A Simple Particle System

Look, it's SMOKE!!! This is a tutorial for Flash users which includes several complex concepts. I will try to explain everything as I go, but if there is some confusion, please send me an e-mail, and I will try to make it clearer. I wrote this in MX, but the concept will work for Flash 5 as well. First off, let's look at the end result.

I started this project with the goal of creating a neat .as file that would allow me to duplicate multiple objects with a single function call.
The .as file and the .fla file are included in the zip file here, but I've listed all the code below.

There is no code INSIDE the particle object, just the two onClipEvents on it, shown below...

I wrote my code in only 3 places.

• in the "dupe.as" file: (This was originally written on frame 1, but it's so versitile, I separated it, so I could use it with other .fla's later)

// simple duplicate function taking parameters for SEED OBJECT & NUMBER of iterations
function dupe(name, howMany) {
for (num=1; num<=howMany; num++) {
duplicateMovieClip(name, name+"_"+num, num);
}
}

• on frame 1 of my movie:

// the #include just imports my external file (above) at compile time.
#include "dupe.as"
// this is the function call to "dupe" in the .as file
dupe("particle", 90);

"So what," you say... Now I have a dogpile of objects... How do I make my "particles" position and move independently?
...I'm glad you asked... This looks like a lot of code, but remember, the pink stuff is just comments...

• I use two onClipEvents attached to the duped "particle" object:

onClipEvent (load) {
//set this size between 20 and 60
this.size =random(40)+20;
this._height = this.size;
this._width = this.size;
//position this particle somewhere left of the middle of the screen
this._x =random(Stage.width)+(Stage.width/2);
this._y =random(Stage.height);
//set this speed between 1 and 21
mySpeed = random(20)+1;
//start at a random point in the sequence
gotoAndPlay(random(40));
}
//
onClipEvent (enterFrame) {
// move this particle to the right
this._x -= mySpeed;
// if this particle is off screen, move to the left and start over
if ( this._x<0- this._width) {
this._x = Stage.width+this._width;
gotoAndPlay(1);
}
}

Every time the object gets duped, the OnClipEvents are duped as well, thus, using the random() function I am able to give each particle a mind of it's own!!!

I wrote this code, and, started tweaking my object, and very quickly I created something interesting. This is a very versitile and simple structure. It can be adapted easily to create and manipulate many types of particle systems. I hope you find it useful.

I changed the graphic, upped the alpha, and dropped the number of iterations in dupe from 90 to 20. Now we have an entirely different effect...

I hope this inspires... Send me an email if you use this idea somewhere. I'd love to see where you take it...

Grins,
     -J