[vtkusers] vtkRenderWindowInteractor

[David Chelberg]

I believe the issue is that often one wants to visualize a real-time
process, while maintaining the ability to use
vtkRenderWindowInteractor.  There does not appear to be a clean way in
vtk to call to a user procedure everytime through the event loop.  The
timer mechanism is used so that while a mouse remains pressed,
rotations, etc. continue to occur, but I am unaware of any way to
maintain all the current mechanisms of vtkRenderWindowInteractor,
while adding a call to a user routine every time through the event
loop, i.e. even during a rotation, the dataset should be continuously
updated. 

This seems to be a capability that many would want.  I've seen traffic
on this list about people wanting a VCR like capability in vtk, but
with an added bonus of allowing a user to manipulate the viewpoint of
the replay of a simulation, etc.  I don't recall the results of the
discussion of this issue.

In looking at vtkXRenderWindowInteractor, I think it wouldn't be too
hard to have a user setable function called every time in the event
loop processing:

  do 
    {
    XEvent event;
    XtAppNextEvent(this->App, &event);
    XtDispatchEvent(&event);
// Right Here!

    } 
  while (this->BreakLoopFlag == 0);

I am most familiar with X event processing, I am sure there is an
equivalent for other systems.  Would someone more familiar with the
architecture of vtk comment on what would the best way of achieving
this end consistent with the vtk architecture?

Thanks,

 -- Prof. David Chelberg (chelberg at ohiou.edu)