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Comment by bscphil | Hacker News Reader

The wind animation doesn't work at all for me in Firefox (on Linux, version 91). I see a few large animation "sheets" where the wind is moving in the same direction, depending on where on the map I look. Works in Chromium. Anyone else have this problem?

Screenshot: https://i.imgur.com/eLyQa6X.jpg

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Weird. I'm using Firefox 91.0.2 on Ubuntu 20.04 and it works fine. Maybe try opening it in a new empty profile and see if it works?

I did end up getting it to work, left a comment here if you're interested: https://news.ycombinator.com/item?id=28488599

Could this be a hardware problem? I've been working on a WebGL project and often different graphics cards have different precision from 8 to 16 to 128 bits. I've seen similar quirks when precision truncates calculations.

Edit: Testing different hardware reminds me of the IE5-8 days. Sigh...

Doesn't work for me on Firefox in Windows either. I've tried a number of things and it seems it just doesn't work on Firefox at all.

Works fine for me in Firefox on Mac.

And for me in Firefox 91.4.0 on Android.

...and for me, FF 92.0, Ubuntu Linux.

Do you happen to be using color management by any chance? Believe it or not (because this does seem insane), disabling full color management fixed the site for me. That is, I changed the setting "gfx.color_management.mode" from 1 (manage all colors) back to 2, the default (which only adjusts the colors of images with tagged color profiles).

It's bonkers, but I think I understand what's happening here, actually. Relatively recently, Firefox started color correcting the content of <canvas> elements. However, some sites will download an image, load it into a canvas created in Javascript, and then use the data for some other purpose.

In particular, Windy downloads a bunch of what appears to be wind data in the form of false color images like [1][2]. Presumably they are using this data to generate the wind animation on the fly in the browser. However, if they're utilizing canvases as part of that process, (my copy of) Firefox is changing the colors out from under them as part of the color management process. Presumably a large enough change in the colors would be enough to break the wind display code completely.

[1] https://ims.windy.com/im/v3.0/forecast/ecmwf-hres/2021091012...

[2] https://i.imgur.com/z3hQKvs.jpg (backup of [1] in case the link dies)

Interesting. It still works for me even with gfx.color_management.mode set to 1. Might be hardware differences or maybe desktop (compositing, etc). I'm using XFCE defaults.

If you don't actually have a profile set, Firefox will (in most cases) treat your screen as sRGB, which means that the colors won't actually be changed.

Wow. Nice find. I also use a canvas to stitch together elevation data encoded as PNGs [1]. Will definitely look into this.

The road to bugs is paved with good intentions.

[1] https://miro.medium.com/max/1024/0*zRx4LGdE_sxxRip7.png

Seems dangerous that color correction would not just happen at the display driver level but would modify the values returned by ctx.getImageData. Good fingerprinting technique though!

I agree, I wish they'd take a different approach.

Have you tried firefox 92?

It works for me on FreeBSD, running "firefox amd64 92.0+build3-0ubuntu0.18.04.1 " in an Ubuntu linux jail.

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