Rough Specular reduces specularity amount?

[vlado]

Does that mean other materials (for example SSS2) will have glossy Fresnel, or is it only on the VrayMtl?

In the first beta, it will be only for VRayMtl and VRayAlSurfaceMtl. Do you want it enabled for other materials and if yes - which ones?

Best regards,
Vlado

[sharktacos]

Vlado, can I talk you into adding a second spec/reflection term to the VrayMtl? I use this all the time (via a blendMtl in additive mode). This additive blend method works, but breaks energy conservation. So could we please get 2 specs on the VrayMtl?

Pleeeeeeeeeeeeeeeeeeease, oh please, oh please, oh please, oh please, oh please, oh please, oh please, oh please, pretty please?

[zeronove]

take a look at this explanation:
https://labs.chaosgroup.com/index.ph...lossy-fresnel/

thanks
so as far as I understand
in rough surfaces glossiness value is the same for every viewing angle but will have less of a Fresnel effect (= reflection dimmed viewed at grazing angles) ...is it correct?

[Morbid Angel]

thanks
so as far as I understand
in rough surfaces glossiness value is the same for every viewing angle but will have less of a Fresnel effect (= reflection dimmed viewed at grazing angles) ...is it correct?

yes...it was wrong this whole time

[zeronove]

yes...it was wrong this whole time

ops

time for me to update

[sharktacos]

In the first beta, it will be only for VRayMtl and VRayAlSurfaceMtl. Do you want it enabled for other materials and if yes - which ones?

Best regards,
Vlado

It would make sense to have it for all skin shaders (sss2 & vraySkin) since human skin is micro-faceted.

There's a lot of other things that could be improved about the spec section of the SSS2: I'd like to have
* reflection IOR (independent of the IOR for the SSS),
* GGX brdf,
* two spec lobes.
In other words, the way spec is done for the ALsurface.
Currently I always disable the spec in the SSS2 and use a blendMtl to add in double-lobe spec from two VrayMtls with different glossiness values.

[Morbid Angel]

most surfaces in real world have macro-facets no? they are just different. Unless its a glass or mirror like surface.

[Ihno]

How about a glossy fresnel map node or a mode for that in the fake fresnel map?
To be able to use glossy fresnel for things like clear coats in blend materials.

[sharktacos]

How about a glossy fresnel map node or a mode for that in the fake fresnel map?
To be able to use glossy fresnel for things like clear coats in blend materials.

That would be useful, however glossy Fresnel changes the edge reflections based on the material's glossiness value. The FresnelTex is independent and so would not know about any material's glossiness values.

Perhaps an extra parameter for "glossiness" could be added to the Fresnel Tex itself? It could default to 1.0 (non-glossy Fresnel) in lieu of a checkbox.

[vlado]

As sharktacos pointed out, a simple texture map will not work accurately. I'm still trying to figure out what is the best thing to do in that case. I have two options:

a) Add an option to VRayMtl to ignore the diffuse and refractive layers and use the Fresnel transparency of the reflective layer as transparency for the whole material. In that case, if you put it as a coat in a VRayBlendMtl material with full blending, without any texture map, it will automatically blend things correctly.
b) Create a new VRayGlossyMtl material that only contains the reflective portion of a VRayMtl material with the Fresnel transparency as transparency for the whole material.

Which option do you prefer?

Best regards,
Vlado

[Morbid Angel]

My vote would be a VRayGLossyMtl......less confusing for users, who just check something without reading what it does might produce crazy results...

[sharktacos]

Well, there is also option C: have 2 spec lobes for the vrayMtl.

Given options A or B, I would also prefer "B" (new VrayGlossyMtl) for the same reasons Dmitry gave. You might also consider calling it something like VrayClearcoatMtl or VrayCoatMtl. Those names seem to better indicate its intended use. Calling it "glossy" to me implies that it has a high gloss, and is thus not microfacet, and that it does not need to get diffuse from somewhere else.

Would this new material be combined with a blendMtl, or would it work more like a bumpMtl does, which has a "base" input for a VrayMtl? The later might be more intuitive. I can see a lot of people assuming that the material should be added to a blendMtl in "additive" mode which, if I understand correctly, would cause it to blend things incorrectly, overriding the material's transparency.

[instinct]

Well, there is also option C: have 2 spec lobes for the vrayMtl.

Given options A or B, I would also prefer B for the same reasons Dmitry gave. You might also consider calling it something like VrayClearcoatMtl or VrayCoatMtl. Those names seem more self-evident to me that they are intended to be used with an additive blendMtl than "VRayGlossyMtl" does.

I'd be fine with either of the two. Not sure if i prefer doubling parts of an existing material or making the UI of the VRayMtl more complex. I definitely do not want a second reflection layer in VRayMtl though.

Cheers,
Thorsten

[sharktacos]

I definitely do not want a second reflection layer in VRayMtl though.

Why is that Thorsten?

[Ihno]

I wouldn't call it option c because two of them are not enough. With the blend mtl we'd have unlimited.
I think I'd also prefare option b + bump map of course

One question for Vlado:
You have Beckmann brdf in the ALSurface MTL.
I'm wondering if this something which also exsists in the Vray MTL under a different name or is it different from what we already have?