Utility functions to easily set some attributes on Maya nodes for Maya USD Export to use.

maya_usd_set_export_attributes_per_node.py

"""Utility functions to easily set some attributes on Maya nodes for Maya USD Export to use.

For example, make it easy to set the purpose, type or kind for the resulting USD Prims.

See Maya USD - Custom Attributes and Tagging for USD:
https://github.com/Autodesk/maya-usd/blob/dev/lib/mayaUsd/commands/Readme.md#custom-attributes-and-tagging-for-usd

"""
from __future__ import annotations
from maya import cmds
from typing import Literal, Union


def _setattr(node: str, attr: str, value: str):
    attr_exists = cmds.attributeQuery(attr, node=node, exists=True)
    plug = f"{node}.{attr}"
    if value is None:
        # Delete attribute
        if attr_exists:
            cmds.deleteAttr(plug)
        return
    
    if not attr_exists:
        cmds.addAttr(node, ln=attr, dt="string")
    cmds.setAttr(plug, value, type="string")


def set_usd_purpose(node, value: Literal["default", "render", "proxy", "guide", None]):
    """Set USD Purpose."""
    _setattr(node, "USD_ATTR_purpose", value)
    

def set_usd_kind(node, value: Union[str, None]):
    """Set USD Kind, e.g. 'component', 'assembly', etc."""
    _setattr(node, "USD_kind", value)
    

def set_usd_type_name(node, value: Union[str, None]):
    """Set USD Type Name, e.g. 'SkelRoot'"""
    _setattr(node, "USD_typeName", value)
    

def set_usd_subdivision_scheme(node, value: Literal["none", "bilinear", "catmullClark", "loop", None]):
    """Set USD Subdivision Scheme for meshes."""
    _setattr(node, "USD_ATTR_subdivisionScheme", value)
    

def set_usd_facevarying_linear_interpolation(node, value: Literal["none", "cornersOnly", "cornersPlus1", "cornersPlus2", "boundaries", "all", None]):
    """Set USD Face-Varying Interpolation rule for mesh texture mapping/shading purposes."""
    _setattr(node, "USD_ATTR_faceVaryingLinearInterpolation", value)
    

# Example usage:
# Apply to current selection
for node in cmds.ls(sl=1):
    set_usd_purpose(node, "proxy")
    # set_usd_subdivision_scheme(node, "none")