FLASH AS3制作数字下落的效果

//This array will contain all the numbers seen on stage

var numbers:Array = new Array();

//We want 8 rows

for (var i=0; i < 8; i++) {

        //We want 21 columns

        for (var j=0; j < 21; j++) {

                //Create a new BitNumber

                var myNumber:BitNumber = new BitNumber();

                //Assign a starting position

                myNumber.x = myNumber.width * j;

                myNumber.y = myNumber.height * i;

                //Give it a random speed (2-7 pixels per frame)

                myNumber.speedY = Math.random() * 5 + 2;

                //Add the number to the stage

                addChild (myNumber);

                //Add the number to the array

                numbers.push (myNumber);

        }

}

//Add ENTER_FRAME so we can animate the numbers (move them down)

addEventListener (Event.ENTER_FRAME, enterFrameHandler);

/*

This function is repsonsible for moving the numbers down the stage.

The alpha animation is done inside of the myNumberMC movieclip.

*/

function enterFrameHandler (e:Event):void {

        //Loop through the numbers

        for (var i = 0; i < numbers.length; i++) {

                //Update the y position

                numbers[i].y += numbers[i].speedY;

                //If the BitNumber is below the stage, move it up again

                if (numbers[i].y > stage.stageHeight) {

                        numbers[i].y = 0;

                }

        }

}
10、双击舞台上的 myNumberMC 影片剪辑，进入myNumberMC编辑状态，添加as图层，选中第1帧，输入代码：

//This variable tells us should we increase the alpha

var increaseAlpha:Boolean;

//We want the number to be invisible at the beginning

numberInside.alpha = 0;

//Calculate a random timer delay (how often we increase the alpha)

var timerDelay:Number = Math.random() * 4000 + 2000;

//Create and start a timer

var timer:Timer = new Timer(timerDelay, 0);

timer.addEventListener (TimerEvent.TIMER, timerHandler);

timer.start ();

//Add ENTER_FRAME so we can animate the alpha change

addEventListener (Event.ENTER_FRAME, enterFrameHandler);

/* 

Timer calls this function.

Timer delay defines how often this is called.

*/

function timerHandler (e:Event):void {

        //Update the increaseAlpha value

        increaseAlpha = true;

        //Calculate a random number (0 or 1)

        var newNumber:int = Math.floor(Math.random() * 2);

        //If the random number is 1, we insert "1" into the text box

        if (newNumber == 1) {

                numberInside.myText.text = "1";

        }

        //Else we insert "0" into the text box

        else {

                numberInside.myText.text = "0";

        }

}

//This function animates the alpha

function enterFrameHandler (e:Event):void {

        //Increase the alpha if increaseAlpha is true

        if (increaseAlpha == true) {

                numberInside.alpha += 0.02;

        }

        //Else we want to decrease the alpha

        else {

                numberInside.alpha -= 0.02;

        }

        //We don’t want the alpha to be over one, so we assign increaseAlpha to be false

        if (numberInside.alpha > 1) {

                increaseAlpha = false;

        }

        //If the alpha is negative, set it to zero

        if(numberInside.alpha < 0) {

                numberInside.alpha = 0;

        }

}
11、切换回场景1，把 myNumberMC 影片剪辑从舞台上删除。

12、完工，测试你的影片。