var photos = new Array ( './images/p1.png', './images/p2.png' , './images/p3.png' );
var n = 3;
var timeout = 6000;
var step = 2;
var foto_timeout = 75;

function change_left(){
  change_vis ( 100 , "photo0" );
  setTimeout ( "change_left()" , timeout );
}
function change_right(){
  change_vis ( 100 , "photo1" );
  setTimeout ( "change_right()" , timeout );
}
function change_vis (  visibility , element , go   ) {
  if ( visibility < -100 ) return;
  e = document.getElementById(element);
  if ( visibility > 0 ) {
    visibility += -step;
    e.style.opacity = visibility / 10;
    e.style.filter = "alpha(opacity="+visibility+")";
    setTimeout ( "change_vis("+visibility+",\""+element+"\",0)" , foto_timeout );
  }
  else if ( visibility == 0 ) {
    if ( e.complete && go == 1 ) {
      visibility += -step;
      go = 1;
      e.style.display = "block";
    } 
    if ( go == 0 ) {
      go = 1;
      e.style.display = "none";
      t_id = Math.floor (  Math.random() *(n) );
      e.src= photos[ t_id ];
    }
    setTimeout ( "change_vis("+visibility+",\""+element+"\","+go+")" , foto_timeout );
  }
  else if ( visibility < 0 ) {
    visibility += -step;
    e.style.opacity = visibility / -10;
    e.style.filter = "alpha(opacity="+(-visibility)+")";
    setTimeout ( "change_vis("+visibility+",\""+element+"\",1)" , foto_timeout );
  }
}
setTimeout ( "change_left()" , timeout );
setTimeout ( "change_right()" , timeout / 2 );