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POAndroid: getAngleChange - weird results
 

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  1. POAndroid: getAngleChange - weird results
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    <p>I'm currently experimenting with some sensors of Android phones. For testing, I'm using a Samsung Galaxy S. As it does not have a gyroscope, I'm using accelerometer and sensor for magnetic field.</p> <p>What I basically want to do, is to get a certain angle, when moving the device. I try to explain: consider you are holding the phone in landscape mode in front of your face and then you turn yourself by 90 degrees to the right. </p> <p>I use the following code to get the current rotation matrix:</p> <pre><code>@Override public void onSensorChanged(SensorEvent event) { if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) { mGravity = event.values.clone(); } if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) { mGeomagnetic = event.values.clone(); } if (mGravity != null &amp;&amp; mGeomagnetic != null) { float R[] = new float[9]; float I[] = new float[9]; boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic); } } </code></pre> <p>This works well and then I use <code>SensorManager.getAngleChange(angleChange, R, lastR);</code> to achieve the angle change. I then get (roughly) 65° in <code>angleChange[1]</code> if I turn myself as described above and do not tilt the phone or change anything else...</p> <p>But if I also tilt the phone by 90° when turning myself (so that display is looking to the ceiling afterwards) I get (roughly) 90° in <code>angleChange[1]</code>.</p> <p>I'm very confused now, why such a rotation affects the value in <code>angleChange[1]</code> and on the other hand why it is needed to get the expected 90°.</p> <p>What I want to achieve is to get the angle when moving the phone as described above (not in 90° degree steps but this sort of orientation change) no matter which other orientation changes (along the two other axes) are made.</p> <p>Is there any possibility for this?</p>
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    1. USfkerber
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    1. COAnother thing is, this method (SensorManager.getAngleChange()) is available from API Version 9, what could be the possible solution to get angle for earlier version supported devices.
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      1. USAnkit
    2. COI'm not quite sure if I get your comment right. Are you asking for a different solution to get the angles if getAngleChange is not available due to older API versions?
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      1. USfkerber
    3. COYa @fkerber. But i copied a method from source of API version 9 and working on it.
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