Class VarjoEyeTrackingHandler

Namespace: mobisim.VR

Drives eye-tracking data acquisition, gaze visualisation, and high-frequency CSV logging for Varjo XR headsets.

public class VarjoEyeTrackingHandler : MonoBehaviour

Inheritance

object→Object→Component→Behaviour→MonoBehaviour→VarjoEyeTrackingHandler

Remarks

The simulator setup pairs a Varjo headset with a physical steering rig so that head gaze direction can be correlated with driving events (e.g., does the participant look toward a pedestrian before yielding?). Two GazeDataSource modes are provided because the Varjo headset exposes two separate APIs: the standard OpenXR InputSubsystem path works with any XR headset and returns fixation point data only, while the Varjo-proprietary GazeAPI additionally exposes per-eye pupil and iris diameter measurements needed for pupillometry-based cognitive-load analysis.

Gaze logging writes directly to a semicolon-delimited CSV file at up to 200 Hz rather than routing through the analysis pipeline (IDataSendService). This was chosen for performance (zero serialisation overhead per frame) at the cost of not sharing the retry and queuing guarantees of the main data-send infrastructure.

Gaze target placement uses a BufferedRaycast over the last 10 frames so transient head micro-jitter does not cause the on-screen fixation indicator to flicker between objects at boundaries. The semantic collision names accumulated across those 10 frames are written to the CSV log so post-hoc analysis can reconstruct what the participant was fixating in each timestep.

The entire implementation is conditionally compiled for UNITY_EDITOR and UNITY_STANDALONE_WIN only; WebGL and other platforms cannot use the Varjo SDK or native file I/O required here.

Fields

calibrationRequestKey

Key to press to request a gaze calibration during runtime.

[Tooltip("Key to press to request a gaze calibration during runtime.")]
public KeyCode calibrationRequestKey

Field Value

KeyCode

fixationPointTransform

Transform representing the fixation point in the scene, used to visualize where the user is looking.

[Header("Visualization Transforms")]
[Tooltip("Transform representing the fixation point in the scene.")]
public Transform fixationPointTransform

Field Value

Transform

frequency

Specifies the frequency at which gaze data is output by the Varjo API.

[Header("Gaze data output frequency")]
[Tooltip("Specifies the frequency at which gaze data is output.")]
public VarjoEyeTracking.GazeOutputFrequency frequency

Field Value

VarjoEyeTracking.GazeOutputFrequency

gazeCalibrationMode

Determines the mode to use when requesting gaze calibration from Varjo.

[Header("Gaze calibration settings")]
[Tooltip("Determines the mode to use when requesting gaze calibration from Varjo.")]
public VarjoEyeTracking.GazeCalibrationMode gazeCalibrationMode

Field Value

VarjoEyeTracking.GazeCalibrationMode

gazeDataSource

Selects which gaze data source to use for tracking (InputSubsystem or GazeAPI).

[Header("Gaze data")]
[Tooltip("Selects which gaze data source to use for tracking.")]
public VarjoEyeTrackingHandler.GazeDataSource gazeDataSource

Field Value

VarjoEyeTrackingHandler.GazeDataSource

gazeOutputFilterType

Sets the filter type applied to the gaze data output from Varjo for smoother or more responsive gaze signals.

[Header("Gaze output filter settings")]
[Tooltip("Sets the filter type applied to the gaze data output from Varjo.")]
public VarjoEyeTracking.GazeOutputFilterType gazeOutputFilterType

Field Value

VarjoEyeTracking.GazeOutputFilterType

leftEyeTransform

Transform representing the left eye�s position and orientation in the scene.

[Tooltip("Transform representing the left eye.")]
public Transform leftEyeTransform

Field Value

Transform

printFramerate

Enables printing of the gaze data framerate to the console during logging for debugging performance.

[Tooltip("Enables printing of gaze data framerate while logging.")]
[SerializeField]
public bool printFramerate

Field Value

bool

rightEyeTransform

Transform representing the right eye�s position and orientation in the scene.

[Tooltip("Transform representing the right eye.")]
public Transform rightEyeTransform

Field Value

Transform

setOutputFilterTypeKey

Key to press to cycle or set the gaze output filter type during runtime.

[Tooltip("Key to press to set the gaze output filter type during runtime.")]
public KeyCode setOutputFilterTypeKey

Field Value

KeyCode

showFixationPoint

Determines whether the fixation point indicator should be visible in the scene.

[Header("Toggle fixation point indicator visibility")]
[Tooltip("Determines whether the fixation point indicator should be visible.")]
public bool showFixationPoint

Field Value

bool

toggleGazeTarget

Key to press to toggle the visibility of the gaze target indicator in the scene.

[Header("Toggle gaze target visibility")]
[Tooltip("Key to press to toggle the visibility of the gaze target indicator.")]
public KeyCode toggleGazeTarget

Field Value

KeyCode

xrCamera

Reference to the XR camera used to transform gaze data into world space.

[Header("XR camera")]
[Tooltip("Reference to the XR camera used for gaze transformations.")]
public Camera xrCamera

Field Value

Camera