var divId = "photodiv";
var imgId = "photoimg"; 
var arImg = new Array(			// 添え字は、nImg
	"http://ume360.goddow.com/img/top1.png",
	"http://ume360.goddow.com/img/top2.png",
	"http://ume360.goddow.com/img/top3.png",
	"http://ume360.goddow.com/img/top4.png",
	"http://ume360.goddow.com/img/top5.png"
);
var pSec = 5.25;
var fSec = .85;
var nRot = 1;

var dSize = arImg.length;
var dOpac = 100;
var nImg = 0;			// 何枚目の画像か？
var stImg;				// start image
var nRot2 = dSize * (nRot+1);

window.onload = pLaunch;

function pLaunch() {
	var theimg = document.getElementById(imgId);
	stImg = theimg.src;

	document.getElementById(divId).style.backgroundImage='url(' + arImg[nImg] + ')';
		setTimeout("pFade()",pSec * 1000);
}

function pFade() {
	var theimg = document.getElementById(imgId);
	var fadeDelta = 100 / (30 * fSec);

	if (dOpac < 2 * fadeDelta ) {
		dOpac = 100;
		if (nRot2 < 1) return;
		pShuff();
		setTimeout("pFade()", pSec * 1000);
	} else {
		dOpac -= fadeDelta;
		setOpac(theimg, dOpac);
		setTimeout("pFade()", 30);
	}
}

function pShuff() {
	var thediv = document.getElementById(divId);
	var theimg = document.getElementById(imgId);

	theimg.src = arImg[nImg];
	setOpac(theimg, 100);

	nImg = ++nImg % dSize; if (--nRot2 < 1) { arImg[nImg] = stImg; }
	thediv.style.backgroundImage='url(' + arImg[nImg] + ')';
}

function setOpac(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
}