Set the Value of an Attribute

In Omniverse, you can use the ChangeProperty command to set the default value or timesample value of an Attribute. With the USD API, you can call Usd.Attribute.Set() to set a default value or timesample value.

USD Python

from pxr import Usd, Sdf, Gf

def set_float_attribute(attr: Usd.Attribute, value: float) -> None:
    """
    See: https://openusd.org/release/api/class_usd_attribute.html
    Args:
        attr: The attribute to set.
        value: A floating point value, i.e. `3.141516`.
    """
    attr.Set(value)

def set_vector_attribute(attr: Usd.Attribute, value: Gf.Vec3f) -> None:
    """
    Args:
        attr: The attribute to set.
        value: A floating point vector, i.e. `(1., 2., 3.)`.
    """
    attr.Set(value)

You can also set a timesample value at a particular time:

from pxr import Usd, Sdf, Gf

def set_float_attribute_at_time(attr: Usd.Attribute, value: float, time_value: float) -> None:
    """
    See: https://openusd.org/release/api/class_usd_attribute.html
    Args:
        attr: The attribute to set.
        value: A floating point value, i.e. `3.141516`.
        time_value: Set a timesample at a particular time.
    """
    attr.Set(value, time_value)

def set_vector_attribute_at_time(attr: Usd.Attribute, value: Gf.Vec3f, time_value: float) -> None:
    """
    Args:
        attr: The attribute to set.
        value: A floating point vector, i.e. `(1., 2., 3.)`.
        time_value: Set a timesample at a particular time.
    """
    attr.Set(value, time_value)

Python Kit Commands

The ChangeProperty command allows users to undo the operation, but you must provide the value to use during the undo operation as the prev parameter.

import omni.kit.commands
from pxr import Gf, Sdf, Usd

prim_path = Sdf.Path("/World/defaultLight")
prim: Usd.Prim = stage.GetPrimAtPath(prim_path)
prop_name = "xformOp:rotateXYZ"
rotation = prim.GetAttribute(prop_name)
omni.kit.commands.execute("ChangeProperty",
    prop_path=Sdf.Path(prim_path.AppendProperty(prop_name)),
    value=Gf.Vec3d(180.0, 0.0, 0.0),
    prev=rotation.Get()
)

You can also set a timesample value at a particular time:

import omni.kit.commands
from pxr import Gf, Sdf, Usd

prim_path = Sdf.Path("/World/defaultLight")
prim: Usd.Prim = stage.GetPrimAtPath(prim_path)
prop_name = "xformOp:rotateXYZ"
rotation = prim.GetAttribute(prop_name)
omni.kit.commands.execute("ChangeProperty",
    prop_path=Sdf.Path(prim_path.AppendProperty(prop_name)),
    value=Gf.Vec3d(180.0, 0.0, 0.0),
    prev=rotation.Get(10.0),
    timecode=Usd.TimeCode(10.0)
)