[Webkit-unassigned] [Bug 237434] 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

Don McCurdy <dm at donmccurdy.com> changed:

           What    |Removed                     |Added
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                 CC|                            |dm at donmccurdy.com

--- Comment #13 from Don McCurdy <dm at donmccurdy.com> ---
> The OpenGL ES drivers do not have the invariance feature and have different kinds of optimizations. Thus the solution does not work on these implementations, unfortunately.

Somehow I'm seeing the opposite behavior while debugging some vertex shader precision issues in the luma.gl (https://luma.gl/) test suite. Tests pass (Chrome 120.0.6099.109) under the OpenGL ANGLE backend — but only if I add the 'invariant' specifier, and tests fail without the specifier. Under the Metal ANGLE backend, the tests always fail on Apple M1/M2. The tests fail with or without the `invariant` specifier in Safari on Apple M1/M2.

Longer writeup and complete GLSL code in:

https://github.com/visgl/luma.gl/issues/1764#issuecomment-1858162100

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