title: How to adjust euler angle by quaternion
body: <p>I am looking for a way of returning an euler angle that has been rotated by a quaternion.</p>
  
  <p>I understand that extracting pitch roll and yaw from a quaternion is problematic at best, but if I could then I would simply add its values to my own in order to get the resulting euler angle.</p>
  
  <p>I could also convert my euler angle to a quaternion and then combine the two but then I would be left with a quaternion that I cant convert into an euler.</p>
  
  <p>I admit I struggle with quaternions at the best of times so any help will be well received.</p>
  
  <p>For clarity I only need to return an euler angle, all other calculations can be done with quaternions if required.</p>
  
  <p>I am using Bullet Physics, Direct X, C++</p>
  
  <p>Thanks.</p>