Error in my Lock Rotation C# Script. Help Please.

Error: Cannot modify a value of UnityEngine.transform.rotation. Consider storing the value in a different variable

I am new to scripting, if someone could help me and give me an explanation why this is happening . I would greatly appreciate it. Thanks

Code (CSharp):

1.         //Lock MouseXandY rotation
2.  
3.         transform.rotation.eulerAngles = new Vector3(
4.             Mathf.Clamp(transform.rotation.eulerAngles.x,minimumX,maximumX),
5.             Mathf.Clamp(transform.rotation.eulerAngles.y,minimumY,maximumY),
6.             Mathf.Clamp(transform.rotation.eulerAngles.z,0,0));
7.     }
8. }

 

well it's telling you...

store the current rotation in a variable, work with that variable, apply that variable back to transform.rotation


edit: it's also not quite that simple, if you google "unity clamp rotation" you'll find quite a few posts on this (it's a common sticking point by the looks of it)

 

Quaternion's are structs. This means, when you get transform.rotation, what you get is a copy of the Quaternion, but not the actual rotation Quaternion itself. Changing the .eulerValues of a rotation's copy will not apply to the original transform like you expect.

This is why we need to make another Quaternion, put the new values in our fresh Quaternion, then send the entire struct back to transform all at once.

Code (csharp):

1. // Get a copy
2. Quaternion updatedQuaternion = transform.rotation;
3. // Modify the copy's eulerAngles
4. updatedQuaternion.eulerAngles = new Vector3(..., ..., ...);
5. // Overwrite the existing transform.rotation
6. transform.rotation = updatedQuaternion;

 

I know this is from the fact that the ORDER of rotations matter, so rotating x first then y is different than rotating y first then x. I'm not sure what the original poster is attempting to do, but it sounds like something I've heard animators talk about, Gimbal Lock.
https://www.google.com/search?q=gimbal lock animation