# HandTrackingModule

The `HandTrackingModule` class enables hand tracking.

## Example

```
//==============================================================================
// The following example demonstrates how to bind the position of a plane to a
// hand.
//
// Project setup:
// - Insert a plane
//==============================================================================

// Load in the required modules
const HandTracking = require('HandTracking');
const Scene = require('Scene');

// Locate the plane and focal distance in the Scene
const plane = Scene.root.find('plane0');
const focalDistance = Scene.root.find('Focal Distance');

// Store a reference to a detected hand
const hand = HandTracking.hand(0);

// Store the z-axis position signal of the focal distance
const focalDistanceZPosition = focalDistance.transform.z;

// Bind the cameraTransform of the hand to the plane's transform
plane.transform = hand.cameraTransform;

// Additionally overwrite the z-axis values with distance taken into account
plane.transform.z = hand.cameraTransform.z.sub(focalDistanceZPosition);

// Bind the hidden property of the plane to a boolean signal that returns true
// when no hands have been detected
plane.hidden = HandTracking.count.eq(0);
```

## Properties

| Property | Description                                                                                                                                              |
| -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `count`  | <p><code>(get) count: ScalarSignal (set) (Not Available)</code></p><p>Specifies a <code>ScalarSignal</code> indicating the number of detected hands.</p> |

## Methods

| Method | Description                                                                                           |
| ------ | ----------------------------------------------------------------------------------------------------- |
| `hand` | <p><code>hand(index: Number): Hand</code></p><p>Returns the <code>Hand</code> indicated by index.</p> |

## Classes

| Class                                                                                           | Description                                            |
| ----------------------------------------------------------------------------------------------- | ------------------------------------------------------ |
| [`Hand`](https://sparkar.facebook.com/docs/ar-studio/reference/classes/handtrackingmodule.hand) | The `Hand` class describes a hand detected in a scene. |


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