Still delving into metaballs. I implemented the suggestions in this page for optimizing, and the results are good. I could even animate it - just barely though, at ~15 FPS on my browser. 
Again, most of this is just copy & paste from the source provided in the tutorial.
Metaballs - move your mouse around. Click to change the target ball.
Still looking for a more elegant solution for Flash. This is done on a very small stage size, with only 4 balls. I want to do a full screen version, with at least 10 balls moving around. 
After seeing a cool demo from the ClockMaker blog, I was inspired to try and recreate the effect. My attempt is not very impressive, but I did manage to figure out how he did it. Although much of this is from his sourcecode, I just thought I’d post a simplified version and put little comments and stuff.
And oh, Merry Christmas to all! 
Click the image to see the movie.
I did a little experimenting with the BitmapData class, and came up with this.
I found this effect from a gallery somewhere, and thought it would be cool to try my hand at it, for learning purposes.
Click on the image below to see the effect.
What’s happening is, I get the size of the image, divide it by the size of the “pixels” I want, then create an array of Rectangles positioned in a grid over the image.
I then fill each Rectangle with the color of the pixel in it’s center by using the getPixel() and fillRect() methods of the BitmapData class.
Here is the central function doing the pixelating.
[sourcecode language='js']
private function pixelate(bitmap:Bitmap, strength:Number):void {
var _x:int = 0; // position of the rectangle
var _y:int = 0;
if (strength > 1){
_strength = 1;
}
var _strength:Number = strength; // multiplier for size of “pixels”
var _w:Number = bitmap.bitmapData.width * _strength; //size of “pixels”
var _h:Number = bitmap.bitmapData.height * _strength;
var nH:int = Math.ceil(bitmap.bitmapData.width / _w); // number of rectangles needed horizontally
var nV:int = Math.ceil(bitmap.bitmapData.height / _h);// number of rectangles needed vertically
var rectangles:Array = []; // Rectangles array
//create rectangles
for (var i:int = 0; i < nV; i ++){
var targH:Number = _h;
if (i >= nV - 1){
targH = bitmap.bitmapData.height - _y;
}
for (var j:int = 0; j < nH; j ++){
var targW:Number = _w;
if (j >= nH - 1){
targW = bitmap.bitmapData.width - _x;
}
rectangles.push(new Rectangle(_x, _y, targW, targH));
_x += _w;
}
_x = 0;
_y += _h;
}
//fill in rectangles
for (i = 0; i < rectangles.length; i++){
var rect:Rectangle = rectangles[i];
var pix:uint = _states[0].getPixel((rect.x + rect.width / 2), (rect.y + rect.height / 2));
bitmap.bitmapData.fillRect(rect, pix);
}
saveCurrentState(bitmap.bitmapData);
}
[/sourcecode]
Now for the reverting to the original image part, I had to improvise. Since I overwrote the BitmapData with a bunch of filled rectangles, I couldn’t do much with it.
So I used an array which stores each “state” the BitmapData is in. And I could just retrieve the BitmapData in the array and copy it into the original BitmapData.
[sourcecode language='js']
private function saveCurrentState(bitmapData:BitmapData):void {
_states.push(bitmapData.clone());
}
private function revertToState(stage:int):void {
try{
bmData.copyPixels(_states[stage], bmData.rect, new Point(bmData.rect.x, bmData.rect.y));
}catch (e:Error){
throw new Error(”Invalid state. “);
}
}
[/sourcecode]
To create the animation, I just called the pixelate() function through a Timer at 300 milliseconds.
Just found this great resource for learning AS3. It is a slideshow created by Grant Skinner showing the basics of the language and some optimization tips. Each page worth an article itself, all 167 of them. It not only sounds good, it looks good. 
http://gskinner.com/talks/as3workshop/
I want to give a heads-up to all those just beginning with AS3 about how it handles memory. I had to find out about this the hard way, and now have to redo a lot of stuff.
Flash Player 9 introduced a new system management feature called a garbage collector (GC). Basically, what it does is “sweep” for objects that can not be used/accessed anymore, and delete them, freeing memory. Until those ‘null’ objects are removed by the GC, they will sit in memory until the Player is closed.
So, whenever you want something to be deleted (escpecially with CPU intensive particle systems), you must be aware of what and where you are referencing your objects, so you could easily remove them. You have to do this by hand. One method is to set all objects you want to delete, and all references to it, to null. Even then, you have to wait for the GC to do its “sweeping motion” for those objects to be deleted.
Another thing to watch out for are event listeners. Make sure you remove any listeners (by calling removeEventListener()) from objects you want to delete, since they also hold a reference to your objects.
Check this article series for more details and info about the GC and resource management in Flash Player 9/AS3.
And lastly, it is about unloading external swf’s through Loader. You might think that using unload() from a Loader would remove that swf completely, but that isn’t the case. In fact, unload() does a pretty poor job at “unloading” swfs. Here is a quote from another article that explains this in great detail:
In AS3, calling Loader.unload() simply removes the reference to the loaded movie. If any other references exist to the loaded content, it will not be unloaded.
My site has been delayed by almost a month now, trying to figure out and fix my memory leak problem. I finally have an idea of what’s wrong, now I have to figure out a solution.
TweenLite is a light-weight tweening engine for AS2 and AS3.
Tweening engines make animating objects through code a breeze. Instead of figuring out how to get to a certain point or value of an object’s property, all you need to do is figure out where you want that property to be (or where you want it to come from), the time it takes to get there, and you have movement.
There are a lot of tweening engines out there, but I prefer TweenLite because it is light (only 3kb), it is easy to use, does what I want it to do, and if I want more functionality, it has two older brothers*.
To get started, first you need to download TweenLite (I’ll be discussing the AS3 version here), and save it into your classpath.
There are 2 static methods you need to know, TweenLite.to() and TweenLite.from().
Those two methods take in three arguments:
- The object you want to animate
- The time, in seconds, the animation will span
- A dynamic Object instance target with predefined properties (this is where you put the values you want to reach)
So, to animate a box, it only takes one line to make it do some crazy stuff.
[sourcecode language='js']
import gs.TweenLite; // import TweenLite
box_mc.x = 0;
box_mc.y = 100;
TweenLite.to(box_mc, 2, {x: stage.stageWidth, y: 200, rotation: 360, scaleX: 2, scaleY:2, alpha: .5});
//this will move the box to the edge of the stage, move it down 100 px, rotate it, scale it to 2x its
//size, and make it transparent, for 2 seconds.
[/sourcecode]
Note that the TweenLite.from() method does the exact opposite of TweenLite.to(). It transforms your object to your third argument properties, and animates them towards the state the object has on the stage (very useful).
There are comments in the .as file itself, and explains some important things. This was to show how useful and indispensible tweening engines are. I can’t beleive how long I’ve strayed away from them, but now, I can’t live without them.
*TweenFilterLite - TweenLite + filtering capabilities
TweenMax - TweenFilterLite + bezier curves
Here is another class I made for my site… It’s nothing fancy, and in fact it could easily be done without this class, but basically, this class creates a rectangular object and fills it with an image from an outside source, tiles it, and you could easily adjust the width and height of the object, and load a new pattern.
Usage:
[sourcecode language='js']
import com.mindfock.display.TiledBG; //import class
…
tiledBG = new TiledBG(”path/to/pattern.gif”, 800, 600);
addChild(tiledBG);
tiledBG.tileWidth = 500 // change width
tiledBG.tileHeight = 500 // change height
tiledBG.newPattern(”path/to/new/pattern.gif”); //changing pattern image
[/sourcecode]