3D Model viewer not loading

user_8929068 0
Viewed 1667

I am using a flutter library called Model Viewer ModelViewer

That's a very nice plugin which works like charm on my dev version of that app. I am using it like this:

  ModelViewer(
          backgroundColor: Colors.black,
          src: 'assets/skull.glb',
          alt: "A 3D model of a skull",
          cameraControls: true,
        ),

And the .glb model is in the assets folder. My flutter is latest stable version as well as the version of this plugin.

The strange thing it that when I build the app bundle and publish the app on google play, when I navigate to the page with the model viewer the widget never loads.

I can only see a white screen.

Both the dev version and the release are tested on a physical device with android 10.

I am not sure how to debug this but would be happy for any suggestions. Can't find any solution from the original repo.

UPDATE

That's the error from the logcat:

2021-04-07 21:42:49.592 8121-8147/? E/flutter: [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: NoSuchMethodError: The getter 'address' was called on null.
    Receiver: null
    Tried calling: address
    #0      _ModelViewerState.build.<anonymous closure> (package:model_viewer/src/model_viewer.dart:127)
    #1      _ModelViewerState.build.<anonymous closure> (package:model_viewer/src/model_viewer.dart:125)
    #2      _WebViewState._onWebViewPlatformCreated (package:webview_flutter/webview_flutter.dart:375)
    #3      CupertinoWebView.build.<anonymous closure> (package:webview_flutter/src/webview_cupertino.dart:35)
    #4      AndroidViewController.create (package:flutter/src/services/platform_views.dart:746)
    <asynchronous suspension>
    #5      RenderAndroidView._sizePlatformView (package:flutter/src/rendering/platform_view.dart:195)
    <asynchronous suspension>

Thank you.

dart flutter google-play android
2 Answers

Yes, you need the internet permissions,

A local server is created by the library (in model_viewer.dart) using _proxy = await HttpServer.bind(InternetAddress.loopbackIPv4, 0);. The WebView connects to this server and displays the model. The web server which we created with HttpServer.bind provides a few files: an html file, a javascript file, the model, and the favicon.ico too.

The code doesn't change based on debug/ release, but it's actually because the debug mode build automatically has this permission which allows internet access, but the Android release one does not. So the WebView successfully connects to the server only in debug. I only found out about this automatic internet permission for debug build from here. Therefore, building the release application (without uploading to the Play Store) should also catch this issue.

Most people won't find this an issue because their apps will need the internet permission by the time they get to adding a 3D model, or they're using a remote 3d model. I've replied to the GitHub issue about this with suggestion on adding the permission to the README. You might be interested to create a PR about that to the repo. :)

user_73658660

Found the solution to this problem.

When you use the Model Viewer you will need to add:

 <uses-permission android:name="android.permission.INTERNET"/>

to your AndroidManifest.xml file.

This way the Widget will be able to simulate the model.

Normally it does it on a local server a.k.a localhost, but when it's released this is changed.

Hope someone will find it useful.

user_89290680
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