day/night cycle and also track days? - unity3d

Question

I'm trying to make a day and night cycle that also keeps track of how many days passed. I watched a tutorial to start and for this post, I removed all the unnecessary stuff like rotating the sun and changing colors.
public class TimeController : MonoBehaviour
{
[SerializeField]
private float timeMultiplier;
[SerializeField]
private float startHour;
private DateTime currentTime;
void Start()
{
currentTime = DateTime.Now.Date + TimeSpan.FromHours(startHour);
}
void Update()
{
UpdateTimeOfDay();
}
private void UpdateTimeOfDay()
{
currentTime = currentTime.AddSeconds(Time.deltaTime * timeMultiplier);
}
}
The biggest issue I have with this is instead of timeMultiplier I'd rather have like a dayLength variable which represents how long a day should last in minutes so one day is 10minutes int dayLength = 600; or something like that, but I'm not sure how I'd implement that.
Also, I tried adding a method for checking if a day has passed, but the code ended up running like 20 times.
public int currentDay = 1;
private void HasDayPassed()
{
if (currentTime.Hour == 0)
{
Debug.Log("New day");
currentDay++;
}
}

Answer 1

Try this code
using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class TimeController : MonoBehaviour
{
public const float SecondsInDay = 86400f;
[SerializeField] [Range(0, SecondsInDay)] private float _realtimeDayLength = 60;
[SerializeField] private float _startHour;
private DateTime _currentTime;
private DateTime _lastDayTime;
private int _currentDay = 1;
private void Start()
{
_currentTime = DateTime.Now + TimeSpan.FromHours(_startHour);
_lastDayTime = _currentTime;
}
private void Update()
{
// Calculate a seconds step that we need to add to the current time
float secondsStep = SecondsInDay / _realtimeDayLength * Time.deltaTime;
_currentTime = _currentTime.AddSeconds(secondsStep);
// Check and increment the days passed
TimeSpan difference = _currentTime - _lastDayTime;
if(difference.TotalSeconds >= SecondsInDay)
{
_lastDayTime = _currentTime;
_currentDay++;
}
// Next do your animation stuff
AnimateSun();
}
private void AnimateSun()
{
// Animate sun however you want
}
}
Also you can remove the range attribute to specify more slower day than the realtime day.