// plane.js by Jan Drda / jan.drda@na-netu.cz

SpriteUrlLeft = "img/plane_left.gif";
SpriteUrlRight = "img/plane_right.gif";
SpriteWidth = 65;
SpriteHeight = 27;
SpriteSpeed = 15;
SpriteDelay = 10000;

var timerID = 0;
var mx = document.body.clientWidth;
var my = document.body.clientHeight;
var x = 0;
var y = 0;
var dx = 0;
var dy = 0;
var r = 0;
var SpriteON = 0;


function Init () {
	if (navigator.appVersion >= "4.0"){ 
		if(navigator.appName == "Netscape") {
		    doc = "document";
		    sty = "";
		} else {
		    doc = "document.all";
		    sty = ".style";
		}
		SpriteObject = eval(doc + '["sprite"]' + sty);
		ImgObject = eval(doc + '["img"]');
		SpriteInit();
	} 
}

function RunSprite() {
	if (SpriteON) {
		SpriteON = 0; window.clearTimeout(timerID); SpriteObject.visibility = "hidden";
	} else {
		SpriteON = 1; window.clearTimeout(timerID); SpriteInit()
	}
}

function SpriteInit() {
	if (SpriteON) {
		mx = document.body.clientWidth;
		my = document.body.clientHeight;
		r = Math.floor(100*Math.random())
		if ((r < 63) && (r > 32)) {
			dy = 0;
		} else { 
			if (r < 33) {
				dy = (-1);
			} else {
				dy = 1;
			}
		}
		
		r = Math.floor(100*Math.random());
		if (r > 50) {
			dx = 2;
			x = 1-SpriteWidth;
			ImgObject.src = SpriteUrlRight;
		} else {
			dx = (-2);
			x = mx-SpriteWidth-2;
			ImgObject.src = SpriteUrlLeft;
		}
		
		r = Math.floor((my-SpriteHeight)*Math.random());
		y = r - SpriteHeight*dy;
		
		SpriteObject.top = (y);
		SpriteObject.left = (x);
		SpriteObject.visibility = "visible";
		MoveSprite();
	}
}

function MoveSprite() {
		if ((x > -SpriteWidth) && (x < mx-SpriteWidth-1) && (y > -SpriteHeight) && (y < my-SpriteHeight))
		{    	y = y + dy;
			x = x + dx;
			SpriteObject.top = (y);
			SpriteObject.left = (x);
			timerID = window.setTimeout("MoveSprite()", SpriteSpeed);
		} else {
			SpriteObject.visibility = "hidden"; 
			timerID = window.setTimeout("SpriteInit()", SpriteDelay);
		}
}

document.write('<div ID="sprite" style="position: absolute; visibility: hidden;" NAME="sprite">');
document.write('<a href="javascript: RunSprite()"><img src="" width="'+SpriteWidth+'" height="'+SpriteHeight+'" border="0" alt="" NAME="img" ID="img"></a>');
document.write('</div>');