I can't believe it took so long for someone to mention BitmapData, it's so easy to do it's incredible. Seriously why isn't BitmapData used so much? You can find a basic tutorial here by me, and an example of it here, instructions at top of screen.

however with flash 8, if you use BitmapData
you can destroy and create ground as much as you want and still have only the one bitmapdata
to destroy ground simply reserve a colour, and when you destroy, draw to the bitmap with that colour, then use threshold() to replace it with the background colour/ full alpha
then you simply use getPixel() to test for background colour, or with alpha you could also use bitmaps hittest using alpha threshold

ok, how can i do that? I don't know how to work whit bitmap thingy.

well psycho goldfish a while ago showed me the engine and told me how it worked.

If you stop thinking about the engine as using "less land", and instead think of it as using more moveable space. Just make the BACKGROUND a mask, and duplicate circles over it. Then do all the engine based on the background, and not the land.

Nice tut -liam- ! Is it possible to have the .fla of the exemple?
here is my msn: louissi_24@hotmail.com

Add me plz.