var elenco_foto = [
'img/home_sail.jpg',
'img/home_cockpit.jpg',
'img/home_diver.jpg',
'img/home_jet.jpg',
'img/home_lady.jpg'];

var elenco_foto_len = 5;
var ix_loop = 1;
var ix_step = 8;
var browser = null;
var obj = null;

function preloader() 
{
	obj = document.getElementById('index_foto_nautica');

	if (window.ActiveXObject) {
        if (navigator.userAgent.toLowerCase().indexOf("msie 5") != -1) {
            browser = "ie";
        } else {
            browser = "ie";
        }
    }
   if (!browser && typeof(XMLHttpRequest) != 'undefined') {
          browser = "ch";
   }
   
	if (document.images)
	{
   		var i = 0;
   		// create object
   		imageObj = new Image();
   		// start preloading
   		for(i=0; i<elenco_foto_len; i++) 
   		{
        imageObj.src=elenco_foto[i];
   		}
   }
   
   	setTimeout('fade_out()',1000);	// suppongo 2s bastino a precaricare tutte le immagini
} 

function setOpacity(value) {
	if(browser == "ie"){
		obj.style.filter = 'alpha(opacity=' + value*10 + ')';
	} else {
		obj.style.opacity = value/10;
	}		
}

function fade_out(){
	if (ix_step >= 0){
		setOpacity(ix_step);
		ix_step = ix_step - 1;
		setTimeout('fade_out()',120);
	}
	else{
		ix_step = 8;
		setTimeout('swap_back()',250);
	}
}
	
function swap_back(){
	
	if (ix_loop < elenco_foto_len-1)
	  		ix_loop = ix_loop + 1;
		else
	  		ix_loop = 0;
	
	obj.src=elenco_foto[ix_loop];			
	setOpacity(10);
	setTimeout('fade_out()',3000);
}