Backdrop Blur for GPUI

[BumpyClock]

I am building an app using GPUI. I wanted to add background blur so that app elements like menu etc can have backdrop blur. Admittedly it doesn't have a lot of value for Zed at the moment but GPUI as a cross platform UI framework, esp for consumer apps could use this. I have a fork that adds that support in. Happy to send in a PR if you'd accept it.

• I know GPUI supports whole window blur. I am specifically talking about elements within the window like menus etc being blurred.

[AnkanMisra]

The whole-window blur via WindowBackgroundAppearance::Blurred is well-supported

On macOS it uses an NSVisualEffectView behind the Metal layer (or CGSSetWindowBackgroundBlurRadius on older macOS), on Wayland it's the KDE org_kde_kwin_blur protocol, on Windows 11 it's DWM composition attributes, but per-element backdrop blur doesn't exist

The core problem is that GPUI is a single-pass forward renderer. Every primitive gets sorted by draw order in scene.rs and blended in one pass

The shadow shader has gaussian blur, but it computes its own alpha analytically and never reads back already-rendered pixels

Backdrop blur requires exactly that: sample what's behind the element, blur it, composite on top

For macOS specifically, the most practical approach would be scoping the existing BlurredView (an NSVisualEffectView subclass) to element bounds instead of the full window

The compositor handles the downsampling so it's cheap, but it's platform-specific

For cross-platform, you'd need to introduce a BlurRegion primitive that tells the renderer to split the draw list, render-to-texture, blur, then resume. paint_layer already tracks layer boundaries via push_layer/pop_layer so there's some infrastructure there, but today it's only used for z-ordering, not render-to-texture. Both the Metal and WGSL backends would need a new pass.

Would love to see your fork if you have this working.

[BumpyClock]

Sorry for the late reply, I added renderer-level per-element blur. It's not super robust, and I quickly hacked it together with codex with some iterations. I forked out gpui completely instead of pinning it to a zed commit I periodically update it to the main zed repo.

GPUI