Rotate rigidbody using MoveRotation() around the global y axis

Questions & Answers
1

Hi, I originally had this code to rotate my game object which worked fine:

transform.Rotate (new Vector3 (0, joytickX, 0), Space.World);
transform.Rotate (new Vector3 (joystickY, 0, 0), Space.Self);

But then I realised I needed to rotate the rigidbody instead so I changed it to this:

Quaternion deltaRotation = Quaternion.Euler (new Vector3 (joystickY, joytickX, 0));
rigidbody.MoveRotation (transform.rotation * deltaRotation);

The problem is that MoveRotation() rotates the game object using it’s local space, of which is fine for the x axis but for the y axis I want it to rotate using the global space instead. How can I achieve this whilst still using MoveRotation()?

3

Old post, but it shows up on Google, so:

the problem was the order of the multiplication. The left-most operand is the one on the outside, and the right-most operand is on the inside.

The only reason your rotation was “local” is because you used the wrong multiplication order in MoveRotation.

rigidbody.rotation * deltaRotation

will add deltaRotation to the current rotation. If your local Y axis is on its side, it will rotate around it.

 deltaRotation * rigidbody.rotation

will rotate around the world Y axis instead, then restore your current rotation

2

You could use Quaternion.AngleAxis():

 Quaternion deltaRotation = Quaternion.AngleAxis(joystickX, transform.up) * Quaternion.AngleAxis(joystickY, Vector3.right);

Without testing, I don’t know the exact recipe. You may have to reverse the order the two rotation are combined and/or negate one the angle.

Also I’d reverse the order in the MoveRotation():

  rigidbody.MoveRotation (deltaRotation * transform.rotation);