// JavaScript Document
var myRecentNum;
function myOpacity(){
		theOp=setInterval("chgOpacity('min')",50);
	}
function chgOpacity(theSta){
		myId=document.getElementById("index_root");
		myBgId=document.getElementById("index_root_bg");
		if(theSta=="min" && myId.filters.alpha.opacity>0 ){
			myId.filters.alpha.opacity-=10;
			}			
		else{
			clearInterval(theOp);
			myId.filters.alpha.opacity=100;
			}
		if(myId.filters.alpha.opacity>=100){
			if(myRecentNum>=3){
				myBgId.style.background="url(img/bg_"+1+".jpg) left top no-repeat";
				}
			else {
				myBgId.style.background="url(img/bg_"+(myRecentNum+1)+".jpg) left top no-repeat";
				}
		}
	}
function root_bg(){
		var myInterval;
		cssNum=2;
		myAllPic=3;
		MM_preloadImages("img/bg_1.jpg","img/bg_2.jpg","img/bg_3.jpg");
		myAlphaInterval=setInterval("myOpacity()",5500);
		myInterval=setInterval("chgBg(cssNum)",6000);
	}
function chgBg(num){
		myRecentNum=num;
		myId=document.getElementById("index_root");
		myId.style.background="url(img/bg_"+num+".jpg) left top no-repeat";
		clearInterval(myAlphaInterval);
		myAlphaInterval=setInterval("myOpacity()",5500);
		cssNum++;
		if(cssNum>myAllPic){cssNum=1;}
	}
//动态加载图像
var MM_index_bg=new Array();
function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!MM_index_bg) MM_index_bg=new Array();
    var i,j=MM_index_bg.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ MM_index_bg[j]=new Image; MM_index_bg[j++].src=a[i];}}
}
//背景音乐控制
var bgCtlSta=1;
function bgCtl(){
	if(bgCtlSta==1){
		document.getElementById("indexBgsound").src="";
		bgCtlSta=0;
		document.getElementById("bgCtl").innerText="开启背景音";
		}
	else{
		document.getElementById("indexBgsound").src="/img/bgsound.mp3";
		bgCtlSta=1;
		document.getElementById("bgCtl").innerText="关闭背景音";
		}
	}