xb-gestures

name: xb-gestures description: >- Detect named hand gestures in an XR Blocks app — pinch, open-palm, fist, thumbs-up, point, and spread — and subscribe to gesturestart / gestureupdate / gestureend events with per-hand name and confidence. Use when triggering actions from poses rather than raw pinch/touch (e.g. point-to-aim, open-palm menu, thumbs-up confirm). Covers enableGestures(), options.gestures.setGestureEnabled, and the xb.core.gestureRecognition event API. For raw hand joints/touch/grab, use xb-hands; for stroke/shape recognition use the strokes API.

xb-gestures: gesture recognition

Builds on hand tracking (xb-hands) to recognize discrete poses and emit DOM-style events.

Setup

const options = new xb.Options();
options.enableReticles();
options.enableGestures();

// Opt specific gestures in (names: pinch, open-palm, fist, thumbs-up, point, spread).
options.gestures.setGestureEnabled('point', true);
options.gestures.setGestureEnabled('spread', true);

options.hands.enabled = true; // gestures need hands
options.simulator.defaultMode = xb.SimulatorMode.POSE; // pose hands on desktop
xb.init(options);

Subscribe to events

xb.core.gestureRecognition is an EventTarget. Subscribe in your Script's init() and unsubscribe in dispose():

class GestureLogger extends xb.Script {
  init() {
    const gestures = xb.core.gestureRecognition;
    if (!gestures) {
      console.warn('Call options.enableGestures() before xb.init().');
      return;
    }
    this._onStart = (event) => {
      const {hand, name, confidence = 0} = event.detail; // hand: 'left'|'right'
      console.log(`${hand} started ${name} (${confidence.toFixed(2)})`);
    };
    this._onEnd = (event) => {
      const {hand, name} = event.detail;
      console.log(`${hand} ended ${name}`);
    };
    gestures.addEventListener('gesturestart', this._onStart);
    gestures.addEventListener('gestureend', this._onEnd);
    // 'gestureupdate' fires continuously while a gesture is held.
  }
  dispose() {
    const g = xb.core.gestureRecognition;
    if (!g) return;
    g.removeEventListener('gesturestart', this._onStart);
    g.removeEventListener('gestureend', this._onEnd);
  }
}

Notes

• Events: gesturestart, gestureupdate, gestureend; event.detail = {hand, name, confidence}.
• Tune providers/thresholds via options.gestures (see src/input/gestures/GestureRecognitionOptions.ts).
• Heuristic detectors ship by default; custom TF-Lite / PyTorch gesture models can be wired in.
• See templates/heuristic_hand_gestures and demos/sim_hand_poses for full examples.