The iPhone Duo fold effect, on your MacBook.

I vibe coded this just for fun copying the new iPhone Duo.

ClamShell reads your MacBook's lid angle and animates the built-in desktop as you close it. Below your chosen starting angle, the desktop appears to tilt toward the hinge, blur, and fade to black. Opening the lid reverses the effect while your desktop is unlocked.

There are two effects:

• Perspective fold takes one desktop screenshot for each fold, then warps, blurs, and dims that frozen image. It needs Screen Recording permission.
• Native blur blurs and dims the live desktop without changing its geometry. Apps keep updating underneath, and no Screen Recording permission is needed.

If you stop moving the lid midway, the animation waits 0.5 seconds by default, then eases back to the normal desktop. Move the lid again to resume. Motion smoothing softens the jumps between the sensor's whole-degree readings.

You can try the effect inside the app with the Preview angle slider, or turn on Follow my lid to drive that preview with the physical lid. Desktop animation is enabled separately. The menu-bar icon lets you show the controls, pause the effect, or quit.

For Apple Silicon Macs running macOS 14 or later. Set up the Homebrew tap once:

brew tap nthanhtin/clamshell https://github.com/nthanhtin/ClamShell
brew trust nthanhtin/clamshell

Then install:

brew install --cask clamshell

Homebrew puts the app in Applications. Update it later with brew update and brew upgrade --cask clamshell.

Or download the ZIP from Releases.

Unzip it, drag ClamShell.app into Applications, and open it. Choose an effect and click Enable desktop animation. Allow Screen Recording for Perspective fold when prompted. If macOS blocks the first launch, see the opening instructions.

To build from source, use Xcode with Metal tools and an Apple Development signing certificate in your keychain.

bash build.sh
open build/ClamShell.app

• Angle range: choose when folding starts and when the screen becomes fully dark. Defaults are 85° and 5°.
• Idle timeout: change how long the lid can stay still before snap-back, or set it to Off to keep the effect visible.
• Movement threshold: choose how far the lid must move to restart the effect. The default 2° helps ignore sensor jitter.
• Motion smoothing: balance responsiveness and softness, from 50–300 ms.

Timeout, threshold, and smoothing are in Animation settings (⌘,). Start at login is in the main window. Settings and the enabled/paused state are remembered between launches.

Tested on an M1 Pro MacBook Pro. Lid sensor access varies by model; manual preview still works without it. The effect runs on your unlocked desktop, so it won't appear over the lock screen after sleep. Desktop captures stay in memory. They aren't saved or uploaded. External displays are left alone, and closing the lid still puts the Mac to sleep normally.

Built with SwiftUI, Metal, IOKit, and ScreenCaptureKit. Thanks to LidAngleSensor and mac-angle for the sensor research, and iphone-duo for the fold reference.

Tests: bash test.sh · Regenerate the icon: bash Tools/render-assets.sh.

Push a version tag to run the tests, publish an Apple Silicon app ZIP, and update the Homebrew cask on main:

git tag v0.1.1
git push origin v0.1.1

No signing secrets needed. Downloads are ad hoc signed and aren't notarized; see the release notes for opening them.

Licensed under MIT.