This is my second Flash animation — my first one is here — so I'm still learning.
From what I've noticed, many animators who use Flash to make something resembling a particle system seem to take the same approach: they first toss out onto the stage a predetermined number of particles, and then choreograph the behaviours of those particles.
I've taken a different approach here: With each new puff of smoke, I spawn a new layer. The layer's lifespan is determined by the visibility of its alpha channel — an alpha channel which fades over time. I, as animator, have no idea how many layers exist on screen at any given moment, nor do I care. I let the computer worry about that. This seems to me to be a good way of thinking about smoke, fireworks, and other effects animation within the Macromedia Flash environment.
One problem: I've been having a hard time under this methodology figuring out how to use Flash's Mask Layers.
It's just been out of luck that I was able to choreograph the smoke puffs such that they faded out before leaving the region defined by the oval outline. I wasn't so lucky with the water glints. It was a lot harder to "contain" them within the oval region and behind the splayed currency. Because of that fact, I had to fall back to the more typical approach of placing a predetermined number of glints in various places and limit the extent of their potential wanderings. What I wanted to do was create the sun glints in the same way I created the smoke puffs: one glint per layer. I also wanted the glints to shimmer as their action scripts dictated without limitation, and to have their appearance clipped back by a masking layer. The problem is that masking layers have to be the topmost layer, and they seem to only affect the layer immediately below them. Advice on how to keep my mask layer on top, and how to have it affect all of the many layers stacked below it, would be appreciated.
Joseph Francis, 7/13/2003