[vtkusers] updating a scene

David.Pont at ForestResearch.co.nz David.Pont at ForestResearch.co.nz
Tue Jul 29 17:27:04 EDT 2003

Hi Luke,
  I have made vis apps where I add actors in response to user events (GUI,
button, checkbox etc). If the user later 'turns them off' I set
VisibilityOff, and if they later 'turn them back on' I set VisibilityOn.
So at the beginning there is a small set of initial actors added, the user
can cause others to be added, the total number of actors can only increase,
but I do not have to create them all up front.
At startup I declare all actors and set them to NULL. On a request to 'turn
on' an actor if it is NULL I build the pipeline and add the actor.

   Dave Pont

                    Luke J West                                                                                                                 
                    <ljw at soc.soton       To:     Jeff Lee <jeff at cdnorthamerica.com>                                                             
                    .ac.uk>              cc:     vtkusers at vtk.org                                                                               
                    Sent by:             Subject:     Re: [vtkusers] updating a scene                                                           

Sorry, I was not at all clear...

I have written my own InteractorStyle and am responding to user events from
there without any trouble. (OnMouseMove, etc.) I can interactively spit out
diagnostic text in a console window, and it's at that point I do my adding
removing of actors, but the changes are not reflected visibly. I've had a
at the contents of the ActorCollection object in the Renderer, and it is
behaving as expected to the Add/Remove calls, but the rendered scene does
even after I call the Render() method of everything I have a handle to.
renderWindow, renderWindowInteractor)

I just discovered I can use visibilityOn/Off in response to the events i'm
capturing and have found that it works, but to use that strategy I would
need to
know up front the actors I want visualise which, as you can imagine, is

thanks very for your comments, jeff - any other ideas?


Quoting Jeff Lee <jeff at cdnorthamerica.com>:

> once you invoke rwi->Start(), your app enters an event loop in which
> case there is no way to change the scene externally (other than
> attaching a UserEvent observer i.e. the 'u' kepress would invoke your
> user method which could add/remove actors... very limited except for
> quick&dirty pipeline vis) until you break the loop (terminate the app).
> your other alternative would be to have your own application-level loop
> for capturing events and manually pass the events to the rwi.  you can
> look at something like vtkQt to see how its done.
> -Jeff
> Luke J West wrote:
> >Thanks for that reply, Jeff,
> >
> >does anybody know of an example that demonstrates "turning actors on and
> off"
> >
> >If I change my scene using _renderer->AddActor(...) or ->RemoveActor
> after
> >rwi->Start(...) and ->Initialize(...) the scene remains unchanged on
> invocation
> >of either renderWindow->Render() and/or rwi->Render() in any order.
> >
> >I have three Renderers but only one RenderWindow.
> >
> >Perhaps there something else I need to do?
> >
> >thanks,
> >
> >luke
> >
> >
> >
> >>_renderWindow->Render();
> >>
> >>Luke J West wrote:
> >>
> >>
> >>
> >>>Hi - should be an easy one...
> >>>
> >>>if I have changed a scene with ->AddActor and ->RemoveActor on a
> >>>
> >>>
> >>vtkRenderer,
> >>
> >>
> >>>what method do I call on what object to reflect the changes on my
> >>>
> >>>
> >>screenobject)
> >>
> >>
> >>>thanks,
> >>>
> >>>
> >>>

Luke J West : Research Assistant : e-Science
Rm. 566/12, School of Ocean & Earth Sciences
Southampton Oceanography Centre, Southampton
SO14 3ZH  United Kingdom
Tel: +44 23 8059 4801  Fax: +44 23 8059 3052
Mob: +44 79 6107 4783

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