public Vector3f getRotationColumn(int i) {
        return getRotationColumn(i, null);
    }
Calculates one of the basis vectors of the rotation. The current instance
is unaffected.

<p>Note: the result is created from a normalized version of the current
instance.

@param i which basis vector to retrieve (&ge;0, &lt;3, 0&rarr;X-axis,
    1&rarr;Y-axis, 2&rarr;Z-axis)
@return the basis vector (a new Vector3f)
jme3-core/src/main/java/com/jme3/math/Quaternion.java