Clapming rotation of child objects in unity

Question

I have a game object that contains another game object that should be able to rotate towards target (imagine a tank turret). And so I've created the below script:

public class Rotator : MonoBehaviour {

    public GameObject _enemy;

    void Update () {
        var actualTarget = _enemy.transform.position;
        var targetDir = actualTarget - transform.position;
        var step = 2 * Time.deltaTime;
        var target = Quaternion.LookRotation(targetDir.normalized, Vector3.up);
        var actual = target * Quaternion.Inverse(transform.parent.rotation);
        var targetRotation = Quaternion.Slerp(transform.localRotation, actual, step);

        targetRotation.eulerAngles = ClampRotation(targetRotation.eulerAngles);
        transform.localRotation = targetRotation;
    }

    private static Vector3 ClampRotation(Vector3 eulerAngles) {
        var x = Mathf.Clamp(eulerAngles.x > 180 ? eulerAngles.x - 360 : eulerAngles.x, -180, 180);
        var y = Mathf.Clamp(eulerAngles.y > 180 ? eulerAngles.y - 360 : eulerAngles.y, -45, 45);

        return new Vector3(x, y, 0);
    }

}

Objects setup:

The rotation of the object named "parent" is 90deg on the Y axis, everything else is not rotated.

Clamping on the y axis works well - the rotation stays between -45 and 45 degrees. The rotation however doesn't work on the x axis (with, or without clamping). So the goal here is that when I move the cube left or right, the red one rotates between [-45,45] degrees around the Y axis and when I move it top or down, the red one rotates between [-180,180] degrees around the X axis. I had some success using the LookAt method of the Transform clas, but for some reason if I try to manually modify eulerAngles of a localRotation it suddenly looses the possibility to rotate backwards on the X axis even though I'm only doing something to the Y values...

user_2385132 · Answer

After long hours of trial and error and browsing the internet frenzily, I managed to find an answer that I could tailor to my needs. Word of comment to the first if statement of the Clamp method - this is useful if I want the object to also be clamped in it's inverted position (if the target is behind it):

void Update() {
    transform.LookAt(_target.transform);

    var rotation = transform.localRotation;
    var eulers = ClampRotation(rotation.eulerAngles);

    transform.localEulerAngles = eulers;
}

private static Vector3 ClampRotation(Vector3 eulerAngles) {
    var x = Clamp(eulerAngles.x, -60, 60);
    var y = Clamp(eulerAngles.y, -45, 45);

    return new Vector3(x, y, 0);
}

private static float Clamp(float angle, float min, float max) {
    if ((angle <= 180 && angle >= 180 - Mathf.Abs(min)) || (angle >= 180 && angle <= 180 + max)) {
        return Mathf.Clamp(angle, 180 - Mathf.Abs(min), 180 + max);
    }

    if (angle > 180f) {
        angle -= 360f;
    }

    angle = Mathf.Clamp(angle, min, max);

    if (angle < 0f) {
        angle += 360f;
    }

    return angle;
}

EDIT:

As it turns out, sometimes it's better to create your own fine-grained solution, you can modify more easily, so to anyone who is interested, you can do what I wanted to do with the below code as well:

void Update() {
    var actualTarget = _enemy.transform.position;
    var targetDir = actualTarget - transform.position;
    var target = Quaternion.LookRotation(targetDir.normalized, transform.up);
    var actual = Quaternion.Inverse(transform.parent.rotation) * target;

    actual.eulerAngles = ClampRotation(actual.eulerAngles);

    var targetRotation = Quaternion.Slerp(transform.localRotation, actual, 8 * Time.deltaTime);

    transform.localRotation = targetRotation;
}

private static Vector3 ClampRotation(Vector3 newRotation) {
    var x = Clamp(newRotation.x, -179, 179);
    var y = Clamp(newRotation.y, -45, 45);

    return new Vector3(x, y, 0);
}

private static float Clamp(float angle, float min, float max) {
    if ((angle <= 180 && angle >= 180 - Mathf.Abs(min)) || (angle >= 180 && angle <= 180 + max)) {
        return Mathf.Clamp(angle, 180 - Mathf.Abs(min), 180 + max);
    }

    if (angle > 180f) {
        angle -= 360f;
    }

    angle = Mathf.Clamp(angle, min, max);

    if (angle < 0f) {
        angle += 360f;
    }

    if (Mathf.Abs(angle) == 360) {
        angle = 0;
    }

    return angle;
}

Clapming rotation of child objects in unity

1 Answers