[Webkit-unassigned] [Bug 282111] New: Float Texture Linear Interpolation Alternatives for iOS

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=282111

            Bug ID: 282111
           Summary: Float Texture Linear Interpolation Alternatives for
                    iOS
           Product: WebKit
           Version: Safari 18
          Hardware: iPhone / iPad
                OS: All
            Status: NEW
          Severity: Blocker
          Priority: P2
         Component: WebGL
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: ar.sedghi at gmail.com
                CC: djg at apple.com, kbr at google.com, kkinnunen at apple.com

Created attachment 473049

  --> https://bugs.webkit.org/attachment.cgi?id=473049&action=review

Correct vs Incorrect rendering

iOS Safari lacks support for the `OES_texture_float_linear` WebGL extension, which is critical for medical imaging applications requiring linear interpolation of floating-point textures. This extension is supported on other major platforms and even on iPadOS, making iOS Safari an outlier. see https://developer.mozilla.org/en-US/docs/Web/API/OES_texture_float_linear

## Issue Description
When attempting to render medical images that use floating-point textures with linear interpolation in WebGL, the rendering fails specifically on iOS devices, while working correctly on other platforms including:
- Desktop browsers
- Android devices
- iPadOS


## Impact
This limitation significantly affects medical imaging applications, particularly:
1. PET (Positron Emission Tomography) scan visualization as their data is float32
2. AI probability maps 
3. Any other aspects of imaging that are float

## Technical Details
- Extension: `OES_texture_float_linear`
- MDN Reference: https://developer.mozilla.org/en-US/docs/Web/API/OES_texture_float_linear
- Current Behavior: Extension is unavailable on iOS Safari
- Expected Behavior: Extension should be available as specified in WebGL standards

## Reproduction Steps
1. Visit https://viewer.ohif.org/viewer?StudyInstanceUIDs=1.3.6.1.4.1.14519.5.2.1.7009.2403.334240657131972136850343327463&seriesInstanceUIDs=1.3.6.1.4.1.14519.5.2.1.7009.2403.879445243400782656317561081015
2. It shows a PT image data rendered in a viewport, it should look black with some bright spots
2. See on iOS the rendering is different than desktop

## Questions
1. What is the rationale behind not supporting `OES_texture_float_linear` on iOS Safari?
2. Are there any recommended alternatives for achieving linear interpolation of floating-point textures on iOS?

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