sheen and sheen tint
Forum rules
Please upload a testscene that allows developers to reproduce the problem, and attach some images.
Please upload a testscene that allows developers to reproduce the problem, and attach some images.
sheen and sheen tint
those two sliders on disney material don't do anything at all... do they?
Re: sheen and sheen tint
I also noticed this, in Cycles they give like the velvet effect.
Usually we need to force it more than 1.0, to 3 or 4, but I also noticed that in Lux it's capped at 1.0, depending on the effect it should give may be reasonable to remove that upper limit.
Usually we need to force it more than 1.0, to 3 or 4, but I also noticed that in Lux it's capped at 1.0, depending on the effect it should give may be reasonable to remove that upper limit.
Re: sheen and sheen tint
Well yes it should create a bit of backscatter effect for quick cheap cloth look but in luxcore it doesn't seem to do anything.
Re: sheen and sheen tint
Yes, I see the same, no effect at all in lux.
Re: sheen and sheen tint
hm. so it does seem to work, but very weak.
no sheen sheen
no sheen sheen
Re: sheen and sheen tint
Always refer the original Disney material to know how it is supposed to work:
If Lux doesn't work like that, it is a bug.
As you can see the expected Sheen behavior is a bit subtle but it is there.
If Lux doesn't work like that, it is a bug.
As you can see the expected Sheen behavior is a bit subtle but it is there.
Re: sheen and sheen tint
All Disney material parameters are, by design, between 0.0 and 1.0. It is the concept around which the material has been developed. If Cycles accepts values over 1.0, it is doing something different from the original Disney concept (and it may not be a good idea because Disney BRDF is now a de-facto industrial standard available across many applications).
Re: sheen and sheen tint
But we don’t have to loose sight that it was an artist driven BRDF, and even from Disney they say that some values can surpass the 1.0 limit to achieve different effects, like the specular one:
https://disney-animation.s3.amazonaws.c ... tes_v2.pdf
Sheen is not mentioned explicitly, but due to its behaviour it’s clear that for it to be useful in many situations we need to be able to push the 1.0 limit, that’s why in Cycles is not limited, to keep in mind that it’s not a "physics" shader, but an "artists" shader
This is from this document:The specular parameter may be pushed beyond one to reach higher ior values but should be done with caution.
https://disney-animation.s3.amazonaws.c ... tes_v2.pdf
Sheen is not mentioned explicitly, but due to its behaviour it’s clear that for it to be useful in many situations we need to be able to push the 1.0 limit, that’s why in Cycles is not limited, to keep in mind that it’s not a "physics" shader, but an "artists" shader
Re: sheen and sheen tint
You can't use values over 1.0 for Sheen, it would break energy conservation law (i.e. it would create light from nowhere). Check the code: https://github.com/LuxCoreRender/LuxCor ... y.cpp#L209juangea wrote: ↑Sat Jan 04, 2020 4:11 pm Sheen is not mentioned explicitly, but due to its behaviour it’s clear that for it to be useful in many situations we need to be able to push the 1.0 limit, that’s why in Cycles is not limited, to keep in mind that it’s not a "physics" shader, but an "artists" shader
Sheen parameter is used for a linear interpolation between 2 colors so if a value > 1.0 it will start to glow. It something can give you a lot of problems. As far as I remember, there was a thread on BlenderArtists about this problem
I could allow values > 1.0 and than clip, between 0.0 and 1.0, the result of the linear interpolation; this solution would not break energy conservation law and allow the user to force the result more toward the sheen tint
Re: sheen and sheen tint
That could be enough, in the end we just need some artistic control to give sheen more appearance, if it’s easy to implement maybe you can add it to a 2.3 build, we can test it and if it’s good enough it can stay, if it looks great it could just be removed