FlowTuts shows how to make an active hover effect in After Effects working with Expressions.

A mechanic of interaction design is having something activate on hover. You can easily recreate this type of effect in Adobe After Effects using Expressions. Check out the latest tutorial from FlowTuts that shows how to make an active hover effect using a null and some code.

When the null is over an element in a layer, the component will activate and display a new image, creating a hover effect. The tutorial takes inspiration from Sergei Prokhnevskiy, who once showed how to trigger properties based on proximity.