PONG PUDDING

var pong_timegrain = 15;
var pong_timeunit = pong_timegrain/100;
var pong_point_size= 15, pong_sqr_point_size = pong_point_size*pong_point_size;
var pong_a_joueur=0.1;

function AddEvent( obj, event, func, mode){ 
  if( obj.addEventListener) 
    obj.addEventListener( event, func, mode? mode:false); 
  else 
    obj.attachEvent( 'on'+event, func); 
}

function Pong(type_jeu) // objet
{
  this.type_jeu = type_jeu;
  this.name = "Pong";
  var me = this;   
  var freed = false;
  var canvas = document.getElementById("c");
  canvas.style.visibility = "visible";
  
  if (type_jeu == "menu")
  {
    canvas.style.backgroundColor = "transparent";
    canvas.style.border = "none";
  } else
  {
    canvas.style.backgroundColor = "#80A0C0";
    canvas.style.border = "1px solid black";
  }
  
  this.tx = parseInt(canvas.getAttribute("width"));
  this.ty = parseInt(canvas.getAttribute("height"));  

  var balle;
  var computer1,computer2;
      
  this.fillpoly = function(c, len, color) // note : c = (x1,y1,x2,y2,x3,y3...)
  {
    if (len < 2) return;
    
    var ctx = canvas.getContext("2d");
    ctx.fillStyle = color;
    ctx.beginPath();
    ctx.moveTo(c[0],c[1]);
    for (var n=2; n<len; n+=2)
    {
      ctx.lineTo(c[n],c[n+1]);
    }
    ctx.closePath();
    ctx.fill();
  }

  var joueur1, joueur2;

  if (type_jeu=="menu") balle = new PetiteBalle(this,30,[this.tx/2,this.ty/2],[10*pong_timeunit,-5*pong_timeunit]); else
  if (type_jeu=="jeu_seul")
  {
    joueur1 = new Joueur(this,40,100, [50,Math.random()*(this.ty-100)+50], [0,0], "blue", [0,0,this.tx*2/3,this.ty]);
    joueur1.name += "1";
    joueur2 = new Joueur(this,40,100, [this.tx-50,Math.random()*(this.ty-100)+50], [0,0], "orange", [this.tx*1/3,0,this.tx,this.ty]);
    joueur2.name += "2";
    balle = new PetiteBalle(this,30,[120,150],[0,0]);
    //computer1 = true;
    computer2 = true;
  } else
  if (type_jeu=="jeu_deux")
  {
    joueur1 = new Joueur(this,40,100, [this.tx-50,Math.random()*(this.ty-100)+50], [0,0], "green", [this.tx*1/3,0,this.tx,this.ty]);
    joueur1.name += "1";
    joueur2 = new Joueur(this,40,100, [50,Math.random()*(this.ty-100)+50], [0,0], "blue", [0,0,this.tx*2/3,this.ty]);
    joueur2.name += "2";
    balle = new PetiteBalle(this,30,[this.tx/2,this.ty/2],[0,0]);
  }
  
  this.free = function()
  {
    if (balle) { balle.free(); balle = null; }
    if (joueur1) { joueur1.free(); joueur1 = null; }
    if (joueur2) { joueur2.free(); joueur2 = null; }
    if (canvas) canvas.style.visibility = "hidden";
    freed = true;
  }  
  
  var prevtime = -1;
  var LeftKey1, RightKey1, UpKey1, DownKey1, RotateLeft1, RotateRight1;
  var LeftKey2, RightKey2, UpKey2, DownKey2, RotateLeft2, RotateRight2;

  var wait = function()
  {
    setTimeout(	loop, 15); 
  }
            
  var loop = function()
  {
    if (freed) return;
    var newtime = (new Date()).getTime();
    if (prevtime==-1) prevtime = newtime; 
         
    var stepcount = Math.floor((newtime-prevtime)/pong_timegrain);
    if (stepcount>50)
      prevtime = newtime; else
    {
      prevtime += stepcount*pong_timegrain;
      if (joueur1) 
      {
        if (computer1)
         joueur1.ia(-1, joueur2, balle); else 
          joueur1.acceleration(LeftKey1?-pong_a_joueur:(RightKey1?pong_a_joueur:0),UpKey1?-pong_a_joueur:(DownKey1?pong_a_joueur:0));
      }
      if (joueur2) 
      {
        if (computer2)
         joueur2.ia(+1, joueur1, balle); else
         joueur2.acceleration(LeftKey2?-pong_a_joueur:(RightKey2?pong_a_joueur:0),UpKey2?-pong_a_joueur:(DownKey2?pong_a_joueur:0));
      }
      for (var k=0; k<stepcount; k++)
      {
        if (balle) balle.step();
        if (joueur1) joueur1.step();
        if (joueur2) joueur2.step();
      }      

      var ctx = canvas.getContext("2d");
      ctx.clearRect(0,0,me.tx,me.ty);
      
      if (balle) balle.dessine();
      if (joueur1) joueur1.dessine();
      if (joueur2) joueur2.dessine();
    }
    
    wait();
  }  
  
  this.canMove = function(obj,nx,ny,vx,vy)
  {  
    var acc_factor = 1;
    if (obj!=joueur1&&joueur1) if (joueur1.ptIn(nx,ny,vx/acc_factor,vy/acc_factor)) return false;
    if (obj!=joueur2&&joueur2) if (joueur2.ptIn(nx,ny,vx/acc_factor,vy/acc_factor)) return false;
    if (obj!=balle&&balle) if (balle.ptIn(nx,ny,vx/acc_factor,vy/acc_factor)) return false;
    return true;
  }
  
  this.go = function()
  {
    wait();
  }
  
  this.keyDown = function(e)
  {
   var keyCode = window.event ? e.keyCode : e.which;
   if (keyCode==37||keyCode==52||keyCode==100) 
   {
     LeftKey1 = true;
     RightKey1 = false;
   } else
   if (keyCode==38||keyCode==56||keyCode==104) 
   { 
     UpKey1 = true;
     DownKey1 = false;
   } else      
   if (keyCode==39||keyCode==54||keyCode==102)
   {
     RightKey1 = true;
     LeftKey1 = false;
   } else
   if (keyCode==40||keyCode==50||keyCode==98) 
   { 
     DownKey1 = true;
     UpKey1 = false;
   } else
   if (keyCode==81) 
   {
     LeftKey2 = true;
     RightKey2 = false;
   } else
   if (keyCode==90) 
   { 
     UpKey2 = true;
     DownKey2 = false;
   } else      
   if (keyCode==68)
   {
     RightKey2 = true;
     LeftKey2 = false;
   } else
   if (keyCode==83) 
   { 
     DownKey2 = true;
     UpKey2 = false;
   }
     // else  alert(keyCode);
   return false;
  }

  this.keyUp = function(e)
  {	
   var keyCode = window.event ? e.keyCode : e.which;
   if (keyCode==37||keyCode==52||keyCode==100) 
   {
     LeftKey1 = false;
   } else
   if (keyCode==38||keyCode==56||keyCode==104) 
   { 
     UpKey1 = false;
   } else      
   if (keyCode==39||keyCode==54||keyCode==102)
   {
     RightKey1 = false;
   } else
   if (keyCode==40||keyCode==50||keyCode==98) 
   { 
     DownKey1 = false;
   } else
   if (keyCode==81) 
   {
     LeftKey2 = false;
   } else
   if (keyCode==90) 
   { 
     UpKey2 = false;
   } else      
   if (keyCode==68)
   {
     RightKey2 = false;
   } else
   if (keyCode==83) 
   { 
     DownKey2 = false;
   }
   return false;
  }

  if (navigator.appName == 'Netscape')
  {
    document.onkeydown = this.keyDown;
    document.onkeyup = this.keyUp;
  } else
  {  
    AddEvent(document.body, "keydown", this.keyDown);
    AddEvent(document.body, "keyup", this.keyUp);
  }
}

function Joueur(jeu, tx, ty, p, v, color, rect) // objet
{
  this.name = "Joueur";
  var nbp = Math.round(ty/pong_point_size);
  var pts = new Array();
  var dir = new Array();
  var dist_pts = ty/(nbp-1);
  var elasticite = 10;
  var a= [0,0];
  var temp_a = [0,0];
  
  for (var i=0; i<nbp; i++)
  {
    pts.push(p[0]+tx/2+(Math.random()-0.5)*pong_point_size/4);
    pts.push(p[1]+(i-(nbp-1)/2)*dist_pts+(Math.random()-0.5)*pong_point_size/4);
    dir.push(v[0]);
    dir.push(v[1]);
  }

  for (var i=0; i<nbp; i++)
  {     
    pts.push(p[0]-tx/2+(Math.random()-0.5)*pong_point_size/4);
    pts.push(p[1]-(i-(nbp-1)/2)*dist_pts+(Math.random()-0.5)*pong_point_size/4);
    dir.push(v[0]);
    dir.push(v[1]);
  }
  
  var len_visible = pts.length;
 
  var lon_diag0 = Math.sqrt(Math.pow(pts[(nbp*2-2)*2]-pts[0],2)+Math.pow(pts[(nbp*2-2)*2+1]-pts[1],2));
  var minmax = calcMinMax(pts,pts.length);
    
  this.dessine = function()
  {
    jeu.fillpoly(pts,len_visible, color);
  }
  
  this.free = function()
  {
  }
  
  this.ptIn = function (x,y,vx,vy)
  {    
    if (x<minmax[0]-pong_point_size||x>minmax[1]+pong_point_size||y<minmax[2]-pong_point_size||y>minmax[3]+pong_point_size) return false;
    for (i=0; i<pts.length; i+=2)
    {
      if (Math.pow(pts[i]-x,2)+Math.pow(pts[i+1]-y,2) < pong_sqr_point_size)
      {
        dir[i] += vx;
        dir[i+1] += vy;
        return true;
      }
    }
    return false;
  }
  
  this.canMove = function(nx,ny,vx,vy)
  {
    if (nx < rect[0]||ny<rect[1]||nx>rect[2]||ny>rect[3]) return false; else
      return jeu.canMove(this,nx,ny,vx,vy);
  }
  
  this.acceleration = function(dx,dy)
  {     
    a = [dx,dy];
  }
  
  this.step = function(stepcount)
  {
    if (!stepcount) stepcount = 1;
    var lon_ref,ndx,ndy;
    for (var k=0; k<stepcount; k++) {
      ia_elapse --;
      for (var i=0; i<2*nbp; i++)
      {
        var i_cur = i*2;
        var i_suiv = ((i+1)%(2*nbp))*2;
        var i_suiv2 = ((i+1)%(2*nbp))*2;
        var i_opp = (nbp*2-1-i)*2;
        
        var i_diag = ((nbp*2-1-i+2*nbp-1)%(2*nbp))*2, diag_bi = false;
        if (i_diag==i_cur) { i_diag = ((nbp*2-1-i+1)%(2*nbp))*2; diag_bi = true; }
        
        var x = pts[i_cur], y = pts[i_cur+1];
        var dx = dir[i_cur], dy = dir[i_cur+1];

        if (i_suiv2-(i_suiv2%(nbp*2))==i_cur-(i_cur%(nbp*2)))
        {
          var x_suiv2 = pts[i_suiv2], y_suiv2 = pts[i_suiv2+1];
          var lon_suiv2 = Math.sqrt(Math.pow(x_suiv2-x,2)+Math.pow(y_suiv2-y,2));
          if (lon_suiv2<1) lon_suiv2 = 1;
          lon_ref = dist_pts;
          
          ndx = (lon_suiv2-lon_ref)*(x_suiv2-x)/lon_suiv2/elasticite*2;
          ndy = (lon_suiv2-lon_ref)*(y_suiv2-y)/lon_suiv2/elasticite*2;
          dx += ndx;          dy += ndy;
          dir[i_suiv2] -= ndx; dir[i_suiv2+1] -= ndy;
        }
        
        if (i_suiv!=i_opp)
        {
          var x_suiv = pts[i_suiv], y_suiv = pts[i_suiv+1];
          var lon_suiv = Math.sqrt(Math.pow(x_suiv-x,2)+Math.pow(y_suiv-y,2));
          if (lon_suiv<1) lon_suiv = 1;
          lon_ref = dist_pts;
          
          ndx = (lon_suiv-lon_ref)*(x_suiv-x)/lon_suiv/elasticite/2;
          ndy = (lon_suiv-lon_ref)*(y_suiv-y)/lon_suiv/elasticite/2;
          dx += ndx;          dy += ndy;
          dir[i_suiv] -= ndx; dir[i_suiv+1] -= ndy;
        }        

        var x_opp = pts[i_opp], y_opp = pts[i_opp+1];
        var lon_opp = Math.sqrt(Math.pow(x_opp-x,2)+Math.pow(y_opp-y,2));
        if (lon_opp<1) lon_opp = 1;
        lon_ref = tx;        
        ndx = (lon_opp-lon_ref)*(x_opp-x)/lon_opp/elasticite;
        ndy = (lon_opp-lon_ref)*(y_opp-y)/lon_opp/elasticite;
        dx += ndx;        dy += ndy;               

        var x_diag = pts[i_diag], y_diag = pts[i_diag+1];
        var lon_diag = Math.sqrt(Math.pow(x_diag-x,2)+Math.pow(y_diag-y,2));
        if (lon_diag<1) lon_diag = 1;
        lon_ref = lon_diag0;        
        ndx = (lon_diag-lon_ref)*(x_diag-x)/lon_diag/elasticite;
        ndy = (lon_diag-lon_ref)*(y_diag-y)/lon_diag/elasticite;
        dx += ndx;        dy += ndy; 
        if (diag_bi) { dir[i_diag] -= ndx; dir[i_diag+1] -= ndy; }

        dir[i_cur] = dx;  dir[i_cur+1] = dy;       
      }

      var i_top = 0;      
      var i_bottom = nbp*2;
      var x_top = pts[i_top], y_top = pts[i_top+1];
      var x_bottom = pts[i_bottom], y_bottom = pts[i_bottom+1];
      var lon = Math.sqrt(Math.pow(x_bottom-x_top,2)+Math.pow(y_bottom-y_top,2));
      if (lon<1) lon = 1;
      lon_ref = Math.sqrt(tx*tx+ty*ty);
          
      dir[i_top] += (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;
      dir[i_top+1] += (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;
      dir[i_bottom] -= (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;
      dir[i_bottom+1] -= (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;

      var i_top = (nbp*2-1)*2;      
      var i_bottom = (nbp-1)*2;
      var x_top = pts[i_top], y_top = pts[i_top+1];
      var x_bottom = pts[i_bottom], y_bottom = pts[i_bottom+1];
      var lon = Math.sqrt(Math.pow(x_bottom-x_top,2)+Math.pow(y_bottom-y_top,2));
      if (lon<1) lon = 1;
      lon_ref = Math.sqrt(tx*tx+ty*ty);
          
      dir[i_top] += (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;
      dir[i_top+1] += (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;
      dir[i_bottom] -= (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;
      dir[i_bottom+1] -= (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;

      var i_top = 0;      
      var i_bottom = (nbp-1)*2;
      var x_top = pts[i_top], y_top = pts[i_top+1];
      var x_bottom = pts[i_bottom], y_bottom = pts[i_bottom+1];
      
      var lon = Math.abs(x_bottom-x_top);
      if (lon<1) lon = 1;
      lon_ref = 0;
      dir[i_top] += (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;
      dir[i_bottom] -= (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;

      var lon = Math.abs(y_bottom-y_top);
      if (lon<1) lon = 1;
      lon_ref = ty;
      dir[i_top+1] += (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;
      dir[i_bottom+1] -= (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;

      var i_top = (nbp*2-1)*2;      
      var i_bottom = nbp*2;
      var x_top = pts[i_top], y_top = pts[i_top+1];
      var x_bottom = pts[i_bottom], y_bottom = pts[i_bottom+1];
      
      var lon = Math.abs(x_bottom-x_top);
      if (lon<1) lon = 1;
      lon_ref = 0;
      dir[i_top] += (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;
      dir[i_bottom] -= (lon-lon_ref)*(x_bottom-x_top)/lon/elasticite/4;

      var lon = Math.abs(y_bottom-y_top);
      if (lon<1) lon = 1;
      lon_ref = ty;
      dir[i_top+1] += (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;
      dir[i_bottom+1] -= (lon-lon_ref)*(y_bottom-y_top)/lon/elasticite/4;
      
      var moydx=0, moydy=0, moyx=0, moyy=0;
      for (var i=0; i<pts.length; i+=2)
      {
        var x = pts[i], y = pts[i+1];
        var dx = dir[i]+temp_a[0], dy = dir[i+1]+temp_a[0];
        if (dx<-pong_point_size/2) dx = -pong_point_size/2;
        if (dy<-pong_point_size/2) dy = -pong_point_size/2;
        if (dx>pong_point_size/2) dx = pong_point_size/2;
        if (dy>pong_point_size/2) dy = pong_point_size/2;
        if (this.canMove(x+dx,y+dy,dx,dy))
        {
          x += dx;
          y += dy;
        } else
        {
          var len;
          if (Math.abs(dx)>Math.abs(dy))
           len = Math.abs(dx); else
           len = Math.abs(dy);
          for (var n=0; n<len; n++)
          {
            if (this.canMove(x+dx/len,y+dy/len,0,0))
            {
              x += dx/len;
              y += dy/len;
            } else   break;
          }          
          
          var bloquex=(dx>0 && !this.canMove(x+1,y,0,0))||(dx<0 && !this.canMove(x-1,y,0,0));
          var bloquey=(dy>0 && !this.canMove(x,y+1,0,0))||(dy<0 && !this.canMove(x,y-1,0,0));
          if (bloquex&&bloquey) { dx = 0; dy = 0; }
          else if (bloquex) { dx = 0; dy = dy*0.9; }
          else if (bloquey) { dy = 0; dx = dx*0.9; }
          
        }
        
        pts[i] = x;
        pts[i+1] = y; 
        moyx += x;
        moyy += y;   
        dir[i] = dx;
        dir[i+1] = dy;
        moydx += dx;
        moydy += dy;
      }
      moydx /= (pts.length)/2;
      moydy /= (pts.length)/2;
      this.v = [moydx,moydy];
      moyx /= (pts.length)/2;
      moyy /= (pts.length)/2;      
      this.p = [moyx,moyy];
      for (var i=0; i<pts.length; i+=2)
      {
        dir[i] = dir[i]*0.87 + moydx*0.1 + a[0];
        dir[i+1] = dir[i+1]*0.87 + moydy*0.1 + a[1];
      }
      temp_a = [0,0];
    }
    minmax = calcMinMax(pts,pts.length);
  }

  var ia_elapse = 0;
  var mode_ia = 0; 
  var ia_effect; 
  this.ia = function(dir, autre, balle)
  {
    if (this.p&&this.v&&balle.p&&balle.v)
    {
      var murx,dirx=0,diry=0, marge=tx/2+balle.taille+pong_point_size;
      if (dir > 0) murx = jeu.tx- marge; else murx = marge;
               
      var behind = (this.p[0] > balle.p[0] + balle.taille + tx/2 && dir > 0) || (this.p[0] < balle.p[0] - balle.taille - tx/2 && dir < 0);
      if (!behind&&mode_ia==-1)
      {
        if ((this.p[0] > balle.p[0] && dir > 0) || (this.p[0] < balle.p[0] && dir < 0)) behind = true;
      }
      var ahead = !behind;
      var incoming = (balle.v[0] > 0 && dir > 0) || (balle.v[0] < 0 && dir < 0);
      var inhome = (balle.p[0] > jeu.tx/2 && dir > 0) || (balle.p[0] < jeu.tx/2 && dir < 0);
      var reachable = (balle.p[0] > rect[0] && balle.p[0] < rect[2]);
      var slow = Math.abs(balle.v[0]) < 10* pong_timeunit;
      var veryslow = Math.abs(balle.v[0]) < 3* pong_timeunit;
      if (!reachable&&slow) incoming = false;
      
      if (incoming || (slow&&inhome))
      {
         if (mode_ia>0) mode_ia = 0;
         
         var mury;
         if (incoming&&!veryslow)
          mury = balle.p[1]+(this.p[0]-dir*marge-balle.p[0])/balle.v[0]*balle.v[1]; else
            mury = balle.p[1];
         var nbbounce=0;
         while (mury<0||mury>jeu.ty) 
         { 
           if (mury<0) mury = -mury; else
           if (mury>jeu.ty) mury = 2*jeu.ty-mury;
           nbbounce++;
         }
         if (nbbounce>=3) mury = balle.p[1];
         
         if (ahead) 
         {
           if (this.p[1]+ty/2 > balle.p[1]-balle.taille && this.p[1]-ty/2 < balle.p[1]+balle.taille)
           {
             if (this.p[1] >= mury) { if (mury > jeu.ty-ty) diry = -1; else diry = 1; } else
             if (this.p[1] < mury) { if (mury < ty) diry = +1; else diry = -1; }
           } else
           {  
             dirx = dir;
           }
         }
         else
         {
           if (this.p[1] < mury-ty/4 && this.p[1] > ty*0.6) diry = 1; else
           if (this.p[1] > mury+ty/4 && this.p[1] < jeu.ty-ty*0.6) diry = -1; else
           { 
              if (this.v[1] < pong_a_joueur) diry = 1; else
              if (this.v[1] > pong_a_joueur) diry = -1;
              if (behind) {
                dirx = -dir;
                if (mode_ia==0)
                {
                  mode_ia = -1;
                  ia_effect = Math.floor(Math.random()*2.9)-1;
                }
                if (this.p[1] < mury-ty/5) diry = 1; else
                if (this.p[1] > mury+ty/5) diry = -1; else
                  diry = ia_effect;
              }
           }
         }
      } else
      {
        var safedist = autre.p[0]+dir*jeu.tx/2;
        if (safedist < tx/2) safedist = safedist < tx/2;
        if (safedist > jeu.tx-tx/2) safedist = jeu.tx-tx/2;
        if ((this.p[0]-safedist)*dir < 0) dirx = dir;
        if (ia_elapse<0) mode_ia = 0;
        if (mode_ia==0) 
        {
          mode_ia = Math.floor(Math.random()*2.9)+1;
          ia_elapse = (Math.random()*5000/pong_timegrain)+(500/pong_timegrain);
        }
        var ywant;
        if (mode_ia==1) ywant = autre.p[1]; else
        if (mode_ia==2) ywant = jeu.ty/2; else
        if (mode_ia==3) ywant = balle.p[1];
        if (this.p[1] < ywant-ty/4) diry = 1; else
        if (this.p[1] > ywant+ty/4) diry = -1;
      }
      if (this.p[1] < ty*0.6&&diry==-1) diry= 0;
      if (this.p[1] > jeu.ty-ty*0.6&&diry==1) diry= 0;
      this.acceleration(dirx*pong_a_joueur,diry*pong_a_joueur);
    }
  }
  
  this.dessine();
}

function PetiteBalle(jeu, taille, p, v) // objet
{
  this.name = "Balle";
  var pts = new Array();
  var dir = new Array();
  var elasticite = 5;
  var temp_a = [0,0];
  
  var nbp = 6;
  for (var i=0; i<nbp; i++)
  {
    var angle = i*2*Math.PI/nbp;
    pts.push(p[0]+Math.cos(angle)*taille/2);
    pts.push(p[1]+Math.sin(angle)*taille/2);
    dir.push(v[0]);
    dir.push(v[1]);
  }

  var pos_int = pts.length;
  pts.push(p[0]);
  pts.push(p[1]);
  dir.push(v[0]);
  dir.push(v[1]);
  
  var lon_cote = Math.sqrt(Math.pow(pts[0]-pts[2],2)+Math.pow(pts[1]-pts[3],2));
  this.taille = taille;

  var len_visible = nbp*2;
  var minmax = calcMinMax(pts,pts.length);
  
  this.dessine = function()
  {
    var pts2 = new Array();
    var cx = (minmax[0]+minmax[1])/2;
    var cy = (minmax[2]+minmax[3])/2;
    var fact = (taille+2*pong_point_size)/taille;
    for (var i=0; i<len_visible; i+=2)
    {
      var x1=(pts[i]-cx)*fact, y1 = (pts[i+1]-cy)*fact;
      var x2=(pts[(i+2)%len_visible]-cx)*fact;
      var y2=(pts[(i+3)%len_visible]-cy)*fact;
      pts2.push(x1+cx);
      pts2.push(y1+cy);
      pts2.push((x1+x2)*0.55+cx);
      pts2.push((y1+y2)*0.55+cy);
    }
    jeu.fillpoly(pts2,len_visible*2, "white");
  }

  this.free = function()
  {
  }

  this.ptIn = function (x,y,vx,vy)
  {    
    if (x<minmax[0]-pong_point_size||x>minmax[1]+pong_point_size||y<minmax[2]-pong_point_size||y>minmax[3]+pong_point_size) return false;
    for (i=0; i<pts.length; i+=2)
    {
      if (Math.pow(pts[i]-x,2)+Math.pow(pts[i+1]-y,2) < pong_sqr_point_size)
      {
        dir[i] += vx;
        dir[i+1] += vy;
        return true;
      }
    }
    return false;
  }
  
  this.canMove = function(nx,ny,vx,vy)
  {
    if (nx < pong_point_size||nx > jeu.tx-1-pong_point_size||
        ny < pong_point_size||ny > jeu.ty-1-pong_point_size) return false;
    return jeu.canMove(this,nx,ny,vx,vy);
  }
  
  this.step = function(stepcount)
  {
    if (!stepcount) stepcount = 1;
    var lon_ref;
    for (var k=0; k<stepcount; k++) {
      for (var i=0; i<nbp; i++)
      {
        var i_cur = i*2;
        var i_suiv = ((i+1)%nbp)*2;
        var i_opp = ((i+nbp/2)%nbp)*2;
        var i_int = pos_int;
        
        var x = pts[i_cur], y = pts[i_cur+1];
        var dx = dir[i_cur], dy = dir[i_cur+1];

        var x_suiv = pts[i_suiv], y_suiv = pts[i_suiv+1];
        var lon_suiv = Math.sqrt(Math.pow(x_suiv-x,2)+Math.pow(y_suiv-y,2));
        if (lon_suiv<1) lon_suiv = 1;
        lon_ref = lon_cote;
        
        dx += (lon_suiv-lon_ref)*(x_suiv-x)/lon_suiv/elasticite;
        dy += (lon_suiv-lon_ref)*(y_suiv-y)/lon_suiv/elasticite;
        dir[i_suiv] -= (lon_suiv-lon_ref)*(x_suiv-x)/lon_suiv/elasticite;
        dir[i_suiv+1] -= (lon_suiv-lon_ref)*(y_suiv-y)/lon_suiv/elasticite;

        var x_opp = pts[i_opp], y_opp = pts[i_opp+1];
        var lon_opp = Math.sqrt(Math.pow(x_opp-x,2)+Math.pow(y_opp-y,2));
        if (lon_opp<1) lon_opp = 1;
        lon_ref = taille;
        
        dx += (lon_opp-lon_ref)*(x_opp-x)/lon_opp/elasticite;
        dy += (lon_opp-lon_ref)*(y_opp-y)/lon_opp/elasticite;
        
        var x_int = pts[i_int], y_int = pts[i_int+1];
        var lon_int = Math.sqrt(Math.pow(x_int-x,2)+Math.pow(y_int-y,2));
        if (lon_int<1) lon_int = 1;
        lon_ref = taille/2;

        dx += (lon_int-lon_ref)*(x_int-x)/lon_int/elasticite/2;
        dy += (lon_int-lon_ref)*(y_int-y)/lon_int/elasticite/2;
        
        dir[i_int] -= (lon_int-lon_ref)*(x_int-x)/lon_int/elasticite;
        dir[i_int+1] -= (lon_int-lon_ref)*(y_int-y)/lon_int/elasticite;
           
        dir[i_cur] = dx;
        dir[i_cur+1] = dy;
      }
            
      var moydx=0, moydy=0, moyx=0, moyy = 0;
      for (var i=0; i<pts.length; i+=2)
      {
        var x = pts[i], y = pts[i+1];
        var dx = dir[i]+temp_a[0], dy = dir[i+1]+temp_a[1];
        if (dx<-pong_point_size/2) dx = -pong_point_size/2;
        if (dy<-pong_point_size/2) dy = -pong_point_size/2;
        if (dx>pong_point_size/2) dx = pong_point_size/2;
        if (dy>pong_point_size/2) dy = pong_point_size/2;
        if (this.canMove(x+dx,y+dy,dx,dy))
        {
          x += dx;
          y += dy;
        } else
        {
          var len;
          if (Math.abs(dx)>Math.abs(dy))
           len = Math.abs(dx); else
           len = Math.abs(dy);
          for (var n=0; n<len; n++)
          {
            if (this.canMove(x+dx/len,y+dy/len,0,0))
            {
              x += dx/len;
              y += dy/len;
            } else   break;
          }          
          
          var bloquex=(dx>0 && !this.canMove(x+1,y,0,0))||(dx<0 && !this.canMove(x-1,y,0,0));
          var bloquey=(dy>0 && !this.canMove(x,y+1,0,0))||(dy<0 && !this.canMove(x,y-1,0,0));
          if (bloquex&&bloquey) { dx = 0; dy = 0; }
          else if (bloquex) { dx = 0; dy = dy*0.9; }
          else if (bloquey) { dy = 0; dx = dx*0.9; }
          
        }
        
        pts[i] = x;
        pts[i+1] = y;
        moyx += x;
        moyy += y;    
        dir[i] = dx;
        dir[i+1] = dy;
        moydx += dx;
        moydy += dy;
      }
      temp_a = [0,0];
      moydx /= (pts.length)/2;
      moydy /= (pts.length)/2;
      this.v = [moydx, moydy];
      moyx /= (pts.length)/2;
      moyy /= (pts.length)/2;
      this.p = [moyx,moyy];
      for (var i=0; i<pts.length; i+=2)
      {
        dir[i] = dir[i]*0.97 + moydx*0.03;
        dir[i+1] = dir[i+1]*0.97 + moydy*0.03;
      }
    }
    
    minmax = calcMinMax(pts,pts.length);
  }
  
  this.dessine();
}

function calcMinMax(c, len)
{
//liste des positions verticales à parcourir
var minx, maxx,x;
var miny, maxy,y;
minx = c[0]; maxx = c[0];
miny = c[1]; maxy = c[1];
for (var i=0; i<len; i+=2)
{
  x = c[i];
  if (x < minx) minx = x; else
  if (x > maxx) maxx = x;
  y = c[i+1];
  if (y < miny) miny = y; else
  if (y > maxy) maxy = y;
}
return [minx,maxx,miny,maxy];
}