Dev: 3D Object into AR with Flutter

I encountered a number of issues with getting complex 3d objects into a Flutter AR app. The Flutter AR components takes either a remote glft file, a format designed for loading 3 objects in a web browser; or sfb a format specific to Sceneform, a 3D rendering component for smartphones. The webformat is fine for simple objects that need to be loaded on the fly but anything with complex detailed textures can quickly run into big file sizes. Futhermore, I am hosting my files on Firebase Storage and a slft object is actually a bundle of files. I will need to handle this at some point, but my intitial task is to implement a complex and detailed 3d asset in the AR view. To do this, given the file size and the fact there will only be a few of them I wanted to embed the complex items with the app’s assets. This requires the SFB format. The trouble here is that there are different versions of the Sceneform plugin. The original version, by Google, was frozen in time, archived as version 1.17.1 and opensourced. This was a copy of the final closed-source version by Google (1.15.0). A further version is 1.16.0 which was built as a Gradle module and which supports the glTF format instead of sfa and sfb. glTF is supported within the Flutter ARCore module as a url based resource and not an asset. However, I could get around this by serving assets through an intergrated http server within my app for the complex static objects.

Yet despite these notices, upon testing the 1.15.0 version I WAS able to embed a remote glTF file using reference 3d objects from the KhronosGroup github repository. KhronosGroup being an American non for profit organisation which focuses on the creation of open standard, royalty-free API’s.

BUT, only some gltf models would show in the AR space.

A duck model works fine:

But, models that more akin to the type of thing I want to use would not show; such a lantern.

Both the duck and the lantern are part of the same Khronos 2.0 library; each has non-embedded textures – separate 2d png files and a bin file. But, something is prevent certain gltf files from rendering in ARCore but not others. If feel like getting to the bottom of this is going to be a drain on time but I do need a solution. And unless I can understand the constraints and limitations of using different types of 3d objects with different implementations of the SceneForm 3d engine; I will be feeling my way in the dark; and this is not how I like to proceed. I will carry out further tests before reaching a conclusion.


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