[vtkusers] setting camera orientation

[Tim Soper]

So I searched online to find any reference as to why there is no easy SetOrientation method as part of the vtkCamera. I 'm not sure I understand. This seems really basic. As of now, I have to port the code snippet below into every application I use. Can anyone explain why this can't just be put into the vtkCamera class directly? Once the three angles are known, the view matrix can be computed. It seems a bit laborious to have to compute the focus and view up explicitly to change the orientation, but I don't see another way of doing this with the current methods in the vtkCamera class.


void SetCameraPositionOrientation( vtkCamera* cam, double position[3], 
                                         double orientation[3] )
{
    double focus[3];
    double viewup[3];

    if( cam == NULL )
        return;

    focus[0] = position[0] - -cos(orientation[0])*sin(orientation[1]);
    focus[1] = position[1] - sin(orientation[0]);
    focus[2] = position[2] - cos(orientation[0])*cos(orientation[1]);

    viewup[0] = cos(orientation[1])*sin(orientation[2])+
                sin(orientation[1])*sin(orientation[2])*cos(orientation[2]);
    viewup[1] = cos(orientation[0])*cos(orientation[2]);
    viewup[2] = sin(orientation[1])*sin(orientation[2])-
                cos(orientation[1])*sin(orientation[0])*cos(orientation[2]);

    //set the camera position and orientation
    cam->SetPosition( position );
    cam->SetViewUp( viewup );
    cam->SetFocalPoint( focus );

}






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