var Frame;
  var Photo;
  var Titre;

  var vignettes;
  var nphoto;
  var lphoto;
  var iphoto;

  var tempo1 = 3;
  var tempo2 = 1;
  var Opacity = 100;

  window.onload = Launch;
  
  function Launch()
  {
  	vignettes = document.getElementById("vignettes") ;
	lphoto= vignettes.getElementsByTagName('a') ;
	nphoto = lphoto.length; iphoto = 0;
  	Photo = document.getElementById("big_pict");

//	alert(nphoto + ' vignettes');
	Frame = document.getElementById("photo");
	Frame.style.backgroundImage='url(' + lphoto[iphoto] + ')';
	Frame.style.backgroundPosition='center';
	Frame.style.backgroundPositionY='38px';	// empirique (marge, padding...)
	Frame.style.backgroundRepeat = 'no-repeat';
	
	Titre = Frame.getElementsByTagName('dt')[0] ;
	Fade();
  }

  function Fade()
  {
     var fadeDelta = 100 / (30 * tempo2);

	if (Opacity < 2*fadeDelta ) 	// fade top out to reveal background image
	{
	  Opacity = 100;
	  Switch();
	  if (iphoto==0) return;	// last photo
      setTimeout("Fade()",tempo1*1000);  // pause before next fade
	}
	else
	{
	  Opacity -= fadeDelta;
	  setOpacity(Photo,Opacity);
	  setTimeout("Fade()",30);  // 1/30th of a second
	}
  }

  function Switch()
  {
	Photo.src = lphoto[iphoto];	// copie background-image to Photo.src
	Titre.firstChild.nodeValue = lphoto[iphoto].title; // Maj du titre de la photo
//	alert('Photo : ' + Photo.src);
	setOpacity(Photo,100);// set img opacity to 100
	iphoto = ++iphoto % nphoto;	// increment rotation counter
	Frame.style.backgroundImage='url(' + lphoto[iphoto] + ')';	// slide next photo underneath
  }

  function setOpacity(obj, opacity) {
    opacity = (opacity == 100)?99.999:opacity;
    obj.style.filter = "alpha(opacity:"+opacity+")";    // IE/Win
    obj.style.KHTMLOpacity = opacity/100;   // Safari<1.2, Konqueror
    obj.style.MozOpacity = opacity/100;    // Older Mozilla and Firefox
    obj.style.opacity = opacity/100;    // Safari 1.2, newer Firefox and Mozilla, CSS3
  }