[Webkit-unassigned] [Bug 237434] New: Precision issue in in Vertex Shader on iPads/M1 (but work on Intel Mac)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=237434

            Bug ID: 237434
           Summary: Precision issue in in Vertex Shader on iPads/M1 (but
                    work on Intel Mac)
           Product: WebKit
           Version: Safari 15
          Hardware: Mac (Apple Silicon)
                OS: iOS 15
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: WebGL
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: jean-sylvestre.zirani at hexagon.com
                CC: dino at apple.com, kbr at google.com, kkinnunen at apple.com

Hi, 


We are developing a geo-positioning application that uses WASM and WebGL. 

We have encountered a strange precision issue in the vertex shader. It happens only on Mac that are not using Intel chip and it happens in every browser that uses Webkit WebGL. 

The easiest way to reproduce the issue is to go to: 

https://prideout.net/emulating-double-precision

If you zoom on San-Francisco and tries to move the dogs around, on Apple M1/iOS you will encounter jittering in both views.

We don't have encountered the issue outside of Mac platforms. The right view is always smooth.



Cheers,
Jean-Sylvestre

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