- upadte documentation for rotation vector
- update method dealing with rotation vector to deal with 4 components
- virtual rotation-vector sensor reports all four components
- improve SensorManager documentation layout
Whent he 4-th component of the rotation-vector is present, we can save
a square-root when computing the quaternion or rotation matrix from it.
Change-Id: Ia84d278dd5f0909fab1c5ba050f8df2679e2c7c8
indeed, by construction of the rotation matrix, it is
guaranteed to have a length of 1.
moreover, the normalization code was missing a square-root,
fortunatelly, since the length is 1, this didn't cause any
damage (since sqrt(1) = 1).
Change-Id: I9facd668caaf5bb3bfccb139ab872f2bb2066365
Rework sensorservice to allow "virtual sensors", that is
sensors that report a synthetized value based on real sensors.
the main change to sensorservice is around managing which real
sensor need to be activated and which rate to use.
The logic for all this has been moved into SensorDevice, which
essentially wraps the sensor HAL but adds two features to it:
- it keeps track of which sensors need to be activated
- it keeps track of what rate needs to be used
For this purpose an "identity" is associated with each real sensor
activation, so we can track them.
On start-up we check for gravity, linear-acceleration and
rotation-vector sensors, if they're not present in the HAL, we
synthetize them in sensor-service.
Change-Id: I841db2c1b37ef127ed571efa21732ecc5adf1800
