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As a quick demonstration, here's an illustration;

Intersecting masks

So I have two shapes (2 and 3), which intersect (4). I want to animate the position (possibly also scale) of these two shapes, while having footage masked inside each numbered area. The shapes should move independently of the footage.

I've gotten as far as masking the footage for 2 and 3, but the intersection is what makes me scratch my head. Is there a way to do this in After Effects CC without any hand-tooling for a mask for the intersecting area?

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My first thought: what happens at the intersection? Is it just overlapping footage, like in the middle of a "dissolve"? My second thought: once you figure that out, I'd be tempted to create the #2 masked shot first, then use that as the "background" for the #3 masked shot. But that's after you figure out what happens when they overlap. (The overlapping area COULD be a third masked shot that you layer on top of the other two masked shots.) – BrettFromLA Apr 22 '14 at 18:49
What exactly is your issue? What do you expect to happen when the masks intersect? Are you masking one footage file with both masks at diffrent areas or does mask 2 and 3 have different footage that they are masking? – Professor Sparkles Apr 22 '14 at 22:40
@ProfessorFartSparkle - it sounds like he wants a different video entirely to play in area 4, so each number has its own video driving it. – AJ Henderson Apr 22 '14 at 23:32
Aaah I see, makes sense now. Then I know an answer for that. – Professor Sparkles Apr 22 '14 at 23:41
up vote 4 down vote accepted

Simply copy the two animated masks to the 4th footage file and set them to "Intersect" instead of "Add". Then they will only reveal the footage that they are applied to when they intersect with another mask. Then put this footage files layer ontop of the others.

Here a screenshot as a reference. enter image description here

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This was the best way I could think of too. – AJ Henderson Apr 23 '14 at 2:02

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