Fresnel in Unity 5 unified shader?

Hello! I'm really looking forward to the unified PBR shader in Unity 5. Currently using marmoset.
I've watched most videos I have found from Unite, but I haven't heard anything about fresnel. Maybe I've missed it, in that case I'm sorry.

So, how does the unified shader handle fresnel input? Can't see it in the inspector properties for the material using the unified shader. Of course I could extend the shader with my own fresnel calculations (if the shader source is given to us), but it would be weird if the standard one didn't have this. Fresnel is a key component in PBR shading in my opinion, and omitting it would prevent us from creating real world materials correctly.

 

Almost all dielectric materials share the same very small range of Fresnel values (about 0.04, I think, in linear space).

So, generally it's easier to just hard code this value into the shader, only metals and some gemstones really need specific Fresnel values, and generally you won't notice it much if you use the values of 0.04 and something above a half for all dielectrics/metals, respectively.

 

I don't really get your answer. Yes, fresnel isn't extremely varied for non-metals (but it is definitely varied), and as you say metals vary. And how do you tell the unified shader that something is a metal, and needs a very different fresnel compared to a plastic, for example? Does the specularity color paramter automatically tune the fresnel value? Is there a metallic-slider (I haven't seen one). At our company we don't create games; we create very realistic representations of real-life objects, which means a flat value doesn't cover it in any way.

Examples of non-metals with highly varying fresnel are wood, porcelain and plastic. And the fresnel of these materials are waaay different than fresnel of chrome or steel.

 

Generally, the standard these days is to have a metalness mask. Where it's 1, the albedo texture defined the specular value of metals (their diffuse is pure black, anyway, being metals). Where it's 0 you get a regular dielectric material where the albedo texture controls the diffuse colour (as most dielectric materials don't have coloured specular reflections, therefore don't need a specular colour value).

 

Ok, this makes sense.
I'm a bit lost now however, because it really seems that there are conflicting ideas on how to work with PBR, even within the different workflows (albedo+spec/metalness).
For example, I'm trying out DDO right now. And pretty much all sample dialectric materials have specular color, and not tiny amounts either. For example a sample wood material, which has a specular map that is pretty much equal to the gloss map. Same with how Marmoset seems to handle this (having a fresnel slider also).

Aras, have you tried DDO with Unity 5? Any hints on getting it right?

Also, say that I'm creating a wood material. The albedo map determines the color; should be some kind of brown normally. The gloss map determins if there are rougher and smoother areas in the wood. The specular map should be all black right (read: not use a specular map, use black color)?

Also, the smoothness-parameter in the Unity 5 unified shader; can it be controlled with alpha in the specular map? There are certain hints that can be interpreted this way, but I'm not 100% sure. If that's the case, what does the alpha value of the specular color do? The same as the slider or nothing or something completely different?

Thanks

 

@Horp1 i remember i saw a video of someone using Ddo with unity 5 on youtube and it works fine , btw , if you watched the video (mastering PBS that aras linked) , he clearly says that the gloss (aka smoothness) is the alpha of the specular map

 

I watched that video 2 times and didn't hear him say that. Must have missed it somehow. Then how about specular color alpha? Is it ignored?

 

Well , because the smoothness slider exists i assume it's ignored.

 

Here´s the reason why I would like to see fresnel controls in Unitys standard shader:


Try to get a similar result with the standard shader - its simply impossible.

 

That is how it is usually implemented, but in reality the index of refraction is a complex number that varies with wavelength. (Where the complex part is the absorption k, which is only nonzero for metals.) So for metals it can actually be quite different:



Supplying a 1D texture with the fresnel color can still be very useful even in 2016. And not just for mobile devices. Besides specific fresnel lookups for metals, there is also thin film reflection:


And it would also help Carsten above. (Hi there, long time no see.) A 1D fresnel texture could be a nice addition to the standard shader.

 

The metallic value in this case should be 0, not 1. Metallic set to 1 means the reflections are multiplied by the diffuse color, which since it's black is dulling them out.

 

I tried with the UnityStandard shader to get as close to the Shaderforge look as possible.
However, you can play with Standard vs Metallic and the diffuse/gloss values as long as you want - you´ll not get a comparable result (try attachment).

Sorry - until now nobody convinced me saying "Fresnel controls are not necessary".

 

Just found the full fresnel formula that includes absorption again:



And remember that both n and k typically vary with wavelength for metals. So for non-metals I think the typical approximation is absolutely fine, but for metals (and even more for thin films) the option to use a 1D fresnel texture can really offer a lot more realism.

 

Ah, now I see clearly what to do !