/*
   Copyright F. P. Marin ( April 07 13:12:53 1997 )
   E-mail: felix@bloch.ciens.ucv.ve
   
   Permission to use, copy, modify and distribute this software and its
   documentation for NON-COMERCIAL purposes and without fee is hereby
   granted provided that this copyright notice appears in all copies.

   F. P. Marin makes no representations or warranties about the suitability
   of the software, either express or implied, including but no limited to
   the implied warranties of merchantability, fitness for a particular
   purpose, or non-infringement. F. P. Marin shall not be liable for any
   damage suffered by license as a result of using, modifying or
   distributing this software or its derivatives.

   HTML code is

   <applet archive="PacmanGas.jar"
              code="PacmanGas.class"
            height=600
             width=600>
   <param name=delay     value="125">
   <param name=maxspeed  value="3">
   <param name=npacmans  value="25">
   <param name=minradius value="10">
   <param name=maxradius value="30">
   You should see a gas of PacMans !!!. Enjoy it !!!
   </applet>
*/
import java.awt.*;


public class PacmanGas extends java.applet.Applet implements Runnable
{      
       boolean running;   
       Graphics gr;
       Image img;
       int delay,nactual,xf,yf;
       Pacman pm[];
       Thread pacmanthread=null;
       

       public void init()
       {
        int minradius,maxradius,maxspeed,n;
        String s=getParameter("npacmans");

        if ( s!=null ) {
           n=Integer.parseInt(s);
           if ( n<1 ) n=1;
        } else n=1;
        pm=new Pacman[n];
        s=getParameter("maxspeed");
        if ( s!=null ) {
           n=Integer.parseInt(s);
           if ( n<3 ) n=3;
        } else n=3;
        maxspeed=n;
        s=getParameter("minradius");
        if ( s!=null ) {
           n=Integer.parseInt(s);
           if ( n<3 ) n=3;
           if ( n>(size().width/10) ) n=size().width/10;
        } else n=3;
        minradius=n;
        s=getParameter("maxradius");
        if ( s!=null ) {
           n=Integer.parseInt(s);
           if ( n<3 ) n=3;
           if ( n>(size().width/10) ) n=size().width/10;
        } else n=3;
        maxradius=n;
        if ( minradius>maxradius ) {
           n=minradius;
           minradius=maxradius;
           maxradius=n;
        }
        s=getParameter("delay");
        if ( s!=null ) {
           n=Integer.parseInt(s);
           if ( n<11 ) n=42;
        } else n=42;
        delay=n;
        nactual=0;
        xf=size().width - 1;
        yf=size().height - 1;
        for ( n=0 ; n<pm.length ; ++n,++nactual )
            pm[n]=new Pacman(minradius,maxradius,(double)maxspeed,this);
        img=createImage(size().width,size().height);
        gr=img.getGraphics();
       }


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


       public void run()
       {
        int i;
        
        running=true;
        while ( true ) {
              repaint();
              try { Thread.sleep(delay); }
              catch (InterruptedException e) {}
              for ( i=0 ; i<pm.length ; ++i ) pm[i].move();
        }
       }


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

    
       public void paint(Graphics g)
       {
        gr.setColor(Color.green.darker());
        gr.fillRect(0,0,size().width,size().height);
        for ( int i=0 ; i<pm.length ; ++i ) pm[i].drawPacman(gr);
        g.drawImage(img,0,0,this);
       }

       
       public void stop()
       {
        if ( pacmanthread!=null ) {
           pacmanthread.stop();
           pacmanthread=null;
        }
       }


       public boolean mouseDown(Event e,int x,int y)
       {
        if ( running ) {
           stop();
           running=false;
        } else start();
        return true;
       }
}



class Pacman extends Point
{
 static boolean Inx,Iny;
 static double Eye_a,Dx,Dy,Phase,Torad=Math.PI/180.0;
 static int I,Oldx,Oldy,Xeye,Yeye;
 boolean col,mouth; // col: true is a random Color. false is yellow 
                    // mouth: true is open mouth. false is closed mouth
 double vx,vy;  // velocity
 int angle,xf,yf,r;   // xf,yf: Maximum position of the center. r: radius
 PacmanGas pg; 


      Pacman(int minr,int maxr,double maxv,PacmanGas thepg)
      {
       super(0,0);
       r=(int)(minr + (maxr - minr)*Math.random() + 0.5);
       pg=thepg;
       xf=pg.xf - r;
       yf=pg.yf - r;
       int dx=(xf - r) + 1,dy=(yf - r) + 1;
       do move((int)(r + dx*Math.random()),(int)(r + dy*Math.random()));
       while ( icrash() );
       vx=maxv*Math.sqrt(Math.random());
       Phase=(2.0*Math.random() - 1.0)*Math.PI;
       vy=vx*Math.sin(Phase);
       vx*=Math.cos(Phase);
       mouth=( Math.random()<0.5 );
       angle=30;
       col=false;
      }

      
      void drawPacman(Graphics g)
      {
       if ( !col )
          g.setColor(Color.yellow.brighter());
       else {
          g.setColor(randColor().brighter());
          col=false;
       }
       if ( mouth )
          g.fillArc(x - r,y - r,2*r,2*r,angle,300);
       else g.fillOval(x - r,y - r,2*r,2*r);
       g.setColor(Color.black);
       Eye_a=Torad*(angle + 60.0);
       Xeye=(int)(x + 0.65*r*Math.cos(Eye_a));
       Yeye=(int)(y - 0.65*r*Math.sin(Eye_a));
       g.fillOval(Xeye,Yeye,r/3,r/3);
       mouth=!mouth;
      }


      boolean icrash()
      {
       for ( I=0 ; I<pg.nactual ; ++I ) {
            if ( this.equals(pg.pm[I]) ) continue;
            Dx=(double)Math.abs(x - pg.pm[I].x);
            Dy=(double)Math.abs(y - pg.pm[I].y);
                   if ( Dx<Dy ) {
                      Dx/=Dy;
                      Dx=Dy*Math.sqrt(1.0 + Dx*Dx);
            } else if ( Dx>0.0 ) {
                      Dy/=Dx;
                      Dx*=Math.sqrt(1.0 + Dy*Dy);
            }
            if ( Dx<=(r + pg.pm[I].r - 1) ) {
               angle=(int)(360.0*Math.random());
               pg.pm[I].angle=(int)(360.0*Math.random());
               return col=pg.pm[I].col=true;
            }
       }
       return false;
      }


      boolean move()
      {
       Oldx=x;
       Oldy=y;
       move((int)(x + vx + 0.5),(int)(y + vy + 0.5));
       Inx=(  ( r<=x ) && ( x<=xf )  );
       Iny=(  ( r<=y ) && ( y<=yf )  );
       if (  ( Inx ) && ( Iny )  ) {
          if ( icrash() ) {
             move(Oldx,Oldy);
             Dx=vx;
             vx=pg.pm[I].vx;
             pg.pm[I].vx=Dx;
             Dx=vy;
             vy=pg.pm[I].vy;
             pg.pm[I].vy=Dx;
             return false;
          }
       } else {
          move(Oldx,Oldy);
          if ( !Inx ) vx=-vx;
          if ( !Iny ) vy=-vy;
          return false;
       }
       return true;
      }


      Color randColor()
      {
       int r,g,b;

       r=(int)(256*Math.random());
       g=(int)(256*Math.random());
       b=(int)(256*Math.random());
       return new Color(r,g,b);
      }
}