How to wait for a frame in c#?

in java:
functionABC()
{
...;
yield;
...;
}
how to wait for "just a frame" in c#?
thx

 

What you want to do is start a coroutine:

http://unity3d.com/support/document...oBehaviour.StartCoroutine.html?from=Coroutine

So in your case

Code (csharp):

1.  
2.  
3. void Start()
4. {
5.  StartCoroutine(ABC());
6. }
7. IEnumerator ABC()
8. {
9.  
10. //returning 0 will make it wait 1 frame
11.  yield return 0;
12.  
13. //code goes here
14.  
15.  
16. }
17.  
18.  

 

or another way:
var i : int = 0;

function update () {

i=i+1;

if (i==2) {
print("this message prints every second frame");
i=0;
}

}

 

Update can run many times per frame, but it's close.

You could try to set something up with FixedUpdate, which runs every frame, based on a set frame rate.

 

Are you sure about this? I thought Update() was defined to execute exactly once per frame. How else would this be accurate?

http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.Update.html

You sure you're not thinking of OnGUI() ?

 

No, just once per frame.

Don't use FixedUpdate for anything except physics code; that's what it's for.

Anyway, the correct answer to the original question is "yield return null". (You can make Start return an IEnumerator; you don't have to start a coroutine.)

--Eric

 

thanks!

 

My bad, ignore late night advice.

Update runs many times per second,(many frames per second), and I got turned around.

 

Here is small class to wait for some amount of frames:

Code (CSharp):

1. public static class WaitFor
2. {
3.     public static IEnumerator Frames(int frameCount)
4.     {
5.         while (frameCount > 0)
6.         {
7.             frameCount--;
8.             yield return null;
9.         }
10.     }
11. }

Here is how you can use it:

Code (CSharp):

1. public IEnumerator CoroutineAction()
2. {
3.     // do some actions here  
4.     yield return StartCoroutine(WaitFor.Frames(5)); // wait for 5 frames
5.     // do some actions after 5 frames
6. }

Found this class here: http://druss.co/2015/05/unity3d-waitforframes-in-coroutine/

 

Absolutely reviving this thread to ask question about that last answer; When you ask for the return of the Coroutine "Frames", it actually waits for the coroutine???? I had previously searched for a way to wait for coroutine to be finished and heard nothing useful!

 

You don't actually have to do a StartCoroutine there, so it's even simpler:

Code (csharp):

1. public IEnumerator CoroutineAction()
2. {
3.     // do some actions here
4.     yield return WaitFor.Frames(5); // wait for 5 frames
5.     // do some actions after 5 frames
6. }

The rules are:
- if you yield a YieldInstruction - like WaitForSeconds or a custom one - the coroutine waits until that returns false for
keepWaiting
- if you yield an IEnumerator or a StartCoroutine, you start that coroutine, and your current coroutine waits until the inner coroutine is done.
- if you yield anything else, you wait a single frame.

 

Here's a question, and possible solution to the original question.

If I use WaitForSeconds in an IEnumerator, and set the time to 0, will the coroutine start again next frame, or immediately?

For example:

IEnumerator ExampleCoroutine()
{
First();
yield return new WaitForSeconds(0);
Second();
}

Will Second() happen on the same frame as First(), or one frame later?

 

My two cents, what about that already present one? https://docs.unity3d.com/ScriptReference/WaitForEndOfFrame.html

 

Hi My i have a simple script!

Code (CSharp):

1. public float ABC;
2. public float framesToWait;
3. void Start{ABC = 0}
4. void Update{ABC = ABC + 1;
5. if (ABC > framesToWait}

 

1. 
   
2. 
   
3. void Start()
4. {
5. StartCoroutine(ABC());
6. }
7. IEnumerator ABC()
8. {
9. 
   
10. //returning 0 will make it wait 1 frame
11. yield return 0;
12. 
    
13. //code goes here
14. 
    
15. 
    
16. }

so i used this script and it actually waited for one frame when i understood it...
but... even when i changed the yield return it kept on waiting only one frame
pls help me wait different amount of frames in this script. (i understand this script and i want to keep doing things i know instead of breaking my head trying to understand other scripts...) if u have any other SIMPLE scripts i might try them.


thx, Tom Markovich.

 

You can also avoid something to be recalled the same frame:

Code (CSharp):

1. public struct OneTime
2. {
3.     private int _frameCount;
4.  
5.     /// <summary> Is first time called this frame? </summary>
6.     public bool IsFirstTimeCalledThisFrame()
7.     {
8.         bool result = _frameCount != Time.frameCount;
9.         _frameCount = Time.frameCount;
10.      
11.         return result;
12.     }
13. }

Then in whatever you don't want to be called more than once in the same frame:

Code (CSharp):

1. // Field:
2. private OneTime _oneTime;
3.  
4. ...
5.  
6. // Avoid recalling the same frame.
7. if (!_oneTime.IsFirstTimeCalledThisFrame()) { return; }

 

To extend on my own answer, looks like after Unity 2018 we got: await Task.Yield()

Tested example:

Code (CSharp):

1.     private async void TryNextFrame()
2.     {
3.         Debug.Log($"{Time.frameCount} Current frame.");
4.         await Task.Yield();
5.         Debug.Log($"{Time.frameCount} This log will appear next frame...");
6.     }
7.  

 

Not the best solution, and coroutines are definitely cleaner, but sometimes that's handy:

Code (CSharp):

1. bool waitForOneFrame = true;
2.  
3. private void Update()
4. {
5.     if (waitForOneFrame)
6.     {
7.         waitForOneFrame = false;
8.     }
9.     else
10.     {
11.         // your code
12.     }
13. }