Wayland: Incorrect UI scaling on high-resolution screen under GNOME 42.5 w/ fractional scaling #102999

New Issue

Markus · 2022-12-07T23:03:19+01:00

Markus commented

2022-12-07 23:03:19 +01:00

System Information
Operating system: Ubuntu 22.04
Graphics card: Radeon 6800XT

Blender Version
Broken: 3.4.0, branch: blender-v3.4-release, commit date: 2022-12-06 18:46, hash: a95bf1ac01, type: release
Worked: 3.3.1, branch: master, commit date: 2022-10-04 18:35, hash: b292cfe5a9, type: release

Short description of error
When running Blender 3.4 on a display with a resolution of 5120x2160 pixels and a fractional scaling factor of 125% configured in GNOME settings, the user interface is rendered extremely small. This was not the case with Blender 3.3.1.

This is running under a vanilla Ubuntu GNOME session with GNOME 42.5. Display server is Wayland.

From testing various combinations, it appears that using fractional scaling larger than 100% actually reduces the UI size in Blender instead of increasing it.

Exact steps for others to reproduce the error

Log in to a vanilla GNOME desktop session using Wayland under Ubuntu 22.04
Under GNOME settings -> Displays turn on "Fractional scaling" and set the scaling value to 125%
Launch Blender 3.3.1 and observe the UI size (e.g. see https://imgur.com/a/0MLM8lz )
Launch Blender 3.4.0 and observe the UI size (e.g. see https://imgur.com/a/RUmvg3O )

**System Information** Operating system: Ubuntu 22.04 Graphics card: Radeon 6800XT **Blender Version** Broken: 3.4.0, branch: blender-v3.4-release, commit date: 2022-12-06 18:46, hash: a95bf1ac01be, type: release Worked: 3.3.1, branch: master, commit date: 2022-10-04 18:35, hash: b292cfe5a936, type: release **Short description of error** When running Blender 3.4 on a display with a resolution of 5120x2160 pixels and a fractional scaling factor of 125% configured in GNOME settings, the user interface is rendered extremely small. This was not the case with Blender 3.3.1. This is running under a vanilla Ubuntu GNOME session with GNOME 42.5. Display server is Wayland. From testing various combinations, it appears that using fractional scaling larger than 100% actually reduces the UI size in Blender instead of increasing it. **Exact steps for others to reproduce the error** 1. Log in to a vanilla GNOME desktop session using Wayland under Ubuntu 22.04 2. Under GNOME settings -> Displays turn on "Fractional scaling" and set the scaling value to 125% 3. Launch Blender 3.3.1 and observe the UI size (e.g. see https://imgur.com/a/0MLM8lz ) 4. Launch Blender 3.4.0 and observe the UI size (e.g. see https://imgur.com/a/RUmvg3O )

Markus commented

2022-12-07 23:03:19 +01:00

Added subscriber: @rasterizer

Jesse Yurkovich commented

2022-12-15 02:46:58 +01:00

Added subscribers: @ideasman42, @deadpin

Jesse Yurkovich commented

2022-12-15 02:46:58 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Jesse Yurkovich commented

2022-12-15 02:46:58 +01:00

@ideasman42 Similar to #103000, might the behavior here be any better if using gnome 43?

Campbell Barton commented

2022-12-15 05:52:51 +01:00

I can't redo this in gnome-shell 43.2 (tested scale 1.25, 1.75 & 3.0 .. all work as expected).

Note that GNOME doesn't support fractional-scaling on my system by default, so I had the impression this feature wasn't officially supported yet.

This is the command I needed to run before being able to access fractional scaling.

gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']"

Did you run this? Or does Ubuntu provide fractional scaling by default?

I can't redo this in gnome-shell 43.2 (tested scale 1.25, 1.75 & 3.0 .. all work as expected). Note that GNOME doesn't support fractional-scaling on my system by default, so I had the impression this feature wasn't officially supported yet. This is the command I needed to run before being able to access fractional scaling. ``` gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']" ``` ---- Did you run this? Or does Ubuntu provide fractional scaling by default?

Campbell Barton changed title from ~~Incorrect UI scaling on high-resolution screen under GNOME with fractional scaling~~ to Incorrect UI scaling on high-resolution screen under GNOME 42.5 w/ fractional scaling

2022-12-15 05:54:00 +01:00

Campbell Barton changed title from ~~Incorrect UI scaling on high-resolution screen under GNOME 42.5 w/ fractional scaling~~ to [Wayland] Incorrect UI scaling on high-resolution screen under GNOME 42.5 w/ fractional scaling

2022-12-15 05:56:08 +01:00

Jesse Yurkovich commented

2022-12-15 07:15:03 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Needs User Info'

Markus commented

2022-12-15 21:33:43 +01:00

Fractional scaling can be easily activated via a toggle in the display settings. When you turn it off, gsettings get org.gnome.mutter experimental-features returns an empty array, when on, ['scale-monitor-framebuffer'] is returned. This is on a vanilla 22.04 LTS installation without any additional packages or configuration.

Fractional scaling can be easily activated via a toggle in the display settings. When you turn it off, `gsettings get org.gnome.mutter experimental-features` returns an empty array, when on, `['scale-monitor-framebuffer']` is returned. This is on a vanilla 22.04 LTS installation without any additional packages or configuration. ![VirtualBox_Ubuntu_15_12_2022_21_28_20.jpg](https://archive.blender.org/developer/F14060358/VirtualBox_Ubuntu_15_12_2022_21_28_20.jpg)

Markus commented

2022-12-15 21:46:55 +01:00

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Campbell Barton commented

2022-12-15 22:37:18 +01:00

While it would be good to workaround this, I'm inclined not to because:

It's fixed in GNOME 43.x.
Fractional scaling works in other (non GNOME compositors - SWAY/KDE).
GNOME considers this an experimental feature doesn't show it in the UI - Ubuntu chose to expose this before it was working properly.
Users can workaround by adjusting Blender's interface scale.

Also, even if we wanted to workaround it, gnome-shell doesn't provide a way to access the version running, although hacks are always possible to figure it out there is a limit to how much Blender can workaround compositor spesific bugs.

NOTE: as I'm not aware of a straightforward solution and fixing would likely be quite time consuming, I don't think working around this bug is a good use of time at the moment. On the other hand if someone is interested to investigate a reasonable workaround, this can be reviewed for inclusion.

While it would be good to workaround this, I'm inclined not to because: - It's fixed in GNOME 43.x. - Fractional scaling works in other (non GNOME compositors - SWAY/KDE). - GNOME considers this an experimental feature doesn't show it in the UI - Ubuntu chose to expose this before it was working properly. - Users can workaround by adjusting Blender's interface scale. Also, even if we wanted to workaround it, gnome-shell doesn't provide a way to access the version running, although hacks are always possible to figure it out there is a limit to how much Blender can workaround compositor spesific bugs. ---- NOTE: as I'm not aware of a straightforward solution and fixing would likely be quite time consuming, I don't think working around this bug is a good use of time at the moment. On the other hand if someone is interested to investigate a reasonable workaround, this can be reviewed for inclusion.

Ptits commented

2022-12-17 18:33:04 +01:00

Added subscriber: @ettavolt

Ptits commented

2022-12-17 18:33:04 +01:00

I do observe this in Blender 3.4.0 on Arch with Gnome 43.2, 2560×1440 125% screen (after I've installed new optional dependency libdecor).
If I start Blender from command line, prepending WAYLAND_DISPLAY=, I get the old blurry XWayland experience.

Probably it comes from the fact that Gnome is yet to implement the official Wayland protocol for fractional scaling.

I do observe this in Blender 3.4.0 on Arch with Gnome **43.2**, 2560×1440 125% screen (after I've installed new optional dependency libdecor). If I start Blender from command line, prepending WAYLAND_DISPLAY=, I get the old blurry XWayland experience. Probably it comes from the fact that Gnome is [yet to implement the official Wayland protocol for fractional scaling](https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2394).

Campbell Barton commented

2022-12-17 23:30:19 +01:00

In #102999#1462254, @ettavolt wrote:
I do observe this in Blender 3.4.0 on Arch with Gnome 43.2, 2560×1440 125% screen

Do you mean the bug is still happening for you on Gnome 43.2? Or that it's been resolved?

> In #102999#1462254, @ettavolt wrote: > I do observe this in Blender 3.4.0 on Arch with Gnome **43.2**, 2560×1440 125% screen Do you mean the bug is still happening for you on Gnome 43.2? Or that it's been resolved?

Ptits commented

2022-12-18 16:25:22 +01:00

I mean that the bug is still happening for me on Gnome 43.2.

Paul Kupper commented

2022-12-28 13:20:54 +01:00

Added subscriber: @pkupper

Paul Kupper commented

2022-12-28 13:20:54 +01:00

The bug is not exclusive to Gnome and does not require fractional scaling. I am experiencing the same issue with Blender 3.4.1 with Sway on a 3840x2160 display with scale set to 1.5 (also works with 1.0).
My guess from looking at the behavior would be: Blender correctly reads the wl_output.scale and uses wl_surface.set_buffer_scale accordingly (the window is not blurry on higher than 1 scale values). However for UI rendering it only takes into account the "resolution scale" user preference and does not multiply it with wl_output.scale.
On a single screen you can work around this by adjusting "resolution scale" accordingly, but with multiple mixed DPI screens you can get vastly different scale on each screen.

Note: Fractional scaling was until very recently not supported by the Wayland protocols, Sway and Gnome currently use the same workaround where they make the Wayland client use the next highest integer scale factor (in my case 2) and render to a larger resolution buffer which is then downscaled by the compositor.

The bug is not exclusive to Gnome and does not require fractional scaling. I am experiencing the same issue with Blender 3.4.1 with Sway on a 3840x2160 display with scale set to 1.5 (also works with 1.0). My guess from looking at the behavior would be: Blender correctly reads the wl_output.scale and uses wl_surface.set_buffer_scale accordingly (the window is not blurry on higher than 1 scale values). However for UI rendering it only takes into account the "resolution scale" user preference and does not multiply it with wl_output.scale. On a single screen you can work around this by adjusting "resolution scale" accordingly, but with multiple mixed DPI screens you can get vastly different scale on each screen. Note: Fractional scaling was [until very recently ](https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/143) not supported by the Wayland protocols, Sway and Gnome currently use the same workaround where they make the Wayland client use the next highest integer scale factor (in my case 2) and render to a larger resolution buffer which is then downscaled by the compositor.

Philipp Oeser removed the

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Wayland: Incorrect UI scaling on high-resolution screen under GNOME 42.5 w/ fractional scaling #102999