gltf node with simetric transformation aren't display in AR with safari on ios

[denis-bolomier-pch]

Description

When Im loading a gltf, all node that have been reverse along an axe doesn't display in the AR view on IOS

the model in my Iphone

the same model in ar mode

As you can see the following pyramid aren't display:

• the front, bottom,right
• the up, back, right

As you can see the following pyramid are display in the wrong orientation:

• front, top, left

The gltf have been created with a mesh called several time with a different transformation.
TEST REVERSE.gltf.zip

Live Demo

https://v.pch.click/viewer.html?short_id=PREQV

Version

https://unpkg.com/@google/model-viewer/dist/model-viewer.min.js

• model-viewer: v1.8.0

Browser Affected

• Chrome, version: xx.x.xxxx.xx
• Edge
• Firefox
• IE
• Safari

OS

• Android
• iOS
• Linux
• MacOS
• Windows

AR

we use the following syntax to have AR

• WebXR
• SceneViewer
• QuickLook

[elalish]

IIRC this is a deficiency in the USDZ format (or at least the way Quick Look interprets it). They don't appear to switch their back-face for a mirroring transform. The only way three.js could work around this is to duplicate geometry, which is complicated and inefficient. Please file a bug on Apple. FYI @mrdoob.