ConstrainRotationAxis.cs

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

namespace Interakt.Components.Constraints {
    public class ConstrainRotationAxis : MonoBehaviour
    {
        public enum ConstraintSpace {
            Local,
            World
        }

        public ConstraintSpace Space;
        public bool LockX, LockY, LockZ;

        private Vector3 OriginalRotation;
        private Vector3 NextRotation;

        void Awake()
        {
            // Store the original rotation of this gameobject
            OriginalRotation = Space == ConstraintSpace.Local ? transform.localEulerAngles : transform.eulerAngles;
        }

        void LateUpdate()
        {
            // Constrained rotation is initially the same as the transform position
            NextRotation = Space == ConstraintSpace.Local ? transform.localEulerAngles : transform.eulerAngles;

            // Constrain  if required 
            if(LockX)
                RevertX(ref NextRotation);
            if(LockY)
                RevertY(ref NextRotation);
            if(LockZ)
                RevertZ(ref NextRotation);

            if(Space == ConstraintSpace.Local)
            {
                transform.localEulerAngles = NextRotation;
            } else {
                transform.eulerAngles = NextRotation;
            }
        }

        void RevertX(ref Vector3 rot)
        {
            rot.x = OriginalRotation.x;
        }

        void RevertY(ref Vector3 rot)
        {
            rot.y = OriginalRotation.y;
        }

        void RevertZ(ref Vector3 rot)
        {
            rot.z = OriginalRotation.z;
        }
    }
}