[android-developers] Re: getRotationMatrixFromVector() broken on Note 3

As a temporary fix you could just copy-paste the original source code from the Android SDK as a drop-in replacement:

    public static void getRotationMatrixFromVector(float[] R, float[] rotationVector) {

        float q0;
        float q1 = rotationVector[0];
        float q2 = rotationVector[1];
        float q3 = rotationVector[2];

        if (rotationVector.length == 4) {
            q0 = rotationVector[3];
        } else {
            q0 = 1 - q1*q1 - q2*q2 - q3*q3;
            q0 = (q0 > 0) ? (float)Math.sqrt(q0) : 0;
        }

        float sq_q1 = 2 * q1 * q1;
        float sq_q2 = 2 * q2 * q2;
        float sq_q3 = 2 * q3 * q3;
        float q1_q2 = 2 * q1 * q2;
        float q3_q0 = 2 * q3 * q0;
        float q1_q3 = 2 * q1 * q3;
        float q2_q0 = 2 * q2 * q0;
        float q2_q3 = 2 * q2 * q3;
        float q1_q0 = 2 * q1 * q0;

        if(R.length == 9) {
            R[0] = 1 - sq_q2 - sq_q3;
            R[1] = q1_q2 - q3_q0;
            R[2] = q1_q3 + q2_q0;

            R[3] = q1_q2 + q3_q0;
            R[4] = 1 - sq_q1 - sq_q3;
            R[5] = q2_q3 - q1_q0;

            R[6] = q1_q3 - q2_q0;
            R[7] = q2_q3 + q1_q0;
            R[8] = 1 - sq_q1 - sq_q2;
        } else if (R.length == 16) {
            R[0] = 1 - sq_q2 - sq_q3;
            R[1] = q1_q2 - q3_q0;
            R[2] = q1_q3 + q2_q0;
            R[3] = 0.0f;

            R[4] = q1_q2 + q3_q0;
            R[5] = 1 - sq_q1 - sq_q3;
            R[6] = q2_q3 - q1_q0;
            R[7] = 0.0f;

            R[8] = q1_q3 - q2_q0;
            R[9] = q2_q3 + q1_q0;
            R[10] = 1 - sq_q1 - sq_q2;
            R[11] = 0.0f;

            R[12] = R[13] = R[14] = 0.0f;
            R[15] = 1.0f;
        }
    }

Interestingly enough the original code does not explicitly throw the exception you mentioned. So it must be some weird Samsung hack. You could try registering with Samsung as a developer and use their support ticket system in order to tell them about this problem. However, I already complained once about one of their SDKs and never heard back from them.

On Wednesday, October 2, 2013 8:41:01 AM UTC-5, String wrote:

I've been getting error reports from users of the Note 3 that boil down to the following:

java.lang.IllegalArgumentException: R array length must be 3 or 4

at android.hardware.SensorManager.getRotationMatrixFromVector(SensorManager.java:1336)

This function, getRotationMatrixFromVector(), is documented as a "Helper function to convert a rotation vector to a rotation matrix. Given a rotation vector (presumably from a ROTATION_VECTOR sensor)". My typical call to this function looks like this:

SensorManager.getRotationMatrixFromVector(R, rotationVector);

Where the rotationVector comes from the hardware accelerometer and gyroscope, and (despite the error message about R) it's with this parameter where the problem lies. It's directly passed from android.hardware.SensorEventListener.onSensorChanged(SensorEvent event) for a Sensor.TYPE_ROTATION_VECTOR event. The event parameter there has a values property that is passed as the rotationVector in the previous call. And according to the docs at
http://developer.android.com/reference/android/hardware/SensorEvent.html#values, this array can legitimately have up to 5 elements - moreover, in Android 4.3, it should have all 5. However, passing an array of length 5 causes the Note 3 to crash on the aforementioned IllegalArgumentException; it seems to expect 4 elements at most.

So, here's the summary: Android 4.3 passes an array with 5 elements to this hardware event, and the Note 3 throws an exception when passed that same array to the system-defined helper function for that event. This behavior does not happen on the other 4.3 devices I have at hand (Galaxy Nexus and Nexus 7); it appears to be a basic flaw in the Samsung implementation of 4.3.

And I know, this all looks like minutiae of a hyper-specific issue - but believe me, it's likely to be encountered by any app using the device's motion sensors. A Google search for getRotationMatrixFromVector returns 51,400 results.

Any comment from Samsung on this would be most welcome, if unlikely.

String

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