Planes

This page is a supplement to the AR Foundation Plane detection 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.

Space setup

To use planes on Meta Quest devices, the user must first complete Space Setup.

Unlike other AR platforms, Meta OpenXR does not dynamically discover planes at runtime. Instead, the Unity OpenXR: Meta queries the device's Space Setup data and returns all plane components that are stored in its Scene Model. Some entities in the Scene Model, such as Tables or Couches, include planes, while others do not.

Important

If Space Setup is not complete, AR Foundation cannot use plane data. If your app requires planes, you can use scene capture to prompt the user to complete Space Setup.

Trackable ID

Unlike other AR platforms, the trackableId property of any ARPlane from the Meta OpenXR platform persists across multiple sessions in the same space setup. This allows you to, for instance, save the trackableId of a user's table to persist a virtual centerpiece on the table each time the user runs your app.

Plane alignment

Also unique to the Meta OpenXR platform is the planeAlignmentThreshold property, which determines the threshold for PlaneAlignment categorization. Plane alignment is calculated by taking each component of the plane's normal vector and finding their difference from 0. If the difference is less than the planeAlignmentThreshold, then the MetaOpenXRPlaneSubsystem will categorize the plane depending on which of the normal vector's components are within the threshold. The x and z components are both checked for horizontal planes while the y component is checked for vertical planes.

Plane classification

This package maps Meta's native semantic label component to AR Foundation's PlaneClassification. Natively, Meta supports multiple classifications per plane, but ARPlane.classification will only contain the first label, or None if the label cannot be determined.

Refer to the table below to understand the mapping between Meta's semantic labels and AR Foundation's classifications:

Meta Label	AR Foundation Label
TABLE	Table
COUCH	Seat
FLOOR	Floor
CEILING	Ceiling
WALL_FACE	Wall
DOOR_FRAME	Door
WINDOW_FRAME	Window
OTHER	Other

Native pointer

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

typedef struct UnityXRNativePlane
{
    int version;
    void* planePtr;
} UnityXRNativePlane;

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

// Marhshal the native plane data from the BoundedPlane.nativePtr in C#
UnityXRNativePlane nativePlaneData;
XrSpace* planeXrSpaceHandle = static_cast<XrSpace*>(nativePlaneData.planePtr);

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