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Angular roughness/Angular glossiness

Posted: Mon Jul 13, 2020 5:09 pm
by Theo_Gottwald
In today's Blender 2.8 tutorial, (the video editor) want to share a secret (or at least very uncommon) technique to make your Blender materials instantly better. It is called angular roughness (or fresnel glossiness etc.) and works both for Eevee and Cycles rendering engines.

Video on the topic:
Angular Roughness

Discussion on the Blender-Artist Forum

As i did not see the Layer-Weight node in Luxcore, my question is, how this is done using Luxcore-Nodes.

Re: Angular roughness/Angular glossynes

Posted: Mon Jul 13, 2020 5:35 pm
by Sharlybg
It is automatic in luxcore :
Lux__fresnel.jpg

Re: Angular roughness/Angular glossynes

Posted: Mon Jul 13, 2020 6:11 pm
by Theo_Gottwald
So that means that for any material that has a roughness, Luxcore does the angular roughness automatic?
Interesting to know.

Re: Angular roughness/Angular glossynes

Posted: Mon Jul 13, 2020 6:17 pm
by B.Y.O.B.
LuxCore does not do this, roughness is not view-dependent in LuxCore.

Re: Angular roughness/Angular glossynes

Posted: Mon Jul 13, 2020 6:28 pm
by Sharlybg
B.Y.O.B. wrote: Mon Jul 13, 2020 6:17 pm LuxCore does not do this, roughness is not view-dependent in LuxCore.
So it is angular Specularity ? if not too. are the current shader definition realistic ?

Re: Angular roughness/Angular glossynes

Posted: Mon Jul 13, 2020 6:44 pm
by Theo_Gottwald
If not, how did Sharlybg make these screenshots?

Re: Angular roughness/Angular glossiness

Posted: Mon Jul 13, 2020 11:27 pm
by chafouin
It's the usual fresnel effect (angular specularity if you will), but it's not angle-dependent roughness.

Re: Angular roughness/Angular glossiness

Posted: Tue Jul 14, 2020 2:37 pm
by Theo_Gottwald
Ok, and which Luxcore Nodes would you use for angular roughness - like in the video - then?

Re: Angular roughness/Angular glossiness

Posted: Tue Jul 14, 2020 7:54 pm
by lighting_freak
Hi all,

I think the "glossy" material node has an option called "IOR". If one select this the amount of reflection is calculated by Fresnel law.

The Fresnel law makes a reflection more bright with more plain observation angle.

Additionally the roughness parameter could be used to scatter this reflected light. Et voila, you got an angular roughness!

BR

Re: Angular roughness/Angular glossiness

Posted: Tue Jul 14, 2020 8:27 pm
by B.Y.O.B.
lighting_freak wrote: Tue Jul 14, 2020 7:54 pm I think the "glossy" material node has an option called "IOR". If one select this the amount of reflection is calculated by Fresnel law.
The IOR mode is just another input method instead of specular color. Internally the IOR is just used to calculate specular brightness for the material.
Afterwards, the calculations happening are the same (according to fresnel laws etc.).
See https://github.com/LuxCoreRender/LuxCor ... y2.cpp#L69
(In BlendLuxCore the specular color is set to 1, 1, 1 in this case).
So the IOR input mode is only useful if you have an IOR table containing the value you want to use for the coating material, e.g. water IOR = 1.33 for a wet leaf or something like that.