Layered material doesn't work properly

[danielsian]

Hello guys

I'm building an eye and I need to blend 2 different materials, as you can see attached.
So, the cornea (lens in front of iris) needs 100% refraction and the sclera (white part) needs a nice SSS.

I know, it's possible to build this eye without blend 2 materials, but the result is not nice like I need, so this workflow looks accurate and should work.

I put SSS in base material slot and a glass material in slot 1 and mask with Amount=1.

It doesn't work.

Anyone has any idea how to make this work?

Project files attached.

[romullus]

Are you trying to build the eye from single object? I'm affraid that's not the way you should do. Usually you need at least two objects, one for cornea and one for sclera. No need for layered materials here.

[danielsian]

As I said, I know it's possible to build an eye in different ways.
This workflow is the most accurate and give to me maximum control about everything.
I've been using this eye without SSS, so I'm not considering to change it.
I have 2 geometries, like in a real eye, 1 for the external shape (cornea+sclera), another one for the internal shape (iris).
Without SSS all I need to do is to use a gradient in refraction channel, so I have a soft transition from cornea to sclera with absolute control and ease animation BTW.
But it doesn't matter, I'm not discussing how to build an eye. This is not the point in my question.

It's impossible to keep everything in a single material due the nature of the SSS in Corona.
Sss is dependent of refraction/opacity, so I need to separate the building of this material  in 2 different materials and blend them using a mask.

In Physical renderer we just stack 2 materials without problems. Here, stacking with this purpose doesn't work, so we need a layered material.
I hope I'm being clear in my explanation.

My request is simple. I need to blend 2 materials (pure refraction and pure SSS) in a layered material.
Layered material isn't being useful in this case and I can't find another way.

Thanks

[danielsian]

Anyone?

[burnin]

I think you're missing the basic principle...

Maybe because C4D SSS is fake! (I haven't seen them integrate better since). It's simple model, surface kind of effect. Why often times even translucency is used to achieve more or better visuals. Even, if PhyR is used. 
But see it, to believe it. Check, if light lits objects on the other side of SSS. ;)

In Corona
SSS is 'proper' volumetric effect. Affecting volume as in whole.
Refraction is surface one. Affecting surface only. What you observe with Corona is  proper result :p

For your case then, simply disable Volumetrics channel and, as you noticed before, use Diffuse along with Translucency to get that impression of SSS light transport :) Play on, to get alike...




Or maybe i'm imagining things again... crazy mind.

[danielsian]

Thanks burnin for you time in replying to me. I really appreciate it.

I understand the phisically accurate principle in Corona, and because of that I'm not questioning why I can't use refraction and SSS in the same material.
In my mind, logically, a layered material should be the solution.
Like in photoshop, we mask layers to reveal what is under.
Looks like the layered material is unfinished, sometimes it has a strange behavior.
The slots inside it should be independent, but this is not what happen.
I understand the volumetric issues from SSS and the surface issues from refraction, but it seems we are ignoring the most basic principle of CGI. Everything is fake in this world.
And Corona calculates everything with precision, what is awesome, but should give some control to the artist take advantage of this fake world. This control means to use a layered material to mask 2 different  materials without problems.

[burnin]

It is layered. Based on your source. Those changes were made only on 'sclera' everything else is left untouched.

Layering from my limited tests, works properly. 

About your understanding...

Hmmm... i don't think you see clearly, thus don't fully understand neither the basic principles nor see the whole picture yet... What computer shading, light transportation is. Also, it seems to me, you're mixing 2D effect with 3D, and also surface shading model properties with volume shading model properties influencing each other as is in nature.

From my understanding... Here (within binary code) we are still mostly (happily) approximating what science finds as physically real and possible to simulate as light transportation with binary calculus. Thus we simplify and make such simulations possible and as plausible as they can be within our limited tech. Why surface shading model is different, a separated mathematical model than volume is.
While in reality Substance (pure or mixed elements) is the Volume and the Surface combined holistically intertwined and mostly defined by micro/nano/molecular/atomic structural pattern that photons collide within thus push each other further, from an atom to an atom... with the speed of light.

& again, of course, i could only be imagining it all... Thus I can only forgive. Hope you can too.

My advice: keep learning.

[danielsian]

Also, it seems to me, you're mixing 2D effect with 3D

I've used a terrible example.
I'm not mixing 2D with 3D, but just trying to explain in a simple way the separation between 2 different things using a mask.

As you said, the mixing is based on the base material, so everything makes sense.
I hope Corona can develop a different way to mix materials independently using simple masks.

Anyway, thanks again for your time!
Cheers