How to achieve this effect

[Tudor “ted” jelescu]

Use Venetian Blinds (Transitions) while animating the layer position.

Tudor “Ted” Jelescu
Senior VFX Artist

[Julien Coudert]

It’s not just masking the shape it’s also “cutting” it giving the movement a delay. Or i miss something.

[Tom Ma]

this is just two layers of the same animation offset in time being revealed, one over the other.

how to do:
create whatever animation you like in a comp.
bring that comp into a new comp.
duplicate the comp, but delay it in time (slide layer to the left 3 or 3 frames)
reveal however you want. venetian blinds were suggested and a good quick fix, but in this case were variable sized masks.