// うしさんの飛行アニメ

// by ゆうくん & Mamiko.S(http://www.nmt.ne.jp/~mamiko/) 1998/08/04



var speed = 30 //アニメーションの移動速度

var ox_obj,W,H

var ox_obj_top,ox_obj_left

var x,y



var t = 0

var dir = 0



var g = -9.8



var vx=30.

var vy=0.0

var dt = 0.1

var r = 100



var ms = navigator.appVersion.indexOf("MSIE");

var ie4 = (ms>0) && (parseInt(navigator.appVersion.substring(ms+5, ms+6)) >= 4)

var nesc = navigator.appName.lastIndexOf("Netscape"); //一致した位置(0)を返す

var nesc4 = (nesc >= 0) && (parseInt(navigator.appVersion.substring(0,2)) >= 4)



function init(){

	if(document.layers){

		x=30.,y=window.innerHeight * 0.7

	}else{

		x=30.,y=document.body.clientHeight * 0.7

	}

	setTimeout('fly()', 100)

}



function fly(){



	if(ie4 || nesc4){

		if(document.layers){

			W = window.innerWidth

			H = window.innerHeight



			y = H/2.5 + r * Math.sin(t)

			x = W/2.5 + r * Math.cos(t)

			ox_obj = eval("document.ox")



			ox_obj.top = y

			ox_obj.left = x



			if (dir == 0) {

				r -= 0.9



			speed = 30

				if (r < 3) dir = 1

				

			} else {

				speed = speed + 0.1

				r += 0.9

				if ( r > window.innerHeight/2.5) dir = 0

	 		}

		}else{

			W = document.body.clientWidth

			H = document.body.clientHeight

			y = H/2.5 + r * Math.sin(t)

			x = W/2.5 + r * Math.cos(t)

			ox_obj = eval("ox.style")

			ox_obj.top = y

			ox_obj.left = x



			if (dir == 0) {

				r -= 0.9

				speed = 30

				if (r < 3) dir = 1

			} else {

				r += 0.9

				speed = speed + 0.1

				if ( r > document.body.clientHeight/2.5) dir = 0

	 		}

		}

	}



	if ( x > W*0.85) {vx = -vx}

	if (x < 0){vx = -vx}

	if (y <= 0.) {vy = -vy;y=-y}

	t = t + dt;

	setTimeout("fly()", speed)

}