Lumen’s art directability has definitely been second to establishing a baseline PBR realism , and the amount of hacks and cheats I’ve found already speaks to some concerningly complex material development for a system that’s meant to ‘just work’.
Pretty much all my work has photorealism as a target so Lumen’s development has generally been good to me, but I understand for nonrealistic rendering it’s very hard to use. The biggest problem seems to be getting screen-space traces to understand what to do, as there’s no easy way to tell them more information about the scene than what’s on-screen (I’d imagine some sort of hack with a mask could be used, but no dev work has gone into a solution from what I’ve seen.
The big problem for me is the lack of multi-bounce specular lighting or a sufficient fallback method. Your work @BananableOffense is very helpful for me to understand the strengths and weaknesses of the different reflection methods, but cubemaps get us back into the same problem we’ve been trying to ray-trace out of (namely static scenes and limited perspectives). I do understand that multiple bounces of reflection incur a significant cost, and a single bounce is generally enough for many non-archviz art cases, but I’ve seen lumen reflections break entirely in any scenes with dull metal, and that’s not something I want to have to hack/art around.