[vtkusers] Should I use one actor per renderer/renderwindow or can they share the same actor?

[David Gobbi]

Hi Sebastien,

Karthik has already given a couple valid reasons, e.g. timestamp
checks between the renderer and the mapper, and resources that a
mapper or property might tie to a particular OpenGL context.  There is
a third reason I can give, and that is that there aren't regression
tests (that I'm aware of, anyway) that verify that it works for the
dozens of different mapper classes in VTK.  And anything that ain't
tested might as well be broken.  A basic vtkActor/vtkPolyDataMapper
with no texture and no shaders is the only prop that I would trust to
add to more than one renderer.

 - David


On Tue, Nov 1, 2011 at 10:52 AM, Sebastien Jourdain
<sebastien.jourdain at kitware.com> wrote:
> Humm,
>
> in fact, you can have many actors for a single mapper and there is no
> reason why you can't put the same actor to several renderers.
> I've done it many time without any issue. Although I was not using LODActors...
>
> Seb
>
> On Tue, Nov 1, 2011 at 12:15 PM, Karthik Krishnan
> <karthik.krishnan at kitware.com> wrote:
>> No you can't shallow copy.. each actor would need its own mapper. Mappers
>> can certainly not be shared. I don't think you can share the vtkProperty's
>> either, if you are using Shaders since will then consume graphic resources.
>>
>>
>> On Tue, Nov 1, 2011 at 9:26 PM, Bryn Lloyd <lloyd at itis.ethz.ch> wrote:
>>>
>>> Hi again,
>>>
>>>
>>>
>>> Actually, could I copy an actor using ShallowCopy in order to create
>>> separate actors for each renderer?
>>>
>>>
>>>
>>> Else, how can I transfer (or even synchronize) the actor parameters in a
>>> simple but complete way? I am thinking of general vtkProp(s), not just
>>> vtkActor.
>>>
>>>
>>>
>>> Thanks for any advice.
>>>
>>>
>>>
>>> --
>>>
>>> Bryn
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> From: Karthik Krishnan [mailto:karthik.krishnan at kitware.com]
>>> Sent: Tuesday, November 01, 2011 3:58 PM
>>> To: Bryn Lloyd
>>> Cc: vtk
>>> Subject: Re: [vtkusers] Should I use one actor per renderer/renderwindow
>>> or can they share the same actor?
>>>
>>>
>>>
>>> Even if it did work, it'd be quite fragile. I can imagine timestamp checks
>>> going wrong (these are used in the mapper to rebuild the geometric
>>> primitives etc).
>>>
>>>
>>>
>>> I can see LODActors getting messed up, when computing last render time
>>> from a renderer, not realizing that its not the same renderer they rendered
>>> on previously.
>>>
>>>
>>>
>>> Its best to create an actor per render window.
>>>
>>>
>>>
>>> --
>>>
>>> karthik
>>>
>>> On Tue, Nov 1, 2011 at 4:24 PM, Bryn Lloyd <lloyd at itis.ethz.ch> wrote:
>>>
>>> Hi
>>>
>>>
>>>
>>> I am working on an application with multiple render windows.
>>>
>>>
>>>
>>> Is it SAFE to use the same actor for each renderer/window, or should I
>>> create an actor per renderer?
>>>
>>>
>>>
>>> BTW. Currently it is OK if I have the same parameters (color, visibility,
>>> etc) in each renderer.
>>>
>>> Thanks for any suggestions
>>>
>>>
>>>
>>> Bryn
>>>
>>>
>>>
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