Texture/Material clarification for Ultra Engine

[reepblue]

Hello,

I'm currently having textures done with PBR in mind. There used to be a discussion about this years ago, but I can no longer find it.

What is the texture standard for merging the roughness, metal, AO, and emissive masks into one texture? If I recall correctly, I'm sure it went as follows.

R - Roughness
G - Metalness
B - Ambient Occlusion 
A - Emissive 

The artist is more familiar with MRAO(E)

R - Metalness
G - Roughness
B - Ambient Occlusion 
A - Emissive

If you want customers to simply be able to drag in any gltf they find on the web, how can/will the engine detect what channels are which since there doesn't seem to be a standard across the board. 

I'm also under the assumption that by changing the "emission" value in the json file, it would automatically multiply the color accordingly? 

[Josh]

I'm doing the same as glTF:
R: AO
G: roughness
B: metal

Emissive is a separate texture, because it's an RGB value.

[Josh]

I was thinking I might make a little utility that lets you drag textures onto their identity, like roughness, metal, etc., and then recombines and saves the textures.