IMU

session.imu reports which way the wearer is looking. The glasses’ inertial measurement unit resolves head pose into two states, "up" and "down", and fires an event each time that state changes. Use it to wake content when someone glances up, or to dismiss it when they look back down. This module needs the IMU hardware requirement in your manifest. Mark it REQUIRED and glasses without an IMU won’t list your miniapp; mark it OPTIONAL and they still run it without head-position events. There is no runtime permission to request.

Head position

src/background/index.ts

const off = session.imu.onHeadPosition(({ position }) => {
  if (position === "up") session.display.render([{type: "text", id: "msg", box: {x: 0, y: 0, w: 576, h: 288}, text: "Welcome back"}]);
  else session.display.render([]);
});

Each HeadPositionData has:

Field	Type	Notes
`position`	`"up" \| "down"`	The new head pose. Fires on each transition, not continuously.

Raw accelerometer

onAccel streams raw accelerometer readings, {x, y, z} in g plus a timestamp. This is G2-only today. On glasses without an exposed IMU stream the subscription succeeds and no events arrive.

src/background/index.ts

const off = session.imu.onAccel(({ x, y, z, timestamp }) => {
  // x, y, z in g; timestamp is Unix ms.
});

Each AccelData has:

Field	Type	Notes
`x`, `y`, `z`	`number`	Accelerometer axes in g (gravity-normalized).
`timestamp`	`number`	Unix ms timestamp of the reading.

Subscribing turns the sensor on and unsubscribing turns it off, so most callers never touch it directly. session.imu.setEnabled(true) drives the sensor by hand when you want to, for instance, a diagnostic toggle. It’s a no-op on glasses without an exposed IMU stream. Gyroscope, magnetometer, and fused orientation aren’t exposed yet.

Cleaning up

Both methods return an unsubscribe function:

const off = session.imu.onHeadPosition(handler);
off(); // stop listening

Subscriptions are ref-counted, so the SDK only talks to the phone on the first subscribe and last unsubscribe of a stream.

Getting Started

Core Concepts

UI Layer

Display

Audio & Speech

Sensors & Input

Camera

Phone & System

Data

Reference

Head position

Raw accelerometer

Cleaning up

​Head position

​Raw accelerometer

​Cleaning up

Head position

Raw accelerometer

Cleaning up