title: determine pitch, yaw, roll from up front right
body: <p>In my didactic openGL appl , I have some objects on the scene, and when I click on one of them I want my camera to look at that object. For that after I determine the clicked object , I compute the up , front and right vectors of the camera  and then I need to be able to calculate the  pitch, yaw, roll angles of the camera. However I am quite clueless about how could I do that , so any help would be great .</p>