Since Eevee now has ability to render soft shadows from Area lights using some kind offset shadowmap accumulation technique, I was wondering of we could have the same for HDRI environments? It’s already possible for example in 3ds Max using pretty much the same technique:
It even handles small, high contrast hot spots such as sun disc very well!
Right now, in order to plausibly set up high contrast HDRI lighting in Eevee, one has to do following:
1, Add HDRI as environment.
2, Find all HDR spots on the environment map and replace them with actual lights Eevee can sample shadows from.
3, Manually match correct intensity, size and color of every single of these lights to the spots on HDRI, which is borderline impossible of the spots aren’t of primitive shapes.
4, In environment node setup, add rayswitch to use clamped version of the HDRI map for diffuse contribution only, as we do not want to wrap HDR version around diffuse, because it would cause double amount of HDR illumination, with half of it being blurred by diffuse normal wrap.
This obviously requires a lot of knowledge and precision to pull off successfully.
Whereas having an option to accumulate environment illumination shadows in the same way area lights now do it would be a bit slower (not realtime), but would greatly reduce both difficulty and room for error in Eevee’s HDRI illumination setup.