Hash :
5697089d
Author :
Date :
2013-10-20T23:52:02
Fixed bug 2156 - Android: Accelerometer values fed to joystick driver are inverted for the X axis and wrong for Z
Denis Bernard
Background information: http://developer.android.com/reference/android/hardware/SensorEvent.html#values
Steps to reproduce: compile testjoystick.c as an android app (change screen size according to your device). While running the app, also run:
adb logcat -c; adb logcat -s 'SDL:*' 'SDL/APP:*'
When tilting the device left/right, the joystick moves in the opposite direction of what one would expect. Or at least, the behaviour is not consistent with the Y axis.
Also when the device sits on a table (obviously not moving), the Z axis value oscillates between -32000 and +32000 (by overflow):
I/SDL/APP ( 1994): Joystick 0 axis 2 value: 32511
I/SDL/APP ( 1994): Joystick 0 axis 2 value: 32575
I/SDL/APP ( 1994): Joystick 0 axis 2 value: 32383
I/SDL/APP ( 1994): Joystick 0 axis 2 value: -32386
I/SDL/APP ( 1994): Joystick 0 axis 2 value: -32450
I/SDL/APP ( 1994): Joystick 0 axis 2 value: -32578
This is caused by the accelerometer yielding a constant value around 9.81 for Z and feeding something like 0.9 to 1.1 to the joystick driver, resulting in the overflow.
Proposed fix in SDLActivity.java (swap X and subtract G from Z reading)