StreetLight/Assets/StreetLight/Serialization/QuaternionConverter.cs

using Newtonsoft.Json;
using System;
using UnityEngine;

namespace Assets.StreetLight.Serialization
{
    public class QuaternionConverter : JsonConverter
    {
        public override bool CanConvert(Type objectType)
        {
            return objectType == typeof(Quaternion);
        }

        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            return new Quaternion();
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            var vector = (Quaternion)value;
            var text = $"({vector.x}|{vector.y}|{vector.z}|{vector.w})";
            writer.WriteValue(text);
        }
    }
}