First here are a couple of tutorials on using shatter(it can be a bit over-whelming):
This tutorial is quite old, but shatter hasn’t changed in 10 years so it’s still relevant: Basic Shatter: Introduction to the Shatter Effect
A new Tutorial from Rob Mize: Shatter-Mation in After Effects
To answer your question though, a layer shatter when it is hit by a 3D force. When you first apply shatter you will get a wireframe plus forces view. The blue lines are the force hitting your layer like a wrecking ball causing it to break up. By twirling down the force parameter you can control when your layer is hit, where it’s hit and how it’s hit.
You can’t reverse shatter a logo per se, you need to shatter the logo and precomp the effect. Now you can apply a Layer > Time > Time Remap to have the shatter reverse and explode out again.
I made an example project illustrating how shatter works and how you would time remap it. Take a look at the tutorials/my project and if you have any more questions, come back and ask.
4977_shatterexample.aep.zip
Johnny Cuevas, Editor
Thinkck.com
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