Problem with gps accuracy circle -- Extension 'GL_EXT_frag_depth' not supported (FF browser)

Hello all,

recently tried to add “accuracy circle” into my geolocation code inside Cesium project, and everything works well on PC

but when I try to see the same page on my mobile phone in Firefox ( Samsung S7 Edge, Android 7.0 ), as soon as I click on “My Location” button got following error msg (otherwise Cesium works ok on mobile)

Atm I’m bound to FF browser only, because for Chrome geolocation require https website which I don’t have right now…

At first thought it was my coding error but then try the example from – , and same thing happened - working on PC but not on mobile phone (!)

Anyone seen this before?


Yes I had that error months ago with an older Cesium release. What version are you using? The frag-depth error on my S7 went away when Cesium implemented an alternative to using the frag-depth Webgl extension

Favor, on your mobile browser, go to and you should see that the frag-depth extension is not supported on your hardware-browser combination.

Thx for the respons Left,

as for Cesium, using latest 1.34 and 1.34-master22385 versions, and on S7 have (probably) the lastest version of FF/Chrome …
About the extension itself, according to, only Chrome support it … so nothing I can do about it.
for the time beign, decided to entirely remove " My Location" functions from my Cesium map page.
Accuracy circle option is highly unreliable because of that “frag-depth error”, so it’s not suitable for production, and also need to upgrade my web server to https since next browsers versions will require https in order to use geolocations functions.


Just to confirm it’s issue related to FF, well … at least on my Samsung S7…

Today upgrade server to SSL and now “accuracy circle” works fine in Chrome (PC & mobile) and Edge (PC).

Screenshot from Chrome

That’s great news! I share your pain upgrading to SSL.

Last year, I had been planning to work with Cesium and geolocation.

When I finally got around to testing geolocation in January, I learned using geolocation in Google’s Chrome was going to force me to upgrade my GoDaddy development server to SSL.

That was an unfortunate extra annual expense for the certificate, and I lost a week of Cesium javascript development time to updating my WordPress site.

I’m glad it’s behind me, and that the pain of upgrading the website is over. But I haven’t had much free time to get back to my geolocation feature in Cesium, so your post caught my eye.

I visited your website, and I admire what you are doing, that’s a very nice web map demo, with the Navigation mix-in, and your Location feature with accuracy circle worked great in Chrome on Windows, here at 34.816623, -92.236355

I’m afraid I will never visit your country in person, but thanks for your virtual tour of Castles, and good luck embedding the Cesium 3D map with your Location!.

-Jon “Left Gully”

Thx Jon,
Cesium is a quite nice visualisations tool, however, I missed better support for vectors like WFS ( to add routing ), vector tiles and full “Clamp to the ground” capabilities. Hopefully some of it will be implemented sometimes soon.
Anyway, now adding 3D objects, and looking for a way to route over the bridges, and other objects like tunnels …