Xb Head Gestures

xb-head-gestures: completed head motion

Head gestures are optional children of xb.input and use the same camera pose

in WebXR and the desktop simulator.

Setup

const options = new xb.Options();
options.enableHeadGestures();
await xb.init(options);

The built-in nod, shake, nod-up, nod-down, shake-left, and

shake-right gestures are enabled by default. A completed motion emits its

generic and directional names, such as nod and nod-down. They emit once

after a complete motion, unlike held hand-pose gestures.

Subscribe

class HeadGestureListener extends xb.Script {
  init() {
    this.onGesture = (event) => {
      const {name, confidence, data} = event.detail;
      console.log(name, confidence, data);
    };
    xb.input.headGestures?.addEventListener('gesture', this.onGesture);
  }

  dispose() {
    if (this.onGesture) {
      xb.input.headGestures?.removeEventListener('gesture', this.onGesture);
    }
  }
}

Tune

options.headGestures.minimumConfidence = 0.65;
options.headGestures.releaseConfidence = 0.4;
options.headGestures.setGestureEnabled('shake', false);
options.headGestures.setGestureConfig('nod', {
  enabled: true,
  threshold: THREE.MathUtils.degToRad(10),
});

For built-ins, threshold is angular amplitude in radians. Event data may

include amplitudeRadians, durationMs, peakAngularSpeed, and

initialDirection.

Custom recognition

Use HeuristicHeadGestureRecognizer.registerGesture() for custom temporal

heuristics. For other backends, implement HeadGestureRecognizer; its

recognize(context) method may return a score map synchronously or as a

promise. HeadGestureContext.samples contains the recent full 6DoF head pose

window.

Do not invent xb.core.headGestureRecognition; the runtime API is the optional

xb.input.headGestures child.