<p>Place a duplicate copy of your red box as the top layer. Put the blue box as the next layer. Set the Blue box's TrkMat (track matte) to Alpha.</p>

CC BY-SA 4.0
2021-06-14T00:20:40.240Z
2021-06-14T00:20:40.240Z
Greg
<p>Example scenario:</p>
<p>I have 4 boxes.
Box 1 is blue, Boxes 2 &amp; 3 are a specific color of red and Box 4 is green.
I would like Box 1 (blue) to only be visible when overlapping a red box.
If Box 1 overlaps Box 4 (green) nothing happens.</p>
<p>My question:
Is there a way I can matte a shape so that it is only visible when it overlaps a specific color?
Essentially like a &quot;Set Matte&quot; effect that is driven by an RGB hex code rather than a layer's bounds.</p>

<after-effects><after-effects-expressions><color>
Matte only over items of a specific color?
Jacob Crocker
# Matte only over items of a specific color?

(Asked by: username_0 on 2021-06-11)

Example scenario:

I have 4 boxes.
Box 1 is blue, Boxes 2 & 3 are a specific color of red and Box 4 is green.
I would like Box 1 (blue) to only be visible when overlapping a red box.
If Box 1 overlaps Box 4 (green) nothing happens.

My question:
Is there a way I can matte a shape so that it is only visible when it overlaps a specific color?
Essentially like a "Set Matte" effect that is driven by an RGB hex code rather than a layer's bounds.

**Tags:** after-effects, after-effects-expressions, color


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## 1 answers

### Answer by username_1 on 2021-06-14. Score: 1

Place a duplicate copy of your red box as the top layer. Put the blue box as the next layer. Set the Blue box's TrkMat (track matte) to Alpha.


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