Opacity over time

Hi, I've been trying to have some blood spatter on the ground in my game over time with this script:

Code (CSharp):

1. float fadeOutTime = 8.0f;
2.  
3.  
4.     void Start()
5.     {
6.         StartCoroutine( FadeOut( fadeOutTime, renderer.material ) );
7.     }
8.  
9.  
10.     IEnumerator FadeOut( float time, Material material )
11.     {
12.         float index = 0.0f;
13.         float rate = 1.0f/time;
14.         while( index < 1.0f )
15.         {
16.             index -= rate;
17.             material.SetFloat ("_Cutoff", index);
18.             yield return null;
19.         }
20.        
21.     }

It doesn't work however. It remains at either maximum or minimum alpha cutoff depending on + or -, can anybody please help? It's supposed to slowly become more and more visible.

 

Hi, I believe "index" stays bellow zero forever. You start off a value of 0 then remove 1/8th every frame, so unless you're using a shader that supports negative cutoff values it wont work.

 

Okay. Thank you for the input

 

This could be done without a Coroutine. I would do something like this:

Code (CSharp):

1. public class Test : MonoBehaviour {
2.  
3.     public float duration = 8f;
4.  
5.     float time;
6.     Material material;
7.  
8.     void Start(){
9.         material = GetComponent<Renderer>().material;
10.     }
11.  
12.     void Update(){
13.         float val = Mathf.Lerp(1f, 0f, time);
14.         time += Time.deltaTime / duration;
15.  
16.         material.SetFloat ("_Cutoff", val);
17.     }
18.  
19. }

 

It works perfectly. I was sure coroutine was the way to go but time += Time.deltaTime / duration; is a new one for me. Thank you very much

 

Also note, to test completion, the returned value of the Lerp will return the second parameter. So If you wanted to destroy the object upon completion, you would do this:

Code (CSharp):

1.     void Update(){
2.         float val = Mathf.Lerp(1f, 0f, time);
3.         time += Time.deltaTime / duration;
4.  
5.         material.SetFloat ("_Cutoff", val);
6.  
7.         if(val <= 0f{
8.             Destroy(gameObject);
9.         }
10.     }

 

Awesome! Thanks