What does "Mask" in HDRP -> LitShader -> Mask Map mean?

Unity Engine
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1

Hello!

At first I thought that “Mask” was formed by the maps (“M” for metallic, “A” for “Ambient Occlusion”, “S” for smoothness, etc.), but I guess that is not the case.

Can somebody please explain why exactely it’s called a “Mask map” and not simply a “map”?
What are we masking here?

Thank you very much!!

2

It does all those things you mentioned. From https://docs.unity3d.com/Packages/com.unity.render-pipelines.high-definition@6.7/manual/Lit-Shader.html#surface-inputs:

"Mask Map

Assign a Texture that packs different Material maps into each of its RGBA channels.
• Red: Stores the metallic map.
• Green: Stores the ambient occlusion map.
• Blue: Stores the detail mask map.
• Alpha: Stores the smoothness map."

Basically this is channel packed texture that holds said maps and actual mask name comes because it also holds detail mask in the blue channel.

Detail mask just indicates the parts that get included in the detail texturing (see detail map on the same doc).

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