Hello all, I am designing a system which uses the Babylon Physics Constraints system. I want to provide the user to ability to specify exactly which rotation axis two bodies are connected, which means that I don’t know this axis at compile time neither can I guarantee that it isn’t a custom axis (n…

Hey, thanks for the report. Indeed, when setting targets on an angular position motor, we were using those targets as the relative orientation between the bodies, instead of the orientation in constraint space. Will get this fixed in a WASM update, so keep an eye out for @babylonjs/havok version 1.3…

Would that be the expected behavior? Babylon.js Playground Babylon.js playground is a live editor for Babylon.js WebGL and WebGPU 3D scenes

Your example works because you know that the axis that the joint should rotate is the Y-axis, so it is as expected. In my application however, this axis is not static. the axis of rotation of the joint is a user-input so i need to be able to reassign this axis (for example to (1, 1, 0)). I underst…

It does seem to be an internal issue in the havok package, which we can’t directly change. I played around with it, and you are right - i would expect it to work. If it’s ok with you, I will wait for @Cedric to confirm and then will see how we can solve this.

Hello everyone! Did anyone find a fix for this issue? I am having the same problem on my application.

Sorry, I was busy. I’ll take a look asap.

Physics Motor Joints with Position mode can't use a custom rotation axis

Bugs

Cedric March 13, 2026, 1:53pm 11

Same diagnostic and it looks a bit like Position motor does not reach target angle

Any idea @eoin ?

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Physics Motor Joints with Position mode can't use a custom rotation axis

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