Solved Trouble with Material Mask aka ColorID | PrismaticaDev Learning Hub | Page 1

south dock Oct 8, 2022, 2:31 PM

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Hello, I'm trying to make a modular character system using techniques described in "Reducing Draw Calls in Unreal!" and "Unlimited Customization" video.

In the Unlimited Customization video, PrismaticaDev describes using a texture with Blue Channel as a mask. By painting only using values of 1, .5, and 0. He was able to get those 3 values and give a color to each individual one. I'm trying to do the same. I've managed to id the 0 and 1 value, but .5 value is causing issues.

I've made a texture for testing. Sectioned off the texture into 0, .5 and 1 and in blue channel in Blender.
I then imported it into unreal, and here's next picture is the result. I can't seem to escape aliasing I believe? I tried using a if node too and has the same problem.

bleak shard Oct 8, 2022, 3:28 PM

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south dock Hello, I'm trying to make a modular character system using techniques described ...

Correcto - that's one of the limitations. You'll need to use 0.5 as your "neutral" colour and then 0 and 1 cannot be next to one another

south dock Oct 8, 2022, 4:13 PM

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Thankyou for the response, looking at the video again I see the texture work, and I understand what you mean.
White and black are intentionally separated.

bleak shard Oct 8, 2022, 4:32 PM

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Yep yep - it's something that it really handy since it can maintain gradients as well. Works great with vertex colour so you can get 8 channels instead of 4

south dock Oct 8, 2022, 6:51 PM

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Solved Trouble with Material Mask aka ColorID

heady hull Oct 9, 2022, 3:44 PM

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@south dock also consider if blender is painting in sRGB color it'll.be applying a gamma curve

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Is 0.5 will actually be like .2 something

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What Charlie is talking about is the Fringe issue you get if you're not doing a strict threshold and have values that straddle the masks

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So it think to avoid that you have to have each mask be contiguous with it's neighbor

south dock Oct 9, 2022, 4:07 PM

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heady hull Is 0.5 will actually be like .2 something

Yeah I i used the color picker and it said my gray value was that.
Thats the number unreal read. I thought I used .5

heady hull Oct 9, 2022, 4:08 PM

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So if you run into resolution issues with 8 bit textures

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you could probably operate with a 32 bit texture inside Blender

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so it should save it as the exact value

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Then in theory you can use unreal engine or other software to convert it to a linear 8-bit format without gamma correction

south dock Oct 9, 2022, 4:24 PM

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I think on texture sample you can Remove "srpg" from import settings. it didn't change anything

heady hull Oct 9, 2022, 4:26 PM

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yeah you need to author it in linear

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https://developer.blender.org/T88646

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Blender is confusing when working with linear vs gamma corrected colors

south dock Oct 9, 2022, 4:42 PM

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I'm going to be honest, this is over my knowledge. I don't really know much about digital art.

heady hull Oct 9, 2022, 4:45 PM

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okay TLDR

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8 bit data can only store 255 values of brightness

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our eyes are very sensitive to the darker values than the brighter values (IIRC)

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So what we do for data our eyes will see, is we store more data in the darker colors and less data in the brighter colors .

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https://en.wikipedia.org/wiki/Gamma_correction

Gamma correction

Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression:

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SOO

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what this means is

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when you display sRGB stuff as linear they tend to look blown out and too bright

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so there has to be an agreement with how the data is stored and how it's displayed

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this is why in blender and in UE you tell it if it's sRGB and linear color texture

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because if it's a sRGB data you'll apply the gamma correction, if it's linear you won't apply a correction

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this is why applying sRGB correction to a normal map breaks it.

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Because with DATA , every part of the data is important

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so with linear data, it's a 1:1 relationship and you just accept the precision loss across the whole range

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So

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a value of 0.5 in linear is stored as 0.5

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I think a value of 0.5 is stored as 0.72974005284072309792068324784902 and then gamma corrected back down to 0.5

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so when dealing with 16-32 bit colors I don't think it does this

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but when dealing with 8 bit colors it does.

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So at the end of the day it depends when you paint a texture with a brightness of 0.5

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sorry this is too complex

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Basically What is visually correct for our eyeballs isn't mathmatically correct for a computer

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so with 8-bit data computers have developed two different systems for storing data depending on if the data is designed to read by a computer or viewed by a human

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and since texture painting is traditionally designed to be read by a human it's often not set up for storing it as computer math data, unless it's a specialty program like substance painter which is set up to say paint height map data as linear data.

#Solved Trouble with Material Mask aka ColorID