Unity - Stuttering character rotation

Question

Am working on the controls and camera movement for my character. What I am trying to do is have the character head be able to rotate left and right and then when the head is rotated a certain amount, the whole character rotates around. I have kinda of done it, the head can move smoothly, but it stutters when it starts rotating everything.

Hopefully it is visible in this GIF.

You may be able to see that the head does rotate smoothly, but when the body starts rotating, it stutters.

Here is the code that is in LateUpdate that handles all the rotations.

this.current_rotation = Quaternion.Lerp(this.current_rotation, Quaternion.Euler(new Vector3(this.pitch, this.yaw, 0)), this.mouse_sensitivity * Time.deltaTime);

this.cam.transform.rotation = this.current_rotation;
this.head.transform.rotation = this.current_rotation;

if(this.head.transform.localRotation.y > 0.3 || this.head.transform.localRotation.y < -0.3){
    Quaternion from = Quaternion.Euler(0, this.player.transform.eulerAngles.y, 0);
    Quaternion to = Quaternion.Euler(0, this.current_rotation.eulerAngles.y, 0);

    Quaternion q =  Quaternion.Lerp(from, to, this.mouse_sensitivity * Time.deltaTime);
    this.player.transform.rotation = q;
}

Answer 1

OK, I couldn't get the sample project working in Unity, but I used the script to recreate it with a couple assumptions, as follows:

• Your Camera_Control.cs script is on the body cube.
• The head cube is a child of the body cube.
• The camera is a child of the head cube

I was able to fix this in two ways:

1. Move the head cube off of the body, so that rotating the body doesn't automatically rotate the head as well.
2. Or, counter-rotate the head when you do rotate the body, to neutralize the effect.

I assume the latter is the style of solution you wanted. So, I add two new Quaternions (essentially reversed), Lerp between them, and assign that to the cam/head transforms.

this.current_rotation = Quaternion.Lerp(this.current_rotation, Quaternion.Euler(new Vector3(this.pitch, this.yaw, 0)), this.mouse_sensitivity * Time.deltaTime);

this.cam.transform.rotation  = this.current_rotation;
this.head.transform.rotation = this.current_rotation;

if(this.head.transform.localRotation.y > 0.3 || this.head.transform.localRotation.y < -0.3){
    Quaternion from = Quaternion.Euler(0, this.player.transform.eulerAngles.y, 0);
    Quaternion to   = Quaternion.Euler(0, this.current_rotation.eulerAngles.y, 0);

    // Reverse 'y' rotation, maintain x/z rotation
    Quaternion headFrom = this.current_rotation;
    Quaternion headTo   = Quaternion.Euler(headFrom.eulerAngles.x, this.player.transform.eulerAngles.y, headFrom.eulerAngles.z);

    Quaternion q = Quaternion.Lerp(from,     to,     this.mouse_sensitivity * Time.deltaTime);
    Quaternion r = Quaternion.Lerp(headFrom, headTo, this.mouse_sensitivity * Time.deltaTime);
    this.player.transform.rotation = q;
    this.cam.transform.rotation    = r;
    this.head.transform.rotation   = r;
}

That should fix the jitter. You'll still have other rotation work to do afterwards, but at least it'll be smooth. :)

Answer 2

From your screenshots it looks like the problem may be from the colliders on your head and body object. You are directly manipulating the transform in your code, but while this is happening the physics engine is also trying to handle the collisions between the two colliders and this will result in erratic movement.

If that is the issue, there are a number of ways to avoid that problem, from changing what objects have colliders to having colliders ignoring each other using layering.