Can you explain to me whats Collapse transformations button and set up your infinite plane comp?
Collapse transformations allows you to set up precompositions, but when you press the collapse transformations button, instead of giving you a flat layer—it brings forward all the transformations in the precomp. For instance you could set up 2 objects in 3D space rotating around each other, drop them into a new comp and they will retain there 3D infomation. Then you could move both images together as a single layer in the final comp.
In your case I used collapse transformations so that we could enable 3D and have it cast shadows in the final composition. If you turn off collapse transformations, the layer would be 2d and wouldn’t cast shadows.
Adobe Help Collapse Transformations
Tutorial explaining Collapse Transformations
Because you wanted to be able to change the color all at once I updated the project. I added another solid to project and placed it at the bottom of the layer stack(IN MY EXAMPLE I have multiple solids, turn them off and on to see how it works). In the shadow-floor layer, I turned Cast Shadows to “ONLY”. Now the floor is invisible except the shadow. So whatever layer you are using for your bkg will create your infinite plane.
Look at my new example project: 6469_precomptextcs5.5v2.aep.zip
Finally if you are new to AE and really want to learn, I strongly suggest you check out the links and info here(in part 4 there are links to great free online tutorials to learn the fundamentals of AE): Getting started with After Effects (CS4, CS5, CS5.5, CS6, & CC)
Johnny Cuevas, Editor
Thinkck.com
“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.