[Android] unity white screen issue

[manasdigin]

Expected Result:
The Unity app should load and display content without requiring interaction with the system UI.

Actual Result:
The screen remains white until the smart sidebar is interacted with, after which the Unity content appears.

Video:
https://youtube.com/shorts/Engs5FKjqhc?si=NaFOy_6yDyEluvBk

Unity version: 2022.3.62f1

Android version: 15

Device model: IQ00 Neo7 pro

plugins used: flutter_embed_unity: ^1.3.1

Flutter version: 3.32.0 on channel

[timbotimbo]

[update]

I just noticed you have an earlier issue with a white screen too.
If this is still the same issue, test 4 is probably the most important, as you were already using an older Flutter version (without impeller) in that old issue.

I've seen white screens like these before in the past couple of years of using Flutter + Unity with 3 different plugins.
They are often a bug in Flutter, sometimes even limited to specific Android devices.
But it can also be a bug in this specific plugin.

I'd like you to try a couple of things to figure out if it is Flutter or this plugin.

1

In Flutter 3.32 the Impeller render engine is enabled on Android.
Can you try this with it disabled?

You can disable it in the androidmanifest file.

<application>
<!-- Add the following meta-tag inside the <application> tag -->
<meta-data
    android:name="io.flutter.embedding.android.EnableImpeller"
    android:value="false" />

2

Is your Flutter version exactly 3.32.0, or a hotfix release like 3.32.8?
You can check by running flutter --doctor.
If you are not using the latest hotfix release, try upgrading to 3.32.8.
The update is safe and should not have any breaking changes.

3

Do you have the white screen issue using the example app in this repo?
flutter_embed_unity/example

If not, maybe a specific transition or widget structure in your Dart code triggers this bug.

4

Because the bug could be specific to this plugin, we'll do a test with an alternative plugin (flutter_unity_widget_2).
flutter_embed_unity is a modern rewrite of that plugin, but it might have introduced a new bug.

Make sure to have a backup (or git source control) of your project before attempting this.

1. Copy or move your Unity project to <flutter project>/unity/<unity-project-folder>/.
   The old plugin assumes that fixed path.
2. Import the fuw unitypackage.
   You don't have to delete the flutter_embed_unity assets, they can coexist in the same project.
3. In Unity click Flutter -> Export Android (Release).
   You don't need to change any gradle files, the current setup should be enough.
4. Make sure your MainActivity.kt doesn't use the custom activity from this plugin.

import io.flutter.embedding.android.FlutterActivity
// import io.flutter.embedding.android.FlutterFragmentActivity;

class MainActivity: FlutterActivity() {  // class MainActivity: FlutterFragmentActivity() {
}

5. Now replace the plugin in Flutter pubspec.

# pubspec.yaml

# remove any lines with flutter_embed
- flutter_embed_unity_android_xxxx :    # if you manually include _2022 or _6000
- flutter_embed_unity: ^1.3.1
+ flutter_unity_widget_2: ^2022.3.0

6. Fix the plugin usage in Dart.
   Just comment out fuction usage like sendToUnity() or pauseUnity(), etc. We only need Unity to load and display.

- import 'package:flutter_embed_unity/flutter_embed_unity.dart';
+ import 'package:flutter_unity_widget_2/flutter_unity_widget_2.dart';


- EmbedUnity( ... )
+ UnityWidget(onUnityCreated: (_) => {}),

7. If Unity works without the white screen using this alternative, it is an issue in the flutter_embed plugin only.

5

If the white screen shows up in all options I mentioned above, try different Flutter versions like 3.29 or 3.35.

[manasdigin]

is this flutter_unity_widget_2 not supported with

Flutter version 3.32.0 on channel stable ?and im using this stable version cuz with this version im getting these error when i import and try to run

FAILURE: Build completed with 2 failures.

1: Task failed with an exception.

• What went wrong:
  Execution failed for task ':flutter_unity_widget_2:compileDebugKotlin'.

A failure occurred while executing org.jetbrains.kotlin.compilerRunner.GradleCompilerRunnerWithWorkers$GradleKotlinCompilerWorkAction
Compilation error. See log for more details

• Try:

Run with --stacktrace option to get the stack trace.
Run with --info or --debug option to get more log output.
Run with --scan to get full insights.
Get more help at https://help.gradle.org.
==============================================================================

2: Task failed with an exception.

• What went wrong:
  Execution failed for task ':app:mergeExtDexDebug'.

A failure occurred while executing com.android.build.gradle.internal.tasks.DexMergingTaskDelegate
There was a failure while executing work items
> A failure occurred while executing com.android.build.gradle.internal.tasks.DexMergingWorkAction
> com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives:
Learn how to resolve the issue at https://developer.android.com/studio/build/dependencies#duplicate_classes.
Type bitter.jnibridge.JNIBridge is defined multiple times: C:\Users\Metafocuz_Flutter.gradle\caches\transforms-4\c369deee139c34e8fd0e2b58e2e2cd3e\transformed\jetified-unity-classes\classes.dex, D:\Metafocuz\MetafocuzFlutter\build\app\intermediates\external_file_lib_dex_archives\debug\desugarDebugFileDependencies\2_jetified-unity-classes.jar:classes.dex

[timbotimbo]

That plugin works fine with 3.32.

I based those steps on the example project in this repo. I ran the example using flutter_embed_unity and then switched it over to flutter_unity_widget_2 and wrote down the steps. So I currently have it running here.

I just realized that I did miss a step,
I also changed the MainActivity to fix the AR bug.
Make sure to use an Acitivty from Flutter and not a custom one from this plugin.

Here is my current MainActivity.kt: (you could also use FlutterActivity).

import io.flutter.embedding.android.FlutterFragmentActivity;

class MainActivity: FlutterFragmentActivity() {
}

(i added this as a step in the instructions above).

Errors with unity-classes.jar and defined multiple times are a conflict between the 2 plugins and how they import that unity-classes file.
So I think your plugin still somehow includes both plugins.

Run flutter clean and make sure no version of flutter_embed is imported in your pubspec.yaml or any of your gradle files.
Also make sure to do the Unity export using the Flutter menu and not Flutter Embed.