// 3D painted fractal mountains,  Evgeny Demidov  12 Oct 2001
import java.awt.*;
import java.awt.event.*;
import java.util.StringTokenizer;
public class @file extends java.applet.Applet
    implements MouseListener, MouseMotionListener {
  int n = 32, n1,  h,w,h2,w2, mx0,my0,  xPol[],yPol[], iCol[][][];
  double rnd,  fiX = .2, fiY = .3, dfi = .01, scale = .8, m20,m21,m22;
  double vert[][][], vert1[][][], Norm[][][][], Norm1z[][][], M[];
  Image buffImage;     Graphics buffGraphics;
  Color col[][];
  boolean painted;

public void init(){
  w = getSize().width;  h = getSize().height;   w2 = w/2;  h2 = h/2;
  String s=getParameter("N");  if (s != null) n = Integer.parseInt(s);
  xPol = new int[3];  yPol = new int[3];
  buffImage = createImage(w, h);   buffGraphics = buffImage.getGraphics();
  col = new Color[4][256];
  for (int i = 0; i < 256; i++){
    col[0][i] = new Color(0, 0, i);
    col[1][i] = new Color(0, (i*220)/256, 0);
    col[2][i] = new Color((i*150)/256, (i*150)/256, (i*50)/256);
    col[3][i] = new Color(i, i, i);}
  s = getParameter("bgColor"); if (s != null){
  StringTokenizer st = new StringTokenizer(s);
   int red = Integer.parseInt(st.nextToken());
   int green = Integer.parseInt(st.nextToken());
   int blue = Integer.parseInt(st.nextToken());
   setBackground( new Color(red, green, blue));}
  else setBackground(new Color(255,255,255));
  addMouseListener(this);
  addMouseMotionListener(this);
  setup();
}

public double R(){ return rnd*(Math.random()-.5);}

public void setup(){
  rnd = 1;
  n1 = n+1;
  iterate();
  vert = new double[n1][n1][3];  vert1 = new double[n1][n1][2];
  double dx = w/(double)n;
  int t = 0;
  for (int i = 0; i < n1; i++) 
   for (int j = 0; j < n1; j++){
    vert[i][j][0] = dx*i - w2;  vert[i][j][2] = dx*j - w2;
    double mi = M[t++];
    if (mi < 0) mi = .01*Math.random();
    vert[i][j][1] = w*mi - w2/2;}
  Norm = new double[n1][n1][2][3];  Norm1z = new double[n1][n1][2];
  iCol = new int[n][n][2];
  for (int i = 0; i < n; i++)
   for (int j = 0; j < n; j++){
     double s =
      ((vert[i][j][1] + vert[i+1][j][1] + vert[i+1][j+1][1])/3 + w2/2)/w;
     if (s < .01) iCol[i][j][0] = 0;
     else if (s+.1*Math.random() > .35) iCol[i][j][0] = 3;
      else if (s+.1*Math.random() > .15)  iCol[i][j][0] = 2;
       else  iCol[i][j][0] = 1;
     s = ((vert[i][j][1] + vert[i][j+1][1] + vert[i+1][j+1][1])/3 + w2/2)/w;
     if (s < .01) iCol[i][j][1] = 0;
     else if (s+.1*Math.random() > .35) iCol[i][j][1] = 3;
      else if (s+.1*Math.random() > .15)  iCol[i][j][1] = 2;
       else  iCol[i][j][1] = 1;
    Norm[i][j][0][0] = vert[i][j][1] - vert[i+1][j][1];
    Norm[i][j][0][1] = dx;
    Norm[i][j][0][2] = vert[i+1][j][1] - vert[i+1][j+1][1];
    double mod = Math.sqrt(Norm[i][j][0][0]*Norm[i][j][0][0] + Norm[i][j][0][1]*
     Norm[i][j][0][1] + Norm[i][j][0][2]*Norm[i][j][0][2]) / 255.5;
    Norm[i][j][0][0] /= mod; Norm[i][j][0][1] /= mod; Norm[i][j][0][2] /= mod;
    Norm[i][j][1][0] = vert[i][j+1][1] - vert[i+1][j+1][1];
    Norm[i][j][1][1] = dx;
    Norm[i][j][1][2] = vert[i][j][1] - vert[i][j+1][1];
    mod = Math.sqrt(Norm[i][j][1][0]*Norm[i][j][1][0] + Norm[i][j][1][1]*
     Norm[i][j][1][1] + Norm[i][j][1][2]*Norm[i][j][1][2]) / 255.5;
    Norm[i][j][1][0] /= mod; Norm[i][j][1][1] /= mod; Norm[i][j][1][2] /= mod;}
  rotate();
}

public void iterate(){
  int nc=n, Max=n1*n1, ncn1;
  double Min=-1;
  M = new double[Max];
  for (int i=n+2; i < n*n1-1; i++) M[i] = Min;
  for (int i=2*n1; i < n*n1; i += n1) M[i] = M[i-1] = 0;
  while ( (nc /= 2) >= 1){
    ncn1 = nc*n1;
    for (int j=ncn1; j < Max; j += ncn1+ncn1){
      for (int i= nc; i < n; i += nc+nc){
        if (M[i+j]==Min)
           M[i+j] = (M[i+j+nc-ncn1] + M[i+j-nc+ncn1])/2.+R();
        if (M[i+j+nc]==Min)
           M[i+j+nc] = (M[i+j+nc+ncn1] + M[i+j+nc-ncn1])/2.+R();
        if (M[i+j+ncn1]==Min)
           M[i+j+ncn1] = (M[i+j-nc+ncn1] + M[i+j+nc+ncn1])/2.+R(); }}
    rnd /= 2.;}
}

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();
  if ( e.isControlDown() ){
    setup();
    repaint();}
  if ( e.isAltDown() ){
    if ( e.isShiftDown() ){ n /= 2;  if (n < 1) n = 1;}
    else n *= 2;
    setup();
    repaint();}
  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 rotate(){
  double ct = Math.cos(fiX), cf = Math.cos(fiY),
         st = Math.sin(fiX), sf = Math.sin(fiY),
         m00 =  scale*cf,    m02 =  scale*sf,
         m10 = scale*st*sf, m11 =  scale*ct, m12 = -scale*st*cf;
         m20 = -ct*sf; m21 = st; m22 = ct*cf;
  for (int i = 0; i < n1; i++)
   for (int j = 0; j < n1; j++){
    vert1[i][j][0] = m00*vert[i][j][0] + m02*vert[i][j][2];
    vert1[i][j][1] = m10*vert[i][j][0] + m11*vert[i][j][1] + m12*vert[i][j][2];}
  for (int i = 0; i < n; i++)
   for (int j = 0; j < n; j++)
    for (int k = 0; k < 2; k++)
     Norm1z[i][j][k] = m20*Norm[i][j][k][0] + m21*Norm[i][j][k][1] +
      m22*Norm[i][j][k][2];
  painted = false;
}

public void mouseMoved(MouseEvent e) {}

public void paint(Graphics g) {
 if ( !painted ){
  buffGraphics.clearRect(0, 0, w, h);
  int ib=0, ie=n, sti=1,  jb=0, je=n, stj=1;
  if (m20 < 0){ ib = n; ie = -1; sti = -1;}
  if (m22 < 0){ jb = n; je = -1; stj = -1;}
  for (int i = ib; i != ie; i += sti)
   for (int j = jb; j != je; j += stj){
    if (Norm1z[i][j][0] > 0){
     xPol[0] = w2 + (int)vert1[i][j][0];
     xPol[1] = w2 + (int)vert1[i+1][j][0];
     xPol[2] = w2 + (int)vert1[i+1][j+1][0];
     yPol[0] = h2 - (int)vert1[i][j][1];
     yPol[1] = h2 - (int)vert1[i+1][j][1];
     yPol[2] = h2 - (int)vert1[i+1][j+1][1];
     buffGraphics.setColor(col[iCol[i][j][0]][(int)(Norm1z[i][j][0])]);
     buffGraphics.fillPolygon(xPol,yPol, 3);}
    if (Norm1z[i][j][1] > 0){
     xPol[0] = w2 + (int)vert1[i][j][0];
     xPol[1] = w2 + (int)vert1[i][j+1][0];
     xPol[2] = w2 + (int)vert1[i+1][j+1][0];
     yPol[0] = h2 - (int)vert1[i][j][1];
     yPol[1] = h2 - (int)vert1[i][j+1][1];
     yPol[2] = h2 - (int)vert1[i+1][j+1][1];
     buffGraphics.setColor(col[iCol[i][j][1]][(int)(Norm1z[i][j][1])]);
     buffGraphics.fillPolygon(xPol,yPol, 3);} }
  painted = true;}
 g.drawImage(buffImage, 0, 0, this);
 showStatus( "n=" + n);
}
public void update(Graphics g){ paint(g); }

}