Update glTF specific shader

[sbtron]

Current one doesn't work on Android and was stripped out.
Need to figure out a better solution.

[AurL]

@sbtron I wonder what's the purpose of using a specific glTF shader instead of the Unity's Standard one ?
The only reason I have in mind is that it doesn't require any image processing (unpacking/repacking)
I guess it could fix this issue ?

Also, just to let you know, we are working on a "Design-time import of glTF 2.0 files" from this project and I guess it could be a good contribution, as we are facing and solving a few of the issues. I just don't know a lot yet about the rules and how our choices/solutions are ok with the rest of the plugin.

[bghgary]

doesn't require any image processing (unpacking/repacking)

It's more than that. Unity doesn't multiply the colors against the texture where as glTF does. Unity doesn't support texture coordinate sets where as glTF does. I think we need to think about supporting both.

[AurL]

Ok thanks @bghgary . +1 for the texture coordinate sets (but colors are multiplied against texture if I'm right).
Anyway, yes it would makes sense to support both 👍

[bghgary]

colors are multiplied against texture if I'm right

Sorry, yeah, it is multiplied if there is a color in addition to texture, but some properties don't behave this way. For example, metallic factor in glTF is not representable in Unity's standard material if metallic texture is also specified. Another example is for the spec-gloss extension where Unity expects only one of specular color or texture but not both.

[stevenvergenz]

This is done.