Cannot cast to base class on Windows 8 Phone/Store

Hello,

I'm developing and maintaining a tween engine for Unity, DOTween, but some users recently encountered an issue with Windows 8 Phone/Store (while everything works perfectly on all other platforms). After some investigation, it seems that the reason is that a derived class fails to be cast to its base one.

Specifically, I have a

Code (csharp):

1. public class Vector3Plugin : ABSTweenPlugin<Vector3,Vector3,VectorOptions>

which, when cast to its base, for example like this:

Code (csharp):

1. Vector3Plugin plug = new Vector3Plugin();
2. return plug as ABSTweenPlugin<Vector3,Vector3,VectorOptions>;

returns null if inside a DLL, or throws an exception

if used directly inside some lose scripts.

This cast should totally be possible, and happens only for Windows 8 Phone/Store targets. Any chance of a workaround, or even better of a possible fix?

Thanks.

 

Way to reproduce for me:
1) Open project from attachment
2) Build Windows Store, target Phone 8.1
3) Build in Release mode and ARM
4) Run on Windows Phone device
5) I see "Tween 2" on the screen, but it should be "Tween 1"

Visual Studio 2013, Unity 4.6.2f1

 

Just FYI, tried it on x86 Windows Phone emulator both from Unity 4.6.3 and Unity 5 RC3 - can't reproduce issue. Looks like a bug which only reproduces on ARM device.

 

@Gaspar could you do that? Since I don't have Windows 8 I can't report it correctly.

 

Reported. Case 676958

 

Hello,

Any news about this issue? That type of cast can't be replaced in the engine, and is severely breaking ports to the WP8 platform.

 

I dont know what else we can do except voting for this:
http://issuetracker.unity3d.com/iss...ss-fails-if-the-app-is-deployed-through-unity

 

I added a big balloon to DOTween's website to report this issue and with a link to the voting.

 

I'm a rather beginner C# programmer, so I'm not sure if this applies, but I found this StackOverflow discussion. It's a bit different, as it's a runtime issue in our case, and not a compiler one. But one of the answers suggests casting to object first and then to the desired type as a workaround, maybe this would help. I don't yet own a WP device, so I can't test it myself.

 

Thanks @myak, I think I tried that already, but I'm gonna try again to be sure.

 

Interesting news, thanks to Rafal who's helping me test various options to try and work around this issue. For now we were unsuccessful, but Rafal discovered an interesting things.

From VS:
Debug build works
Release build doesn't and generates the known error
Master build (which apparently should be the build to set for final production) works!

So in the meantime you can use master build. @Aurimas Cernius, maybe this info can be useful to you?

 

I encountered the issue, as stated by Izitmee the Master build will work if executed or deployed from Visual Studio.

Unefortunately it will not work if the build is deployed by others means, which can lead to issues during app certification or worst once the app is live on the store.

 

I have an idea for a way to fix this issue (even if I hope Unity fixes it on their side too), since this seems to happen only with Unity's "interchangeable" structs (Vector2/3/4, probably also Color/Color32), because they kind of break some rules of the C# language.

I'm sending a test copy to Rafal and we'll see.

 

Hi,

I've done 12 test builds Izitmee's test package with the following SDKs:

UNITY Windows Phone 8 platform: debug, release, master

UNITY Windows Store platform:
Universal App: debug, release, master
Phone 8.1 SDK: debug, release, master
desktop SDK 8.1: debug, release, master

In all cases the test passed correctly and with no debug errors.

Cheers,
Rafal

 

Note that @rafaellop's test passed correctly when tweening integers, not when tweening a Unity Vector3, which is the real issue. We're trying more tests now to find a workaround for that.

 

@Tautvydas Zilys Thank youuuuu I believe the reason is the way the implicit Vector2/3/4 (as well as Color/Color32) interchangeable cast is implemented in the Unity Engine.

 

Thank you @Tautvydas Zilys !

In the meantime I created an alternative version of DOTween which works on WP8.1 too (and on all other platforms). It's slightly slower (but just slightly) so I'll scrap it as soon as you'll have a viable alternative, but in the meantime I'm attaching it here. To make it work, I replaced Vector2/3/4, Color/Color32 and Quaternion (I actually thought Quaternion didn't fall into the issue, but after additional tests apparently it did too) with custom struct implementations, which implicitly cast to Unity's correct format only when applying the final values. That way, the "guilty" cast which couldn't happen is now happening and everything works.

Cheers!

 

Hi,

that is another interesting workaround, didn't think of that, thanks. I'm going to make some tests to see what might be the most efficient one and will report back.

 

Tests made. I was actually surprised, but apparently the Wrapper version is faster than the Surrogate one (the custom Vector3/etc implementations). Also, I made the tests many times, and I don't know how this is possible (and still believe my computer must've gone crazy), but it seems that the Wrapper version is even slightly faster than using Vector3 directly (I'm testing from a regular Win executable build).

Tweening 64,000 transforms (with disabled renderers) in a loop
Regular Vector3 version, average FPS: 29,5
Vector3 Wrapper version, average FPS: 29,75
Vector3 Surrogate version, average FPS: 28,4

Also, the Vector3 Wrapper version is the one that maintains the most constant FPS. I can only say that this is very nice. Thanks @Tautvydas Zilys

 

As long as it's faster I'm ok even if you explain it with chicken voodoo

 

Any news on this?

 

Thanks for the feedback, good point - I keep my eyes open for future builds.

 

Hey @MrEsquire, in the meantime you can download the Hyper-Compatible version of DOTween, which uses the workaround that Tautvydas suggested (just overwrite the existing files, run the Setup as usual, and the code stays the same).

 

@lzitmee I can argue why the workaround is faster than the "original" with the implementations of unity internal (you say they "because they kind of break some rules of the C# language" (I will like to know the specific observations).

I think wrapping them inside normal structs, make the compiler able to infer more things at compile/runtime for do a little optimization and that is why you see the difference, in other words this workaround not only help pass the error caused by the internal way unity does things, but also give more hints to the compiler on how to make it fast.

Im sure if you could reverse (engineer) some loops of the code and compare them, you will see more direct usage of the structs with the workaround than with their actual implementation.

So I hope that unity technologies does solve this for make other people code a little more fast (they already know it will).

 

Hi,

has this been fixed in Unity 5.4.2f2?

 

Nope, as far as I know.

 

@Izitmee Does the normal version of DoTween now work with UWP? Or should we still use the Hyper-compatible version?

Also, would it be possible for you to add a crossfade extension to audio sources? So we could crossfade between two audio sources. I'm still surprised this isn't part of Unity's native implementation.

 

@Tautvydas-Zilys You mean it's fixed? That would be awesome

@Ben-BearFish I have no way of testing it. If you could try it, to be on the safe side, and let me know it would be great About cross-fade, I do use DOTween to make cross-fades between audios (in my DeAudio library for example), but it's not something I can add directly into DOTween. I mean, it would go beyond it's scope, since it would mean dealing with multiple audio instances etc, so it's something I feel would be wrong to add to a tween engine

 

@Izitmee Understood. I didn't realize you wrote additional libraries. I'll look at DeAudio. Thanks. Does DeAudio work with the Hyper-compatible version of DoTween?

Also, after looking at the DeAudio API how does it know which audio to crossfade? I only see there is one parameter for an audioclip. Does it Crossfade the currently playing audioclip?

Are there any OnComplete events for Playing a clip?

 

Everything works with the hyper-compatible version

DeAudio also manages audioClips etc, so it knows everything that's currently playing. The cross-fade is just tweens fading out all playing clips, and another one fading in the new one.

 

Wohoooooo \o/

 

@Izitmee I was hoping to play Clip1, then Crossfade to Clip2 before Clip1 is over, then Crossfade to Clip3 before Clip2 is over, then Crossfade back to Clip1 before Clip 3 is over.

Is it possible to do something like this with DeAudio for a situation like I wrote? I can't seem to come up with a good solution for that yet.