HingeConstraint does not behave as expected about joltphysics

[jrouwe]

What you've created with the example code is this:

The constraint enforces the local space mPoint1 and mPoint2 to coincide in world space. It also enforces that the green axis align in world space. If the red axis align in world space we have HingeConstraint::GetCurrentAngle() == 0.

In your example, as soon as the simulation starts, the bodies move together so that their COM's coincide (because both points were set to 0):

and then they can rotate like this (the shared green axis):

[fhoenig]

Thanks for clarifying. This is indeed the behavior I have observed.

I guess the confusion came from HingeConstraintSettings when defined in world space. In that case the really only meaningful way to "fill out" that struct is to set point and axis to the same values, like in all examples. I thought you could define two relative rotational degrees of freedom with this single constraint. Like a wheel that rotates but also can "squat" sideways, like some cars when accelerating.