XR Trackable Items

A trackable is something that can be tracked during application execution. This is an object whose position and orientation can be detected. You can use that information to add 3D elements associated with those trackables. While a trackable is detected, its world transform matrix is updated based on real-world object changes. There are different types of trackables that can be detected by Evergine: planes, images, and faces. They all extend XRTrackableItem as the base class.

Supported Devices

Currently, in Evergine, the following devices have Trackable Items support:

Device	XR Platform
Android	ARCore

XRTrackableItem

This base class holds information that is common to any trackable element.

Properties and Methods

Property	Description
ID	Gets the trackable identifier. This is internally generated by Evergine and will be unique for all detected trackables.
Transform	Stores position and orientation information for the detected trackable. It will be continuously updated while the application is running with real-world object information.

XRPlaneTrackable

This class represents plane detection. Depending on the XR platform implementation, you can use XRPlaneDetectionType to detect just vertical or horizontal planes, or even enable both types of plane detection.

Properties and Methods

Property	Description
BoundaryPolygon	Holds information about the vertices for an approximation of the polygon boundaries for a detected plane. Values are relative to the XZ plane and should be transformed by the trackable transform information to get boundaries in world-relative coordinates.
Size	Estimated width and length of the plane.
Type	Type of detected plane: horizontal with upward or downward facing, or vertical plane.

XRImageTrackable

Trackable for images, whether they are static or in motion.

Properties and Methods

Property	Description
DatabaseIndex	Indicates the index of the image in the internal images database.
Name	Indicates the name of the image in the internal images database.
Size	Size of the detected image.
TrackingMethod	Depending on the tracking state: if the image is not being tracked, is tracked by the last pose information, or full tracking.

XRFaceTrackable

This class is used for face tracking. A single face at a time will be detected.

Properties and Methods

Property	Description
MeshVerticesPointer	Pointer to the native face mesh vertices buffer.
MeshVerticesCount	Number of face mesh vertices.
MeshTextureCoordinatesPointer	Pointer to the native face texture coordinates buffer.
MeshTextureCoordinatesCount	Number of texture coordinates.
MeshNormalsPointer	Pointer to the native face mesh normals buffer.
MeshNormalsCount	Number of normals.
MeshTriangleIndicesPointer	Pointer to the native mesh index buffer.
MeshTriangleIndicesCount	Number of indices.
LeftForeheadPose	Pose for the left forehead.
RightForeheadPose	Pose for the right forehead.
NosePose	Pose for the nose.