I’ve addes this to the ideas page:
Still I’d like to discuss this here in case I missed something or devs need further explanation what this is about (text copied from the idea post).
So… years after this exact issue was discussed, I’m now facing a situation where the design of the Physical turns out to be indeed limiting. I remember discussing it back then, and now I realized that it’s a limit that can’t be solved using Corona’s Physical Material.
Back then I asked for a simple filter/amount slot in reflections. It turns out it is needed, let me explain:
- I have a long row of windows that all have the same material but need slight differences in reflection amount to make it look less artificial (simulate dirt if you want), and best use a noise map for this
- right now IOR is controlling both refraction and reflection and there’s no other way of controlling reflection amount other than changing IOR
- this works fine for reflective objects… however, with refractive materials you will affect the refractive IOR, making whatever is visible behind the window distorted, the strength of distortion being related to the strength/opacity of the map
In my opinion, this is a design flaw and needs to be addressed.
I imagine support will try to suggest using coating for this but please think about it - it won’t work. It would work if I could produce refractions without reflections in the base setting and then add coating and map amount or absorption, but this isn’t possible either.
Right now my only option is to use ‘thin mode’, which will not produce refractions (may work depending on the case, but it certainly not ideal if refractions are needed), or use the Legacy Mtl.
Autodesk’s Physical Mtl for example offers a slot for the amount of reflection. It’s exactly what would be needed. Now I understand that simply diminishing reflections by that map is not physically correct but surely there’s a way for you to internally diminish reflection based on that map without sacrificing physical (fresnel) accuracy. It really is needed, as was originally discussed when the Physical material was designed.