if (event.sensor.type == Sensor.TYPE_ACCELEROMETER) {
                mGravity[0] = alpha * mGravity[0] + (1 - alpha) * event.values[0]
                mGravity[1] = alpha * mGravity[1] + (1 - alpha) * event.values[1]
                mGravity[2] = alpha * mGravity[2] + (1 - alpha) * event.values[2]
                // mGravity = event.values;