Hi Tim,
That’s sad to hear, I was holding out hope that it might still be possible in Lightmass since it’s baked and non-dynamic.
I’ve put together a sample project for you with some example trees (not pictured in this thread). One has two-sided polys with a single-sided material, the other is has single sided polys with a two-sided material.
This includes a test map which demonstrates different options turned on and off (shadow casting and mobility) - see attached file for project.
Take a look and let me know what you think.
Thanks!
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