Resetting world changes collider

Omniverse Isaac Sim
1

Isaac Sim Version

4.5.0
4.2.0
4.1.0
4.0.0
4.5.0
2023.1.1
2023.1.0-hotfix.1
Other (please specify):

Operating System

Ubuntu 22.04
Ubuntu 20.04
Windows 11
Windows 10
Other (please specify): Ubuntu 24.04

Topic Description

I use a custom extension to debug my code in IsaacSim*. My workflow is

  1. Open a stage that I want to work with
  2. Open my “debug extension” that runs code to actuate an Articulation in the stage
  3. Execute that code via my custom extension
  4. Debug/adapt the code, reset my extension, do it all over again

The code I use to reset the stage is inspired by all the Example Extension provided and is the following:

    def _on_reset(self):
        asyncio.ensure_future(self._on_reset_async())

    async def _on_reset_async(self):
        self._stage = omni.usd.get_context().get_stage()
        self._world.clear_all_callbacks()
        self.scene.clear(registry_only=True)
        await self._world.play_async()
        await update_stage_async()
        await self._world.reset_async()
        await self._world.pause_async()
        await omni.kit.app.get_app().next_update_async()

At first sight, this looks fine – the simulation stops, the objects move back to their initial position etc. However, there is a mesh in the scene I am currently working on which I want to assign a triangle-mesh collider to. I used the physics toolbar → Set Static Collider functionality to do so. The collision behavior of this particular body changes with my reset, and I have no idea why (see below). Further, the collider debug view does not show any changes - it seems to be out of sync with the actual simulation.

Detailed Description

This is the stage after some time steps. The collision works as expected:

image
image498×388 75.2 KB

This is the stage after some time steps after resetting my extension. The “fingers” are in collision with the blue object here. The blue body collider is shown as a meshcollider, but behaves like a convex decomposition/overapproximation:

image
image498×388 82 KB

Steps to Reproduce

  1. Load stage
  2. Reset via the extension reset method
  3. Collision behavior changes

For completeness, I have attached the stage I am working on.
stage.zip (7.3 KB)

Logs

The logs already give a reason for this behavior: PhysicsUSD: Parse collision - triangle mesh collision (approximation None/MeshSimplification) cannot be a part of a dynamic body, falling back to convexHull approximation: /World/doublepipe/doublepipe/mesh13. For dynamic collision please use approximations: convex hull, convex decomposition, box, sphere or SDF approximation. However, I did not find any information about how to make this body non-dynamic? It doesn’t move in my simulation, it doesn’t have physics attributes except for the collider, and I get the same error message even when I right click -> lock it.

*Side question: Debugging over a custom extension for every new feature is really tedious but still faster than starting a new IsaacSim App every time I fix a minor bug in my code. Is there really not better option for debugging in IsaacSim?