Simply put, I need find some sort of shadowing method that works over extremely long ranges - as in, on the range of 50-100 kilometers. Cascaded shadows certainly don’t work, and distance field shadows are very hateful of existence when forced to work over these distances. And to make things fun, it also needs to have penumbral effects a la DF shadows. Is this even possible with what the engine can do right now, or will something homecooked have to be made?
If it doesn’t work with distance field shadows then your only option is baked shadows, if you need a dynamic light, then you don’t have an option that also has a shadow penumbra
It does have to be dynamic. I mean, the shadow penumbra is mostly just a bonus, I’ll settle with any shadow solution that works over these ranges, really… only other thing that comes to mind is a homemade shadow volume setup, I guess.