It’s just Going around problems of accessibility. If only it were easy to detect the base item via BP you wouldn’t need to have these insane workarounds…
Re the grass material you asked info on
Gigantic mess from afar:
getting into it a bit
Normal winds
Mixed to vertex color + normal (output goes to normal)
Camera fade
UV1 is used in the normal above to do this. (moving calcs to a UV solves some performance, though not by much in this case).
Per instance fade (requested by op originally)
The rest of that mess is just the color setup for changing with the MPC.
Most of that setup is actually shown in the Learning tab within the master materials section I think. I modified the normal winds for my needs a smidge but the theory was simple enough. The scale of the normal map affects the offset you see in color.
The normal map itself is usually something simple - take a picture of clods, convert it to a normal. or waves, waves work good. I think the tut uses the water form Boy and his Kite.
This is the effect of that material with a blank texture on the vertex version of the grass (no transparency at all), colored for debug.
And I also gained 20fps swapping the mesh 