Cannot write to joint attribute using Python

I am trying to set up a joint programmatically. Steps to reproduce:

  1. Open a blank scene in Isaac Sim 2022.2.0.
  2. Open the Script Editor
  3. Run the following script
from pxr import Gf, UsdGeom, UsdPhysics
import omni

stage = omni.usd.get_context().get_stage()

body0 = UsdGeom.Xform.Define(stage, "/World/Body0")
body0.AddTranslateOp().Set(Gf.Vec3d(1, 2, 3))
body1 = UsdGeom.Xform.Define(stage, "/World/Body1")
body1.AddTranslateOp().Set(Gf.Vec3d(4, 5, 6))
joint = UsdPhysics.RevoluteJoint.Define(stage, "/World/Joint")
joint.GetLocalPos0Attr().Set(Gf.Vec3d(0, 0, 0))
joint.GetLocalPos1Attr().Set(Gf.Vec3d(0, 0, 0))

Expected result: The local positions should be reset to (0, 0, 0)
Actual result: The positons are set to (3, 3, 3) and (-3, -3, -3). It seems the last two statements had no effect.

Thanks for any help!

could it be that you are trying to pass in Gf.Vec3d, should be Gf.Vec3f.

I changed the last two lines and replaced Gf.Vec3d by Gf.Vec3f, but that does not change anything in the result.

This is really strange… I hope to find a workaround.

What I found though is that I can change that properties when I open another python tab and enter this:

But this does not help, because I need to create and change the joint from within the same script.

Edit: It also works when I run these commands from the original Python tab. It seems something important is happening after the script exits.

I did identified the issue, will fix it for the next release, sorry about the trouble.


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