// Nota: daqui deve partir o link para a pagina, depois do DHTML rolar.

function Alerta() {
        if (document.layers){var guga=document.gugagif;hidden="hide"}
        else {if (document.all){var guga=document.all.gugagif.style;hidden="hidden"}}

        guga.visibility="visible";
}

// Note: this was written a long time ago

ball_stationary = new Image()
ball_stationary.src = "ball-stationary.gif"
ball_animated = new Image()
ball_animated.src = "ball-animated.gif"

ns4 = (document.layers) ? 1:0
ie4 = (document.all) ? 1:0

function parabola(obj,type,xDistance,yDistance,xDirection,yDirection,xinc,speed) {
        if (ns4) this.obj = document.layers[obj]
        if (ie4) this.obj = document.all[obj].style
        this.type = type
        this.xDistance = xDistance
        this.yDistance = yDistance
        this.xDirection = xDirection
        this.yDirection = yDirection
        this.xinc = xinc
        this.speed = speed
        this.active = 0
        this.i = 0
        this.multiplier = this.yDistance/Math.pow(this.xDistance/this.type,2)
        this.startX = parseInt(this.obj.left)
        this.startY = parseInt(this.obj.top)
        this.x = this.startX
        this.y = this.startY
        // the decreasing values used for the arcing parabola
        // represents how much less the ball will bounce each time
        this.xdec = 25
        this.ydec = 50
        this.move = moveParabola
}

function moveParabola() {
        this.i += this.xDirection*this.xinc
        this.x = this.startX + this.i
        this.obj.left = this.x
        if (this.type == 1) {
                this.y = this.startY + this.yDirection*this.multiplier*Math.pow(Math.abs(this.i),2)
                this.obj.top = this.y
        }
        if (this.type == 2) {
                this.y = this.startY - this.yDirection*this.multiplier*Math.pow(this.xDistance/2-Math.abs(this.i),2) + this.yDirection*this.yDistance
                this.obj.top = this.y
        }
}

function init() {
        ball = new parabola("balldiv",1,125,250,1,1,3,20)
}

// this is the dropping parabola that first starts the animation
function bounce1() {
        if (ball.active) {
                if (Math.abs(ball.i) < ball.xDistance) {
                        ball.move()
                        setTimeout("bounce1()",ball.speed)
                }
                else {
                        // after it drops, the parabola has to change into an arcing parabola
                        // to continue bouncing.  Must reset the following values...
                        ball.type = 2
                        ball.yDirection = -1
                        ball.i = 0
                        ball.yDistance -= ball.ydec
                        ball.startX = ball.x
                        ball.startY = ball.y
                        // Important: the multiplier is used in the calculation of the parabola
                        // if you change the xDistance,yDistance, or type you must recalculate it
                        ball.multiplier = ball.yDistance/Math.pow(ball.xDistance/ball.type,2)
                        setTimeout("bounce2()",ball.speed)
                }
        }
}

// this is the arcing parabola that continually runs after the initial drop
function bounce2() {
        if (ball.active) {
                if (Math.abs(ball.i) < ball.xDistance) {
                        ball.move()
                        setTimeout("bounce2()",ball.speed)
                }
                else {
                        // each time the ball hits the ground I decrease both the xDistance
                        // and yDistance to make it appear as if it's slowing down
                        // must also recalculate the multiplier each time
                        ball.i = 0
                        ball.xdec *= 0.9
                        ball.ydec *= 0.9
                        ball.xDistance -= ball.xdec
                        ball.yDistance -= ball.ydec
                        ball.startX = ball.x
                        ball.startY = ball.y
                        ball.multiplier = ball.yDistance/Math.pow(ball.xDistance/ball.type,2)
                        if (ball.yDistance > 0 && ball.xDistance > 0) setTimeout("bounce2()",ball.speed)
                        else {
                                changeImages("off");
                                window.setTimeout('Alerta()',1500); //parada ao terminar o movimento
                                ball.active = 0
                        }
                }
        }
}

function start() {
        if (!ball.active) {
                if (ball.x == 593) {  // if at the end, reset it
                        reset()
                        start()
                }
                else {
                        changeImages("on");  // else start the drop
                        ball.active = 1
                        bounce1();
                        //alert ('oi'); //inicio ao apertar o botao start
                }
        }
}

function stop() {
        ball.active = 0
        changeImages("off");
        //alert ('oi'); //parada ao apertar o botao stop
}

function reset() {
        if (!ball.active) {
        changeImages("off")
        ball.active = 0
        ball.i = 0
        ball.type = 1
        ball.xdec = 25
        ball.ydec = 50
        ball.xDistance = 125
        ball.yDistance = 250
        ball.yDirection = 1
        ball.multiplier = ball.yDistance/Math.pow(ball.xDistance/ball.type,2)
        ball.startX = 5
        ball.startY = 40
        ball.x = ball.startX
        ball.y = ball.startY
        ball.obj.left = ball.x
        ball.obj.top = ball.y
        }
        else {
                ball.active = 0
                setTimeout("reset()",50)
        }
}

function changeImages(which) {
        if (which == "on") {
                if (ns4) document.layers["balldiv"].document.images["ballimg"].src = ball_animated.src
                if (ie4) document.images["ballimg"].src = ball_animated.src
        }
        if (which == "off") {
                if (ns4) document.layers["balldiv"].document.images["ballimg"].src = ball_stationary.src
                if (ie4) document.images["ballimg"].src = ball_stationary.src
        }
}