[Tydra] MaterialBinding API

[syoyo]

Geom Prim(e.g. GeomMesh) has a materialBinding class variable, but its not enough just lookup it, since parent node(non Geom Prim, e.g. Xform) may contain materialBinding, which we need manually lookup from .props and do type check if it is defined as Relationship.

#39

We need handy materialBinding access API in Tydra.

MaterialBinding

https://graphics.pixar.com/usd/release/api/class_usd_shade_material_binding_a_p_i.html

API in Tydra may be something like:

tydra::GetMaterialBindingRelationship(const Stage &stage, const Prim &prim)

Expected behavior

• If given Prim has MaterialBinding(aldo do a check if MaterialBindingAPI is activated(authored)), return it
• If not, search parent Prim's MaterialBinding info
• Determine strength based on bindMaterialAs

Details

https://graphics.pixar.com/usd/release/wp_usdshade.html#material-resolve-determining-the-bound-material-for-any-geometry-prim

Discussion and Optional

• MaterialBinding could have multiple relationship target?
• Consider Collection API

[syoyo]

Initial MaterialBinding API now has been supported in Tydra(dev branch)