I know you can set the sun angle but at some point (sunset or sunrise) the sun goes dark, as you would expect in a real-world example.
I do Reflected Ceiling Plans in SU however and is would be great to have shadows coming from below or “underground” to accomplish this.
I thought about setting a daytime scene then somehow trying to use
vector.reverse to generate the opposite direction but
shadow_info only seems to accept NorthAngle, lat, long, and time settings, none of which will generate the desired outcome I don’t think.