Subtract shaders - no longer works, but new sheen node can get pretty close

[moony]

@Ace Dragon

At first I was skeptical that you would be able to just subtract one shader from another in a pathtracing environment, but it seems like you have a strong theory on how such a node would work (flip some of the shading values from positive to negative for starters).

Now if someone can produce a proof of concept patch for inclusion into Master, the iridescent effects look quite good.

Given that we can add, mix and by the looks of it, subtract shaders - would it be worth having a more general “shader math” node that allows the full range of mathematical functions to be carried out at a shader level (e.g. multiply, divide etc).

[Random_CGI_Guy (Leo)]

whats the node setup?

[moony]

I’ll have to dig it out - it’s been a while. I’ll get back to you

[AlphaChannel (Dr Salty Lout)]

6th post down, why dont you build it?

[moony]

Hmm - I have just tried to recreate this effect in both Blender 3.4 and 3.5 alpha - and it doesn’t work in either.

I even tried loading an old file with a ‘subtract shader’ in it - and that doesn’t work either.

Maybe the devs changed something to disallow negative values being passed into the colour slot of cycles materials.

Shame if they have because it produced some interesting effects.

[moony]

I have found another way to get reasonably close to this effect using the new Sheen node in the 4.0 alpha. It’s not quite as nice and cannot be used with anisotropy - but it is usable.