Rotating on X Y Axis only.

I'm trying to write a script to rotate the camera using the mouse, but I can't stop it from tilting on the Z axis.

Code (csharp):

1. float axisX = Input.GetAxisRaw("Mouse X");
2. float axisY = Input.GetAxisRaw("Mouse Y");
3. gameObject.transform.Rotate(new Vector3(-axisY, axisX, 0), Space.World);

Using this code if I move the mouse in an XY axis (towards the corners of the screen) the camera starts tilting on the Z axis.

What am I doing wrong?

 

Try adding this.

Code (csharp):

1.  
2.  
3. function LateUpdate(){
4. gameObject.transform.rotation.z = 0;
5. }
6.  
7.  

 

I tried this:

Code (csharp):

1.     void LateUpdate() {
2.         Quaternion zlock = this.transform.rotation;
3.         zlock.z = 0;
4.         gameObject.transform.rotation = zlock;
5.     }

and I still get rotation on Z. even though debug.log(gameobject.transform.rotation); shows a 0 on the z axis, when I look at the transform on the editor I can see the Z value changing, and it's never 0.

 

local or global issue ?

 

Not sure, I've tried

Code (csharp):

1. gameObject.transform.Rotate(new Vector3(-axisY, axisX, 0), Space.Self);
2. gameObject.transform.Rotate(new Vector3(-axisY, axisX, 0), Space.World);
3.  
4. gameObject.transform.RotateAround(Vector3.up, axisX * Time.deltaTime);
5. gameObject.transform.RotateAround(Vector3.right, -axisY * Time.deltaTime);
6.  
7. gameObject.transform.RotateAroundLocal(Vector3.up, axisX * Time.deltaTime);
8. gameObject.transform.RotateAroundLocal(Vector3.right, -axisY * Time.deltaTime);

and still get the same problem.

 

transform.rotation is a 4D quaternion, and rotation.z does not correspond to the z axis nor is it in degrees.

To see what's happening, click on an object in the editor, then use the rotate tool to rotate it on the x axis by say 45 degrees, then rotate it on the y axis by 45 degrees, and watch what happens to the rotation in the inspector. Instead, you could basically do what the standard first person controller/MouseLook script does, namely have an empty object for y axis rotation and the camera as a child of that object for x axis rotation. By the way you can just write "transform.Rotate", you don't need "gameObject.transform.Rotate".

--Eric

 

Thanks, that worked.

 

It solves.
But, can someone please explain what is going on there. Is that the "Gimbal Lock" problem using Euler angles?

 

I can understand why it works even thought im still trying to understand why a lateUpdate function wouldnt work.Thanks it was bugging me but i used your tips and it worked

 

We can also use different spaces for each rotation.

Code (CSharp):

1. transform.Rotate(Vector3.up, axisX, Space.World);
2. transform.Rotate(Vector3.right, axisY, Space.Self);

You can do this with a single object.

Edit: Y rotation has to be in world space.

Code (CSharp):

1. transform.Rotate(Vector3.up, axisX, Space.Self);
2. transform.Rotate(Vector3.right, axisY, Space.World);

This will not work.

 

It doesn’t work because a rotation in Unity is naturally expressed as a 4 dimensional construct known as the Quaternion. Here’s some educational stuff —

https://quaternions.onlin/
https://eater.net/quaternions


You are used to the three dimensional representation of a rotation shown within the editor which is expressed in Euler angles. In code, to AVOID gimbal locking, we rotate things with quaternion. You can use transform.rotation.eulerAngles but I do believe that’s a get only property. I think all assignments have to be done in quaternion.


Also, there’s this

https://docs.unity3d.com/ScriptReference/Quaternion-operator_multiply.html

 

Id hate to be the thread police here, but this was from 2016, and prior to that 2012 !

Using the correct technique gimbal locking should be non-existent. The rasteriser that unity engine was built with the guidance of had not implemented quaternion. The mythos of quaternion being fundamental to the engine is specific to the auto-wrap values of its struct and nothing more. Operating on an Euler angle is different to operating on a vector 3, however a vector 3 can be converted to Euler angles without any unwanted operation.

 

Sheesh! I really need to pay more attention to dates on the OP. Good call, sorry about the necro.