Feature request: V-ray cloth/fabric material

[sharktacos]

There is currently not a compiled version for Maya on Github. However, I bet if you asked them nicely they could get you one.

[TheScope]

Thanks for the reply. I managed to compile one for Maya 2017 and 2018 myself by now. Actually not that hard with the instructions from the repo.

[sharktacos]

out of curiosity, is the alpha attribute exposed in the version you compiled?

[TheScope]

No, there is no alpha attribute available.

[CCOVIZ]

Hey guys !

A good cloth shader is indeed very welcome! I think this shader is a good starting point. Being able to generate our own patterns is extremely useful! But this approach still lacks a few things to create realistic cloth appearance, especially in close up :

_this is limited to woven pattern (so no knitting pattern generation)
_No fiber scattering at grazing angles
_No fiber details on close-up

There are a lot of papers that solve these issues and I have to say that what researchers manage to do these days is really impressive !

Here is an example model for knitted yarn generation :

https://www.cs.cornell.edu/projects/...itchmeshes.pdf

There are a tremendous amount of papers on the subject but i'd like to share these two with you, which are imho the most impressive: THIS IS FULL PROCEDURAL

https://shuangz.com/projects/procyar...cyarn-sg16.pdf

https://shuangz.com/projects/procclo...oth-egsr17.pdf

Some results :

[joconnell]

Thanks for the reply. I managed to compile one for Maya 2017 and 2018 myself by now. Actually not that hard with the instructions from the repo.

Heya Florian!

Have you got a link to those instructions? I've no idea how Git works and I don't do c++ yet but I've gotta jump in at some point!

[CCOVIZ]

Heya Florian!

Have you got a link to those instructions? I've no idea how Git works and I don't do c++ yet but I've gotta jump in at some point!

Hey!

Detailed instruction on this page : https://github.com/Thunderloom/Thund...tends/vraymaya

[sharktacos]

Heya Florian!

Have you got a link to those instructions? I've no idea how Git works and I don't do c++ yet but I've gotta jump in at some point!

John,
There are also compiled versions on Github now for Maya under the releases section:
https://github.com/Thunderloom/ThunderLoom/releases

If you need a complied install for VrayNext, you can get it here:
https://github.com/Thunderloom/Thund...ya2018_v01.zip

[sharktacos]

_this is limited to woven pattern (so no knitting pattern generation)
_No fiber scattering at grazing angles
_No fiber details on close-up

CCOVIZ,

1) It is possible to get knit fabrics by rotating the UVs on the Thunderloom shader 45 degrees. I have illustrated this approach here:
https://docs.sharktacos.com/texture/fabricShader.html

here's a pic of the results for a knit cotton shirt:
https://docs.sharktacos.com/images/t...knitShirtB.png

2) Grazing angle effects can be simulated by inputting a vrayFalloff texture into the diffuse color. This is essentially the same as the sheen parameter on many BRDF shaders. This is a phenomilogical rather than physically based approach, but it allows for a lot of artistic control, including being able to darken at grazing angles (like denim does), rather than lighten (as velvet does).

3) It is true that this shader does not work in closeup, but to be fair it should be clarified that that "close-up" here does not mean close-up photos, but macro photography. In other words, the level of detail that you can get with the Thunderloom shader is detailed enough to see what you could with the naked eye, but not enough to see what you would with a magnifying glass. Then again, a BRDF shader of something like plastic does not give you that kind of macro detail either, but instead gives a physically based surface approximation at normal/typical viewing distances.

That's not to say there are not things in the shader that could be improved upon. For example I would like to see it work with bump maps in order to get subtle wrinkling. Currently the guys writing the shader are working on using multiple scattering in the shader calculated for each fabric fiber, which will allow the shader to calulate Fresnel and the resulting R (primary spec) and TRT (secondary spec) for each fiber, rather than for the whole object.

[CCOVIZ]

CCOVIZ,

1) It is possible to get knit fabrics by rotating the UVs on the Thunderloom shader 45 degrees. I have illustrated this approach here:
https://docs.sharktacos.com/texture/fabricShader.html

here's a pic of the results for a knit cotton shirt:
https://docs.sharktacos.com/images/t...knitShirtB.png

2) Grazing angle effects can be simulated by inputting a vrayFalloff texture into the diffuse color. This is essentially the same as the sheen parameter on many BRDF shaders. This is a phenomilogical rather than physically based approach, but it allows for a lot of artistic control, including being able to darken at grazing angles (like denim does), rather than lighten (as velvet does).

3) It is true that this shader does not work in closeup, but to be fair it should be clarified that that "close-up" here does not mean close-up photos, but macro photography. In other words, the level of detail that you can get with the Thunderloom shader is detailed enough to see what you could with the naked eye, but not enough to see what you would with a magnifying glass. Then again, a BRDF shader of something like plastic does not give you that kind of macro detail either, but instead gives a physically based surface approximation at normal/typical viewing distances.

That's not to say there are not things in the shader that could be improved upon. For example I would like to see it work with bump maps in order to get subtle wrinkling. Currently the guys writing the shader are working on using multiple scattering in the shader calculated for each fabric fiber, which will allow the shader to calulate Fresnel and the resulting R (primary spec) and TRT (secondary spec) for each fiber, rather than for the whole object.

Hey, thanks for your feedback.

1) Well, you can fake it that way for sure but that's still a woven pattern. It will work for small patterns like in your example but definitely not for big knitted fabric.


2-3) There is a debate here. I use to work on high-res archviz renders on my side and I'm pretty sure the thunderloom shader will quickly show its limits (assumption here, I compiled it for Vray next for 3ds max and it does not seems to work sadly). No need to go macro IMHO, render a 6-8k shot near a sofa and you'll have plenty of details. What's more, with fiber model, you get thickness from thin geometry so welcome SSS! Ans no need to scatter fiber geometry anymore, which is really memory intensive. But yeah you have to trade artistic control over physical accuracy, I can't deny that.

"Currently the guys writing the shader are working on using multiple scattering in the shader calculated for each fabric fiber, which will allow the shader to calulate Fresnel and the resulting R (primary spec) and TRT (secondary spec) for each fiber, rather than for the whole object."

That's neat!!!

[joconnell]

Thanks for the links guys, reading this now!

[CCOVIZ]

Sharktacos,

I've read your google doc and it's very informative thank you! Finally, we're not really far from the paper I've posted, the thunderloom shader is building a yarn structure too, the only missing part is the procedural fiber generation. My most wanted feature is the flyaway fibers that create fuzziness TBH. I know you can fake it with a fallof map but that definitely does not look near as good. Just look at what those guys are able to produce with Fstorm Geopattern (similar to Vraypattern) :

Don't you think it would be awesome to keep the ease of use and the procedural nature of the thunderloom shader while being able to bring real fiber fuzziness to it? (A scatter program is still way too memory hungry for those densities)

[sharktacos]

Yes, it certainly would be better. My concern is that currently no commercially available renderer has a fabric shader. So as an artist I'd like to have a shader now, even if it is not perfect, rather than waiting for the perfect and having nothing in the meantime, if that makes sense. :^)

[sharktacos]

Regarding the above image, this appears not to be a fabric shader, but rather a way to instance geometry for the yarn fibers, similar to using displacement. It's very cool, but I don't think it replaces the need for a fabric shader.

[CCOVIZ]

Regarding the above image, this appears not to be a fabric shader, but rather a way to instance geometry for the yarn fibers, similar to using displacement. It's very cool, but I don't think it replaces the need for a fabric shader.

I totally agree, it won't replace a cloth shader at all, it's way less convenient. It is basically a piece of geometry scattered over the base mesh while keeping continuity between patches :




It looks good but you have to model it by hand (fastidious and time consuming, even more if you want to modify it afterward) and you'll still see some tiling under certain lighting condition. The whole point here was just to highlight the fact that real fiber fuzziness gives far far superior results

My concern is that currently no commercially available renderer has a fabric shader. So as an artist I'd like to have a shader now, even if it is not perfect, rather than waiting for the perfect and having nothing in the meantime, if that makes sense.

Yeah, I totally agree here too. I'm absolutely not blaming you for using this, it's better than nothing indeed (I actually wish I could too, but my build is not working properly on Vray next for 3ds). I just read elsewhere that devs planned to include the tunderloom shader in a future release. The real question is, rather than implementing a tech that does half of the job, isn't it time to consider a more advanced implementation, considering the recent progress in that regard? The whole point of my intervention here is to give those researches a bit more visibility and to raise some voices to push those arguments a bit