# XRMarkerTrackingFeature

This OpenXRInteractionFeature configures Android XR extensions `XR_ANDROID_trackables` and `XR_ANDROID_trackables_marker` at runtime and provides XRImageTrackingSubsystem implementation that works on Android XR platform.

Note: due to the dependency on [XRSessionFeature](https://developer.android.com/develop/xr/unity/reference/class/Google/XR/Extensions/XRSessionFeature#classGoogle_1_1XR_1_1Extensions_1_1XRSessionFeature), its priority must be lower than it so the feature registration happens after XrInstanceManager creation.

## Summary

### Inheritance

Inherits from: `OpenXRFeature`

| ### Public attributes ||
|---|---|
| [ExtensionStrings](https://developer.android.com/develop/xr/unity/reference/class/Google/XR/Extensions/XRMarkerTrackingFeature#extensionstrings)` = "XR_ANDROID_trackables " + "XR_ANDROID_trackables_marker"` | `const string` The OpenXR Extension string. |
| [FeatureId](https://developer.android.com/develop/xr/unity/reference/class/Google/XR/Extensions/XRMarkerTrackingFeature#featureid)` = "com.google.xr.extensions.marker_tracking"` | `const string` The feature ID string. |
| [UiName](https://developer.android.com/develop/xr/unity/reference/class/Google/XR/Extensions/XRMarkerTrackingFeature#uiname)` = "Android XR (Extensions): Image Tracking (Marker)"` | `const string` The UI name shows on the XR Plug-in Management panel, help users to understand validation errors and expected fixes. |

| ### Public static attributes ||
|---|---|
| [IsExtensionEnabled](https://developer.android.com/develop/xr/unity/reference/class/Google/XR/Extensions/XRMarkerTrackingFeature#isextensionenabled)` => _extensionEnabled` | `bool` Gets if the required OpenXR extension is enabled. |
| [RequiredPermission](https://developer.android.com/develop/xr/unity/reference/class/Google/XR/Extensions/XRMarkerTrackingFeature#requiredpermission)` = AndroidXRPermission.SceneUnderstandingCoarse` | `readonly `[AndroidXRPermission](https://developer.android.com/develop/xr/unity/reference/namespace/Google/XR/Extensions#androidxrpermission) Runtime permission required to enable scene understanding. |

## Public attributes

### ExtensionStrings

```c#
const string ExtensionStrings =
            "XR_ANDROID_trackables " +
            "XR_ANDROID_trackables_marker"
```  
The OpenXR Extension string.

Used to check if this extensions is available or enabled.  

### FeatureId

```c#
const string FeatureId = "com.google.xr.extensions.marker_tracking"
```  
The feature ID string.  

### UiName

```c#
const string UiName = "Android XR (Extensions): Image Tracking (Marker)"
```  
The UI name shows on the XR Plug-in Management panel, help users to understand validation errors and expected fixes.

## Public static attributes

### IsExtensionEnabled

```c#
bool IsExtensionEnabled => _extensionEnabled
```  
Gets if the required OpenXR extension is enabled.

When OpenXR runtime is waiting, it returns `null`. Otherwise, it indicates whether the XR_ANDROID_trackables and XR_ANDROID_trackables_marker extensions are available on current device.  

### RequiredPermission

```c#
readonly AndroidXRPermission RequiredPermission =
            AndroidXRPermission.SceneUnderstandingCoarse
```  
Runtime permission required to enable scene understanding.