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Zach Rowe
Zach Rowe
Known Participant
May 18, 2025

After Effects GLB import: 3d overlapping vs stacking order

  • May 18, 2025
  • 4 replies
  • 381 views

Im animated a knitting simulation. The needle needs to be obscured by the grooves and the cylinder as it rotates. But as you can see it is not. Seems like simple geometry, any ideas on how to fix? These are models that were built in blender. Im using the advanced renderer because seems like this is the only renderer that supports 3d model imports. Heres a link to frame.io upload: 3d GLB overlapping issue 

4 replies

David.Arbor
Community Manager
David.ArborCommunity Manager
Community Manager
May 20, 2025

You're welcome! Adam gave a great explanation of what's happening behind the scenes. With this knowledge, you can actually use bin breakers in really creative ways. 
I recently took a Mixamo model of a character climbing and put it on top of a mountainside I made in Cinema 4D. Since the two models weren't designed with each other in mind, there was no way I was going to get the character to look like it was actually climing up the mountain without intersecting the geometry.

I intentionally added an adjustment layer in between the character and the mountain, and boom, the character renderered on top of the mountain all the time. Then, I added a shadow catcher beneath the character, and I very quickly had a simple composite that looked like the character is actually scaling the wall!


- David, After Effects Engineering Team

 

 

 

Zach Rowe
Zach RoweAuthor
Known Participant
May 20, 2025

Thanks Adam and David, 

As I continued working the problem went away, I didnt noticed how it got fixed but I suspect is was a layer creating two seperate 3d bins. I never knew what that rectangle around the 3d toggles was so thanks for explaining.

A
Community Manager
adam_youngCommunity Manager
Community Manager
May 19, 2025

Hey Zach! Any chance your scene has multiple 3D models with a 2D layer in between? If that's the case then models above the 2D layer in the timeline will always render on top of models listed below the 2D layer, regardless of where they are in space.

In the timeline, a rectangle gets drawn around the 3D switch for layers that get drawn in the same bin. In the first image the comp has two bins, separated by a 2D text layer, so the whale in the back gets drawn on top of the two whales that are closer to the camera. But moving the text to the bottom of the layer stack puts all three whales in the same bin, so they render as part of the same 3D scene.

 

Hopefully reordering your layers to make sure the models are all part of the same bin helps, but if that isn't the issue let us know!

 

 

David.Arbor
Community Manager
David.ArborCommunity Manager
Community Manager
May 19, 2025

Hey @Zach Rowe ,

 

Are the needle and the cylinder separate pieces of geometry? If so, it looks like you might have an adjustment layer or a "bin breaker" in between the two. Can you post a full UI screenshot of your timelien showing the layers and making sure the switches and not blend modes are visible? Both columns are ok, but you can see whether a 3D bin is broken by looking at the outline drawn around the 3D switch box and how many layers it extends to.

 

Thanks,
- David, After Effects Engineering Team

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