18 Creating and Managing Trackers
Q3Tracker_GetPosition
function to get the position of a tracker.
TQ3Status Q3Tracker_GetPosition ( TQ3TrackerObject trackerObject, TQ3Point3D *position, TQ3Vector3D *delta, TQ3Boolean *changed, unsigned long *serialNumber);trackerObject
A tracker object.position
On exit, the current position of the specified tracker.delta
On exit, the change in position since the last call toQ3Tracker_GetPosition
.changed
On exit, a Boolean value that indicates whether theposition
ordelta
parameter was changed (kQ3True
) or not (kQ3False
).serialNumber
On entry, a tracker serial number, orNULL
. On output, the current tracker serial number.
Q3Tracker_GetPosition
function returns, in the position
parameter, the current position of the tracker specified by the trackerObject
parameter. In addition, it can return, in the delta
parameter, the relative change in position since the previous call to Q3Tracker_GetPosition
.
On entry, if the value of delta
is NULL
, the relative contribution is combined into the reported position. If the value of delta
is not NULL
, then delta
is set to the relative motion that has been accumulated since the previous call to Q3Tracker_GetPosition
. In either case, the position accumulator is set to (0, 0, 0) by this function.
If the value of the serialNumber
parameter is NULL
, Q3Tracker_GetPosition
fills in the position
and delta
parameters and returns the value kQ3True
in the changed
parameter. Otherwise, the value specified in the serialNumber
parameter is compared with the tracker's current serial number. If the two serial numbers are identical, Q3Tracker_GetPosition
leaves the two coordinate parameters and the serialNumber
parameter unchanged and returns the value kQ3False
in the changed
parameter. If the two serial number differ, Q3Tracker_GetPosition
fills in the two coordinate parameters, updates the serialNumber
parameter, and returns the value kQ3True
in the changed
parameter.
If the specified tracker is inactive, then the position
parameter is set to the point (0, 0, 0), the delta
parameter is set to (0, 0, 0) if it is non-NULL
, and the changed
parameter is set to kQ3False
if it is non-NULL
.
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