I'm following a tutorial on AE and it is completely confusing to me as I cannot get the desired result.

Here are the steps in the tutorial:

  • Select a group of comps
  • Pre-compose them into new comp
  • Collapse transformations on the new pre-composed comp (press the starry button)

The desired result I want is the transformation view being snapped to just around the rocket, but somehow it doesn't work as I expected. What am I missing here? Screenshots below:

Group comps and make a pre-composed comp

enter image description here

The area should fit just around the rocket but it doesn't.


I get the feeling you think collapse transformation means something that it doesn't.

What Collapse Transforms does is to leave all the transformation properties in the subcomp intact and available to the comp that it's nested in. It's basically like you've got all the layers still in the outside comp, just grouped into one layer for ease of organisation.

Without collapse transforms on the subcomp is pre-rendered and treated like a single piece of footage. So, for example if any of the layers of the sub-comp extend off the edge of the sub-comp's boundaries they won't be cropped with collapse transforms on.

Here are two subcomps, both contain text that extends past their outside edges:

enter image description here enter image description here

And here they are in the outer comp. Top one is collapsed, bottom aint.

enter image description here

If you scale down a raster layer in the subcomp and then scale it up to its original size in the outer comp, without collapse transforms on it will be pixelated, because it gets pre-rendered to the resolution of the subcomp, and then scaled up in the outer comp.

Here they are scaled down in the subcomp:

enter image description here enter image description here

And here's the outer comp with both layers scaled back up:

enter image description here

Another effect of collapsing transforms is that you lose the ability to change the transfer mode of the subcomp in the outer comp. The layers in a collapsed transform-ed subcomp apply whatever transfer mode they have inside the subcomp, again, like they were actually in the outer comp, just grouped together.

enter image description here

What Collapse transforms doesn't do is automatically crop the subcomp to fit its components. Is that what you were expecting?

  • kind of what I'm expecting. But if it is not, then it has to be some kind of inconsistence between versions of Adobe After Effects because in the tutorial I'm following it behaves like what I'm expecting – YaphatS Aug 21 '16 at 17:00
  • can you take a look at the tutorial? I'm sorry it's in Vietnamese, not English, but I think judging from the behaviors of the application is possible. The part I want explained is around 13:30 to 14:20 youtube.com/watch?v=Mct3wkTXApk – YaphatS Aug 22 '16 at 2:44
  • In that tutorial it behaves as normal: in the outer comp you'll see the layer handles shrink to fit the layers in the subcomp when collapse transforms is on, but the subcomp will stay the same size. You could resize the subcomp if you like, with CT on that won't make any difference anyway. – stib Aug 22 '16 at 4:43

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