Hello again…yeah, I like this forum too.
In Motion proper you can’t really (yet); I suppose that could be a reason to buy After Effects! 🙂
In Shake, of course, there is a way to do this:
[Shake, so Motion folks will have to bear with us, or just ignore us, whichever is easier!]
1) Use a Reorder Node again to create your Shake z channel (rgbar)
2) Feed that into a DepthSlice Node
3) Then feed that into your main animation File-In node’s Mask input
4) Adjust center, lo, and hi parameters in DepthSlice to literally slice different sections of your animation, based on the depth data
5) Then in your main animation File-In, activate autoAlpha and add a File-Out and render with the Animation codec (colors+)
You’d have to do this several times obviously to get each depth layer, but then you could separately filter each one in Motion, then do the final composite back in Shake.