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RegisterVuforiaStartedCallback no longer fully works

August 30, 2016 - 2:45pm #1

Vuforia SDK Version: 6.x -

Description with steps to reproduce: Previously, we use this callback to know that vuforia is truely done doing everything it needs to do. We have found many cases where it's not really ready if you're doing anything complex. So far, we only see the behavior in the editor....but it's worrysome...and unproductive because we now have to do builds to test something...or write hacky code to get around it. Here's a cute way to expose it...

- have 2 scenes. Both have vuforia (an ARCamera).
- the first scene to load, register a callback to vuforia, RegisterVuforiaStartedCallback, then handle that event and immediately set vuforia.enabled to false (shut it down).
- then at your leisure, load the other scene either via code or a button or whatever. The other scene can just be an ARCamera.

You will get a "Could not deinitialize the tracker."...which i presume throws vuforia into a bad state, which then screws us up for the next scene. During the next scene, you'll see a "cant create dataset".

- if you repeat the steps above, but replace the correct callback with one that we know happens even later, such as RegisterBackgroundTextureChangedCallback...then no problem. You can also use the first callback, but then add a StartCoroutine for a delay. These things tell me that something wasn't really finished before we got the RegisterVuforiaStartedCallback.

Here's a quick chunk of code to automate this: http://codepaste.net/7he7t3

win7 64, unity 5.4, vuforia 6.x
// reason we noticed was that we have some stuff failing after upgrade...all related to this callback...all fixed by adding a delay


Development OS (Mac OS X, Windows, Linux): win7 -

Mobile OS and Version: android -

Mobile Device Manufacturer and Model name: any -

Do the Vuforia Sample Applications show the same behavior?: do

RegisterVuforiaStartedCallback no longer fully works

October 5, 2016 - 10:45pm #7

I can't remember if it was on device or not...cause I already worked around it some time ago. If you guys found it, but it was only on the editor...that would still be something to fix since it stops development...that's probably how I found it...and i would never do something one way on the editor, but another way on the platform...cause you could never debug complex problems then.

To your suggestion though....

We only have one scene file in this instance. Everything that needs to run at some point...gets initialized but then paused or disabled. Imagine you want to display something else first...and it includes whatever expensive thing...so you turn off systems that you dont need. Vuforia is one of those.

What I do now instead of the above...is the scene simply has no ARCamera. When I first need the functionality...I create one.

Anyway this was just one example...at the time when i found this...that wasn't the only thing getting screwed up from that callback. Basically...today...everytime I need that callback I just use the background update callback because it truely can't run unless vf is truely finished. I would prefer to go back to the other one though when the editor works the same as the platform (i'm assuming you're correct that it only happens in the editor).

my current higher priority is this: https://developer.vuforia.com/forum/arvr-switching-overrides-world-center-mode

and general iOS10 instabilities...not sure yet if it's vuforia, unity, or ios10

RegisterVuforiaStartedCallback no longer fully works

October 5, 2016 - 11:31am #6


Thank you for your patience as our core engineering team investigated your report.

We believe we've found the root cause, but it seems this is specific to Play Mode. Please again confirm that you are seeing this behavior on device.

Additionally, there is confusion about your app stopping Vuforia immediately after starting it, just to then load a different scene (which re-initializes Vuforia from scratch). Could you either:

  • Deactivate the VuforiaBehaviour before starting it
  • Not use Vuforia in the first scene at all

In both cases we don't believe you would have this problem.


RegisterVuforiaStartedCallback no longer fully works

September 8, 2016 - 2:49am #5

Sorry I can't go into several specifics. PM is still outside of my company.

But...the simplest case would be exactly the case in the test code. I realize that most AR apps are pretty trivial and silly. But at a professional level..the first thing you do is disable vuforia after it loads so you can display something on top of it or any number of other things. Instructions for example. Oh but you can just let vuforia run anyway...the UI will cover it. But...again...in a professional setting that doesn't fly. You can't pass cert with that kind of stuff. Fudging around just leads to more and more fudging and pretty soon you have a mess. That's actually *why* you had that callback...and in 6.x its freshly broken.

RegisterVuforiaStartedCallback no longer fully works

September 7, 2016 - 12:36pm #4


Can you please provide me with details about the types of app use cases where this callback's issue was observed?

Feel free to PM me with details if you so choose.


RegisterVuforiaStartedCallback no longer fully works

August 31, 2016 - 5:26pm #3

Ah yes...sorry...it's the unity extension...6.0.114

RegisterVuforiaStartedCallback no longer fully works

August 31, 2016 - 1:34pm #2


Thanks for the report. I have escalated to core engineering for review.

Can you please confirm if the Vuforia Unity Extension version is 6.0.112 or 6.0.114?


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