I'm obviously missing the obvious here. But how do you count the number of emitted particles at any given time? Imagine a particle emitter that sits in the top of the game canvas, and dropping particles that falls to the bottom. At the bottom there is some "dude" catching the particles and gets a point for each catched particle. There scoreboard may read something like "Points: 4 of 7" and a little while later it may read "Points: 8 of 13". How do you get the 7 and the 13?