| Tobii Pro SDK C API
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| Data Fields | |
| TobiiResearchNormalizedPoint3D | unit_vector | 
| TobiiResearchValidity | validity | 
Provides properties for the HMD gaze direction.
| TobiiResearchNormalizedPoint3D TobiiResearchHMDGazeDirection::unit_vector | 
The 3D unit vector that describes the gaze direction.
| TobiiResearchValidity TobiiResearchHMDGazeDirection::validity | 
The validity of the gaze direction data.