.obj loaded Model materials are off

[Shane-oo]

• three version: 0.160.0
• @types/three version: 0.160.0
• three-stdlib version: 2.28.12

Problem description:

Materials loaded with the MTLLoader and OBJLoader are not the same as threes.js' loaders. Colours are different between the two. this is colours loaded with three.js mtl and obj loader:

and this is colours loaded with three-stdlib mtl and obj loader:

Suggested solution:

I believe we are missing the commit: https://github.com/mrdoob/three.js/commit/f49819bc21babf06c935f902f64629daab9f8ddc where colours are converted from SRGB to Linear. There might be something else but I believe this could be it.

Thank you!