[codenameakshay]

What

Android OpenGL live wallpapers get an optional renderer uniform, u_tilt (vec2, -1 to 1 per axis). Apps also get WallpaperCapabilities.supportsTilt, so a shader declares u_tilt only when the plugin and the device support it. Version 3.6.0.

• Source. TYPE_GAME_ROTATION_VECTOR, or the accelerometer when the device has no game rotation vector. Without either sensor, u_tilt stays (0, 0).
• Meaning. x grows as the right edge dips. y grows as the top edge leans away. Both are measured from a rest pose that follows how the user holds the phone, with a time constant of about 7 s. Pitch uses the Y/Z cross component, so it stays signed when the rest pose is upright.
• Battery. The sensor samples at about 15 Hz (66,667 µs), and the renderer eases the value each frame. TiltLifecycle registers the sensor only while the engine is visible and the linked program reads u_tilt. It unregisters on invisible, surface loss, render failure, a new configuration without u_tilt, and destroy. The sensor, its events and the lifecycle all stay on the render thread.
• Validator. It accepts u_tilt only as a non-array vec2.
• Capabilities. supportsTilt is true on Android when OpenGL live wallpapers are supported and a tilt sensor exists, and false on iOS. The Pigeon field is added at the end.

Note: 3.5.0 already accepted an unknown uniform vec2 u_tilt; and left it at (0, 0). The validator rejects only bad types and samplers. Shaders that declare it still work on 3.5.0.

Tests

• fvm flutter test: 63 passed. fvm flutter analyze: no issues.
• Kotlin :async_wallpaper:testDebugUnitTest: 179 tests, 0 failures. This includes TiltTrackerTest (rest pose, clamping, zero and NaN, reset, decay, signed upright pitch), TiltLifecycleTest (visibility, renderer, failure and destroy transitions, no per-frame re-registration), and ShaderContractTest (u_tilt vec2 accepted; float and array rejected).
• tool/check_pigeon.sh: bindings current.
• Codex (gpt-6.1-sol) reviewed and fixed lifecycle, pitch sign and array findings in b110e08. I reverted one part of it, a hand-written legacy capabilities transport, because the Dart bindings and the hosts ship in one version.

Device proof (Android emulator, Prism scratch build on this branch)

Sensor registration from dumpsys sensorservice. Opening Settings unregisters (-), and going home registers again (+) at 66,667 µs:

14:35:55 - 0x5f676172 pid=25426 uid=10214 samplingPeriod=   N/A  us batchingPeri
14:35:58 + 0x5f676172 pid=25426 uid=10214 samplingPeriod=   66667us batchingPeri
14:36:07 - 0x5f676172 pid=25426 uid=10214 samplingPeriod=   N/A  us batchingPeri
14:36:10 + 0x5f676172 pid=25426 uid=10214 samplingPeriod=   66667us batchingPeri

Tilt through the emulator's virtual accelerometer (fused Game Rotation Vector). Far and near regions shift in opposite directions: on a left roll, far +7 px and near -5 px; on a right roll, the opposite signs.

10 s mp4

The emulator's fused sensor gives small, uneven magnitudes. The owner must check how tilt feels on a real phone. FULL_TILT (0.34) and the per-frame ease (0.15) are the values to tune.

Release order

1. Merge and publish async_wallpaper 3.6.0 (owner).
2. Bump Prism to async_wallpaper: ^3.6.0. That turns tilt on for Prism's 3D live wallpaper with no other change (Prism PR: Hash-Studios/Prism, branch t3/day7-3d-live-wallpaper).

Do not publish from this PR; the owner publishes.

🤖 Generated with Claude Code