I want to use an .fbx mesh to block light from entering a room (except for holes cut for windows). The mesh itself must stay invisible. I know marking it "shadows only" will hide it from the camera, but light still passes through it unless I mark the mesh as "lightmap static" as well. The problem is that this is a huge mesh that doubles the number lightmaps required, and it won't even be seen. Is there a better way to do this?
I am using the Lightweight Render Pipeline in Unity 2019.1.4f1 on Windows 10. Using CPU to render on an Intel Core i5 laptop.