How can I reset and repeat a Mathf.Lerp?

Hi,

This Mathf.Lerp in the Update function makes the objects materials alpha channel turn from .50f to the value of 0.0f over time. (It becomes transparent and then the game object is disabled)
How do I make it so that it resets on awake? I mean how do I make it start over when the game object is enabled again?

Code (CSharp):

1.  
2. void Update()
3.     {
4.  
5.    
6.         time += 3f * Time.deltaTime;
7.         Color c = rend.material.GetColor("_TintColor");
8.         c.a = Mathf.Lerp(.50f, 0.0f, time);
9.         rend.material.SetColor("_TintColor", c);
10.  
11.  
12.  
13.  
14.     }

 

The Lerp(valueA, valueB, lerpValue) function is quite simple: it interpolates between valueA and valueB according to the lerpValue. If lerpValue is 0 or smaller, it returns valueA, if it is 1.0 or larger, it returns valueB, and if it is anything inbetween, it returns the weighted average between those two. For example, if lerpValue is 0.2, it returns 80% * valueA + 20% * valueB.

Long Story short: you control the output value with the third value. This is currently time. Instead, use a Counter that you set to 0, and update by adding Time.deltaTime whenever you want to re-start the lerp.

There are also Pingpong lerps availabe, so it may be highly beneficial if you re-read the lerp Manual pages, as you can save a lot of work if you use them well.

 

YES! This!

Define a variable for the timer such as

float lerpTimer = 0f;

variable and then increment it by

lerpTimer += Time.deltaTime;

Then plug that into the function

Lerp(a,b,lerpTimer);

.
When you want to restart the loop, make sure the a and b values are good and then reset the counter!

lerpTimer = 0f;

 

Something like this:

You call

TimeReset();

when you want to restart the Lerp

Code (CSharp):

1.  
2.     private float time;
3.  
4.     private void Awake()
5.     {
6.         TimeReset();
7.     }
8.  
9.     private void Update()
10.     {
11.         time += 3f * Time.deltaTime;
12.         Color c = rend.material.GetColor("_TintColor");
13.         c.a = Mathf.Lerp(.50f, 0.0f, time);
14.         rend.material.SetColor("_TintColor", c);
15.     }
16.  
17.     void TimeReset()
18.     {
19.         time = 0f;
20.     }
21.  

 

You'll also want the original color to be recorded and rendered when the gameobject becomes active again

Something like this maybe?

Code (CSharp):

1.     private float time;
2.     private readonly float lerpSpeed = 3f;
3.  
4.     Color originalColor;
5.     Color fadedColor;
6.  
7.     private void Awake()
8.     {
9.         originalColor = rend.material.GetColor("_TintColor");
10.  
11.         LerpReset();
12.     }
13.  
14.     private void Update()
15.     {
16.         time += lerpSpeed * Time.deltaTime;
17.         fadedColor = rend.material.GetColor("_TintColor");
18.         fadedColor.a = Mathf.Lerp(.50f, 0.0f, time);
19.         rend.material.SetColor("_TintColor", fadedColor);
20.  
21.  
22.         if (Input.GetKeyDown("a")) LerpReset();
23.            
24.     }
25.  
26.     void LerpReset()
27.     {
28.         rend.material.SetColor("_TintColor", originalColor);
29.         time = 0f;
30.     }

 

Thank you very much @EdGunther. That is exactly what I was looking for and thank you for the explanation as well. I'll definitely look more into the Lerp function as it can help with a lot of things. It works exactly as I wanted it to, and now I can change the "if" statement to react with the players health script when he gets shot. Thank you

 

Thank you for the explanation. Yes I will be looking over what lerp can do again and how it all works. The example from Ed down below makes a lot of sense and is in line with your explanation. Great example, help and motivation. Thank you