Resolved Coroutine wait until a condition?

I'm making a Cutscene in a Coroutine, so I want to do something and then make the game wait until a continueCutscene bool is true, so it goes on with the cutscene, something like this

Code (CSharp):

1. IEnumerator Cutscene()
2.     {
3.         //Cutscene Stuff
4.         continueCutscene = false;
5.         yield return new WaitUntil(continueCutscene == true);
6.         //More Cutscene Stuff and End the cutscene
7.     }

However, I don't know how to do the syntax yield return new WaitUntil(continueCutscene == true); so the program actually waits for a condition to become true, how do I do that?

 

You need to pass in a delegate function into

WaitUntil

; the condition to wait for needs to be outside of the coroutine.
For example:

Code (CSharp):

1. public class Example : MonoBehaviour {
2.    IEnumerator StartTask() {
3.       Debug.Log("Start");
4.  
5.       yield return new WaitUntil(SomeLongAsyncTaskOrWhatever);
6.  
7.       Debug.Log("Finish");
8.    }
9.  
10.    //Returns false while the task is still running, and true when it's finished.
11.    bool SomeLongAsyncTaskOrWhatever() {
12.       //etc..
13.    }
14. }

With the way you're trying to structure your setup though, you can probably do something like this instead...

Code (CSharp):

1. public class Example : MonoBehaviour {
2.    bool isCutscenePlaying;
3.  
4.    void StartCutscene() {
5.       isCutscenePlaying = true;
6.       StartCoroutine(Cutscene());
7.    }
8.  
9.    IEnumerator Cutscene() {
10.       while(isCutscenePlaying) {
11.          //Cutscene stuff.
12.       }
13.    }
14. }

...And then just set

isCutscenePlaying

back to false whenever the cutscene finishes.

 

I tried bringing my bool out of the Coroutine, but it doesn't work. It tells me that I can't convert from 'bool' to a System.Func<bool>. This is the code

Code (CSharp):

1. //Start Cutscene
2. continueCutscene = false;
3.                     StartCoroutine(Cutscene());
4.  
5. IEnumerator Cutscene()
6.     {
7.         //Cutscene
8.         yield return new WaitUntil(continueCutscene);
9.         //Cutscene
10.     }

 

easier to do it like this

Code (CSharp):

1.     IEnumerator Cutscene()
2.         {
3.             //Cutscene Stuff
4.             continueCutscene = false;
5.  
6. while(continueCutscene == false)  {
7.             yield return null;
8. }
9.             //More Cutscene Stuff and End the cutscene
10.         }
11.  

 

Yes, that code worked! I just changed the if to summarize it as if (!continueCutscene), thank you very much!!

 

Code (CSharp):

1. //Useful when we want to hold a IEnumerator method which is using for/while loop until the passed "checkMethod" returns true
2. //It is needed coz in IEnumerator method we cant pass boolean variable by reference
3.  
4.  
5. using System.Collections;
6. using System.Collections.Generic;
7. using UnityEngine;
8. using kFramework;
9. public class CoroutineLoopTest : MonoBehaviour
10. {
11.     // Start is called before the first frame update
12.     void Start()
13.     {
14.         StartCoroutine(WrongWayToPauseLoop());
15.         StartCoroutine(CorrectWayToPauseLoop());
16.     }
17.     // Update is called once per frame
18.     IEnumerator WrongWayToPauseLoop()
19.     {
20.         print("Start");
21.         int index = 0;
22.         while (index <= 20)
23.         {
24.             //This will not stop while loop or for loop
25.             yield return null;
26.             print("WrongWay Index= " + index);
27.             index++;
28.         }
29.         print("End");
30.     }
31.     IEnumerator CorrectWayToPauseLoop()
32.     {
33.         print("Start");
34.         int index = 0;
35.         while (index <= 20)
36.         {
37.             //Hold the coroutine loop until space button is clicked
38.             yield return WaitUntilTrue(IsSpaceKeyPressed);
39.             print("CorrectWay Index= " + index);
40.             index++;
41.         }
42.         print("End");
43.     }
44.     bool IsSpaceKeyPressed()
45.     {
46.         return Input.GetKeyDown(KeyCode.Space);
47.     }
48.  
49.        public IEnumerator WaitUntilTrue(Func<bool> checkMethod)
50.         {
51.             while (checkMethod() == false)
52.             {
53.                 yield return null;
54.             }
55.         }
56.  
57.  
58. }

 

You are passing just a bool variable as a parameter to WaitUntil. That doesn't work like that.
I had the same error and I solved it like the following.

1. You may leave your code as is. Your continueCutscene variable it's okay.
2. Add the following line.

Code (CSharp):

1. private bool CanContinueCutScene() => continueCutscene;

3. Or alternativelly, add the following function, which it's equivalent.

Code (CSharp):

1. private bool CanContinueCutScene(){
2.     return continueCutscene;
3. }

4. Change your line

yield return new WaitUntil(continueCutscene);

to the following:

Code (CSharp):

1. yield return new WaitUntil(CanContinueCutscene);

That way, you are using your function as a way to "check" whether or not some condition has met.

The variable thing doesn't work because is just something that stores a value.WaitUntil requieres something that can check the value of something, thus a function.

 

Very solid explaination, fitted to my brain. Thank you

 

Yes you need a delegate, a Func<bool>, not a bool.

I'm surprised no one has mentioned lambda functions. It's much more concise.

Code (CSharp):

1. // Change this
2. yield return new WaitUntil(continueCutscene == true);
3.  
4. // to this
5. yield return new WaitUntil(() => continueCutscene);

There's no point in ever putting someBool == true. They always evaluate to the same thing.