Substrate Material Refraction Help

Hello I’m trying to get substrate refraction to work, so far it’s going well and it’s working the only issue I’m having I can’t get zero refraction. If you have a black and white mask and you want refraction only in the white parts how can I zero refraction wherever there’s black in the mask? For me it’s leaving behind a very subtle dark tint

What I’ve done is, I have a Substrate Slab BSDF - Simple. In Roughness I have 0, in SSS MFP I have 1, in Normal I have a Normal map, in Refraction I have a Lerp A is 1, B is 0 and Alpha is a mask texture. However there’s a subtle very subtle black tint where the black of the mask is in, I don’t know how to completely remove that dark tint, it’s very subtle but it’s visible nonetheless.

I’m also trying to get myself familiar with FX shading using Substrate, so take my suggestion with a grain of salt.

The “black tint” is coming from reflection, and with Slab BSDF, I found that you will always get reflection no matter your trasmittance thickness and F0 , F90 value, so you need to use ‘Substrate Coverage Weight’ to mask off the coverage/presence of this shader on those pixels.
(Using a super high value for transmittance thickness + zero out F90 could suppress reflection, though not completely.)


If this material is supposed to be completely transparent, with no surface reflection and only used for refractive distortion, I would suggest using BSDF Unlit + any of the 4 translucent blend modes. They behave the same as long as you don’t hook up Emissive and Transmittance Color.


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Thank you!! That was it!! Using a Substrate Coverage Weight solved the issue! I appreciate you for sharing the knowledge!