WebGL inverted in Chrome Canary on Angle DX11

[Alecazam]

We are now seeing an inverted canvas in our app in the latest Chrome Canary.  Chrome does not exhibit this.  In both cases, (Nvidia and Intel) the Angle DX11 path was taken.  I have a Nvidia GTX 950, and a user is on Intel HD Graphics (again we need the vendor/card id in the string).  These are latest graphics.

That includes scroll bars, rulers, and the canvas itself.  Were there recent changes that would have caused this?  I ran some other WebGL examples, and they look fine, but they're not using glCopyTexSubImage2D like our editor does. 

[Alecazam]

So Chrome, Firefox Nightly, and Edge on the same system are fine.

[Miao, Qiankun]

Do you have a small test case to reproduce this issue?

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[Alecazam]

No, we just had reports about it from users today and yesterday (on Linux).  I've given account access to Figma with Ken and other WebGL members.   Given this and the DX9 bugs that I suspect with glCopyTexSubImage2D, I'm leaning towards just not calling that function.  I should be able to emulate it with a shader.

[Alecazam]

We have even more people reporting this as of yesterday (probably the lastest Chrome Canary update).  

On Linux, we're seeing the following on Ubuntu 16.0.4 on a users system on app startup with existing Chrome.  "WebGL hit a snag" message and the following error.  This isn't something we call, so it's an internal issue.  This is with the default open source GPU driver (Noveau), so you might see more reports on this.  The same system and driver works with Firefox.  The same driver and Chrome work on Linux Fedora.  I'll file these on the Chrome bug channel, but thought the info might be useful.

vendor:"NVIDIA Corporation" renderer:"NVS 4200M/PCIe/SSE2"

GL_INVALID_OPERATION : glGenSyncTokenCHROMIUM: fence sync must be flushed before generating sync token

WebGL: CONTEXT_LOST_WEBGL: loseContext: context lost

[Andre Weissflog]

FYI, the current Chrome Canary (54.0.2811.0 canary 64-bit) is completely borked for me on Windows7, it cannot even open basic webpages, but goes directly into Aw-Snap pages (with or without WebGL, doesn't matter), looks to me like a badly broken build made it through.

[Zhenyao Mo]

Folks,

Thanks for bring this to our attention. Please file a chrome bug at
crbug.com with repro steps and about:gpu content, so we could look
into this.

Mo

[Alecazam]

So I replaced copyTexSubImage2D with a copy shader that fixes all of our D3D9 bugs with that routine.   It still doesn't fix the flipped canvas in Canary though.  We render upside down due to GL's goofy lower left origin, and then flip the canvas when we copy to the backbuffer.  All of our content - scroll bars, etc are upside down now in Canary on Windows (and no other browser).  It doesn't matter about the DX9 vs. DX11 backend.  Both seem to be broken now.  We've had reports from about 5 users since last Tuesday.

[Andre Weissflog]

Here's a bug report for inverted colors I'm seeing in Windows7 on current Chrome Canary, note however that the problem does not occur in WASM, PNaCl, or in asm.js on OSX:

https://bugs.chromium.org/p/chromium/issues/detail?id=633500

And a crash-bug where I'm not sure whether it's related to the JS engine or WebGL (this particular asm.js application has been triggering at least one JS engine error in the past, the current crash happens across platforms):

https://bugs.chromium.org/p/chromium/issues/detail?id=633497

Cheers,

-Floh.