18 Creating and Managing Trackers

18 Q3Tracker_GetEventCoordinates

You can use the Q3Tracker_GetEventCoordinates function to get the settings (coordinates) of a tracker that were recorded at a particular moment (typically, the time of a button click) by a previous call to Q3Tracker_SetEventCoordinates.

TQ3Status Q3Tracker_GetEventCoordinates (
TQ3TrackerObject trackerObject, 
unsigned long timeStamp, 
unsigned long *buttons, 
TQ3Point3D *position, 
TQ3Quaternion *orientation);
trackerObject
A tracker object.
timeStamp A time stamp.
buttons On exit, the button state value of the specified tracker at the specified time.
position On exit, the position of the specified tracker at the specified time. If the tracker is absolute, this parameter contains the absolute coordinates of the tracker. If the tracker is relative, this parameter contains the change in position since the last call to Q3Tracker_GetEventCoordinates.
orientation On exit, the orientation of the specified tracker at the specified time.

DESCRIPTION


The Q3Tracker_GetEventCoordinates function returns, in the buttons, position, and orientation parameters, the button state value, position, and orientation of the tracker specified by the trackerObject parameter, at the time specified by the timeStamp parameter. You can set any of the buttons, position, and orientation parameters to NULL to prevent Q3Tracker_GetEventCoordinates from returning a value in that parameter.

Q3Tracker_GetEventCoordinates selects the set of event coordinates whose time stamp is closest to the value specified in the timeStamp parameter. Any event coordinate sets that are older are discarded from the tracker's ring buffer. If the ring buffer is empty, Q3Tracker_GetEventCoordinates returns kQ3Failure.

DESCRIPTION

3D Graphics Programming with QuickDraw 3D - 21 OCT 1995

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