Hi to all and sorry for my english... In these days I'm studying directx and yesterday I was in trouble with a third person camera and quaternions... I was following a tutorial for XNA rewrited for directx in c++. Scenario: little landscape with a xwing flying over it. Arrowleft and arrowright execute a roll and up/down a pitch. A and Z walk forward and backward. The main question is: after a rolling round Z the X axis is not update to the new position and I don't know why. This is the tutorial: http://www.riemers.net/eng/Tutorials/XNA/Csharp/Series2/Flight_kinematics.php and this is my project (sorry for the ugly code): http://rapidshare.com/files/138592134/My_third_person_camera.rar.html Could you help me? Thanks for any help!!