Site appears to have changed to no longer have blue background - tried setting the color manually, but didn't see the artifact at that point. Also checked archive.org, but it shows a white background a ways back (maybe the CSS isn't archived and is pulled from a live source?).

I'm guessing we'll have to investigate when this shows up again on another site. Let me know if there's anything else needed to repro.

Repro case: https://www.adobe.com/products/photoshop/features.html

Stripes appear when --gpu-rasterization-msaa-sample-count=2 or more
Stripes disappear when MSAA is disabled by setting it to 0: --gpu-rasterization-msaa-sample-count=0

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You can click the "Dark mode" button on the right sidebar to turn on the blue background.

Unable to reproduce this issue on Windows 10 with chrome version  #58.0.3004.3

Observed that with flag --gpu-rasterization-msaa-sample-count=16, didn't see any artifact in websites "http://www.metafilter.com/" and "https://www.adobe.com/products/photoshop/features.html"

Attaching a screen-cast for reference. Could you please look into it and let us know your observations.

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#5, the bug is GPU-specific probably. Also, make sure the GPU rasterization itself is enabled, not just MSAA: "--force-gpu-rasterization" or chrome://flags/#enable-gpu-rasterization

I can reproduce this on my NVidia GPU - as woxxom@ says, probably GPU specific. Will continue investigating.

Bisected this to the following Skia change:

Relax check for gpu use of static src-over XP
https://chromium.googlesource.com/skia.git/+/abe795e4db533c2e230be0c2be868754e5a02a7e

egdaniel@, any ideas on what about that CL might cause these artifacts?

So I haven't been able to repo this on either of my Nvidia cards (both Quadros with basically ToT nvidia drivers). What cards are people reproing on? I've also tried windows and linux. I've force GPU and set the msaa count as described above.

So the only effect of that change is the following. Before that change if we were blending a color with src-over (Src + (1-SrcAlpha)*Dst), and we knew that SrcAlpha would be 1, then we just disabled blending and outputed Src as the color.

With the change we just stick with setting the fixed function blending to [1,1-SrcAlpha] for all cases. This is technically the more safer of the approaches as we are using the blend requested by the draw. So most likely this seems like it would be a bug in Nvidia msaa blending if this is showing up. Though without being able to repo this myself its hard for me to confirm.

Adding csmartdalton@ who may have more insight on what's happening with nvidia msaa draws here.

Hmm, this isn't repro'ing on my work Quadro. May be driver or GPU specific, etc... So far i've only repro'd on my home computer, which has a GTX1080 and a fairly recent driver. Let me try to narrow this down a bit further.

Ok, I think I must have missed it the first time I tried on the Quadro, I've now been able to consistently repro using:

Quadro K2200, Geforce GTX 750 Ti, and GeForce GTX 1080

It seems to work across a range of drivers (tried various drivers back to 2015), but I've confirmed that it definitely happens on driver version 21.21.13.7866

Note that I'm using --force-enable-gpu-rasterization and --gpu-rasterization-msaa-sample-count=8

Also, make sure you toggle the "dark" theme (via the right side-bar) on metafilter, or it won't show up.

Finally, it's a bit fainter on my machine than on the screenshot above. I've attached a new screenshot. At some window widths it's a bit harder to see, if you resize the window's width back and forth a bit it makes it easier to notice.

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Okay so I have been able to repo the bug now. Given that this is a Windows only bug (or though it seems from the reports and my ability to repo), I wonder if this is actually some bug in Angle. On windows if I use --use-gl=egl (default, uses angle), I see the bug. If I use --use-gl=osmesa or --use-gl=desktop I do not see the bug, which is why I wonder if this is some Angle state issue. (Note, --use-gl=desktop seems to be pretty unstable in many other ways and hangs often).

Adding geofflang@ in case he has any thoughts or has seen anything like this on NVidia + ANGLE before. See 2nd paragraph of comment #9 for an explanation of what the change is - seems pretty safe, so it's weird that it leads to corruption.

Haven't seen this particular issue before.  CCing the rest of the team because we'll likely have to work around this if the root cause is discovered.

geofflang@, do you (or one of the other ANGLE folks) have time to look into this - per #12 this sounds like an ANGLE issue.

We can take a look but we'll probably need a couple weeks, about to travel to GDC/MTV for a meetup.

 Issue 715013  has been merged into this issue.

I'm seeing a very similar issue, but the website linked in the bug appears normally on my PC. I've been trying to produce a minimal replication but I only seem to be able to reproduce this on codepen.io.

Replication: http://codepen.io/shortercode/pen/VbpXJj

Have attached full about://gpu text dump along with screenshot

Highlights:

NVidea driver ver: 21.21.0013.7653
GPU: GeForce GTX 980 Ti
Flags: none
Rasterization: Hardware accelerated

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 Issue 718586  has been merged into this issue.

As requested from  Issue 718586 

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Hi, any updates here? Bumped into some discussion about this on Stack Overflow and /r/webdev:

https://stackoverflow.com/questions/41946156/strange-diagonal-lines-in-chrome-chromium-bug
https://www.reddit.com/r/webdev/comments/697gmt/im_getting_these_weird_diagonal_lines_in_my/

ericrk, are you able to repro this still?  I'm no longer able to on any of the linked sites with a GTX 770 in 58 or 61.  Maybe a driver update fixed it...

I'm still getting diagonal lines regularly on a GTX970 on Windows 10 64-bit with the latest WHQL drivers.

This still reproduces for me on ToT (Canary) on Quadro K2200 with driver version 21.21.13.7711 (the lastest I can get from Windows Update).

geofflang@, did you set "--force-enable-gpu-rasterization" and "--gpu-rasterization-msaa-sample-count=8", as well as forcing the "dark"theme on metafilter?

sorry, for #24, I should have written "--force-gpu-rasterization". 

Yep, using --force-gpu-rasterization --gpu-rasterization-msaa-sample-count=8 --no-sandbox on the metafilter website with the dark theme.  Driver version is 22.21.13.8233 (382.33 in NVIDIA versioning).  I'll try reverting my driver a bit.

Still no repro for me on the 21.21.13.7633 (376.33 driver).  I'll try at home tonight on my GTX 970.

Were you ever able to get a repro?

 Issue 735390  has been merged into this issue.

@ericrk Yep, I found a computer that could repro it but I haven't made much progress finding out what causes it yet.  It doesn't repro when attempting to use nvidia's graphics debugging tools.

Was able to get a trace using RenderDoc that showed the issue.  Problem is that on the interior edges of some quads, not all sub-pixels are being touched by the triangles and the the background is showing through.  I can iterate through the sub-samples of the renderbuffer and see that less than half of them are hit for some pixels.

I checked the vertex inputs and outputs and there doesn't appear to be any rounding issues, all triangles share the exact same vertex positions.

I tried to create a stand-alone repro using the same vertex coordinates on a multisampled renderbuffer but no luck reproducing yet.

Here is an updated codepen that forces re-rasterization every frame to help debug the issue: https://codepen.io/anon/pen/qjXYMj .  Also of note is that if the div is set to any width other than 100%, the issue does not show.  It seems that it's split into smaller quads at that point, this may be a workaround.

General CSS workaround for web devs until this issue gets resolved:

div {
	position: relative;
	z-index: 0;
}
div:before {
	content: '';
	display: block;
	position: absolute;
	top: 0; right: 0; bottom: 0; left: 0;
	z-index: -1;
	background: inherit;
}

https://codepen.io/anon/pen/MoEzQV

I have a website using large background elements with a purple color and it's particularly conspicuous:  http://imitone.com/manual/

Running an NVidia GeForce GTX 1080 Founders' Edition.

Eric, do you know who on the Skia team would be able to try making a workaround for this (changing full-width quads into several smaller quads)?  It's unclear if this is a driver bug but it seems less and less likely that ANGLE will be able to do anything about it.  I'm going to keep trying to figure out exactly what combination of factors triggers it.

Attached another example of this bug. https://userspice.com/ footer.
GTX 970, Win 7 running Chrome 59.0.3071.115

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Any news ?

I'm sure we could implement such a workaround in Skia. However, I think we should we first contact NVIDIA. They might be able to provide a narrower or simpler workaround as well as provide a fix in future drivers.

I have been seeing this around randomly for a while now. The footer on https://uber.com and https://uber.design got some white lines on a black background. I'm also seing the lines at the other pages linked in comments.

Intel Pentium G3258 and GTX 970, Windows 10 with Chrome 59.0.3071.115 (64-bit).

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I'm experiencing the same issue. It recently started happening to me. Attached GPU information.

It happens consistently on the codepen linked in #18

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Bug still persist on lastest version of chrome and nvidia driver.... 

it's a bug of chrome or nvidia?

I've spent more time on this over the last couple weeks but I can't pin down the factors that cause it to happen.  I've re-created standalone samples which use the exact same draw parameters and GL state as in a graphics capture of Chrome as it repros the bug but I always get correct multisample coverage results.

Also worth noting is that depending on the GPU, different pages reproduce the error in Chrome.  On my 770GTX, it shows in slide previews in google slides but not on any of the repros posted in this bug.  A Quadro M2000 does repro from the posted codepens.

Olli:  Is there a way we can forward this to the D3D11 driver team?  It appears to be an architecture-specific bug (or behaviour difference, at least) that affects how triangle seams are blended when doing multisampled rendering.  The repros are doing very simple quad drawing but the destination render target does not get fully covered.  I can provide very detailed repro instructions but I've been unable to create a standalone repro.

In case anything changed since last time I submitted gpu.html 
in comment 20, https://bugs.chromium.org/p/chromium/issues/detail?id=691262#c20

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With 385.41 bug persist... -_- 

With Firefox last version, bug is fixed... 
But I think there is a lot of difference between FF and Chrome in rendering engine.

https://yadi.sk/i/Ud14kGph3MgPTY

Same problem. What to do?

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As far as I know those artifacts in Comment 45, are caused by some SVG.
It does not matter where on the page it is.

A similar issue:
https://stackoverflow.com/questions/46091634/svg-fill-artifact-in-chrome

Version 61.0.3163.91 still affected :( but now it work on 2k/4k display...

I'm seeing this issue now on every 5th site out of 10. The issue exists for at least a year now... Attached a video about the GitHub comment area. After some playing, seems like it's not happening on zoom levels other than 100%.

Specs:
GeForce GTX745 1920x1080
Windows 7
Chrome Version 61.0.3163.100 (Official Build) (64-bit)

For some reason the attachment is not there at my comment, here you go: https://drive.google.com/file/d/0By_Fy6XTj0CIVHZlaTJENzhSRjA/view?usp=sharing

RE: comment #49, I _do_ see it at zoom levels other than 100%, but not at _all_ other zoom levels. It happens—in my case—at any zoom level that is a multiple of 25%. So 50%, 75%, 100%, 125%, etc. It doesn't happen at 25% itself, however, nor at "odd" zooms like 67%, 80%, 110%, etc.

As someone who has dabbled in 3D graphics as well as web development, it feels like there's two polygons (triangles) making up the background color rectangle, and that the diagonal line between them is imperfectly positioned, or perhaps is anti-aliased. Sometimes a rounding error can cause this.

If this _is_ the case, then I doubt browser rendering engines delve that deeply into how backgrounds are rendered. In other words, I can imagine they get involved with rendering backgrounds on rectangles at specific z-depths, but I highly doubt they specify or control the polygons that actually make up those rectangles.

Ergo, Nvidia, we're looking at _you_.

Sorry about the delayed response. Geoff - can you provide the detailed repro instructions? We could really use a standalone repro case though, otherwise it's hard to say for certain whether this is a bug in Chromium or on our side.

Seen the glitch on certain pages, e.g. https://material.io/icons/

Chrome Version 62.0.3202.62 (official build) (64-Bit)
GPU: MSI GeForce GTX 970 with 387.92 Nvidia driver
OS: Windows 10 Pro 64-bit

On my system, the seams show if I open the pen provided in comment 18: https://bugs.chromium.org/p/chromium/issues/detail?id=691262#c18

However, when I exported that pen and opened it locally, there were no seams. So I downloaded the full codepen page and stripped down the code as much as possible so that the seams still occur. The result is attached (minimal.html). There is also a screenshot how it looks in my Chrome (minimal.png).

It appears to be necessary, that there are certain CSS rules, SVG and an iframe, and the SVG must fulfill some unknown criterion - if I change a single digit of the SVG path (from 13 to 14) in the attached HTML, save the file and reload it in Chrome, the seams are gone!

I tried to script this in a way, that you could press a key and it would change the SVG path and thus the seams should disappear, but I couldn't make it work properly. After the path change, it required me to resize the browser window (make it very narrow, then wide again) to somehow trigger a refresh. I'm not sure what actually makes it refresh and the seams to disappear.

Maybe this helps a bit to track down the issue. Thanks!

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Geoff can send report to nvidia? 
this bug is very frustating....

Olli: I've attached a RenderDoc capture of the issue from https://codepen.io/anon/pen/qjXYMj .

If opened on a Maxwell GPU (I used a quadro M2000) you'll see diagonal seams where the mutlisample coverage was incomplete on the draw call with event ID 2340.

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Thanks for the RenderDoc capture, it should be very helpful to debug the issue on our side! The bug has been reported to NVIDIA's D3D driver team.

TCs could be much more helpful, if you ask them and provide with some contacts ;)

FYI same issue with a Radeon card.

I have the same issue on a Mac Book Pro 2017 (High Sierra 10.13.1), Chrome 62 and a Radeon Pro 560 4 GB. Turning off GPU rasterization in chrome://flags/ solves the problem (obviously not a fix).

FYI This mac comes with two graphics card, if you go on battery, the integrated Intel card is used. When the integrated Intel card, the bug does not occur.

FYI The bug is also not reproducible on Firefox with the Radeon card, only on Chrome.

HTH.

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I should point out, the above bug report occurs on an (intranet) navigation, using hover changing the opacity with a transition of 1s.

Happens to me on Google Slides as well, with a dark theme. (I don't think you need another repro case at this point, just pointing it out.) I'm on a GTX 970 if that helps. Windows, Chrome version 63.0.3239.84 (Official Build) (64-bit).

I've been experiencing this rendering artefact for at least the last 6 months, even after having upgraded from GTX 970 to an nVidia GTX 1080 Ti on the Intel platform. It doesn't happen on Intel chipsets with integrated graphics, for example, on the same version of Chrome/Win 10. Both computers have the latest drivers installed.

Any ETA for this bug??

Probably never. I have this bug for more than a year already. I experience it on the whole list of websites which is really annoying. I had a lot of different problems with Chrome recently. Maybe it isn't worth to stick with it anymore? Idk...

 Issue 802830  has been merged into this issue.

I'd like to report that the issue was present on Chrome 63 and I just upgraded to Chrome 64 and the issue is no longer present.

Is this a confirmed fix?

It also looks like it's fixed for me. (Reply to comment 67)

I deleted my previous comment saying that it's fixed after switching graphics cards, just went to the UPS website and it occured again on the GTX 1070 (After switching from the GTX 970). Sorry to those diagnosing this issue.

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... Welp nevermind, I was on 63, just upgraded to v64 and it seems resolved to me now. Whatever you did worked.

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Checking the codepen in #18, this issue appears to be fixed for me as well after upgrading from 63 to 64. Win7 64-bit, GTX 960, driver 388.43.

Anyone from the Chrome team have an idea what fixed this in Chrome 64? Was there some kind of a workaround in Skia?

Skia added a workaround to implement clears as draws on D3D11 ANGLE. That could possibly be related.

The newest stable release on my Win 10 HP Spectre x360 (2017 edition) also exhibits the same problems as my desktop Intel i7 + nVidia 1080 Ti.

I've attached a capture of an two animated layers exhibiting this behaviour.

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@ #74: That doesn't appear to be the same bug, could you file a new one with the contents of your about:gpu pasted in?

This bug didn't appear to be related to clears from the traces I was able to grab.

Sure, will do.

Going to close this as fixed now.  Not seeing the issue anymore due to differences in how Chrome does rasterization/compositing.

 Issue 853519  has been merged into this issue.