Suggestion: Reverse A-Trous Iterations

[alaingalvan]

Hi, great job on this demo! I did notice that there's some edge artifacts between the walls of the Cornell Box that may benefit from using a reverse A-trous iteration scheme (where you iterate from large to small) like in this tweet:

https://twitter.com/NateMorrical/status/1180302300549500928

Note how the walls of his Cornell box don't have edge artifacts.

This would involve changes here to this section of your project from what I can see here.

Realtime-path-tracing-in-chrome/Cornell box/main.js

Line 579 in 56a8cb0

atrousMaterial.uniforms.uStep.value *= controller.stepMultiplier;

[Domenicobrz]

@alaingalvan First of all: thank you a lot for your article! I tried this little experiment after reading it, I had no hope of understanding the ideas behind the algorithm without it

If you cloned this repo recently, I just fixed a strange bug that ruined filtering across all edges on some gpus, whereas the live demo didn't had it

I've made a new branch where I'll experiment with the "reversed filter" in the next days, thank you :) or if you want to make a PR feel free to do so!