Light fades out but not back in

I have a main light in my game and I want the light to slowly fade out over time and then fade back to full intensity and then fade back out and etc. so something similar to night and day. Sadly, the code I have right now fades the light out like I want it to but it goes back to starting intensity instead of fading back in. This is what my code is right now. Any help would be greatly appreciated.

void Update () {
if (mainLight.intensity <= 1) {
#if DEBUG
print (mainLight.intensity);
#endif
mainLight.intensity = Mathf.Lerp(1,0,Time.time / 5);
}
if (mainLight.intensity <= 0) {
#if DEBUG
print ("Light intensity is 0");
#endif
mainLight.intensity = Mathf.Lerp(0,1,Time.time / 5);
}
}

 

Hey there friend. To make our life easier can you, next time, use the code tag for you code.

So you problem is that you are confusing Time.time which is the time in seconds since the start of the game
with Time.deltaTime which is the time in seconds it took to complete the last frame.

So you should have something like:

Code (CSharp):

1. mainLight.intensity = Mathf.Lerp(1,0,Time.deltaTime * speed);

^
||
Did you see that cool "code" tag usage?

 

Unity says speed does not exist in current context. Am I missing something?

Thanks for the code tag. I tried searching before I posted but I gave up .

 

Yeah, by speed I mean a value that you define to control how fast the fade is animated.
You have 2 options:

Code (CSharp):

1.     //Option A: declare a global speed and set it from inspector
2.     public float Speed;
3.  
4.     void Update()
5.     {
6.         if (mainLight.intensity <= 1)
7.         {
8. #if DEBUG
9.             print(mainLight.intensity);
10. #endif
11.             mainLight.intensity = Mathf.Lerp(1, 0, Time.deltaTime * Speed);
12.         }
13.         if (mainLight.intensity <= 0)
14.         {
15. #if DEBUG
16.             print("Light intensity is 0");
17. #endif
18.             //Option B: or just hardcode it directly into your lerp
19.             mainLight.intensity = Mathf.Lerp(0, 1, Time.deltaTime * 0.5f);
20.         }
21.     }

 

Hmm. Neither of the options seemed to work.

 

yeah my bad, I was tired. Try this:

Code (CSharp):

1. mainLight.intensity = Mathf.Lerp(mainLight.intensity, 1, Time.deltaTime * 0.5f);

 

The Lerps are off, even the last one produces a logarithmic effect where it never quite reaches the target. But more importantly -

The way those conditionals are written won't work.
Let's say the intensity starts at 1. It will go down to zero, and then ...
1) The first conditional still runs, putting at zero again.
2) The second condition runs, putting it at slightly above zero.
3) Next frame, the first conditional runs and puts it at zero ...
End result, it would freeze at a tiny bit above totally dark.

You need an additional state variable for which direction the light is changing. Something like this:

Code (csharp):

1. public float speed;
2. private float direction = 1f;
3.  
4. private void Update () {
5.    mainLight.intensity += Time.deltaTime * speed * direction;  // Lerp not needed
6.    if(mainLight.intensity >= 1f) {
7.       direction = -1f;
8.    }
9.    else if(mainLight.intensity <= 0f) {
10.       direction = 1f;
11.    }
12. }

You could technically save a float and flip the sign of speed instead. But that gets screwed up if anything external wants to change the speed, and is less clear.

 

Take my code with the exact solution and don't actually learn anything. Also my version is better.

Code (CSharp):

1.  
2.     public float Speed;
3.  
4.     void Start()
5.     {
6.         StartCoroutine("AnimateIntensity");
7.     }
8.  
9.     private IEnumerator AnimateIntensity()
10.     {
11.         var t = 0f;
12.         var destination = mainLight.intensity <= 0.5f ? 1 : 0;
13.         while (t <= 1)
14.         {
15.             mainLight.intensity = Mathf.Lerp(mainLight.intensity, destination, t);
16.             t += Time.deltaTime * Speed;
17.             yield return null;
18.         }
19.  
20.         StartCoroutine("AnimateIntensity");
21.     }

 

Thanks everyone! It works just fine! Thanks!