Cannot modify a value type return value of `UnityEngine.Transform.rotation'

Unity Engine
1

I’m trying to make a cube look at the player:

        transform.rotation.y = Mathf.Lerp(transform.rotation.y, targetLook.y, smoothLook * Time.deltaTime);

This is the error I’m getting:
CS1612: Cannot modify a value type return value of `UnityEngine.Transform.rotation’. Consider storing the value in a temporary variable

Can anyone tell me why this is happening? I’ve been having this issue with several other rotation-changing functions as well. Please and thanks.

PS: I cant use transform.LookAt in this situation

2

The warning message is exactly telling you what to do, so fixing it schould be simple. As to Why.
Rotation is of type Quaternion and a Quaternion is a value type (struct) and not a reference type (class).
Value types are returned by copy. So when you say “Hey whats your rotation” than you are getting a copy of the object and not the actual object back. Modifieing a copy is more or less useless except when you assign the copy back to the rotation.

2 Likes
3

Translation

Quaterion tempRotation = transform.rotation;
tempRotation.eulerAngles = new Vector3(0,0,0);
transform.rotation = tempRotation;

Don’t set xyzw of a quarterion directly unless you know what you are doing. For clarification you do not know what you are doing.

1 Like
4

Great. Thanks for the help.