In this Quicktip, Aharon Rabinowitz shows you how to control the way particles are emitted from a picture or text, when using a layer emitter. He’ll be exploring a feature called Layer Sampling.
Layer Sampling is a feature controls whether or not particles are revealed by a layer’s alpha channel, or, depending on the setting, if they are emitted at all. If you have ever wanted to blow up text, this tutorial will help.This is also a great technique for creating underwater simulations (Ex.: bubbles created from a layer’s motion).