title: How to rotate a QQuaternion on two axes
body: <p>I'm working with qglwidget and various gestures for an android app and the topic of Quaternions is thoroughly confusing so its been mostly guess and check. I've been able to make a rotation about one axis by some number of degrees using: </p>
  
  <pre><code>rotation=QQuaternion::fromAxisAndAngle(QVector3D(1,0,0),delta.y())*rotation;
  </code></pre>
  
  <p>This has the desired results as does the same statement in the x direction. </p>
  
  <p>My question is, for one, is the the correct way of doing a rotation? And two, if I want to rotate on two axes do I just do: </p>
  
  <pre><code>rotation=QQuaternion::fromAxisAndAngle(QVector3D(1,0,0),delta.y())*rotation;
  rotation=QQuaternion::fromAxisAndAngle(QVector3D(0,1,0),delta.x())*rotation;
  </code></pre>
  
  <p>Or is there a one line statement that will work just as well?</p>