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How to get accurate fresnel value to mix material ?

PostPosted: Wed Mar 21, 2018 9:59 am
by fantome
Hi Guys,

I would like to understand how would you proceed in octane to blend material.
It looks that you can only mix material, so it blend in % according to the input value.

i would like to be able to use a correct fresnel function in order to do my blending.
the only one i have find is the fallof map.

the problem is that the fallof map use a strange skew factor to control the fresnel.
the behavior is describe here.
viewtopic.php?f=9&t=44730#p222947

but i would like to know how i could i use something similar base on the IOR of medium A and medium B.
basically for air to water i can enter the 2 IOR value in input and it give me the correct fresnel repartition in output.

Basically i need the octane equivalent of the fresnel VEX function.
http://www.sidefx.com/docs/houdini/vex/ ... esnel.html

Thanks for your Lights !
Cheers
E