Unity Clamp Direction Angle

ClampDirection.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;

public class ClampDirection : MonoBehaviour
{
	public Transform targetObj;

	public float clampAngle;
	public Vector3 clampedDir;
	public float smooth;

	private void Update()
	{
		Vector3 dir = targetObj.position - transform.position;
		Debug.DrawRay(transform.position, dir.normalized * 3f, Color.green);
		Debug.DrawRay(transform.position, transform.forward * 3f, Color.red);

		var newClampedDir = GetClampedDirection(dir, transform.forward, transform.up, clampAngle);
		clampedDir = Vector3.Slerp(clampedDir, newClampedDir, smooth * Time.smoothDeltaTime);

		Debug.DrawRay(transform.position, clampedDir * 3f, Color.cyan);
	}

	public Vector3 GetClampedDirection(Vector3 currentDir, Vector3 basisDir, Vector3 up, float maxAngle)
	{
		float APPROX_180 = 179.0f;
		float angle = Vector3.SignedAngle(basisDir, currentDir, up);
		var ratio = Mathf.Abs(angle) / APPROX_180;
		ratio = Mathf.Clamp(ratio, 0f, maxAngle / APPROX_180);

		var behindLeftRotation = Quaternion.AngleAxis(-APPROX_180, up);
		var behindRightRotation = Quaternion.AngleAxis(APPROX_180, up);

		var behindLeftVector = behindLeftRotation * basisDir;
		var behindRightVector = behindRightRotation * basisDir;

		var newClampedDir = currentDir;

		if (angle < 0f)
		{
			newClampedDir = Vector3.Slerp(transform.forward, behindLeftVector, ratio);
		}
		else
		{
			newClampedDir = Vector3.Slerp(transform.forward, behindRightVector, ratio);
		}

		return newClampedDir;
	}
}