Anchors

This page is a supplement to the AR Foundation Anchors manual. The following sections only contain information about APIs where Meta Quest exhibits unique platform-specific behavior.

Tip

When developing an AR app, refer to both the AR Foundation documentation as well as the required packages for each platform you support.

Optional feature support

Meta OpenXR implements the following optional features of AR Foundation's XRAnchorSubsystem:

Feature	Descriptor Property	Supported
Trackable Attachment	supportsTrackableAttachments
Synchronous Add Anchor	supportsSynchronousAdd
Save Anchor	supportsSaveAnchor	Yes
Load Anchor	supportsLoadAnchor	Yes
Erase Anchor	supportsEraseAnchor	Yes
Get Saved Anchor Ids	supportsGetSavedAnchorIds
Async Cancellation	supportsAsyncCancellation

Platform-specific success and error codes

On OpenXR platforms, the XRResultStatus.nativeStatusCode returned by AR Foundation's ARAnchorManager.TryAddAnchorAsync is a wrapper around OpenXR's XrResult.

You can use the XRResultStatus.nativeStatusCode property to access the underlying XrResult value, as shown in the example below:

// This is not optimal. For better performance, reuse a saved reference instead.
var anchorManager = Object.FindAnyObjectByType<ARAnchorManager>();

// Create an anchor at an arbitrary pose.
// You could modify this code to use the position of a raycast hit instead.
var pose = new Pose(Vector3.zero, Quaternion.identity);
var result = await anchorManager.TryAddAnchorAsync(pose);

// To access OpenXR error and success codes, use the nativeStatusCode property
var xrResult = (XrResult)result.status.nativeStatusCode;

// Prints "Success", or the error or success code associated with this operation
Debug.Log(xrResult);

Persistent anchor GUIDs

On Meta's OpenXR runtime, the SerializableGuid returned by ARAnchorManager.TrySaveAnchorAsync is the same value as the input anchor's trackableId.

Native pointer

XRAnchor.nativePtr values returned by this package contain a pointer to the following struct:

typedef struct UnityXRNativeAnchor
{
    int version;
    void* referencePointPtr;
} UnityXRNativeAnchor;

Cast the void* referencePointPtr to an XrSpace handle in C++ using the following example code:

// Marhshal the native anchor data from the XRAnchor.nativePtr in C#
UnityXRNativeAnchor nativeAnchor;
XrSpace* anchorXrSpaceHandle = reinterpret_cast<XrSpace*>(&nativeAnchor.referencePointPtr);

To learn more about native pointers and their usage, refer to Extending AR Foundation.