > Math.PI / 2)
              lsys += 'l';
            else
              lsys += 'r';
          ang = 3 * Math.PI / 2; 
        }
        else
        {
          if (ang != Math.PI / 2)
            if (ang > Math.PI / 2)
              lsys += 'r';
            else
              lsys += 'l';
          ang = Math.PI / 2;
        }
        for (loop = 0; loop < Math.abs(ydiff) / SNAP; loop++)
          lsys += 'd';
      }
      lastpoint.move(x,y);
    }
  }

  public void paint(Graphics g)
  {
    if (mode == 0)
      get_template(g);
    else if (mode == 1)
      draw_lsys(g);
  }

  public void iterate()
  {
    String str = "";
    int loop = 0, loop2, loop3;
    int count;
    
    while (loop < lsys.length())
    {
      count = 0;
      if (lsys.charAt(loop) == 'd')
      {
        do
        {
          loop++;
          count++;
        }
        while (loop < lsys.length() && lsys.charAt(loop) == 'd');
        loop--;
        for (loop2 = 0; loop2 < good.length(); loop2++)
          if (good.charAt(loop2) == 'd')
            for (loop3 = 0; loop3 < count; loop3++)
              str += 'd';
          else
            str += good.charAt(loop2);
      }
      else
        str += lsys.charAt(loop);
      loop++;
    }
    lsys = str;
  }
}