Unity3d。 CharacterJoint不正确

Question

I created a scene with two cubes. I want first cube to fallow rotation of second cube. For it to work, I set joint.targetRotation and slerpDrive properties. And it work fine. But sometimes, I noticed that it start rotating infinitely, like no slerpDrive is defined. For example, to reproduce, you can see this script:

public class TestScript : MonoBehaviour
{
    [SerializeField]
    Rigidbody _connectedBody;
    void Awake()
    {
        var rigid = GetComponent<Rigidbody>();

        var joint = gameObject.AddComponent<ConfigurableJoint>();
        joint.autoConfigureConnectedAnchor = false;
        joint.connectedBody = _connectedBody;
        joint.connectedAnchor = Vector3.zero;
        joint.anchor = Vector3.zero;

        joint.rotationDriveMode = RotationDriveMode.Slerp;

        var drive = new JointDrive()
        {
            positionSpring = 100f,
            maximumForce = float.MaxValue
        };

        joint.slerpDrive = drive;
        // joint.xDrive = drive;
        // joint.yDrive = drive;
        // joint.zDrive = drive;

        joint.targetRotation = Quaternion.Euler(10, 0, 0);
    }

    void FixedUpdate()
    {
        var joint = gameObject.GetComponent<ConfigurableJoint>();

        joint.axis = Vector3.right;
    }
}

A cube with this script is rotating infinitely. Why? If you comment this line joint.axis = Vector3.right; , it stop rotating. But I do not understand why is it happening.

Answer 1

Well, you are calling your joint.axis = Vector3.right; inside of void FixedUpdate() , Vector3.right is identical to Vector3(1, 0, 0) , meaning every update, you are giving a new position to which you are asking it to move to, giving it infinite motion.

What you should aim to do, is trigger the movement at the right moment.

I'd advise you to create "Debug bindings" with unity (basically just dedicate some binding to try stuff out) so that you have tactile feedback for your behaviours. Giving you easy access to start and stop it.