Stylised foliage lighting, how to cast shadows but recieve only indirect

I’m trying to achieve a look similar to The Witness for my foliage and trees, and feel i have it down for the most part with this (very average) test tree.
This is done using edited vertex normals, and self shadow only checked.

However, doing this means the leaves no longer cast shadows - is there a way to have the leaves cast shadows while only receiving indirect shadows themselves?
Or a work-around such as having a duplicate, invisible mesh cast shadows or some such?


An invisible, shadow casting mesh does seem to be the best workaround to me.

It would be so good to have more shadowing options. What I would need for my trees is to cast static shadows but only receiving dynamic light.(too much memory for lightmaps).

Lightmaps can be fairly low res and compress pretty reasonably - how tight are your memory constraints?

With low resolution lightmaps shadows bleeds every where and result is unusable. Lowest usable resolution is 256. Multiply that with thousand trees and you see the problem.

Thanks guys, looks like invisible shadow casting mesh is the way to go. Not sure if i should make a new thread for this question, but any ideas on how to regulate opacity of individual faces based on angle to camera? When foliage faces are seen side on or near side on it can kinda ruin the look.