[Webkit-unassigned] [Bug 229986] New: WebGL Canvas will not update when using putImageData with small area update.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=229986

            Bug ID: 229986
           Summary: WebGL Canvas will not update when using putImageData
                    with small area update.
           Product: WebKit
           Version: Safari 14
          Hardware: Mac (Intel)
                OS: macOS 11
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: WebGL
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: lktc420 at hotmail.com
                CC: dino at apple.com, kbr at google.com, kkinnunen at apple.com

Created attachment 437468

  --> https://bugs.webkit.org/attachment.cgi?id=437468&action=review

The issue html that can reproduce the bug.

Overview: 

When using Three.js WebGLRender and use canvas texture, if the canvas call putImageData with small area, the associate WebGL canvas will not update image.

Steps to Reproduce: 
You can 100% easily reproduce the bug using the attachment index.html.
Just click the page to see if the canvas update and showing a small rect with random color updating.

And see this comment in file:
// Without below 2 lines, the webgl canvas will not update.
// textureCanvasCtx.fillStyle = '#00000000';
// textureCanvasCtx.fillRect(0, 0, 0, 1);

this is the workaround to fix it.

Also, when enable canvas recording in inspector, the webgl canvas will update correctly, wierd problem.

Actual Results: 
When click page, webgl canvas not updating to show the small rect.

Expected Results: 
When click page, webgl canvas should updating to show the small rect.

Build Date & Hardware: 
MacOS 11.5.2
Safari 14.1.2

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