Thanks for the update, iamtheonly.  I spent several hours trying to trim down a project to a very small reproducible case.  It's really tough and time consuming, the issue presents after 50 sometimes 100 scene restarts, but other times it's right away.  Very random.  Anyways, since the fix is working, I'm moving on.  The issue is definitely there.  Hopefully someone else will stumble upon this and be able to create the reproducible case and submit a proper bug report.



 

Hey there!

Sorry to get back to this so late. For me when testing on S8 I didn't have to "mash" the button to make this happen. The sample video you provided was a good repro case and should result in the black screen eventually. As dpizzle said, the problem is random though..

I do agree that this somewhat is a adversarial use case, but yeah, in the first post I mentioned that the app is going to be used on a fair where multiple exhibitors can take the phone and try the app and need the option to quickly reset the experience instead of closing and running the app again.

Anyways, the delay when initializing is working and it's not that noticable so I'm gonna stick with that.

Hello,

FYI, regardless of whether or not this is an adversarial case, I've opened a ticket for core engineering to look into the issue to see if there are ways to make Vuforia more robust.

Thanks,

Vuforia Engine Support

I agree, not standard at all, but the problem runs much deeper than this, this is just currently how I can reproduce on command every time.

The problem appears on normal scene switching in normal situations after Vuforia has inited. The problem is quite random though, and hard to figure.  

When I have time, I'll delve into it and provide a more normal example that reproduces often enough.  Please consider this issue open, until that time.

 

Hello,

I was able to reproduce by using your hint to press it multiple times in succession, without waiting for the background image to be re-rendered.

That being said, this use case seems adversarial and unlikely to occur in a real app. If you disagree, can you better explain the use case where you would reset a scene (with ARCamera) multiple times in succession, and not wait for Vuforia to complete initialization by using the provided APIs?

• Vuforia has initialized (before trackers and camera are started): VuforiaARController.Instance.RegisterVuforiaInitializedCallback(OnVuforiaInitialized);
• Vuforia trackers and camera have started: VuforiaARController.Instance.RegisterVuforiaStartedCallback(OnVuforiaStarted);
• bool hasVuforiaStarted = VuforiaARController.Instance.HasStarted;

Thanks,

Vuforia Engine Support

Everything looks right.  All the build settings are default, so you should be good on that.  Try mashing the button as fast as you possible can.  You're pressing it really slow.  

I'm pretty busy right now, but I'll attempt to get you a better reproducible case/project early next week.

Hello,

Here's our Unity project and testing on the iPhone 8 Plus: https://www.dropbox.com/s/ro2hp8yob33sxyg/iPhone8Plus.zip?dl=0. Let me know if you see anything obvious that we missed.

I suggest you share your test project by zipping up the Unity Project folder. Perhaps there is something in the build settings that differs?

Thanks,

Vuforia Engine Support

Unity 2018.3.2 and 2018.3.3

Vuforia 8.0.10

iOS 12.0.1



You're saying you created the project from the video, ran on an iOS device and then pressed the button as fast as you could, and it still didn't black screen?  

I'm really surprised, happens every time on all iOS devices we have.  Disconnect from xcode if you're debugging, seems to happen less when in that mode.

 

Hello,

Thanks for the additional info. Still no luck on our side using Unity 2018.3.3f1.

Can you provide the versions of Unity you're using? I don't see them referenced in this thread.

Thanks,

Vuforia Engine Support

Here's a video that might help debug things:  https://www.dropbox.com/s/bc9pyspsva7bh31/BlackScreenBug.mp4?dl=0  

I didn't say in the video, this was running on iPhone 8+.  We've seen on about 4 different iOS devices, so I doubt it's device dependent.

Also, I can confirm adding the delay like iamtheonly suggests, solves the issue for us as well.  

Hello,

We attempted to reproduce the issue but were unable to using these steps with SDK 8.0.10 & Unity 2018.3.3f1:

1. Created a new project, importing a Vuforia Core Samples 8.0.11
2. Opened the Ground Plane scene
3. Added functionality to reset the scene with the existing reset button
   • In PlaneManager.cs, in the ResetScene( ) function, added the following line of code at the bottom of the function:
     • SceneManager.LoadScene("3-GroundPlane", LoadSceneMode.Single);
   • This makes the reset button re-load the scene
4. Built and ran on Android and iOS
   • Tested with Galaxy S8 (Android 7.0)
   • Tested with Galaxy S6 (Android 6.0)
   • Tested with iPhone 7 (iOS 12.0.1)

Is this an accurate repro scenario? Are we calling LoadScene() with the same parameters?

Thanks,

Vuforia Engine Support

Hello,

Thanks for the report and follow-ups. We're looking into it.

-Vuforia Engine Support

Fixed using delayed initialization

Vuforia config -> delayed initialization

Disable Vuforia Behaviour on ARCamera

Run this in start

private IEnumerator DelayedInit()

    {

        VuforiaRuntime.Instance.InitVuforia();

        yield return new WaitForSeconds(0.1f); // Wait time to let init finish. If black screen still persists increase wait time

       

        Camera.main.GetComponent<VuforiaBehaviour>().enabled = true;

       

    }

Consider adding like a text with "loading" if it takes too long to start up whole thing.

Looks like Vuforia isn't checking if Initialization was complete to run Behaviour on automatic, and reloading scene somehow breaks this? No idea how this is different than first time app launch (works everytime)

Can't edit post due to some error

I've recorded a video how this looks: https://www.youtube.com/watch?v=huQ0Fy7FCtM

Yes please take a look at this Vuforia!  We are seeing this as well. Thanks iamtheonly, for creating a simple reproducable case, was about to do this today.

I have seen this on a range of IOS devices (iPad Pro, iPad 2018, and iPhone 8+).  I never encountered it prior to Vuforia 8, but can't be sure it wasn't there.  It seems to happen at random and can't quite figure out the cause.  At first I thought it had to do with loading a scene before Vuforia fully initializes, and thought I could work around it, but that's not always the case.  

And like iamtheonly said, tracking works fine, the camera view is just black.  On one of our projects we can recover by going to a different scene, on another one of our project, black camera view persists no matter what you do.