Hi!
I have a Renderman shader on which i’m reading a mesh int primvar ( using PxrPrimvar ) to switch between different textures.
This works nicely, but if i create a Relationship on my mesh instead of creating a primvar, it’s not working
Are there any limitations to this workflow?
Thanks a ton!
Hi @dietchmatch. I believe primvars must be attributes.
There is a mechanism which allows a primvar’s value to be delegated to a relationship by nesting an idFrom relationship within the primvar’s namespace. See Universal Scene Description: UsdGeomPrimvar Class Reference. Search for “Id attribute API” for more info.
checked, but not sure how to implement it 
and actually i don’t think it’s what i need.
Maybe the issue of not getting the value from the relationship lays in renderman and not in usd
having this works
which is actually a primvar called MAPS defined on the “geometry” prim and travelling down
but if set that via a relationship like this
on which i’m creating a relationship called primvars:MAPS pointing to a primvar that’s called MAPScoat_c_geo living on my geometry prim, it doesn’t
any hints on how to achieve something like that?
Thanks!
I think the short answer is “no”.
Creating a relationship with a “primvars” prefix is not “dereferenced” to pull the target primvar up to the prim that defines the relationship. It’s a cool idea, but nothing in the USD code or Hydra code makes this interpretation of relationships in the “primvars” namespace.
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Thanks a ton Mark!
i’ll try to have a primvar for getting the primvar name … a bit cumbersome i know but let’s try out