// 3D percolating cluster,  Evgeny Demidov, 17 Dec 2001
  import java.awt.*;
  import java.awt.event.*;
  import java.util.StringTokenizer;
  public class applet-math-cluster3D extends java.applet.Applet
    implements MouseListener, MouseMotionListener, KeyListener, ActionListener{
    int w,h, h2,w2, mx0,my0, iCol[], maxCl, hBut = 30,
      xi[],yi[],zi[], x1[],y1[],zs[], Fx[][],Fy[][],
      L = 30, L1, cl[][][];
    double p = .312,  fiX = .2, fiY = .3, dfi = .01, scale, z1[];
    boolean painted = false;
    Image buffImage;  Graphics buffGraphics;
    Label lbP;        TextField tfP;      Button btNew;
    Color[] col;
  
  public void init() {
    w = getSize().width;  h = getSize().height - hBut;  h2=h/2; w2=w/2;
    String s=getParameter("L");
    if (s != null) L = Integer.parseInt(s);
    s=getParameter("p");
    if (s != null) p = Double.valueOf(s).doubleValue();
    int L3 = L*L*L, L2 = L+2;  L1 = L+1;
    scale = w2/(Math.sqrt(3.)*L);
    xi = new int[L3];  yi = new int[L3];  zi = new int[L3];
    x1 = new int[L3];  y1 = new int[L3];  zs = new int[L3];
    z1 = new double[L3];
    for (int i = 0; i < maxCl; i++){
     xi[i] = 2*(int)(10*(Math.random() - .5));
     yi[i] = 2*(int)(10*(Math.random() - .5));
     zi[i] = 2*(int)(10*(Math.random() - .5));
     zs[i] = i;}
    cl = new int[L2][L2][L2];
    for (int i = 0; i < L2; i++)
     for (int j = 0; j < L2; j++)
      for (int k = 0; k < L2; k++) cl[i][j][k] = -1;
    Fx = new int[3][];  Fy = new int[3][];           // 3 cube faces
    for (int i = 0; i < 3; i++){ Fx[i] = new int[4]; Fy[i] = new int[4];}
    col = new Color[256];
    for (int i = 0; i < 256; i++) col[i] = new Color(i, i, i);
    iCol = new int[3];
    buffImage = createImage(w, h);   buffGraphics = buffImage.getGraphics();
    addMouseListener(this);   addMouseMotionListener(this);
    lbP = new Label("p", Label.RIGHT);  add(lbP);
    tfP = new TextField( "" + (float)p, 5);  add(tfP);
    tfP.addKeyListener(this);
    btNew = new Button("New");   btNew.addActionListener(this);
    add(btNew);
    built();
  }
  public void built(){
    for (int i = 1; i < L1; i++)
     for (int j = 1; j < L1; j++)
      for (int k = 1; k < L1; k++) cl[i][j][k] = 0;
    int i0 = L/2,
    dx[] = {1,-1,0,0,0,0}, dy[] = {0,0,1,-1,0,0}, dz[] = {0,0,0,0,1,-1};
    cl[i0][i0][i0] = 1;
    for (int i = 0; i < 6; i++)
      cl[(xi[i]=i0+dx[i])][(yi[i]=i0+dy[i])][(zi[i]=i0+dz[i])] = 2;
    int nb = 5;
    do{
     int n = nb--, xn = xi[n],  yn = yi[n],  zn = zi[n];
     if (cl[xn][yn][zn] == 2){
      if (Math.random() > p) cl[xn][yn][zn] = -1;
      else{
       cl[xn][yn][zn] = 1;
       for (int i = 0; i < 6; i++){
        int xt = xn+dx[i],  yt = yn+dy[i],  zt = zn+dz[i];
        if (cl[xt][yt][zt] == 0){
         cl[xt][yt][zt] = 2;
         xi[++nb] = xt;  yi[nb] = yt;  zi[nb] = zt;}}}}
    } while (nb >= 0);
    maxCl = 0;
    for (int i = 1; i < L1; i++)
     for (int j = 1; j < L1; j++)
      for (int k = 1; k < L1; k++)
       if (cl[i][j][k] == 1){
         xi[maxCl] = 2*(i-i0); yi[maxCl] = 2*(j-i0); zi[maxCl++] = 2*(k-i0);}
    for (int i = 0; i < maxCl; i++) zs[i] = i;
    rotate();
  }
  public void destroy(){
    removeMouseListener(this);  removeMouseMotionListener(this);
  }
  public void mouseClicked(MouseEvent e){}       // event handling
  public void mousePressed(MouseEvent e) {
    mx0 = e.getX();  my0 = e.getY();
    e.consume();
  }
  public void mouseReleased(MouseEvent e){}
  public void mouseEntered(MouseEvent e) {}
  public void mouseExited(MouseEvent e)  {}
  public void mouseDragged(MouseEvent e) {
    int x1 = e.getX();  int y1 = e.getY();
    if ( e.isShiftDown() )  scale *= Math.exp(-(y1 - my0)/(double)w);
    else   fiX += dfi*(y1 - my0);
    fiY += dfi*(x1 - mx0);   mx0 = x1;  my0 = y1;
    rotate();
    repaint();
    e.consume();
  }
  public void mouseMoved(MouseEvent e){}
  public void keyTyped(KeyEvent e){}
  public void keyPressed(KeyEvent e){}
  public void keyReleased(KeyEvent e){
    final int keyEnter = 10;
    if (e.getKeyCode() == keyEnter){
      try{ p = Double.valueOf(tfP.getText()).doubleValue();
      }catch(NumberFormatException ne){}
      built();
      repaint();
    }
    e.consume();
  }
  public void actionPerformed(ActionEvent e){
    built();
    repaint();
  }
  public void rotate(){
    double ct = Math.cos(fiX), cf = Math.cos(fiY),
           st = Math.sin(fiX), sf = Math.sin(fiY),
           ix = scale*cf,                   kx =  scale*sf,
           iy = scale*st*sf, jy = scale*ct, ky = -scale*st*cf,
           iz = -255*ct*sf,  jz = 255*st,   kz = 255*ct*cf;
    int  Vx[] = {(int)(ix+kx), (int)(ix+kx), (int)(ix-kx), (int)(ix-kx), // cube
                (int)(-ix+kx),(int)(-ix+kx),(int)(-ix-kx),(int)(-ix-kx)},
    Vy[] = {(int)(iy+jy+ky), (int)(iy-jy+ky), (int)(iy-jy-ky), (int)(iy+jy-ky),
           (int)(-iy+jy+ky),(int)(-iy-jy+ky),(int)(-iy-jy-ky),(int)(-iy+jy-ky)},
    x0123[] = {Vx[0],Vx[1],Vx[2],Vx[3]}, y0123[] = {Vy[0],Vy[1],Vy[2],Vy[3]},
    x4567[] = {Vx[4],Vx[5],Vx[6],Vx[7]}, y4567[] = {Vy[4],Vy[5],Vy[6],Vy[7]},
    x0374[] = {Vx[0],Vx[3],Vx[7],Vx[4]}, y0374[] = {Vy[0],Vy[3],Vy[7],Vy[4]},
    x1265[] = {Vx[1],Vx[2],Vx[6],Vx[5]}, y1265[] = {Vy[1],Vy[2],Vy[6],Vy[5]},
    x0451[] = {Vx[0],Vx[4],Vx[5],Vx[1]}, y0451[] = {Vy[0],Vy[4],Vy[5],Vy[1]},
    x3762[] = {Vx[3],Vx[7],Vx[6],Vx[2]}, y3762[] = {Vy[3],Vy[7],Vy[6],Vy[2]};
    if (iz > 0){ Fx[0] = x0123; Fy[0] = y0123;}
    else{ Fx[0] = x4567; Fy[0] = y4567;}
    if (jz > 0){ Fx[1] = x0374; Fy[1] = y0374;}
    else{ Fx[1] = x1265; Fy[1] = y1265;}
    if (kz > 0){ Fx[2] = x0451; Fy[2] = y0451;}
    else{ Fx[2] = x3762; Fy[2] = y3762;}
    iCol[0] = (int)Math.abs(iz);  iCol[1] = (int)Math.abs(jz);
    iCol[2] = (int)Math.abs(kz);
    for (int i = 0; i < maxCl; i++){          // clusters grid
      x1[i] = (int)(ix*xi[i] + kx*zi[i]);
      y1[i] = (int)(iy*xi[i] + jy*yi[i] + ky*zi[i]);
      z1[i] = iz*xi[i] + jz*yi[i] + kz*zi[i];}
  //System.out.println(" Hi"+"  ");
    for (int i = maxCl - 1; --i >= 0;){
      boolean flipped = false;
      for (int j = 0; j <= i; j++) {
        int a = zs[j],  b = zs[j + 1];
        if (z1[a] > z1[b]) {
          zs[j + 1] = a;   zs[j] = b;
          flipped = true;
        }
      }
      if (!flipped) break;
    }
    painted = false;
  }
  
  public void paint(Graphics g) {
   if ( !painted ){
    int px[] = new int[4],  py[] = new int[4];
    buffGraphics.setColor(Color.blue);
    buffGraphics.fillRect(0, 0, w, h);
    for (int l = 0; l < maxCl; l++){
      int k = zs[l];
      for (int i = 0; i < 3; i++){
        for (int j = 0; j < 4; j++){
          px[j] = w2 + x1[k] + Fx[i][j];   py[j] = h2 - y1[k] - Fy[i][j];}
        buffGraphics.setColor(col[iCol[i]]);
        buffGraphics.fillPolygon(px,py, 4);} }
    painted = true;}
   g.drawImage(buffImage, 0,hBut, this);
   showStatus( "fiX=" + (int)(360*fiX) + "   fiY=" + (int)(360*fiY));
  }
  public void update(Graphics g)   {  paint(g);  }
  
  }