[osg-users] switch between two camera

Robert Osfield robert.osfield at gmail.com
Tue Mar 17 01:40:13 PDT 2009

Hi Yin,

For scene graph related render to texture work use a Camera in the scene
graph.  NodeMask and switches can be used.


2009/3/16 Lingyun Yu <lingyun.yu.06 at gmail.com>

> Hi Robert,
> I also meet the same problem, I have 128 snapshots of particles, and I want
> to use those 128 shapshots to make an real time animation.
> First thing I tried, was using a update callback function and bind it on my
> geode, everytime I just updated all positions of particles. But obviously it
> was quite slow.
> Then I tried to use two view, and each one has it's own camera, and render
> two snapshots in the same time. Well, it works, but still very slow.
> Then I tried to use one view but two cameras, and load three snapshots in
> the same time, two below two caremas, one below my Root. because I do really
> need to update it. And link the right snapshots while I need to render it.
> Somehow it is still slow, and while it switches snapshots and I use
> trackball, it is played not fruently.
> So my question is, basicly I need to render un-structed points dataset, and
> I have a lot snapshots, do you have any idea how can I make an realtime
> animation fruently?
> Looking forward to your reply and thank you very much.
> Yun
> 2009/3/16 Robert Osfield <robert.osfield at gmail.com>
>> Hi Peter, Benoit et,
>>  On Mon, Mar 16, 2009 at 8:15 PM, Peter Amstutz <
>> peter.amstutz at tseboston.com> wrote:
>>> The way I handled this in my application was to create multiple instances
>>> of osgViewer::Viewer with a separate camera for each view but all bound to
>>> the same output window.  On each render iteration, draw just the active
>>> camera.
>> I'm afraid I really wouldn't recommend this solution, having multiple
>> viewers just to alternate between views is complicated implementation and
>> conceptual wise and you'd be very lucky for it to work in anything other
>> that very limited usage models.  Using multiple viewers will cause problems
>> with threading, timing codes, it'd be a right old mess.
>>> The best solution depends on exactly what you need to display; I decided
>>> to switch between completely independent scenes because my 2D and 3D views
>>> looks actually render somewhat different geometry (the 2D ortho view is an
>>> abstracted version of the "real" 3D geometry).  Having entirely separate
>>> scenes is also pretty straightforward although it imposes some overhead due
>>> to duplication of resources that could otherwise be shared between among
>>> views.
>> In your case you are talking about multiple Views, and this is fine, but
>> you don't use multiple Viewers for it, you'd use a single CompositeViewer
>> with multiple Views.  You can add and remove Views, or just toggle Camera's
>> on/off using NodeMask's.
>> For Benoit having a single master Camera track different CameraView nodes
>> in the scene might well be the most convinient way to manage things.
>> Robert.
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> --
> Cheers,
> Yun
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