Python USD ModelLink is an Omniverse Extension that offers a library to easily develop kit applications. This library allows you to connect Python classes and OpenUSD Prims using decorators. Corresponding instances of the Python class are created as soon as a corresponding prim is added to the stage. The instance is also removed when the prim is deleted. Attributes can be easily observed. You can easily register for various events. Dependency Injection is also used to be able to use all common Omniverse/OpenUsd objects.

• Use Omniverse Extension Manager

The connection of Python classes and OpenUSD Prims are called link.

Import what you need, read the API Documentation for all possibilities.

from modellink import linked, on_update, usd_attr

Define which UsdSchema should be connected to your Python class ('Cube', in this case). Links can also be created without UsdSchema, see API documentation.

@linked('Cube')
class MyDevice:
    ...

If necessary, just have a few Omniverse or OpenUsd objects injected, e.g. the Stage.

Python USD ModelLink uses a library called 'Injector' for dependency injection. For more information see: https://pypi.org/project/injector/

    @inject
    def __init__(self, stage: Usd.Stage ) -> None:
        ...

Event decorators starting with 'on_' and in this example the 'update' event is used. So the name for the decorator is: 'on_update'.

    @on_update
    def update(self, prim: Usd.Prim):
        self.rot += 0.5
        setRotate(prim, Gf.Vec3f(0.0, self.rot, 0.0))

You can also simply observe Usd Prim attributes.

    @usd_attr('size')
    def attr_size_change(self, val: float):
        carb.log_info(f"attr_change .size={val}")

from injector import inject
from modellink import linked, on_update, usd_attr


@linked('Cube')
class MyDevice:

    @inject
    def __init__(self, stage: Usd.Stage ) -> None:
        carb.log_info("init called!")
        self._stage = stage
        self.rot = 0.0

    @on_update
    def update(self, prim: Usd.Prim):
        self.rot += 0.5
        setRotate(prim, Gf.Vec3f(0.0, self.rot, 0.0))

    @usd_attr('size')
    def attr_size_change(self, val: float):
        carb.log_info(f"attr_change .size={val}")

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