Rolling camera and then interacting with the view provide incorrect interactions

[mwestphal]

Describe the bug
Rolling the camera (by pressing 6) and then interacting with the mouse is incorrect.
The camera "jerks" back to the original position.

To Reproduce
Steps to reproduce the behavior:

1. Open the file using f3d --dry-run dragon.vtu
2. press 6
3. interact with view

Expected behavior
No jerking

[mwestphal]

Caused by

    // orthogonalize up vector based on focal direction
    vtkMath::MultiplyScalar(dir, dot);
    vtkMath::Subtract(up, dir, dir);
    vtkMath::Normalize(dir);
    camera->SetViewUp(dir);

in /vtkF3DInteractorStyle.cxx

Since rolling camera does not impact view-up, im not sure of the right way to fix this.

TopViewCamera as the same issue

[mwestphal]

No obvous fix, moving back

[samoncrief]

I'm looking into this now, feel free to assign it to me

[mwestphal]

Sure, assigned.

A possible implementation is to store a temporary view-up when rolling