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Invert alpha, invert colours, 2 shapes intersecting

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Martin Cankov
Invert alpha, invert colours, 2 shapes intersecting
on Sep 13, 2016 at 11:09:25 pm

I'm trying to recreate these lines in After Effects, which will keep the color and shape out of the square, but once they come across they mask the square. I usually keep searching on google until I find the solution, but this time I don't even know how to query this. Please, can anybody give me a hint? thank you!







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Dave LaRonde
Re: Invert alpha, invert colours, 2 shapes intersecting
on Sep 14, 2016 at 12:04:21 am
Last Edited By Dave LaRonde on Sep 14, 2016 at 12:07:11 am

  • Make sure you have the Modes pane visible in the AE comp.
  • Make the trapezoid-shaped object -- the stripes are light blue. The rest is transparent. Personally, I'd put it in a nested comp, but that's me. It's not necessary.
  • Make a light blue rectangle. Duplicate it, change the duplicate to dark blue, and put the layer beneath the light blue rectangle.
  • Put the trapezoid on the uppermost layer. Duplicate it. Parent the lower trapezoid to the upper trapezoid; you will animate the position of the upper trapezoid. It's the only layer you animate.
  • Duplicate one of the rectangle layers and make it the new uppermost layer.


So here's how the layers lay out from top to bottom:
1. Rectangle
2. Upper Trapezoid
3. Lower Trapezoid (parented to upper Trapezoid)
4. Light Blue Rectangle
5. Dark Blue Rectangle

Now it's time to set up the track mattes.

Make layer 1, Rectangle, an Alpha Inverted Alpha Matte of layer 2, Upper Trapezoid.
Make layer 3, Lower Trapezoid, an Alpha Matte of Layer 4, Light Blue Rectangle.

When you move layer 2, Upper Trapezoid, you should see the behavior exhibited by your example. If you don't, change the track matte type to Alpha Matte on layer 2, and change the track matte type on layer 4 to Alpha Inverted Matte; I have trouble keeping the two straight.

Have Fun.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Martin Cankov
Re: Invert alpha, invert colours, 2 shapes intersecting
on Sep 14, 2016 at 11:30:17 pm

Thanks Dave. I have just put the set up together step by step as you noted above, but it seems it's not going to work this way, as the strips(trapezoids) are covering each other and only one strip (trapezoid) could be seen. Is there any other fix?



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Dave LaRonde
Re: Invert alpha, invert colours, 2 shapes intersecting
on Sep 15, 2016 at 3:57:43 am

Okay, before you give up, precompose that trapezoid. In order for my trick to work, the trapezoid has to be a single layer.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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