Seems A.RABBITS code works, and workds quite well... But, with a few caveats:
- The effect is broken when the material is applied to a mesh used in foliage mode. The same mesh/material works perfectly as a billboard as a static mesh, but rotates through the air (rather that simply angling its face towards the camera) when used in foliage mode. I'm guessing this has something to do with the world position somehow being reported as the origin of the landscape, instead of the actual correct location of the mesh... Maybe someone with more material editor know-how can tweak it to work in foliage mode?
- The material doesn't work if applied as a material to a LOD mesh. This is disappointing, as it would have the most potential in this situation (at a certain distance from the camera, swap in a billboard material plane in place of the higher poly geo)
Wonder if anyone else can figure out how to tweak this for perfection?
For now, it seems the best bet for my scene is to use foliage mode (Rather than hand place an entire field made of 5 different grasses...), which rules out the billboard material for now