unity-game-enginegame-physics

have an object rotate back to zero over time

In a Coroutine I'm setting the velocity of a rigid body to follow the touch screen location:

rb.velocity = direction * touchDragPhysicsSpeed;

But I also want its rotation to trend back toward zero degrees. How can I do that?

AI keeps telling me to do something like this:

Quaternion targetRotation = Quaternion.Euler(Vector3.zero);
rb.MoveRotation(Quaternion.Slerp(rb.rotation, targetRotation, rotationCorrectionSpeed));

But that MoveRotation line gives the error:

Argument 1: cannot convert from 'float' to 'UnityEngine.Quaternion'

Is this the right approach? If so, how can I fix the error? Or is there a better way?

Solution

  • Sounds like your rb is actually a Rigidbody2D in which case indeed rb.rotation is a float (the single Z-axis rotation - the only one that matters for 2D)!

    you rather want

    rb.MoveRotation(Mathf.Lerp(rb.rotation, 0, rotationCorrectionSpeed));

    As you want to rotate towards the closest multiple of 360

    var target = Mathf.Round(rb.rotation / 360f) * 360;
rb.MoveRotation(Mathf.Lerp(rb.rotation, target, rotationCorrectionSpeed));

    This should rotate the shortest way to the closest multiple of 360.

    General hint: Instead of blindly trusting AI rather consult the API ;)