egui_glass 0.1.0

Apple Liquid Glass style surfaces for egui, rendered on the GPU through egui-wgpu paint callbacks. One fragment shader does everything: continuous-corner signed-distance shape, edge refraction (lensing) with optional chromatic aberration, mip-based backdrop blur, tint / vibrancy, specular rim, inner border and drop shadow. No animation.

Requirements

Runtime dependencies of the library: egui, egui-wgpu, wgpu, bytemuck, and serde (optional, feature serde). The demo additionally uses eframe, image, serde_json, rfd and log.

Run the demo

git clone https://github.com/heonny/egui-glass.git
cd egui-glass
cargo run -p egui_glass_demo

The first build compiles wgpu and takes a few minutes. To package it as a macOS app see Build the macOS app. Left panel: sliders for every style parameter, the presets (Regular, Clear, Dark, Panel), a Live backdrop toggle, and Export / Import buttons that save the settings as JSON. A dark tint switches the page to a macOS-style dark theme. Sidebar items switch between the bundled photos (examples/asset); drop an image file onto the window to load your own. Drag the glass panels around.

Environment knobs for screenshots: LG_PHOTO=<index>, LG_SCROLL=<px>, LG_PRESET=dark|clear, LG_LIVE=0 (start with the live backdrop off).

Build the macOS app

The demo can be packaged as a regular .app (Dock icon, Launchpad, Finder):

scripts/bundle-macos.sh does the work: uses the icon from assets/branding (the prebuilt EguiGlass.icns, or generates one from a 1024 px PNG you pass as an argument), copies the sample photos into Contents/Resources/asset, writes Info.plist, ad-hoc signs the bundle and, with --install, copies it to /Applications and strips any quarantine flag. It needs sips, iconutil and codesign, all part of macOS.

On the first launch from Finder, macOS shows "Apple could not verify ... is free of malware" because the app is not notarized: open System Settings > Privacy & Security and click Open Anyway once. To ship a build that opens without the prompt, sign with a Developer ID and notarize:

CODESIGN_IDENTITY="Developer ID Application: <name> (<team id>)" \
NOTARY_PROFILE="<keychain profile from: xcrun notarytool store-credentials>" \
make install

Uninstall by deleting /Applications/Egui Glass.app; the app stores nothing else.

Use the library in your own app

You do not need this repository checked out; add the crate as a git dependency (pin a rev or tag for reproducible builds) and make sure eframe uses the wgpu backend:

[dependencies]
eframe = { version = "0.35", default-features = false, features = ["default_fonts", "wgpu"] }
egui = "0.35"
egui_glass = "0.1"                                     # from crates.io
# egui_glass = { version = "0.1", features = ["serde"] }             # GlassStyle: Serialize / Deserialize
# egui_glass = { git = "https://github.com/heonny/egui-glass.git" }   # or track the repository

Minimal app (also in the repo as examples/demo/examples/minimal.rs, run it with cargo run -p egui_glass_demo --example minimal): register the pipeline and a backdrop once, then draw glass wherever you like.

use eframe::egui;
use egui_glass::{Glass, GlassButton, GlassStyle, GlassToolbar};

struct App;

impl App {
    fn new(cc: &eframe::CreationContext<'_>) -> Self {
        let rs = cc.wgpu_render_state.as_ref().expect("eframe must use the wgpu renderer");
        egui_glass::init(rs, 1);                                   // msaa samples of NativeOptions
        let wallpaper = egui::ColorImage::filled([256, 256], egui::Color32::from_rgb(70, 130, 180));
        egui_glass::set_backdrop(&cc.egui_ctx, rs, &wallpaper);    // any ColorImage: photo, gradient, ...
        Self
    }
}

impl eframe::App for App {
    fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
        egui::CentralPanel::default().frame(egui::Frame::NONE).show(ui, |ui| {
            egui_glass::show_backdrop(ui, ui.max_rect());          // draw the backdrop, record where it is
            let style = GlassStyle::regular();
            egui::Area::new(egui::Id::new("card")).movable(true).constrain(false).show(ui.ctx(), |ui| {
                Glass::new(style).show(ui, |ui| {
                    ui.heading("Hello glass");
                    GlassButton::new("Continue").style(style).show(ui);
                });
            });
            egui::Area::new(egui::Id::new("bar")).movable(true).constrain(false).show(ui.ctx(), |ui| {
                GlassToolbar::new(style).show(ui, |ui| {
                    let _ = ui.button("Undo");
                    let _ = ui.button("Share");
                });
            });
        });
    }
}

fn main() -> eframe::Result {
    let options = eframe::NativeOptions { renderer: eframe::Renderer::Wgpu, ..Default::default() };
    eframe::run_native("glass", options, Box::new(|cc| Ok(Box::new(App::new(cc)))))
}

API at a glance:

GlassStyle fields (all in logical points): corner_radius (f32::INFINITY = capsule), corner_smoothing (0 = circular arc, 0.6 = the continuous look of iOS corners, 1 = max), blur, refraction, edge_width, chromatic, tint, brightness, saturation, specular, border, shadow, shadow_radius. Presets: regular(), clear(), dark(), panel(), panel_dark(). Use panel() for large surfaces (sidebars, sheets): heavy blur, almost no lensing. Text on glass picks a light colour automatically when the tint is dark.

Corners use the corner-smoothing model popularised by Figma (a Bezier ease into a shorter circular arc, spanning (1 + smoothing) * radius along each edge), evaluated as a signed-distance field in the shader. No Apple curve constants are used.

How it works / limits

egui paints in a single render pass, so a shader cannot read the pixels already drawn behind a widget in the same frame. By default glass therefore refracts a backdrop image you register with set_backdrop (a wallpaper, a photo) and place with show_backdrop; anything egui draws on top of it shows as the page colour through the glass. This is cheap and matches Apple's guidance that glass floats above content and is never stacked on glass.

Each glass surface costs one draw call (a single triangle) and one 256-byte uniform slot; the backdrop is uploaded once with a linear-light mip chain, and blur is a 5-tap sample at a mip level.

Live backdrop (optional)

LiveBackdrop lifts that limit: the content you pass to LiveBackdrop::run is laid out a second time in a twin egui context (same memory, no input events) and rendered off screen without the glass, then used as this frame's backdrop. Glass then refracts everything beneath it, text included, with no frame of lag. The cost is one extra layout and draw of that content per frame.

// once, after init and before set_backdrop / register_native_texture
let live = LiveBackdrop::new(rs, Some(font_definitions));
// every frame: content inside, glass outside
live.run(ui, page_color, |ui| page(ui));
Glass::new(style).show(ui, |ui| { /* floats over the page */ });

Images drawn inside the content must be registered with egui_glass::register_native_texture (or set_backdrop) so the off-screen pass can draw them too.

Development

cargo test --workspace --all-features
cargo clippy --workspace --all-targets --all-features

See CLAUDE.md for the project layout and the design rules the code follows.

Trademark note

"Liquid Glass" is Apple's name for its design language; egui_glass is an independent reimplementation of the look, not affiliated with or endorsed by Apple. The term is only used descriptively in this documentation.

License

MIT. See LICENSE.