The XR_EXT_hand_tracking_data_source extension differentiates between optical tracking and control-derived pose. See impact on gestures, UI and fallback.
Direct answer
The ratified extension XR_EXT_hand_tracking_data_source allows an OpenXR application to request and discover the source of joint poses: unobstructed hands, such as optical tracking or gloves, or data derived from a held controller. The application declares accepted fonts when creating the tracker and queries the active font next to the joints. This distinction avoids assuming that individualized fingers exist when the runtime is estimating a hand from the control.
The same pose can have different capabilities
Optical tracking provides individual articulation; a control can generate an approximate representation. Fine gestures should not depend on the second case.
Active source may change during the session
The user switches between hands and controls. The interface needs to update affordances, help, and tolerance without restarting the experience.
Application declares what it can accept
The list of requested sources acts as a contract. If none are active, the joins should be treated as invalid, not zero.
Fallback preserves task, not just animation
A pinching action can become a trigger; pointing can use the control's ray. The objective is to maintain results and accessibility across devices.
Nexus Reading
XR portability requires knowing the origin and trust of the input. Robust designs design semantic actions before mapping specific gestures or buttons.
FAQ
What fonts does the extension differentiate?
Unobstructed hand, such as optical tracking, glove or mocap, and source based on insured control.
Can the font change at runtime?
Yes. The active state is consulted along with the joint positions.
What to do without an accepted source?
Treat tracking as inactive and offer another input method.
Essential guides to delve deeper into the decision
This editorial analysis was produced by Nexus from the official sources below, consulted on September 21, 2026. The text is original and interprets practical implications for companies.
- Khronos — XrHandTrackingDataSourceEXT: unobstructed sources and controller, rules and integration with the tracker.
- Khronos — XrHandTrackingDataSourceStateEXT: active source query, chaining and behavior when there is no valid source.
Date reported by main source: OpenXR 1.1 specification consulted on September 21, 2026; technical analysis.