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Shading Model - Cloth, Opacity Not Work

Hi. Sorry for the my little English.

I try to make Cloth material. Shading model has Opacity and Opacity Mask. Therefore i want to use Opacity, but for me something work wrong. See below screenshot.

Light Pink parts must have some opacity, but don't work. Opacity works for me if i change blend mode to traslucent but this wil be another material.

Why opacity doesn't work with Shading Model - Cloth? May be i did something wrong.

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Product Version: UE 4.17
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asked Sep 14 '17 at 07:57 AM in Using UE4

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The shading model is, as far as I know, only responsible for calculating how the material influences any light that hits it; it doesn't have to do with transparency.

Unfortunately, the masked mode can only make parts visible or invisible and ignores everything inbetween. If you need something visible for only 50% (or any other value but 100% or 0%), you are pretty much limited to the translucent material mode (and additive, if I'm not mistaken, but I reckon you are not looking for a glowing dress). I remember reading somewhere the reason for the limited functionality of the masked mode had to do with the deferred renderer they are using in UE4.

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answered Sep 14 '17 at 08:28 AM

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avatar image Luciferium Sep 14 '17 at 10:40 AM

Yep, i want to have value different from 0% and 100%. I understand what "Opacity Masked" get only value 0% or 100%. But i don't look on "Opacity Masked". I try to use "Opacity". I use Blend Mode - Masked just becouse see it in example content.

But even if i change Blend Mode - Masked to Opaque (default mode), Opacity still active, it mean what i can use him, in any case i don't know for what there need Opacity.

"Opacity" activate by "Shading Model - Cloth".

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avatar image cridia Sep 14 '17 at 10:58 AM

As long as the blend mode is not translucent or additive, it simply won't give you the result you want. Normally, opacity mask is for either 0 or 100% visible values and opacity supports anything in between. However, according to the documentation in subsurface based models, opacity will instead be used do determine how much light can scatter through the surface. While the documentation on shading models is outdated, considering how you said that opacity appears when selecting the cloth model, I'm going to assume that cloth is also a subsurface like shading model.

in other words, as long as you don't select translucent as your blend mode, the function of opacity will be different and won't give you what you want.

avatar image Luciferium Sep 14 '17 at 01:30 PM

Very sad it hear. But i believe, what people find some solution. May be i just make something wrong. Because cloth this "skinning mesh". I can't always separate it's how I want.

Two separate mesh, it definitely bad solution i think.

How cloth can be "Shading Model - Translucent", it's very different shading model. Ofcourse I understand cloth has some translucent effect in real life, but inside UE translucent work only how truly translucent material. "Shading Model - Translucent" deactivate Metallic / Specular / Roughness / Normal, this is unacceptable for clothes, I think.

I can use "Translucent" but it incorrect. Need to do many material tweaks. And in final result i can't back Metallic / Specular / Roughness / Normal channels.

Also, I still not understand why Shading Model - Cloth activate Opacity channel if I can't use him?

I try to wait on more variants.

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avatar image cridia Sep 14 '17 at 01:48 PM

A simple solution (albeit with a bit of extra work) to your problem is setting up your mesh to have multiple materials. You can find more info on this in the UE4 documentation (or search for multiple materials on one mesh). This way, you don't have to split the mesh and can still have both translucent as well as opaque materials on one mesh. Did the same with my character; since the skin needed subsurface whereas the rest didn't. I changed this after having rigged and animated the thing so it should be possible. Since you won't be changing the uv for this, you won't even need to change the texture. Just assign an extra material ID in your 3D software.

Furthermore, when setting the mode to translucent there should be additional options somewhere to enable roughness and so on as well. By default it is off, but the setting is there under a separate translucency group if I remember correctly.

avatar image Luciferium Sep 15 '17 at 09:39 AM

I know about material ID and I said about it above.

How you can change material ID without change topology in my case. My mesh topology doesn't match the texture. See screenshots below.

You talk about "Translucent - Lighting Mode", it doesn't help me. Only "Surface ForwardShading" and "Surface TranslucencyVolume" can activate channels what was dieactivated before. But these two mode work correctly only for glass / water.

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