Working with 3D comps inside other comps...

[Shawnbarryoftoronto]

Hi all,

I've created a 3D cube by placing comps and rotating and snapping all the sides together. I'm using comps so I can drop an image in and the images become the surface of the cube. I then slave all the cube parts to a null layer to use as controls for the final cube. I need to create several cubes in this same manner to create an environment in which these cubes live and move about. Here's the issue:

If I leave the 6 comps (top, bottom, 4 sides of the cube) as layers of the main comp, they behave like a cube - I can rotate them and see the sides, etc. However, if I take those separate comps and pre-comp them so I can have various cubes nicely organized as cube 1, cube 2, etc., then the cube starts behaving strangely. If I leave 3D layer un-checked, the cube remains 3D but I can't rotate it using the null. I can scale it with the null, so they are connected, but can't rotate it. If I check 3D, it collapses into a flat layer, but can be rotated by the null.

I'm totally baffled at this point. Feel like I can't find the sky-scraper I'm standing in front of, in that this HAS to be so obvious I just can't see it. I don't even know what to screen cap to help this explanation. Basically, how do I create a 3D cube with images without just having 75 layers in one composition all loose and un-organized? Seems like it should just work, but mine defies logic. Let me know what to screen cap if that helps.

[Rick Gerard · Accepted solution]

To keep 3D layers active when they are part of a nested (pre) comp you have to collapse transformations.

Normal workflow -

• Set up you 3 D layers in the main comp and add lights and camera
• Select the 3D layers you want to group and pre-compose those layers only moving all attributes to the new comp
• Turn on Collapse Transformations in the pre-comp
• The nested comp now interacts with the main comp Camera and lights.

If that doesn't solve your problem we need a screenshot of the main comp with the modified properties of the layers giving you problems revealed (uu + Print Screen + paste to the forum), a screenshot with at least one of the 3D layers selected and modified properties revealed, and a screenshot of the flow chart of your project. 

[Shawnbarryoftoronto]

Thanks Rick - would never have known how to even discover that issue. Don't do a lot in 3D.

The last question is, how do I line up the anchor point of the 3D precomp wih the anchor point of the null? Is there a click or do I have to eye-ball drag?

ADDENDUM: scratch that. II just rebuilt the cube from scratch, realizing that the issue was the position of the elements, not the cube's anchor points.

Thanks again Rick!

[Rick Gerard]

The easiest way to build a cube:

1. Create a square shape or solid layer the size of one of the faces
2. Make the layer 3D
3. Press the 'a' key to reveal the anchor point and change the z value to half the width of the layer (shape)
4. Duplicate the layer 5 times
5. Press 'r' to reveal the rotation property, leave layer 1's rotation alone, set layer 2's y to 90º, layer 3's y to 180º, layer 4's y rotation to 270º, layer 5's x rotation to 90º, and layer 6's x rotation to 270º
6. Add a 3D null at the center of the comp and name it Cube Null
7. Parent all six sides to the Cube Null
8. If you need to add graphics or videos to the faces of the cube you can make the layers 3D, add 1 pixel to the z anchor point, hold down the Shift key and Parent the layers to the appropriate side of the comp to snap it to the same position and orientation as the parent, move the layer below the cube face and set track matte alpha. If you also need to see the face of the cube turn the layer back on.
9. If you really want to get fancy pre-compose the completed cube, collapse transformations, drag the pre-comps timeline below the main comp timeline, add a Controller null to the main comp, add a 3D position and rotation expression controller to the Controller null and use the pickwhip to tie the Cube null to the controllers. Now you can move the original cube around in 3D space and control the rotation from the main comp. Finnish the project by adding lights and a camera.

The whole process should take you about 10 minutes and it looks like this:

[Shawnbarryoftoronto]

Thanks again for extra help. I created the cubes properly and have them spinning and moving. I stopped short of your extra bits like lights and such. Wrestling with the results too much, so I may have to revisit that part later. Can't get the cubes to cast shadows - specifically, I can't find a way to select the cube and select "cast shadows" - there seems no such option on the cube precomps. Did I miss a step?

[Rick Gerard]

You have to enable cast shadows with the original layers. Anything you do to a 3D layer that is in a pre-comp will show up in the main comp if you collapse transformations. They will even cast shadows on a layer in the main comp.

[Shawnbarryoftoronto]

Awesome - you got me to where I needed to be, Rick. Thanks again for the help.