Bug 261270 - Texture swizzling disabled in ANGLE on iOS simulator
Summary: Texture swizzling disabled in ANGLE on iOS simulator
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: ANGLE (show other bugs)
Version: Safari Technology Preview
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2023-09-07 04:21 PDT by Kimmo Kinnunen
Modified: 2023-09-14 04:22 PDT (History)
6 users (show)

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Description Kimmo Kinnunen 2023-09-07 04:21:28 PDT
Fails:
webgl/2.0.y/conformance2/extensions/webgl-stencil-texturing.html

Alexey writes:
The iOS-16-Simulator-WK2-Tests-EWS failure in conformance2/extensions/webgl-stencil-texturing.html that blocks https://github.com/WebKit/WebKit/pull/17476 caused by the following:
That test asserts sampling both depth and stencil values.
The ES 3.0 spec defines sampled depth as [D, 0, 0, 1.0].
MSL spec explicitly says that green, blue, and alpha values are undefined. In practice it's either [D, 0, 0, 1.0] or [D, D, D, 1.0].
ANGLE uses texture swizzling to enforce ES 3.0 values for unused channels.
Texture swizzle support has been force-disabled on iOS Simulator during the initial WebKit-to-Chromium ANGLE upstreaming.
https://chromium-review.googlesource.com/c/angle/angle/+/2950067/33/src/libANGLE/renderer/metal/DisplayMtl.mm#954
Comment 1 Radar WebKit Bug Importer 2023-09-14 04:22:14 PDT
<rdar://problem/115485988>