Need help with Quaternion locking

Scripting
1

Please help.

I am trying to develop a puzzle game in which you must rotate a cube one face at a time, but I am having a great deal of trouble with the Quartenion.Euler function. It seems that when the Z axis is locally pointing in the direction of Y (i.e. when rotation X equals 90 or 270), attempts to rotate on that Z axis only results in rotations on the Y. :(:face_with_spiral_eyes:

I desperately need to be able to rotate the cube to view each and every side. I have tried everything to fix this, but just cannot fathom the reason for it.

a simplified version of my code (which I created to check that I wasn’t going crazy) is:

using UnityEngine;
using System.Collections;

public class cubeRotate2 : MonoBehaviour {
	private float mouseShiftX;
	private float mouseShiftY;
	public float Xdegrees;

	// Use this for initialization
	void Start () {
		Xdegrees = 90.0f;
	}
	
	void Update () {
		mouseShiftX =  Screen.width/2 - Input.mousePosition.x;
		mouseShiftY = Screen.height/2 - Input.mousePosition.y;
		
		transform.rotation = Quaternion.Euler(Xdegrees, mouseShiftX, mouseShiftY);
	}
}

The other values of X which I have tested (namely 0 and 180) present no such problems, and even the reverse; when the X axis is locally pointing in the direction of Y, presents no such issues. Please Help.

2

it will probably be easier to deal with localRotation

3

Sounds like Gimbal Lock

4

Remarkably, the answer seems to be a combination of both your answers, jlcnz and Tseng. So, my thanks to you both. :):slight_smile:

Looking at the diagrams on the link submitted by Tseng gave me the idea to add a couple of empty game objects in the scene, such that the scene Hierarchy looks like:

cubeRotateZ
cubeRotateY
Cube

And attached to the cube, the script (the cube controls the Xrotation only; cubeRotateY, the localY; and cubeRotateZ, the localZ only) :

using UnityEngine;

using System.Collections;

public class cubeRotate2 : MonoBehaviour {

	private float mouseShiftX;
	private float mouseShiftY;
	public float Xdegrees;
	public Transform rotatorY; //link up empty gameobjects in editor
	public Transform rotatorZ; 

	void Start () {
		Xdegrees = 90;
	}

	void Update () {
		mouseShiftX =  Screen.width/2 - Input.mousePosition.x;
		mouseShiftY = Screen.height/2 - Input.mousePosition.y;

		transform.localRotation = Quaternion.Euler(90, 0, 0);
		rotatorY.localRotation = Quaternion.Euler(0, mouseShiftX, 0);
		rotatorZ.localRotation = Quaternion.Euler(0, 0, mouseShiftY);
	}

}

It’s rough, and still needs a lot of work: but it’s getting there. So thank you.

5

You can of course also try using Transform.Rotate, maybe it takes care of the gimbal lock