Cutoff problem

[Deflaminis]

Hello, I'm having some weird issues with cutoff threshold, and I'm not sure what's going on.

I have a simple refractive material, no reflections on it. When I put the cutoff threshold to 1.0, it renders black. (expected) When I put the cutoff to .999 it doesn't seem to do anything different from having it at 0.0. It refracts the entire span of the floor I've got this on. There is nothing between 1.0 and .999, it's just sort of an on/off switch instead of a cutoff/threshold. Maybe my scene scale? Maybe only works if you have reflections AND refractions? Not really sure but I appreciate any tips. Examples and dummy scene below.

I am on 3.30.04. Thanks very much!


Cutoffweirdness.zip

[Zdravko.Keremidchiev]

This is because you are using 255/255/255 white color for the refraction slot. Try using slight darker color like 249/249/249 and then try to set cutoff values between 0.94 and 0.9 and you will see the effect.

[Deflaminis]

That never would have occurred to me. Thanks!

Out of curiosity, why is that? Is 255 just sort of a floodgate to let everything in?

[Zdravko.Keremidchiev]

Maybe yes, I'm not sure about the exact math behind this. Generally we would advise not to use full 255 white colors for the materials slots.

[Deflaminis]

Fair enough, I did know that. Thank you!