import java.applet.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;

public class Spiral extends Applet implements Runnable, MouseMotionListener {
  int    _radius; // 0  1  2  3  4  5  6   7   8   9  10  11   12   13   14   15   16   17     18    19    20     21     22     23
  int[]  _fibonacci={0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657};
  int    _patterns=_fibonacci.length-8;
  int    _index=0;
  int    _drawn=0;
  double _phi=1.61803399; // Golden Ratio
  double _anglestep=2 * 3.141592654 * _phi; // (circle (Golden Ratio)) in Radians
  double _scale=1;
  Graphics2D      _big;
  BufferedImage[] _bi=new BufferedImage[_patterns];
  public void paint(Graphics g) {((Graphics2D)g).drawImage(_bi[_index],0,0,this);}
  public void init() {
    _radius=(getSize().width < getSize().height ? getSize().width : getSize().height)/2;
    new Thread(this).start();
    addMouseMotionListener(this);
  }
  public void run() {for(_drawn=0; _drawn<_patterns; ++_drawn) drawSeedHeadImage(_drawn);}
  public void mouseDragged(MouseEvent e) {}
  public void mouseMoved(MouseEvent e) {
    int NewIndex=Math.max(0,(int)(_drawn-_drawn*Math.hypot(e.getX()-_radius,e.getY()-_radius)/_radius));
    if(_index==NewIndex) return;
    _index=NewIndex;
    repaint();
  }
  public void drawSeedHeadImage(int n) {
    _bi[n]=new BufferedImage(2*_radius,2*_radius, BufferedImage.TYPE_INT_RGB);
    _big=_bi[n].createGraphics(); // Use a back-buffer to paint on:
    _big.drawImage(_bi[n],0,0,this);
    _big.setColor(Color.white);
    _big.fillRect(0,0,getSize().width, getSize().height);
    _big.setStroke(new BasicStroke(2.0f)); // 2-pixel lines
    _big.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    _big.translate(_radius,_radius);
    float[]   Split={0.f, 0.5f, 1.f}; // Background:
    Color[] Colours={new Color(0.f,0.f,1.f,.6f), new Color(1.f,0.f,0.f,.8f), new Color(0.f,0.f,1.f,.2f)};
    _big.setPaint(new RadialGradientPaint(0,0, _radius, Split, Colours));
    disk(0,0, _radius);
    drawSeedHead(n);
  }
  public void drawSeedHead(int n) {
    int   Seeds=_fibonacci[n+=_fibonacci.length-_patterns];
    int SpiralA=_fibonacci[n=(int)(n/_phi)]; // The most natural curves are here.
    int SpiralB=_fibonacci[n+1];            // one will be clockwise, its neighbour anticlockwise.
    _scale=_radius/(Math.sqrt(Seeds)+_phi/2); // Draw the seed head:
    for(int i=1; i<Seeds; ++i) {
      _big.setColor(getRainbowColour((new Double(i))/Seeds));
      int x=X(i);
      int y=Y(i);
      if(i>SpiralA) _big.drawLine(x,y, X(i-SpiralA),Y(i-SpiralA));
      if(i>SpiralB) _big.drawLine(x,y, X(i-SpiralB),Y(i-SpiralB));
      circle(x,y,(int)(_scale*_phi/2));
    }
    _big.setFont(new Font("Sans Serif",java.awt.Font.BOLD,18));
    _big.setColor(Color.black);
    _big.drawString("SpiralA="+Integer.toString(SpiralA), 1-_radius, 18-_radius);
    _big.drawString("SpiralB="+Integer.toString(SpiralB), 1-_radius, 36-_radius);
    _big.drawString("Seeds="+Integer.toString(Seeds), 1-_radius, 54-_radius);
  }
  private int X(double n) {return (int)(_scale*Math.sqrt(n)*Math.sin(n*_anglestep));}
  private int Y(double n) {return (int)(_scale*Math.sqrt(n)*Math.cos(n*_anglestep));}
  public void circle(int x, int y, int r) {_big.drawOval(x-r,y-r, 2*r,2*r);}
  public void disk(int x, int y, int r) {
    int mx=x-r, my=y-r, d=2*r;
    _big.fillOval(mx,my,d,d);
    _big.drawOval(mx,my,d,d);
  }
  private Color getRainbowColour(double Ratio) {return new Color(GetGreen(Ratio + 1/3.), GetGreen(Ratio), GetGreen(Ratio - 1/3.), 0.5f);}
  private float GetGreen(double n) { // 1 __ Returns the amplitude of Green through the spectrum:
    if(n<0.) n=n+1;           //GetGreen /  \__ shift the X-Axis 1/3 backwards or forwards to get red and blue
    if(n>1.) n=n-1;                  // 0  n   1
    if(n<1/6.) return new Float(n * 6.);
    if(n<1/2.) return 1.f;
    if(n<2/3.) return new Float((2/3. - n) * 6.);
    return 0.f;
  }
}