WebGL Xbox One Browser Compatibility

Hello, I tried to search but didn't find anything about console (Xbox One) Browser Compatibility for WebGL.

The official documentation https://docs.unity3d.com/Manual/webgl-browsercompatibility.html says:
"Note that Unity WebGL content is not currently supported on mobile devices. It may still work, especially on high-end devices, but many current devices are not powerful enough and don’t have enough memory to support Unity WebGL content well. For this reason, Unity WebGL shows a warning message when trying to load content on mobile browsers (which can be disabled if needed)."

But I don't know if they consider the Xbox One browser as a "mobile browser".

Does anyone know if the Xbox One browser can run (simple) WebGL games?
And are there some things that I should know if I target the Xbox One browser?

It's only a small 2d game that I want to show to friends, all of them have a Xbox One, but a few of them don't have a PC, that's why I would like to build for the Xbox One browser.

 

I made a very basic test with the default WebGL template and uploaded it to itch, the game was 2d pure UI without any input code. The game loads fine on the Xbox One Edge browser, size was a bit weird (something was cut off) but it seems to work fine in full screen mode. I played the game with the virtual cursor and the UI button worked fine too.

There was a message which said something about the app using custom input (I don't know the exact message, because I don't use the english browser) and the cursor was gone and I had to press a specific button (it's shown in a help popup) to return the virtual cursor. I didn't try to use any other input code, but since the app showed this message I assume that actual xbox controller input would work in game code and the app hides the cursor so you could use the stick for ingame controls instead.

I will maybe test some actual Xbox controller input in the future, but currently I don't need it, because my game is 2d with only UI button input, so I will just tell my friends to use the virtual mouse cursor to play my game.

But this was just a very simple / small prototype, my "real" game uses more "advanced" stuff like a C# JSON plugin and code to load files from the StreamingAssets and code to store/load strings in the PlayerPrefs, I will test if all of these things work in the Xbox browser at the weekend.

And I will use a different WebGL template for auto size scaling.

 

PS4 Pro with System Software 8.00: "Your browser does not support WebGL."

 

There seems to be a issue with System.Text.Json and WebGL, it doesn't throw any errors and the Deserialize method returns an object, but the object has a list property which is empty after the method call. The same code works just fine in the editor. I checked the browser console log and there is no error message at all.

I thought it maybe a error because I use custom generic JsonConverter<T> classes and create their instances with the Activator.CreatInstance, but I disabled code stripping and added some debug logs and they seem to be created properly, even with the generic Activator call, so I don't know what else could be the issue, because I don't know how the System.Text.Json Deserialize method is implemented.

I will try to add more debug log calls in the methods tomorrow, but kinda hard to find the error, because there is no error message, no way to debug the webgl build (or is there?) and every build takes very long for some reason, even on my gaming pc

 

Do you know Microsoft C# Blazor client side project? As far as I know they also use WebAssembly and you can debug the C# code in Visual Studio while debugging the web site. And if I understand correctly they don't even need to compile their C# code to C++ / WebAssembly because they wrote a (smaller) .NET runtime in WebAssembly which can interperte the C# code directly at runtime without compiling it to a different language. I don't know how they do it and maybe I understood something wrong, but maybe they could share some of their tricks

Buut back to topic, before I debug more or setup a bug report project: System.Text.Json is from a NuGet package. My Unity project is set to target .NET 4.x, so I downloaded the .NET 4.7 version (newest) of the NuGet package in a seperate C# project in Visual Studio and copied all the dlls from the package to my Unity Plugin folder. This is the "right" way to do it correct? Or is this not supported and only worked by coincidence in my Windows standalone build?
The package claims to be "cross platform" so no windows specific code and they even use it in their own C# web projects templates.They also have a package for .NET Standard 2.0, maybe I should try that one instead.

The weird thing is that the deserialize method call actually works, it creates the correct instance and doesn't throw, but doesn't fill the list property, so I assume that I *should* work and it's just a special case, maybe it's because of the custom converter to handle abstract types, I will check if the deserializer has some additional logging properties.


Update:

I added additional debug logs can I can confirm that the error happens, because Lists are not deserialized at all, this isn't even related to converters like I thought before, because it also happens with other classes, which don't have a custom converter.

But I had a similar problem when I first started with System.Text.Json the problem was that the List property needs a public setter, because it doesn't fill existing List instances unlike Newtonsoft.

// This doesn't work with System.Text:Json, because a public setter is needed
public List<MyClass> Items { get; } = new List<MyClass>();

// This works just fine in Unity windows build and editor but not during WebGL build
public List<MyClass> Items { get; set; } = new List<MyClass>();

Note: The setter is not used anywhere else other than the initialize value and during deserialization. But the property getter and list members ARE used in game code.

This there any chance that IL2CPP somhow removes the setter, because it "thinks" that the setter isn't needed, because it's only used during reflection?

Btw I disabled code stripping, so it can't be that, maybe it's some other kind of optimization?

 

Okay I give up on System.Text.Json I made a new small example project, for some reason it throws an actual exception in this new test project, but I still don't know how to fix it. The code works just fine in editor, but fails again during WebGL.

Should I upload the project somehwere, so you can have a look at it?

The problem (at least with the int property) seems to be that the deserializer uses some generic stuff and there is no AOT code for these. And I don't know how to force AOT to generate the code for these, because the classes are internal.

In the mean time I will write my own simple json reader/writer which doesn't require any generics or custom converters, the format is very simple anyways and I need special support for abstract types which requires converter hacks in both System.Text.Json and Newtonsoft anyways. Hopefully it will work in WebGL or at least I will have full access to the code, to debug it properly. And it will not require all these external dlls, I have to import 9 depending dlls just for System.Text.Json.

 

I tried windows build with IL2CPP and I get the same error there, so it's a problem with AOT, it's a very long stack trace, but the actual error happens, because it can't create an instance of type System.Text.JsonPropertyInfoNotNull'4 (so generic), because no AOT code was generated for it.

It's a class that the serializer uses internally, I have no control over it, so I can't add any attributes or other workarounds.

 

If you need JSON parser that works with Unity and WebGL, Unity maintains newtonsoft.json package.
https://docs.unity3d.com/Packages/com.unity.nuget.newtonsoft-json@2.0/manual/index.html

it's written there that it's for internal use, but according to one of the maintainers the package is supported.
https://forum.unity.com/threads/newtonsoft-json-package.843220/

 

I spent a few hours to write my own json (de)serializer annnd it didn't work with IL2CPP (at first), but after reading the documentation I realized that the Windows IL2CPP supports C# debugging, so I attached the debugger to the player and my deserializer uses reflection PropertyInfo.CanWrite to check if the property should be read, but the CanWrite returned false during the IL2CPP build even with a public setter, because the setter wasn't used any where other than the initializer and the IL2CPP build thought it's a good idea to remove the setter (tbh it's a bad to remove a public property setter during the build, I mean we made it public for a reason and not for fun, but that's a different topic).

After spending some more time in the documentation I added a link.xml and added a single line to preserve the whole dll, because Im not going to bother to add a attribute to every single "dummy" data class.

So end of the story. It finally works with IL2CPP build and I could run it on the Xbox and I learned many new things about Unity / IL2CPP..

Btw I search for "Unity IL2CPP PropertyInfo.CanWrite" and other people have similar problems and frustration, maybe they should move this property "optimization" to a higher lever, because my stripping level was set to low and it still happend.