WebGPU frontend not working with window opacity

[max-legrand]

What Operating System(s) are you seeing this problem on?

Windows

Which Wayland compositor or X11 Window manager(s) are you using?

No response

WezTerm version

20240701-070926-69686f45 x86_64-pc-windows-msvc

Did you try the latest nightly build to see if the issue is better (or worse!) than your current version?

Yes, and I updated the version box above to show the version of the nightly that I tried

Describe the bug

When using the WebGPU front end, setting the window opacity does not work. Reverting back to OpenGL restores the transparency effect.

To Reproduce

No response

Configuration

config.front_end = "WebGpu"
config.webgpu_power_preference = "HighPerformance"
config.webgpu_force_fallback_adapter = true
local gpus = wezterm.gui.enumerate_gpus()
config.webgpu_preferred_adapter = gpus[1]
config.window_background_opacity = 0.8

Expected Behavior

Background should become transparent, however, it just darkens. Setting opacity to 0 results in a completely black background.

Logs

No response

Anything else?

No response

[hjm7]

For me, window opacity work when vulkan, but dx12 not work.

[wez]

FWIW, this is not a wezterm issue per-se, but due to upstream wgpu/drivers. Changing the front end or gpu adapter selection may yield different results.

https://wezfurlong.org/wezterm/config/lua/config/front_end.html?h=front_en#webgpu

[0xJWLabs]

@wez OpenGL works, but WebGpu font rendering is better though.