MacBook Duo
Demo
Effects
How it works
Privacy
Requirements
Download .dmg
Your desktop follows the lid.
As you close the lid, the built-in display is captured and rendered as a rigid pane that rotates around the hinge, expands, blurs and dims until it disappears into the hinge. Stop the lid and the effect holds; open it and the effect reverses back to the sharp desktop.
Live mock · {{ styleLabel }}
Lid {{ angle }}° Resting 130°
A CSS mock of the real Metal pipeline, driven by the same curves — tilt, four-level blur pyramid and dimming — so you can see the arc without closing your lid.
DEMO
One lid, six ways to disappear.
A screen recording of the app running on real hardware — the lid closing and reopening, the menu bar readout following the sensor, each style picked from the menu.
Read the source →SIX EFFECTS
Every style renders the desktop pixel-for-pixel at rest.
So the overlay never pops when it appears, and every style ends black so the display sleeps on a blank frame.
| Style | What you see | Blur / dim |
|---|---|---|
| Duo DEFAULT | The desktop tilts around the hinge, expands toward you, softens and disappears. | blur → 4 levels dim .35 → .90 |
| Shutter | Six rigid panels slide down behind one another, with overlapping edges and contact shadows, until the stack rests on the hinge. | sharp dim .80 → 1.0 |
| Iris | Eight dark blades close around the desktop with a restrained 35° mechanical twist, bevelled edges and seams. | blur → 2 levels dim .75 → 1.0 |
| Roll | A roller rises from the hinge and the desktop winds down onto it like a retracting projector screen, shaded as a cylinder. | sharp dim .85 → 1.0 |
| Accordion | The desktop pleats into horizontal folds that collapse toward the hinge, faces alternating light and dark with crease shadows. | sharp dim .80 → 1.0 |
| Fade | A plain black veil. Needs no screen capture. Used automatically with Reduce Motion enabled in Accessibility settings. | no capture |
HOW IT WORKS
Sensor to overlay, 30–120 times a second.
ReferenceAngleTracker
LidProgressModel
CriticallyDampedFilter
IOKit HID feature report, polled 30–120 Hz. Movement beyond a dead zone becomes eased progress; whole-degree reports are smoothed without overshoot.
FrameStore
Own process excluded, overlay window sharingType = none. One IOSurface-backed frame, wrapped as a Metal texture. Capture starts on the first degree of closing motion.
FoldRenderer
OverlayWindow
A four-level blur pyramid and a projective fold composite, drawn into a borderless, click-through window on the built-in display only.
Any failure — sensor timeout, capture error, permission revoked, display change — tears the overlay down and restores the desktop. Emergency Stop (⌃⌥⌘F) works system-wide.
PRIVACY
Desktop frames never leave this Mac.
The latest captured frame lives in GPU memory only. Nothing is written to disk, uploaded, or analyzed.
HARDWARE
Apple silicon MacBook with the continuous lid-angle sensor. Macs that only expose an open/closed switch run in manual mode — the preview still works, automatic lid-following is disabled.
SOFTWARE
macOS 13 or newer. Xcode 16 or newer to build from source. Unit tests cover the geometry, progress mapping, sensor filter, reference tracking and the Metal pipeline.
PERMISSIONS
Screen Recording, requested on first launch. Keep the same signing identity between rebuilds, otherwise macOS forgets the grant.