//--- 最大表示数 ---
SnowCnt = 25;

//--- 画像座標 ---
SnowX = new Array( SnowCnt ); // X
SnowY = new Array( SnowCnt ); // Y
SnowS = new Array( SnowCnt ); // Speed

//--- Window size ---
var winX, winY;

//--- Browzer Type ---
BwType = 0;


var i, n;

if( document.getElementById )
{
	BwType = 1;	// IE5
}
if( (document.all) && (BwType==1) )
{
	BwType = 2;	// IE4
}

//if( BwType == 0 )
//{
//	alert("ブラウザが対応していません");
//	return;
//}

switch( BwType )
{
	case 1:
		winX=window.innerWidth +window.pageXOffset-15;
		winY=window.innerHeight+window.pageYOffset;
		break;
	case 2:
		winX=window.document.body.clientWidth +document.body.scrollLeft;
		winY=window.document.body.clientHeight+document.body.scrollTop;
		break;
	default:
		break;
}

for( i=0; i<SnowCnt; i++)
{
	document.write("<img src='snow.gif' style='position:absolute;left:-200px;' name='snow"+i+"'>");

	SnowX[i] = Math.floor(Math.random()*winX);
	SnowY[i] = Math.floor(Math.random()*winY);
	n        = Math.floor(Math.random()*4)+1;

	switch( n )
	{
		case 1:
			SnowS[i]=4;
			document.images["snow"+i].height=4;
			document.images["snow"+i].width=4;
			break;
		case 2:
			SnowS[i]=8;
			document.images["snow"+i].height=6;
			document.images["snow"+i].width=6;
			break;
		case 3:
			SnowS[i]=12;
			document.images["snow"+i].height=8;
			document.images["snow"+i].width=8;
			break;
		default:
			SnowS[i]=4;
			document.images["snow"+i].height=2;
			document.images["snow"+i].width=2;
			break;
	}
}

imMain();


function imMain()
{
	var x,y,n,i;

	switch( BwType )
	{
		case 1:
			winX=window.innerWidth +window.pageXOffset-15;
			winY=window.innerHeight+window.pageYOffset;
			break;
		case 2:
			winX=window.document.body.clientWidth +document.body.scrollLeft;
			winY=window.document.body.clientHeight+document.body.scrollTop;
			break;
		default:
			break;
	}

	for( i=0; i<SnowCnt ;i++ )
	{
		SnowY[i] += SnowS[i];

		// 画面下部を越えたか？
		if( SnowY[i] > winY )
		{
			n        = Math.floor(Math.random()*5)+1;
			SnowX[i] = Math.floor(Math.random()*winX);

			switch( n )
			{
				case 1:
					SnowS[i]=8;
					document.images["snow"+i].height=4;
					document.images["snow"+i].width=4;
					break;
				case 2:
					SnowS[i]=12;
					document.images["snow"+i].height=6;
					document.images["snow"+i].width=6;
					break;
				case 3:
					SnowS[i]=16;
					document.images["snow"+i].height=8;
					document.images["snow"+i].width=8;
					break;
				default:
					SnowS[i]=6;
					document.images["snow"+i].height=2;
					document.images["snow"+i].width=2;
					break;
			}
			SnowY[i] =- document.images["snow"+i].height;
		}

		x=SnowX[i];
		y=SnowY[i];

		if(BwType==1)
		{
			if( x > winX-document.images["snow"+i].width-16 )
			{
				x=-100;
			}
		}else{
			if( x > winX-document.images["snow"+i].width )
			{
				x=-100;
			}
		}

		if( y> winY-document.images["snow"+i].height )
		{
			y=-100;
		}
		document.images["snow"+i].style.left=x;
		document.images["snow"+i].style.top=y;
	}

	// 割込処理
	if( BwType==2 )
	{
	  setTimeout("imMain()",35);
	} else {
	  setTimeout("imMain()",10);
	}
}