1、新建Flash文档，设置：宽、高为 400 × 400 ，保存。
2、用椭圆工具在舞台上画一个 20 × 20 大小的圆。 (你能选择任意的颜色）
3、右键单击圆形，把它转换成影片剪辑，注册点居中。
4、在ActionScript导出的复选框中打勾 ，做类链接，类名为" Particle " 。图1：
5、把圆形从舞台删除，新建ActionScript 3.0文件。图2：
6、我们编写一个外部的Particle类。在编译器中输入代码：
package {
import flash.display.MovieClip;
public class Particle extends MovieClip {
//We need different speeds for different particles.
//These variables can be accessed from the main movie, because they are public.
public var speedX:Number;
public var speedY:Number;
public var partOfExplosion:Boolean = false;
function Particle ():void {
}
}
}7、保存在fla文件的同一目录下，名为 " Particle " 。图3：
8、切换到我们的fla主文档。首先我们在舞台上生成粒子实例。在第一帧输入代码：
//We need few imports for the color
import fl.motion.Color;
import flash.geom.ColorTransform;
/*We want 20 particles at the start
particlesArray is used when we animate each particle */
var numberOfParticles:Number = 20;
var particlesArray:Array = new Array();
//Each time a hit occurs, we want to create 10 new particles
var numberOfExplosionParticles:uint = 10;
//This loop creates the first particles and gives them speed and coordinates
for (var i=0; i
9、测试你的影片，效果如图。图4：
10、随机地选择一个粒子产生爆炸效果。爆炸后，生成新的粒子。最后，删除舞台上爆炸的粒子。把下列代码块加入到动作面板： //Call for the first explosion
startExplosions ();
/*This function makes a random particle to explode.
From here, the chain reaction begins.*/
function startExplosions ():void {
//Select a random particle from an array
var index = Math.round(Math.random() * (particlesArray.length-1));
var firstParticle:Particle = particlesArray[index];
//Set a random tint
var ct:Color = new Color();
ct.setTint (0xFFFFFF * Math.random(),1);
//Create 10 new particles because of explosion
for (var i=0; i 11、添加方法 enterFrameHandler，更新粒子坐标，使粒子动起来。输入下列代码：
//This function is responsible for the animation
function enterFrameHandler (e:Event):void {
//Loop through every particle
for (var i=0; i 12、方法 " checkForHit" 是最难的部份，碰撞检测。输入代码：
/*This function checks whether two particles have collided*/
function checkForHit (particleOne:Particle, particleTwo:Particle):void {
/*Let’s make sure we only check those particles, where one is moving and the other
is stationary. We don’t want two moving particles to explode. */
if ((particleOne.partOfExplosion == false && particleTwo.partOfExplosion == true) ||
particleOne.partOfExplosion == true && particleTwo.partOfExplosion == false ) {
//Calculate the distance using Pythagorean theorem
var distanceX:Number = particleOne.x - particleTwo.x;
var distanceY:Number = particleOne.y - particleTwo.y;
var distance:Number = Math.sqrt(distanceX*distanceX + distanceY*distanceY);
/* If the distance is smaller than particle’s width, we have a hit.
Note: if the particles were of different size, the calculation would be:
distance 13、代码全部完成，测试你的影片。也可以设置不同背景的舞台，画任意的图形。
最后完整的代码：
//We need few imports for the color
import fl.motion.Color;
import flash.geom.ColorTransform;
/*We want 20 particles at the start
particlesArray is used when we animate each particle */
var numberOfParticles:Number = 20;
var particlesArray:Array = new Array();
//Each time a hit occurs, we want to create 10 new particles
var numberOfExplosionParticles:uint = 10;
//This loop creates the first particles and gives them speed and coordinates
for (var i=0; i
附件下载：
Particle.rar
粒子.rar
本文转自：http://www.5uflash.com/flashjiaocheng/Flash-as3-jiaocheng/5300.html
