Support V2 of PhysicallyBased Materials

[kwokcb]

Tasks

Direct Translation Equilvalence

Goal: Produce the functionally equivalent MTLX materials as V1 but parsed V2 data.
Assumption: All colors are linear (lin_rec709)
Completion : Done

• Uses linear input colors parsed from new JSON color structures
• Enforce usage of proper specular color format for glTF, OpenPBR and StandardSurface
• Generate new translated materials

Custom Definition + Translators

Goal: Produce a new V2 definition and equivalent V2 translators
Completion: Some remapping for V2 format color has been done.

• Finish new nodedef and translators.
• Issue: There is no versioning for translators so may need a new nodedef id
• Issue: TBD if translators will inject colorspace shader nodes during shader generation. This can be tested without dependence on PB.
• Issue: Handling of different colorspaces (see below)
• Issue: Handling of different types using same input semantic / name

Colorspace Handling

• Produce MTLX variants which use different colorspaces other than linear.

Web Handling

• Port to JS for interactive site.
• TBD: Should allow both V1 and V2 as input ?