is there a reason why rect area lights are so slow? can it be accelerated in any manageable way? and how do others fare, for instance babylon, is RAL for them also just something that is only feasible on the desktop?
Real-time area lights are not really area lights, they are just an approximation. But it’s still a lot of work. You can see the code three.js uses here
It’s a lot of extra code that runs in the fragment shader, i.e. for every pixel, every frame. Perhaps someone will come up with a faster approximation than this, but they will never be as fast as the other light classes.
I haven’t benchmarked just how slow they are, but in the meantime, I’ve internalized all of this as a heuristic: area lights are slow.
In terms of speeding them up, the obvious thing would be to a baking workflow. But that would only help with static scenes.
By the way @baze, sorry for slightly hijacking your thread here. I hope you’re still finding this info useful.
baking is something i will need to get into at some point. i hear it all the time and i see stunning examples, but no idea how i’d be able to pull it off. thanks for your explanations and sorry if i got carried away - it’s just so interesting to me!