Rotating the UpVector - Custom free roaming camera

[NovaCoder]

I'm still having 'issues' with my custom camera class. So far I've found out that all you need to rotate your camera's view (no translation yet) is to rotate your target point around the camera's origin.

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 core::vector3df CameraPos; 
 CameraPos = this->getAbsolutePosition(); 

 nRotX = (MousePos.X) * -1.0f; 
 nRotY = (MousePos.Y) * -1.0f; 


 // Rotates around Y 
 Target.rotateYZBy(-nRotY, CameraPos);    

 // Rotates around X 
 Target.rotateXZBy(nRotX, CameraPos); 

So this code seems to work ok apart from when you rotate past the camera's straight up position, this is because I also need to rotate the Camera's UpVector. I tried something like following code but it's introducing 'roll'.

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UpVector.rotateYZBy(-nRotY, core::vector3df(0,0,0)); 
UpVector.rotateXZBy(nRotX,, core::vector3df(0,0,0)); 
UpVector.normalize();

Does anyone know how to correctly rotate the UpVector for my implementation?

This code is in the Maya sceneNode class but looks kinda nasty:

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if (nRotY >= 90.0f && nRotY <= 270.0f)
  UpVector.set(0, -1, 0);
else
 UpVector.set(0, 1, 0);

I had a look on the Net and found something that said I should generate a new 'Left' point using the crossproduct of the Target and the current Up and then rotate the Up around it...is that correct?


Also I've notice that with my code my target (target object added using 'addTestSceneNode' without a rotation value specified) not only rotates around the camera's origin but also rotates around its own Axis, is this just an Engine bug or am I doing something silly?

ThanX