C Specification

The xrGetMarkersML function is defined as:

// Provided by XR_ML_marker_understanding
XrResult xrGetMarkersML(
    XrMarkerDetectorML                          markerDetector,
    uint32_t                                    markerCapacityInput,
    uint32_t*                                   markerCountOutput,
    XrMarkerML*                                 markers);

Parameters

Parameter Descriptions

  • markerDetector is the detector object to retrieve marker information from.

  • markerCapacityInput is the capacity of the markers array or 0 to indicate a request to retrieve the required capacity.

  • markerCountOutput is filled in by the runtime with the count of marker atoms written or the required capacity in the case that markerCapacityInput is insufficient.

  • markers is a pointer to an array of XrMarkerML atoms, but can be NULL if propertyCapacityInput is 0.

  • See the Buffer Size Parameters section for a detailed description of retrieving the required markers size.

Description

Get the list of current snapshotted marker atoms, must only be called when the state of the detector is XR_MARKER_DETECTOR_STATUS_READY_ML.

If xrGetMarkerDetectorStateML has not been called and returned XR_MARKER_DETECTOR_STATUS_READY_ML since the last invocation of xrSnapshotMarkerDetectorML, the runtime must return XR_ERROR_CALL_ORDER_INVALID.

The returned atoms are only valid while in the XR_MARKER_DETECTOR_STATUS_READY_ML state. The runtime must return the same atom value for the same uniquely identifiable marker across successive snapshots. It is unspecified what happens if the detector is observing two markers with the same identification patterns.

Assuming the same set of markers are in view across several snapshots, the runtime should return the same set of atoms. An application can use the list of atoms as a simple test for if a particular marker has gone in or out of view.

Note that XrMarkerML atoms are only usable with the XrMarkerDetectorML that returned them.

This function follows the two-call idiom for filling the markers.

Valid Usage (Implicit)
Return Codes
On success, this command returns

  • XR_SUCCESS

  • XR_SESSION_LOSS_PENDING

On failure, this command returns

  • XR_ERROR_FUNCTION_UNSUPPORTED

  • XR_ERROR_VALIDATION_FAILURE

  • XR_ERROR_RUNTIME_FAILURE

  • XR_ERROR_HANDLE_INVALID

  • XR_ERROR_INSTANCE_LOST

  • XR_ERROR_SESSION_LOST

  • XR_ERROR_CALL_ORDER_INVALID

See Also

XR_ML_marker_understanding, XrMarkerDetectorML, XrMarkerML, xrCreateMarkerSpaceML, xrGetMarkerNumberML, xrGetMarkerReprojectionErrorML, xrGetMarkerStringML

Document Notes

For more information, see the OpenXR Specification

This page is extracted from the OpenXR Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2024, The Khronos Group Inc.

This work is licensed under a Creative Commons Attribution 4.0 International License.