How did they reduce a composition to a single layer in another composition

Question

I've been watching this solar youtube video to create a solar surface and I don't understand how he took 3 layers in the "Star Map" composition and made them into one layer on the "Sun" composition. What is this technique?

Thanks

Answer 1

I just figured it out. In After Effects 2020 the technique is called layer grouping. This can be achieved by:

1. Go to "Layers" menu item
2. Choose "Pre-compose..."
3. Give the layer group a name you prefer
4. Select the option: "Move all attributes into the new composition"
5. check the box "Open New Composition"

At the end of this. All your layers in the first composition have been grouped together into a new composition. The new layer is given the name you typed in option 3 above.