Scripting error (523159)

Unity Engine
1

I’m working on a youtube tutorial for creating a day/night cycle and I’ve run into an error.

the error is:

NullReferenceException: Object reference not set to an instance of an object
GameTime.SetUpLighting () (at Assets/DayNight-Package/Scripts/GameTime.cs:115)
GameTime.Start () (at Assets/DayNight-Package/Scripts/GameTime.cs:58)

the code is:

using UnityEngine;
using System.Collections;

public class GameTime : MonoBehaviour 
{
	public enum TimeOfDay
		{
		Idle,
		SunRise,
		SunSet,
		}
	public Transform[] sun;
	public float dayCycleInMinutes = .5f;
	public float Idle = 0;
	public float SunRise = .11f;
	public float SunSet = .6f;
	public float skyboxBlendModifier = 5;
	private Sun[] _sunScript;
	private float _degreeRotation;	
	private float _timeOfDay;
	private float _dayCycleInSeconds;
	private const float SECOND = 1;
	private const float MINUTE = 60 * SECOND;
	private const float HOUR = 60 * MINUTE;
	private const float DAY = 24 * HOUR;
	private const float DEGREES_PER_SECOND = 360 / DAY;
	private TimeOfDay _tod;
	private float _noonTime;
	private float _morningLength;
	private float _eveningLength;



	void Start () 
	{
		_tod = TimeOfDay.Idle;
		_dayCycleInSeconds = dayCycleInMinutes * MINUTE;
		RenderSettings.skybox.SetFloat("_Blend",0);
		_sunScript = new Sun[sun.Length];
		for(int cnt = 0; cnt < sun.Length; cnt++)
		{
			Sun temp = sun[cnt].GetComponent<Sun>();
			if (temp = null)
			{
				Debug.LogWarning("Sun script not found. Adding it.");
				sun[cnt].gameObject.AddComponent<Sun>();
				temp = sun[cnt].GetComponent<Sun>();
			}
			_sunScript[cnt] = temp;
		}
		_timeOfDay = 0;
		_degreeRotation = DEGREES_PER_SECOND * DAY / (_dayCycleInSeconds);
		SunRise *= _dayCycleInSeconds;
		SunSet *= _dayCycleInSeconds;
		_noonTime = _dayCycleInSeconds / 2;
		_morningLength = _noonTime - SunRise;
		_eveningLength = SunSet - _noonTime;
		SetUpLighting ();	
	}



	void Update () 
	{
		_timeOfDay += Time.deltaTime;
		if (_timeOfDay > _dayCycleInSeconds) 
		{
			_timeOfDay -= _dayCycleInSeconds;
		}
		for (int cnt = 0; cnt < sun.Length; cnt++) {
			sun [0].Rotate (new Vector3 (_degreeRotation, 0, 0) * Time.deltaTime);
			}
		if (_timeOfDay > SunRise  _timeOfDay < _noonTime) 
		{
			AdjustLighting(true);	
		} else if(_timeOfDay > _noonTime  _timeOfDay < SunSet) {
			AdjustLighting(false);
		}
	if (_timeOfDay > SunRise  _timeOfDay < SunSet  RenderSettings.skybox.GetFloat ("_Blend") < 1) 
		{
				_tod = GameTime.TimeOfDay.SunRise;
				BlendSkybox ();
		} else if (_timeOfDay > SunSet  RenderSettings.skybox.GetFloat ("_Blend") > 0) {
				_tod = GameTime.TimeOfDay.SunSet;
				BlendSkybox ();
		}else{
			_tod = GameTime.TimeOfDay.Idle;
		}	
	}



	private void BlendSkybox()
	{
		float temp = 0;
		switch (_tod) 
		{
		case TimeOfDay.SunRise:	
			temp = (_timeOfDay - SunRise) / _dayCycleInSeconds * skyboxBlendModifier;
			break;
		case TimeOfDay.SunSet:
			temp = (_timeOfDay - SunSet) / _dayCycleInSeconds * skyboxBlendModifier;
			temp = 1 - temp;
			break;
		}
		RenderSettings.skybox.SetFloat("_Blend",temp);
	}



	private void SetUpLighting()
	{
		for (int cnt = 0; cnt <_sunScript.Length; cnt++) 
		{
			if(_sunScript[cnt].giveLight)
			{
				sun[cnt].GetComponent<Light>().intensity = _sunScript[cnt]._minLightBrightness;
			}
		}
	}


	private void AdjustLighting(bool brighten)
	{
		if (brighten) 
		{
			float pos = (_timeOfDay - SunRise) / _morningLength;
			for(int cnt = 0;cnt <_sunScript.Length; cnt++)
			{
				if(_sunScript[cnt].giveLight)
				{
					Debug.Log(pos);
					_sunScript[cnt].GetComponent<Light>().intensity = _sunScript[cnt]._maxLightBrightness * pos;
				}
			}
		} else {

		}
	}
}

Any help would be greatly appreciated. Thanks!

2 
if (temp = null)

This is likely your problem. One equal sign is assignment. Two equal signs is comparison. This code assigns temp to “null”, and then returns “null”. I imagine the if statement considers a return value of “null” to be false (they probably both map to 0, but I’d need to double check that). The if statement fails, and then you skip straight to this:

_sunScript[cnt] = temp;

Which assigns “null” as your script. When you try to use it later, you generate an error.

Hope that makes sense. That’s a common beginner mistake and easy to overlook.

P.S. Just to be completely clear; you want to replace that with:

if (temp == null)

and you should probably be good.

3

That fixed it!

It makes sense, and thank you. In bashing out the code while following along with the tutorial I must have totally missed that part.

Thank you very much!