Tacking this onto the thread where you ask about rendering these parts differently
Using Z makes a lot of sense, and would be pretty easy to add. I wasn’t sure what the LAST_VISIBLE_LED in your FastLED map was for, but it seems to be a pretty good indicator of the split between the foreground and background.
Modifying the code above slightly to add a Z, with a value based on that:
map[pixelIndex] = [x,y, pixelIndex > LAST_VISIBLE_LED ? 0 : 5]
Note that without much modification, most 3D patterns will use the Z and make sheep-shaped differences in animation.
(for this preview I turned off the 3D focal length so I can visually overlap the sheep layers, and turned on gapFill, these are hackable using a browser console in the previewSettings global)