View Full Version : Animating multiple masks over a single layer (diagram included)

01 January 2010, 02:47 PM
Hi guys,

This has been bugging me for a while now!

I want to animate multiple masks (independently) over a single layer.

here's a diagram:

Referring to my diagram, I have 5 different shaped masks

each has a different motion path (represented by the white dotted line)

they all cut through one layer (the blue rectangle)

I can't use normal masks (because I want to animate them)

The only thing I can think of is to put my five shapes into one precomosition

then to place that precomposition directly above my blue rectangle layer

then to set the TrkMat for the blue rectangle layer to: Alpha Inverted Matte "five shapes Precomposition"

But I've had no luck with this approach!

Any Idea how to go about this?


01 January 2010, 05:09 PM
You can animate masks in AE. You need to click the stopwatch icon for the Mask Shape. That'll let you animate the shape of your mask over time.

If you set all your masks to Subtract you'll cut through your blue solid.

01 January 2010, 06:06 PM
Thanks ernpchan,

but I want to animate the position of the mask over time - not its shape.

specifically, I want it to follow a path that I created in illustrator.

(I may be missing something completely obvious!!)

01 January 2010, 06:46 PM
Well if you grab all the points of your mask you could move the mask as a whole. But that's really not the easiest way to do that as sometimes you don't grab all the points and end up messing up your mask shape.

Do this. Make a new solid. Draw out the shape that you need on that solid. Now animate the position of that solid. Repeat these steps for all your other shapes. Now pre-comp all those layers and use that as your track matte. The benefit of this is if you need to change the shape of your mask you only need to change that one one mask versus having to redo all your mask shapes if you had animated the mask. The other benefit is that it'll be easier to adjust and tweak your animation path. I don't believe you can see the animation path of a mask but you will for your solid.

01 January 2010, 05:46 PM
Thanks ernpchan that worked perfectly!

01 January 2010, 06:05 PM
you can also double-click your mask to move it as a whole unit...

01 January 2010, 12:36 AM
If you select the mask in the layers panel, not only will it select every point in the mask, but you can press ctrl+T (free transform) to move it about or rotate it as needed. This would provide much more flexibility that the precomping method, imo.

CGTalk Moderation
01 January 2010, 12:36 AM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.