Fixed scaling not working in iOS AR QuickLook when auto generating USDZ

[milesgreen]

Description

Auto-generated USDZ is amazingly awesome. Thanks for all the work that has gone into that @elalish, @kolodi, @mrdoob !

While testing out this feature, it appears that setting ar-scale="fixed" in conjunction with using auto-generated USDZ, is no longer forcing the scaling to be fixed in QuickLook. The user is able to scale the object.

When not using auto generation and providing an ios-src USDZ path and setting ar-scale="fixed", this still works, and the user is unable to scale object in QuickLook.

Live Demo

https://muddy-pinnate-rutabaga.glitch.me/

Version

• model-viewer: v1.7.1

Browser Affected

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

OS

• Android
• iOS
• Linux
• MacOS
• Windows

AR

• WebXR
• SceneViewer
• QuickLook

[elalish]

Yes, I believe this is because Safari does not handle query params on Blob URLs. I believe this means the whole Quick Look API is killed off, which is unfortunate. Please file a bug on Apple.

[uprealdigital]

ok I get it but why does it work when specifying a Usdz file? Isn't it passing a parameter there as well?

[elalish]

In that case it's passing a normal string URL, on which query params work. When we auto-generate, we have to pass a Blob, which is where their bug is.

[uprealdigital]

Ah ok gotcha! Thanks for the explanation!
I guess the way to go is to provide a usdz file to avoid those kinds of hurdles. Cheers

[maciekglowka]

Thanks for pointing this issue.
I've had recently a problem with auto-generated usdz not being displayed in quick look at all. The spinner just keeps spinnig.
It seems that removing ar-scale param solves the problem for now.
Although I'd like to have a fixed scale eventually.
(I've seen the problem on iOS 15.2)

http://tests.glowka.atthost24.pl/ - a small test with ar-scale set to fix, where the problem can be seen.

[seadeep42]

Happened to me too.

Took me a while to realize ar-scale is crashing the quick look on iOs. Would it be helpful to add this as a note in the documentation?

[maciekglowka]

This, or do not attach it to usdz blob for now.

[elalish]

Indeed, I can repro. Actually I had a similar experience when I loaded https://modelviewer.dev/examples/scenegraph/#variants the first time in Quick Look (it took ages, but did eventually work), but the second time it was fast (that one does not have ar-scale set. But yes, it seems markedly worse with the ar-scale attribute. Agreed we should probably just disable this until Apple fixes it. Would any of you be so kind as to file a bug or two on https://bugs.webkit.org/ about this? That's the best place I've found to report Quick Look issues.

[maciekglowka]

Thanks
Reported: https://bugs.webkit.org/show_bug.cgi?id=236069

[elalish]

@grorg Here's a QuickLook issue for you, and it even has a webkit bug! For everyone else, @grorg works at Apple and said he'd love to be notified of any Apple-related problems we have (thank you!), so please feel free to @ mention him.

[milesgreen]

Fixed scaling when using auto USDZ now works in Safari iOS 15.5