# AHeadTrackerEvent

## Summary

| ### Public attributes ||
|---|---|
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1a75378404b33e10235e233f01965e3019` | `int32_t` This value changes each time the reference frame is suddenly and significantly changed, for example if an orientation filter algorithm used for determining the orientation has had its state reset. |
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1af1142dcffb78b6db7c56e8a6264d2848` | `float` The fields rx, ry, rz are an Euler vector (rotation vector, i.e. |
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1adf2ed833b32410d6504fd0ff83165335` | `float` |
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1a0014848e0334260615ab245a31ae2bfe` | `float` |
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1a8d4f2c836a462ca43117ca0a3544eb83` | `float` The fields vx, vy, vz are an Euler vector (rotation vector) representing the angular velocity of the head (relative to itself), in radians per second. |
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1a43ec4fd672c0d206665bd4dfaa85a52d` | `float` |
| `https://developer.android.com/ndk/reference/struct/a-head-tracker-event#struct_a_head_tracker_event_1aaed8f32ad9f859993975ed6946fb7c9f` | `float` |

## Public attributes

### discontinuity_count

Declared in `android/sensor.h`

```scdoc
int32_t AHeadTrackerEvent::discontinuity_count
```
This value changes each time the reference frame is suddenly and significantly changed, for example if an orientation filter algorithm used for determining the orientation has had its state reset.

### rx

Declared in `android/sensor.h`

```text
float AHeadTrackerEvent::rx
```
The fields rx, ry, rz are an Euler vector (rotation vector, i.e.

a vector whose direction indicates the axis of rotation and magnitude indicates the angle to rotate around that axis) representing the transform from the (arbitrary, possibly slowly drifting) reference frame to the head frame. Expressed in radians. Magnitude of the vector must be in the range \[0, pi\], while the value of individual axes are in the range \[-pi, pi\].

### ry

Declared in `android/sensor.h`

```text
float AHeadTrackerEvent::ry
```

### rz

Declared in `android/sensor.h`

```text
float AHeadTrackerEvent::rz
```

### vx

Declared in `android/sensor.h`

```text
float AHeadTrackerEvent::vx
```
The fields vx, vy, vz are an Euler vector (rotation vector) representing the angular velocity of the head (relative to itself), in radians per second.

The direction of this vector indicates the axis of rotation, and the magnitude indicates the rate of rotation.

### vy

Declared in `android/sensor.h`

```text
float AHeadTrackerEvent::vy
```

### vz

Declared in `android/sensor.h`

```text
float AHeadTrackerEvent::vz
```