0-1 Fresnel IOR does not match IOR mapping

[yavor.rubenov]

Hello,

The mix map does the following: mixAmount*Color1 + (1-mixAmount)*Color2. So if for some point the mixAmount is 0.5 you get Color1/2+Color2/2 = 1/2*(Color1+Color2). Now if you invert this you get 2/(Color1+Color2).

For the 0-1 case and again mixAmout=0.5 you get (1/Color1)*0.5 + (1/Color2)*0.5 = 0.5*(1/Color1 + 1/Color2). Now if you add the values in the parenthesis you get 0.5*( (Color2+Color1)/(Color1*Color2) ). If you invert that - you don't get the same as the other case - and the result is different.

It would work if you do the mixing with the normal values and invert after that if that is an option ?

Best regards,
Yavor

[LudvikKoutny]

Hello,

It would work if you do the mixing with the normal values and invert after that if that is an option ?

Best regards,
Yavor

Isn't that exactly what I tried to do in post #10 here? -> http://forums.chaosgroup.com/showthr...469#post717469

It still does not work, even when inverting the entire result of the mix... :/

Or did I misinterpreted what you meant?

EDIT: There is still that scene in second post of this thread. It would be best to download it, try the solutions out and see if the right part of the image matches the left. There's been quite a few people here shooting suggestions from the hip, but none of them worked even in that simple repro scene

[yavor.rubenov]

In post 10# you've the result in both cases in the Fresnel IOR slot. What I've meant is to put the non inverted mix in the IOR and the inverted in the Fresnel IOR:



That way the results are much closer.

Best regards,
Yavor

[LudvikKoutny]

In post 10# you've the result in both cases in the Fresnel IOR slot. What I've meant is to put the non inverted mix in the IOR and the inverted in the Fresnel IOR:

[ATTACH=CONFIG]34864[/ATTACH]

That way the results are much closer.

Best regards,
Yavor

Oh yes! Thanks a lot!

Can't believe I missed that. It actually does work even if both are in Fresnel IOR slot... It seems I was idiot enough to forget to switch CompTex from Add to Divide when I created a new one.

Thanks again... so lesson learned. When converting fresnel mapping to 0-1 range, invertion of value should come as a very last node before input slot

[yavor.rubenov]

Glad that helped