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Incorrect output on some hardware when gl.clearColor arguments identically zero
Reported by
ri...@standardcyborg.com,
Dec 12 2017
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Issue descriptionUserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Safari/537.36 Steps to reproduce the problem: 1. create a webgl context 2. create a floating point framebuffer using oes_texture_float extension 3. clear the framebuffer with color [0, 0, 0, 0] 4. draw a triangle to the framebuffer with color [1, 0, 0, 0.5] and blending (gl.ONE + gl.ONE_MINUS_SRC_ALPHA) 5. draw the framebuffer to the screen using blending (gl.ONE + gl.ONE_MINUS_SRC_ALPHA) What is the expected behavior? A 50% opacity red triangle is drawn to the screen. What went wrong? Output is a white screen with no triangle, but only on some computers. A workaround is to set any of the components in the color in step 3 to not-identically-zero. For example, clearing the floating point framebuffer in step 3 to [0, 0, 0, 1e-30] fixes the problem on affected computers. Changing the 50% opacity a bit, it seems to be merely completely blown out (saturated at rgb = [1, 1, 1]). It could be some color space issue or some other optimization, but the output seems exceptionally washed out and displays a sharp cliff between identically zero and almost-zero clearcolors. My computer has specs: MacBook Pro (Retina, 13-inch, Early 2015) Processor: 2.7 GHz Intel Core i5 Memory: 8 GB 1867 MHz DDR3 Graphics: Intel Iris Graphics 6100 1536 MB My nearly-identical macbook pro (Late 2013, Retina, Intel Iris 1536 MB) works fine. Every other laptop in the office of ten works fine. However, we're aware of some client's computers that also display the same bug. Did this work before? Yes 59.0.3071.86 Does this work in other browsers? N/A Chrome version: 63.0.3239.84 Channel: stable OS Version: OS X 10.11.6 Flash Version: Chrome version <= 59.0 displays the expected result Chrome version > 59 displays a white screen Firefox latest displays the expected result This is also visible in the plotly.js library with this test mock: https://rreusser.github.io/plotly-mock-viewer/#gl3d_bunny Firefox and Chrome <= 59.0 display the expected plot. Newer chrome displays a nearly-white screen. Results attached above. Changing the clearColor to not-identically-zero fixes this problem also. That bug report is here: https://github.com/gl-vis/gl-plot3d/issues/9
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Dec 12 2017
One last note is that we create thumbnails on the client so we know for certain that this is occurring on at least two separate computers. I don't know details about the client's computer. Otherwise we were inclined to chalk it up to a glitchy gpu, but it seems a bit unlikely it would fail in exactly the same way if just a bad gpu.
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Dec 12 2017
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Dec 12 2017
Could this be related to bug 792966 ?
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Dec 12 2017
Unable to reproduce the issue on reported chrome version 63.0.3239.84 using MacBook Air Sierra 10.12.6, we have also checked it on MacBook retina 10.12.6 and MacBook retina 10.13.1, still unable to reproduce the issue with steps mentioned below: Steps followed to reproduce the issue: 1) Launched chrome and navigated to URL: https://codepen.io/rsreusser/pen/MrgNda 2) Able to see red triangle on the screen as expecetd @Reporter: Can you please try to test the issue by creating a new person on your Mac 10.11.6, if the issue still persists can you please upgrade your Mac to 10.12.6 Sierra or 10.13.1 High Sierra and try to reproduce the issue Thanks!
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Dec 12 2017
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Dec 12 2017
It's not related to 792966. Reporter, your machine is on an outdated macOS 10.11.6. Have you seen other machines in your office with 10.11 which don't see this problem? I suspect it may have been fixed in 10.12.
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Dec 14 2017
I didn't expect the OS upgrade to fix this since it remained dependent upon the Chrome version, but upgrading to os x 10.13.2 leads to the expected behavior. I'd failed to re-upgrade after wiping my work computer. We'll retain our failsafe since it's best if it doesn't fail for users. I'm content to consider fixed, close, and hope it serves as a sign post in case someone else encounters it. Thanks.
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Dec 14 2017
Thank you for providing more feedback. Adding requester "sc00335628@techmahindra.com" to the cc list and removing "Needs-Feedback" label. For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot
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Dec 14 2017
Submitter: we don't have any 10.11 machines in house any more so can't verify this, but if you run this variant of your pen: https://codepen.io/anon/pen/xpbBNB what is printed to the console? If we can detect this bug via gl.readPixels then we can write a conformance test for it. I'm not 100% sure if just the on-screen result is wrong, or if the actual WebGL rendering result is.
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Dec 14 2017
@Reporter: Can you please respond to Comment#10, hence adding Needs-Feedback label Thanks!
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Dec 14 2017
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Jan 22 2018
Mac triage: marking this WontFix. Reporter in #8 remarked that they are happy to have this issue closed (and have upgraded their machine) so followup is unlikely. |
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Comment 1 by ri...@standardcyborg.com
, Dec 12 2017