Isn’t doing anything. Reason?
Actually it does something in cycles.
It changes the roughness.
It is not affecting the render with one point light.
It changes the roughness in cycles.
Thank you. Blender should have a way to mark that it is only for cycles.
If I turn off nodes, it has a marked affect on Eevee render. Is this a bug?
Huh… I don’t use eevee aside from material previz in lookdev mode, so I’m not terribly familiar with it, but when you disable nodes, the diffuse bsdf gets a specularity value added, so that seems to be why.
You are right, the more specularity, the more roughness has an affect. WIth spec=0, no affect.
Diffuse Shader - Roughness 0 = Lambertian diffuse surface, roughness 1 = full rough Oren-Nayar surface, which is useful for powdery and porous surfaces. Not implemented in Eevee yet.
Principled Shader - Roughness controls both diffuse and specular roughness, and the visual impact is obviously more pronounced if specular > 0. At specular = 0, you should get the old DisneyDiffuse, which is an improved diffuse over regular diffuse, in which exit IOR is considered. It is not the same as Oren-Nayar. Also not implemented in Eevee yet.
I don’t know how accurate Disney is incorporated into Principled.
The roughness slider for the Principled BSDF does work in Eevee if the specularity >0.
Yes, because then it controls specular roughness.