Solution not found :(

Hi guys.
I've follow your suggestion about use quaternions to rotate my camera into the space and the upside/down problem that i had using the lookAt method of the Camera class, seems to be fixed
(here the previous video to show you)



Before i've used the spherical coordinates.. when you move the mouse in x direction i change the yaw angle, and when you move in y direction i change the pitch angle.
After modified the angles, i compute the unitary vector that represent the orientation of the camera:

   direction.x=sin(yaw)*sin(pitch);
   direction.y=cos(pitch);
   direction.z=sin(pitch)*cos(yaw);

Finally i use the "lookAt" method to orientate the camera along the "direction" Vector3.
But the side effect is that, when pitch angle go outside the interval (0,PI), the camera flips upside down.

So, i've changed the approach.. no more lookAt but quaternions.

void MyCamera::lookAt(Vector3* dir) {

  //no more used
  //mCamera->lookAt(dir->x,dir->y,dir->z);

   Vector3 src =  mCamera->getDerivedOrientation() * Vector3::NEGATIVE_UNIT_Z;      // Orientation from initial direction. Camera points to (0,0,-1)
   Quaternion quat = src.getRotationTo(*dir);
   mCamera->rotate(quat);
}

And this is the result:



i've changed the starship mesh with a more clear xyz axis mesh: x is in red, y in green and z in blue.
First i try to do a yaw rotation, around the Y axis... it works fine.
Then pitch rotation and.. well! it works! no more upside-down.
But.. when i combine both and give freedom to camera move something strange happens: moving it cause a side effect: some roll rotations starts to appears and the more i rotate clockwise my mouse, the more the roll appears... and rotating the mouse in other direction changes the roll direction too..

Why??

And how can i remove it?