Unity - Smoothed mouse look for an FPS

SmoothMouseLook.cs

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

public class SmoothMouseLook : MonoBehaviour
{
	private List<float> _xBuffer = new List<float>();
	private List<float> _yBuffer = new List<float>();
	private int _bufferIndex;

	private float _targetRotX; // Used because _rotatorX needs its rotation assigned (instead of added).

	[Header("Settings")]
	public float _sensitivityX = 1.5f;
	public float _sensitivityY = 1.5f;

	[Space]
	public float _minX = -90f;
	public float _maxX = 90f;

	[Space]
	[Tooltip("The more steps, the smoother it will be.")]
	public int _averageFromThisManySteps = 3;

	[Header("References")]
	[Tooltip("Object to be rotated when mouse moves up/down. Usually your Camera.")]
	public Transform _rotatorX;
	[Tooltip("Object to be rotated when mouse moves left/right. Usually your Player root GameObject for an FPS.")]
	public Transform _rotatorY;

	private void Start()
	{
		// Matches whatever your rotator is set to
		_targetRotX = -_rotatorX.localEulerAngles.x;
	}

	private void LateUpdate()
	{
		var mouseDeltaX = Input.GetAxisRaw("Mouse X") * _sensitivityX;
		var mouseDeltaY = Input.GetAxisRaw("Mouse Y") * _sensitivityY;

		var (AveragedX, AveragedY) = GetAverages(mouseDeltaX, mouseDeltaY, _averageFromThisManySteps);

		// Clamp X
		_targetRotX += AveragedY;
		_targetRotX = Mathf.Clamp(_targetRotX, _minX, _maxX);

		// Rotate
		_rotatorX.localRotation = Quaternion.Euler(-_targetRotX, 0f, 0f);
		_rotatorY.Rotate(0f, AveragedX, 0f, Space.World);
	}
	
	(float AveragedX, float AveragedY) GetAverages(float mouseDeltaX, float mouseDeltaY, int steps = 3)
	{
		// Add entries until reached max number of steps, then mutate current entries only
		if (_xBuffer.Count < steps)
		{
			_xBuffer.Add(mouseDeltaX);
			_yBuffer.Add(mouseDeltaY);
			_bufferIndex = steps - 1;
			return (0f, 0f);
		}
		// Remove entries if max steps is reduced
		else if (_xBuffer.Count > steps)
		{
			Remove();

			void Remove()
			{
				if (_xBuffer.Count > steps)
				{
					_xBuffer.RemoveAt(0);
					_yBuffer.RemoveAt(0);

					Remove();
				}
			}

			return (0f, 0f);
		}
		// Mutate entries
		else
		{
			_xBuffer[_bufferIndex] = mouseDeltaX;
			_yBuffer[_bufferIndex] = mouseDeltaY;

			_bufferIndex++;

			if (_bufferIndex >= steps)
				_bufferIndex = 0;
		}

		// Average
		var totalX = 0f;
		var totalY = 0f;

		for (int i = 0; i < steps - 1; i++)
		{
			totalX += _xBuffer[i];
			totalY += _yBuffer[i];
		}

		return (totalX / steps, totalY / steps);
	}
	
}