Unable to set mask/matte correctly in AE

[johns66786249]

So, I have a solid layer that I've animated to move across the screen. At one point, it occupies about half of the screen, and I want a 2nd layer to be overlaid on this solid layer, but nothing else. However, when I try to either set a matte for this 2nd layer, it either masks everything or nothing. Further, when I try to do a track matte (all four variants), it also masks either everything or nothing. It appears to be that the mask is applied to the original position of the solid layer, and fails to take into account that it moves!

Is there any way for me to get this 2nd layer to be overlaid on this solid layer properly? I feel like this is something AE should support since generally you want to mask where a layer CURRENTLY is, not where it USED to be, but I can't figure out how to do it right. Thanks!

[Mylenium]

Nothing unusual here. Works as designed Simply pre-compose the moving solid before using it as a matte. You have to read up on AE's internal rendering order and how it is affected by things that may change the order in which the operations are applied like collapsed transformations or layer styles and how effects are intra-layer, not comp space based.

Mylenium

[Kyle Hamrick]

Depending on how things are set up, it might also be worth looking at the Set Matte effect. Since you can now specify whether effects with a layer parameter take effects/masks into account, you may be able to solve your problem without precomping.

[johns66786249]

Unfortunately one of the things I tried was Set Matte, and it didn't work. I'm pretty sure Set Matte applied the matte to the layer's original position, not the position at the time of the animation.

[Roei Tzoref · Accepted solution]

Unfortunately one of the things I tried was Set Matte, and it didn't work. I'm pretty sure Set Matte applied the matte to the layer's original position, not the position at the time of the animation.

for set matte to work with including the transform properties, the collapse switch needs to be turned on (for source also if there was a change in transform)

if this does not work, show us your setup with screenshots or screen capture so we can get a better understanding on what's the issue exactly.

[johns66786249]

Wow, that was a really simple solution, thanks for pointing that out to me!

[Roei Tzoref]

you are welcome. track matte would work here as well. set matte's advantage is that it can be anywhere in the stack and multiple layers can use it. the disadvantage is that you need to set collapse on both source and matte and sometimes it requires pre-composing (if it's pixel layers that don't have a collapse switch).