Flash AS3教程：制作数码下落的动画特效

在这个教程中，将学习如何创建数字落下的动画。

演示：

1、新建Flash文件，属性设置： 400 × 400 ，背景黑色，帧频30。图1

2、选文本工具，创建一个动态的文本。输入数字 1。

3、在属性面板中为实例命名 " myText" 。设定字号为 15 ，颜色#00ff00。图2：

4、按字符嵌入按钮，嵌入字符集。设置如图3：

5、把本文转换成 影片剪辑 。命名为 " numberInsideMC" 。将注册点设定为左上角。图4：

6、在属性面板中为实例命名 " numberInside" 。图5：

7、把 " numberInsideMC" 再次转换成影片剪辑。 提供新的影片剪辑名字 " myNumberMC" 。将注册点设定为左上角。图6：

8、按Ctrl+L组合键，打开库面板，右键单击 " myNumberMC" 选属性(CS4、CS3为链接)作类的绑定，链接名为 " BitNumber" 。图7：

9、新建图层，改名 as 层，选中第1帧，输入下列代码：

//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。