// dragoric.java - from fergusmurray.members.beeb.net
// 'Murray Dragons'
// or what happens to the curlicue fractal
// (which is a discretisation of the equations of the Cornu spiral/Fresnel
//  spiral/Euler's spiral/the clothoid)
// when you animate it.
// This version  Fergus Crawshay Murray, January 2000.
// Any comments or suggestions to dragons@fergusmurray.co.uk.

import java.awt.*;
import java.applet.Applet;

public class Dragoric extends java.applet.Applet  implements Runnable {
// Notes on variables:
// _frame   - incremented each 'frame'
// _brush   - represents the kind of 'paintbrush' used - 0 means lines,
//            n (!=0) means squares of size n
// _symm    - kind of symmetry imposed
// _dir     - whether the shape is going in 'reverse' or not
// _ang     - angle of the turtle
// _angV    - rate of change of _ang
// _seed    - rate of change of _angV, main crucial param in overall shape
// _sin[]   - sine lookup table (also used for cosine)
// _pal[]   - all the colours
// _clear   - true if it's time to clear the frame
// _leng    - length of 'dragon' calculated each frame
// _prop    - length actually drawn (which part is drawn shifts each frame)
// _rate    - indicates the rate of change of the 'dragon'
// _zoom    - level of zoom
// _ecce    - 'eccentricity' - distance from centre each 'dragon' starts at
// _wipe    - number of frames between automatic wipes
//            (-1 means automatic wiping is turned off)
// _wipeCnt - number of frames until the next automatic wipe.

   Thread  _thr;
   Color   _pal [] = new Color  [256];
   double  _sin [] = new double [257];
   boolean _clear  = true,
           _paused = false;
   int     _frame  = 0, _w, _h, _cX, _cY, _brush,
           _symm   = 1,
           _dir    = 1;
   double  _seed   = 0.0001;
   int     _leng   = 72,
           _prop   = 64,
           _rate   = 100,
           _zoom   = 4,
           _ecce   = 0,
           _wipe   = -1,
           _wipeCnt;
   public Scrollbar lengBar, propBar, rateBar, zoomBar, ecceBar, wipeBar;
   public Label     wipeLbl;
   public TextField seedBox;
   public Checkbox  reverseBox, pauseBox;
   public CheckboxGroup drawGrp, symmGrp;

   public void init ()
   { int   i;
     float hue = 0;
   // Create lookup tables for colour and trig funcs.  get w, h, center
      for (i = 0; i < _pal.length; i++) {
         _pal[i] = Color.getHSBColor (hue, (float)1.0, (float)1.0);
         hue += 0.0036;
      }
      for (i = 0; i < _sin.length;i++)  {_sin [i] = Math.sin (i*Math.PI/128);}
      _w = getWidth();   _h = getHeight();   _cX = _w/2;   _cY = _h/2;

   // build the dang gui
      setBackground (Color.black);
      setLayout (new BorderLayout ());
     Panel pan = new Panel ();
      add ("East", pan);
      pan.setBackground (Color.black);
      pan.setLayout (new GridLayout (34, 1));
      seedBox = new TextField ();
      pan.setForeground (Color.white);
      pan.add (new Label ("Seed"));
      pan.setBackground (Color.white);
      pan.setForeground (Color.black);
      pan.add (seedBox);
      pan.setForeground (Color.black);
      seedBox.setText ("0.0001");
     Button seedBtn   = new Button ("Input seed");
     Button reseedBtn = new Button ("Random seed");
     Button wipeBtn   = new Button ("Wipe");
      pan.add (seedBtn);
      pan.add (reseedBtn);
      pan.add (wipeBtn);
      pan.setBackground (Color.black);
      pan.add (new Panel ());
      pan.setForeground (Color.white);
      pan.add (new Label ("Length"));
      lengBar = new Scrollbar (Scrollbar.HORIZONTAL,  144, 4, 1,  5555);
      pan.add (lengBar);
      pan.add (new Label ("Length visible"));
      propBar = new Scrollbar (Scrollbar.HORIZONTAL, 5555, 4, 1,  5555);
      pan.add (propBar);
      pan.add (new Label ("Rate of curl"));
      rateBar = new Scrollbar (Scrollbar.HORIZONTAL,  768, 4, 1, 10000);
      pan.add (rateBar);
      pan.add (new Label ("Zoom"));
      zoomBar = new Scrollbar (Scrollbar.HORIZONTAL,    8, 4, 1,    22);
      pan.add (zoomBar);
      pan.add (new Label ("Eccentricity"));
      ecceBar = new Scrollbar (Scrollbar.HORIZONTAL,    0, 4, 0,   300);
      pan.add (ecceBar);
      wipeLbl = new Label ("Wipe");
      wipeBar = new Scrollbar (Scrollbar.HORIZONTAL, 1000, 4, 1,  1000);
      pan.add (wipeLbl);
      pan.add (wipeBar);
      pan.add (new Panel ());
      drawGrp = new CheckboxGroup ();
      pan.add (new Checkbox ("Lines",       drawGrp, true));
      pan.add (new Checkbox ("Dots",        drawGrp, false));
      pan.add (new Checkbox ("2x2 squares", drawGrp, false));
      pan.add (new Checkbox ("3x3 squares", drawGrp, false));
      pan.add (new Panel ());
      pan.add (new Label ("Symmetry:"));
      symmGrp = new CheckboxGroup ();
      pan.add (new Checkbox ("1 R",      symmGrp, true));
      pan.add (new Checkbox ("2 R",      symmGrp, false));
      pan.add (new Checkbox ("1 R, 1 M", symmGrp, false));
      pan.add (new Checkbox ("1 R, 2 M", symmGrp, false));
      pan.add (new Panel ());
      reverseBox = new Checkbox ("Reverse", null, false);
      pan.add (reverseBox);
      pauseBox = new Checkbox ("Pause", null, false);
      pan.add (pauseBox);

      scrollUpdate ();   checkUpdate ();
   }

   public boolean action (Event evt, Object arg)
   // deal with any button presses.
   {  if (evt.target instanceof Button) {
        String bname = (String)arg;
         if (bname.equals ("Random seed")) {
            seedBox.setText (Double.toString (Math.random ()));
            _seed = ((Double.valueOf (seedBox.getText ())).doubleValue ())
                    * (2*Math.PI);
            _clear = true;
         }
         if (bname.equals ("Input seed")){
         // seedBox.setText ("0.0001");  // reset it
            _seed = ((Double.valueOf (seedBox.getText ())).doubleValue ())
                    * (2*Math.PI);
            _clear = true;
         }
         if (bname.equals ("Wipe"))
            _clear = true;
         return true;
      }
      else return false;
   }

   public boolean keyDown (Event evt, int key)
   // check if the Enter key has been pressed.  (to input seed)
   {  if (key == Event.ENTER) {
         _clear = true;
         _seed = ((Double.valueOf (seedBox.getText ())).doubleValue ())
                 * (2*Math.PI);
         return true;
      }
      else return false;
   }

   public boolean handleEvent (Event evt)
   // check for other user-interface events.
   {  if      (evt.target instanceof Scrollbar) {scrollUpdate ();  return true;}
      else if (evt.id==Event.MOUSE_DOWN || evt.id==Event.MOUSE_DRAG)
                                      {_cX = evt.x;  _cY = evt.y;  return true;}
      else if (evt.target instanceof Checkbox)  {checkUpdate ();   return true;}
      return super.handleEvent (evt);
   }

   public void scrollUpdate ()
   // update values associated with scrollbars.
   {  _leng = lengBar.getValue ();
      _prop = propBar.getValue ();
      _rate = rateBar.getValue ();
      _zoom = zoomBar.getValue ();
      _ecce = ecceBar.getValue ();
      _wipe = wipeBar.getValue ();
      _wipeCnt = _wipe;
      if (_wipe > 995)
           {wipeLbl.setText ("Wipe: never");  _wipe = -1;}
      else  wipeLbl.setText ("Wipe: every " + wipeBar.getValue ());
   }

   public void checkUpdate ()
   // update values associated with checkboxes.
   { String bx = drawGrp.getCurrent ().getLabel ();
      if (bx == "Lines")          _brush = 0;
      if (bx == "Dots")           _brush = 1;
      if (bx == "2x2 squares")    _brush = 2;
      if (bx == "3x3 squares")    _brush = 3;
     String s = symmGrp.getCurrent ().getLabel ();
      if (s == "1 R")             _symm = 1;
      if (s == "2 R")             _symm = 2;
      if (s == "1 R, 1 M")        _symm = 3;
      if (s == "1 R, 2 M")        _symm = 4;
      if (reverseBox.getState ()) _dir = -1;
      else                        _dir =  1;
      _paused = pauseBox.getState ();
   }

   public void start ()
   {  if (_thr == null) {_thr = new Thread (this);  _thr.start ();}  }

   public void run ()
   {  while (_thr != null) {
         if (! _paused)  {repaint ();  _frame++;}
         try {_thr.sleep (10);}  catch (InterruptedException e) {}
      }
   }

   public void paint (Graphics gfx)   // the GUTS
   { double realx, realy,  ang, angInc;
     int    x, y, ox, oy,  i;
      if (! _paused) {
         if ((_wipe != -1) && (_wipeCnt-- == 0))
            {_clear = true;  _wipeCnt = _wipe;}
         if (_clear) {
            gfx.setColor (Color.black);
            gfx.fillRect (0, 0, 1280, 1024);
            _clear = false;
         }
         _seed = _seed + 0.00000004 * _rate * _dir;
         realx = realy = _ecce;   x = y = ox = oy = (int) _ecce;
         ang = angInc = 0;
         for (i = 1; i <= _leng; i++) {
            ang += angInc;   angInc += _seed;
            if (ang    > Math.PI*2)  ang    -= Math.PI*2;
            if (angInc > Math.PI*2)  angInc -= Math.PI*2;
            if (ang    < 0)          ang    += Math.PI*2;
            if (angInc < 0)          angInc += Math.PI*2;
            realx += _zoom * (CosQ (ang));   x = (int)realx;
            realy += _zoom * (SinQ (ang));   y = (int)realy;
            gfx.setColor (_pal [(i+_frame) % 255]);
            if ((i+_frame) % _leng < _prop){
               if (_symm == 1){
                  plot (_cX+x, _cY+y, _cX+ox, _cY+oy, _brush, gfx);
                  plot (_cX-x, _cY-y, _cX-ox, _cY-oy, _brush, gfx);
               }
               if (_symm == 2){
                  plot (_cX+x, _cY+y, _cX+ox, _cY+oy, _brush, gfx);
                  plot (_cX-x, _cY-y, _cX-ox, _cY-oy, _brush, gfx);
                  plot (_cX-y, _cY+x, _cX-oy, _cY+ox, _brush, gfx);
                  plot (_cX+y, _cY-x, _cX+oy, _cY-ox, _brush, gfx);
               }
               if (_symm == 3){
                  plot (_cX+x, _cY+y, _cX+ox, _cY+oy, _brush, gfx);
                  plot (_cX-x, _cY-y, _cX-ox, _cY-oy, _brush, gfx);
                  plot (_cX-x, _cY+y, _cX-ox, _cY+oy, _brush, gfx);
                  plot (_cX+x, _cY-y, _cX+ox, _cY-oy, _brush, gfx);
               }
               if (_symm == 4){
                  plot (_cX+x, _cY+y, _cX+ox, _cY+oy, _brush, gfx);
                  plot (_cX-x, _cY-y, _cX-ox, _cY-oy, _brush, gfx);
                  plot (_cX-y, _cY+x, _cX-oy, _cY+ox, _brush, gfx);
                  plot (_cX+y, _cY-x, _cX+oy, _cY-ox, _brush, gfx);
                  plot (_cX+x, _cY-y, _cX+ox, _cY-oy, _brush, gfx);
                  plot (_cX-x, _cY+y, _cX-ox, _cY+oy, _brush, gfx);
                  plot (_cX-y, _cY-x, _cX-oy, _cY-ox, _brush, gfx);
                  plot (_cX+y, _cY+x, _cX+oy, _cY+ox, _brush, gfx);
               }
            }
            ox = x;   oy = y;
         }
      }
   }

   public void plot (int x, int y, int ox, int oy, int br, Graphics g)
   // draw a line or a square, as appropriate.
   {  if (br == 0) g.drawLine (x, y, ox, oy);
      else         g.fillRect (x, y, br, br);
   }

   public void update (Graphics g)  {paint (g);}

   public double SinQ (double angle)
   {  return _sin [((int)(256+angle*128/Math.PI))%256];  }

   public double CosQ (double angle)
   {  return _sin [((int)(192+angle*128/Math.PI))%256];  }

}