[vtkusers] camera movement

[Thomas Faust]

Hi vtk-users.

I'm trying to improve the interactorstyle to match the requirements we have.
The rotation of the camera is basicly the same than in 
vtkInteractorStyleJoystickCamera. But the Rotation() in this class have to be 
adjusted a little bit.

If the user moves the mouse vertical the camera should move around the vocal 
point (which ist the middle of the users part of interest) only in 
Z-direction.
And a horizontal moouse movement should move the mouse in X-Y-direction.

(For this reason, the functions Azimuth() and Elevation() are not very 
usefull)

Can anybody give me a usefull algorithm to move my camera in the right 
directions?

Thanks, Tom