Most of the choices were based off the ‘average’ of Epic example content, docs, and the majority of professional client work I’ve done across various studios. Epic doesn’t follow their own guidelines a good part of the time as well, often having meshes without a prefix, some with the S_ prefix, some with SM_, etc.
In places I found Epic to be inconsistent, I gave more weight to ‘what I’m used to seeing out in the world’. The goal is definitely not to introduce new radical concepts or change some paradigms, but to find a common base we can all speak.
In practice I found ‘metallic maps’ are extremely rare, as usually you push the value to 0 or 1. In things that require a combination of 0 and 1 values, this map is usually packed into a texture that contains other pieces of data for the sake of memory and performance. Packing a roughness, metallic, and any other single channel data together is definitely the way to go. It is unfortunate that many bulk texture services don’t pre-pack these channels for you. A packed texture might read something like T_CargoCrate_RMM, for ‘Roughness, Metallic, Mask’. It is true that packing a metallic channel and a mask channel together is somewhat ambiguous, however also in practice I’ve found metallic generally gets packed before mask, in the rare situation that both channels exist. If you require a metallic map, generally the metallic map also makes a great mask, unless you’re masking something seperately.
In any case, when it comes to the very technical nature of texture packing, the guide could definitely elaborate more on it. I plan to have a section specifically for textures in the future, but I’m hoping a tech artist who knows more about the subject would step up and help shell it out.
Also:
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