Bug 171432 – gl.readPixels with type gl.FLOAT does not work

• Status: RESOLVED
• Resolution: FIXED
• Component: WebGL

Although floating point textures are supported through the "OES_texture_float" extension, reading back the pixels with

gl.readPixels(x, y, width, height, gl.RGBA, gl.FLOAT, pixels);

throws an error:

"WebGL: INVALID_ENUM: readPixels: invalid type"

A running example: https://cindyjs.org/examples/cindygl/34_cpuimagergba.html (It works with recent versions of Chromium and Firefox)

[Radar WebKit Bug Importer]

<rdar://problem/31905150>

[Michael Herzog]

One of the three.js example demonstrates the bug, too. It is broken since a while now. A fix for this issue would be great.

https://threejs.org/examples/webgl_read_float_buffer.html

[Dean Jackson]

Created attachment 366336 [details]
Patch

[EWS Watchlist]

Attachment 366336 [details] did not pass style-queue:


ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3545:  One line control clauses should not use braces.  [whitespace/braces] [4]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3547:  One line control clauses should not use braces.  [whitespace/braces] [4]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3563:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3564:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3565:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3566:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3567:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3569:  Extra space before )  [whitespace/parens] [2]
Total errors found: 8 in 5 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[EWS Watchlist]

Comment on attachment 366336 [details]
Patch

Attachment 366336 [details] did not pass ios-sim-ews (ios-simulator-wk2):
Output: https://webkit-queues.webkit.org/results/11709880

New failing tests:
fast/canvas/webgl/readPixels-float.html

[EWS Watchlist]

Created attachment 366357 [details]
Archive of layout-test-results from ews122 for ios-simulator-wk2

The attached test failures were seen while running run-webkit-tests on the ios-sim-ews.
Bot: ews122  Port: ios-simulator-wk2  Platform: Mac OS X 10.13.6

[Dean Jackson]

Created attachment 366365 [details]
Patch

[EWS Watchlist]

Attachment 366365 [details] did not pass style-queue:


ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3545:  One line control clauses should not use braces.  [whitespace/braces] [4]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3547:  One line control clauses should not use braces.  [whitespace/braces] [4]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3563:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3564:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3565:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3566:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3567:  Extra space before )  [whitespace/parens] [2]
ERROR: Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3569:  Extra space before )  [whitespace/parens] [2]
Total errors found: 8 in 6 files


If any of these errors are false positives, please file a bug against check-webkit-style.

[Antoine Quint]

Comment on attachment 366365 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=366365&action=review

> Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3547
> +        }

Style checker isn’t happy here, with reason!

[Dean Jackson]

Comment on attachment 366365 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=366365&action=review

>> Source/WebCore/html/canvas/WebGLRenderingContextBase.cpp:3547
>> +        }
> 
> Style checker isn’t happy here, with reason!

Nope, that's a style checker issue. This single line is a macro that's expanded to multiple statements.

[Dean Jackson]

Committed r243681: <https://trac.webkit.org/changeset/243681>