/*

	JJBM,   25/08/2008, JavaScript_include.js



	Width XHTML 1.1 document.body.clientHeight not return height of client area (of the window).

	Change code for run into a square.

*/



var k_ball_large = 50;

var k_ball_spring = -0.8;

var k_sys_friction = 0.999;

var k_sys_time_inc = 0.3;

var k_sys_gravity = -9.8;



var balls = new Array();

var wx, wy, wxtop; // tamaņo ventana y cota x

var sx, sy; // scroll ventana



	function Ball_Move() {



		// simple euler



		this.x += this.vx * k_sys_time_inc;

		this.y += this.vy * k_sys_time_inc;



		this.vx += this.ax * k_sys_time_inc;

		this.vy += this.ay * k_sys_time_inc;



		this.vx *= k_sys_friction;

		this.vy *= k_sys_friction;



		this.ax = 0;

		this.ay = 0;



		if( this.y < k_ball_large ) {

			this.y = k_ball_large

			this.vy *= k_ball_spring

		}

		if( this.x < 0 ) {

			this.x = 0

			this.vx *= k_ball_spring

		}

		if( this.x > wxtop ) {

			this.x = wxtop

			this.vx *= k_ball_spring

		}



		this.ay += k_sys_gravity;



		this.c.style.left = (sx + this.x) + "px";

		this.c.style.top = (sy + wy - this.y) + "px"; // flip Y world axis



	}

	function Ball_OnClick(e) {

		this.c.style.display = 'none';

		balls[ this.idx ] = null;

	}

	function Ball_Img_OnClick(e) {

		balls[ this.idx ].OnClick(e);

	}

function Ball( idx ) {



	this.Move = Ball_Move;

	this.OnClick = Ball_OnClick;



	this.idx = idx;



	// position, velocity and aceleration (the forces are implicit)

	this.x = 0.0;

	this.y = wy;

	this.vx = 0.0;

	this.vy = 0.0;

	this.ax = 60.0 + Math.random() * 100.0;

	this.ay = 0.0;



	// new DIV

	this.c = document.createElement('div');

	// new IMG

	var i = new Image();

	i.src = "data/articulo/pelota-" + ( parseInt( Math.random() * 100 ) % 10 ) + ".png";

	i.idx = this.idx;

	i.onclick = Ball_Img_OnClick;

	// IMG inside DIV

	this.c.appendChild( i );

	this.c.style.position = "absolute";

	this.c.style.left = sx + "px";

	this.c.style.top = sy + "px";

	// DIV inside BODY

	document.body.appendChild( this.c );

}



function GetWindowWidth() {

	return document.getElementById('peloteo').clientWidth;

}

function GetWindowHeight() {

	return document.getElementById('peloteo').clientHeight;

}



function GetOffsetLeft( o ) {

	if( o == undefined || o == null )

		return 0;

	return GetOffsetLeft( o.offsetParent ) + o.offsetLeft;

}



function GetOffsetTop( o ) {

	if( o == undefined || o == null )

		return 0;

	return GetOffsetTop( o.offsetParent ) + o.offsetTop;

}



function BallManager() {

	var i

	for( i = 0; i < balls.length; i++ )

		if( balls[i] != null )

			balls[i].Move();

}



function NewBall() {

	var i;

	// we search empty

	for( i = 0; i < balls.length; i++ )

		if( balls[i] == null )

			break;

	// i-th are free

	balls[i] = new Ball(i);

}



function myOnLoad() {



	wx = GetWindowWidth();

	wy = GetWindowHeight();

	wxtop  = wx - k_ball_large;



	sx = GetOffsetLeft( document.getElementById('peloteo') );

	sy = GetOffsetTop( document.getElementById('peloteo') );



	if( balls.length <= 0 )

		setInterval( "BallManager()", 20 );



	NewBall();



	setInterval( "NewBall()", 3000 );

}