The plugin doesn't work if physics are running on a separate thread.

[dexmoh]

I've noticed that the plugin doesn't work and throws an error on line 399 in plugin.gd if physics/3d/run_on_separate_thread is enabled in project settings. I'm assuming this is because the plugin is trying to raycast outside of physics process.

This isn't such a big deal since you can just disable running physics on a separate thread while using the plugin, but I thought it would be worth reporting.

Godot version: 4.5 (but probably the same issue on other versions too)

[Dev-Marco]

Thanks for the hint. Gonna look into it asap.

[Dev-Marco]

Hi again, and sorry for the long delay.

After some investigation, I was able to identify the root cause of the issue and work out a solution. The problem was that World3D.direct_space_state is not accessible when the physics/3d/run_on_separate_thread setting is enabled. This limitation is explicitly mentioned in the World3D documentation:

Note

[...] When using multi-threaded physics, access is limited to Node._physics_process() in the main thread.

Because reliably reproducing the existing behavior with physics-based colliders under these constraints would have been difficult, I decided to take an alternative approach that turned out to be more robust overall. Previously, placing the 3D cursor via Shift + Right Click required the target object to have a collider. The new system instead performs raycasts against mesh geometry, making it independent of the physics system and therefore fully compatible with physics/3d/run_on_separate_thread.

At this stage, I’ve disabled the old collider-based mechanism rather than removing it entirely. My plan is to introduce a proper settings panel in the future, allowing users to choose which method they prefer, with the new mesh-based approach being the default.

The current working implementation can be found in this commit: 476a010 on the branch wip/3-multi-threaded-physics. It will be merged into main once I’ve finished the documentation and some minor refactoring.

As a small side note, I’m also planning to switch the license from MIT to ISC. Functionally, this changes nothing for users; the ISC license is simply a bit more concise and easier to read.

Once the changes are merged into main, I’ll close this issue.

Thank you again for using the plugin — I hope this makes it even more useful for your workflow.

Kind regards,
Marco