[osg-users] Renderer and SceneView classes

Dan R nicetan at gmail.com
Sun Nov 8 04:09:45 PST 2009


OK thank you for the information. So whatever aspects of SceneView
that Renderer is using now will eventually become part of the Renderer
itself. I see that now. I'm not really interested in creating a
separate library I just want to get OSG working for this project, but
I can see that it would be a huge task porting it to a different
language with different constraints. Anyway it's been a great learning
experience going through the code.

One further question, does actual rendering get invoked via the
Renderer->cull() method? It looks like that then calls cull() and then
draw() on the SceneView. Or is it the GraphicsContext->runOperations()
that ends up rendering?

Thanks,
Dan

On Sun, Nov 8, 2009 at 12:26 PM, Robert Osfield
<robert.osfield at gmail.com> wrote:
> Hi Dan,
>
> SceneView is part of the original beginnings of the OSG, when it was
> single threaded, single context, and is now scheduled for deprecation.
>  It will eventually be replaced entirely by functionality in
> osgViewer::Renderer, but for now I've simply reused SceneView.
>
> With any project that is a decade in the making you'll find a lot of
> history of it's evolution still in it, it's partly down to reusing
> code that does the job, and partly about maintaining backwards
> compatibility during transitions.  So if you want to learn about the
> scene graph design and implementation keep this it mind that is living
> project, it's not only evolved alot through it's history, but it's
> still evolving a good old rate.
>
> As for creating a new scene graph in another language, I guess the OSG
> isn't too bad a place to start, but if you want to develop a really
> successful project you'll need under stand about wider project
> management as well as just the technical aspects of design and
> implementation.  It also take a lot of work to write a full featured
> scene graph, hundreds of thousands of lines of code, and many man
> hours.
>
> Robert.
>
> On Sat, Nov 7, 2009 at 12:46 PM, Dan R <nicetan at gmail.com> wrote:
>> Hello, I'm new to OSG and am just looking over the code structure to
>> better learn how a proper scene graph library is laid out. I'm
>> interested in using (porting a stripped down version) of osg for a
>> project I'm working on in another language. I pretty much understand
>> the flow of the graph, however, when it comes down to the actual
>> rendering traversal I get a bit lost. So I have these two questions,
>> but maybe being directed to some older posts would be good answers...
>>
>> 1) The osgViewer::Renderer class appears frequently throughout the
>> code, however, it seems to be based around the osgUtils::SceneView
>> class. The SceneView class says that it's deprecated. Does this also
>> mean that the Renderer class is deprecated, or simply that any calls
>> to SceneView are no longer used in the normal work flow?
>>
>> 2) In a SingleThreaded case, where are the operations that result in
>> rendering the Drawables get added? I see that in the
>> renderingTraversals method, it first traverses the graph with a
>> getBound() call, then goes through each camera and does a cull() (this
>> uses a Renderer object from my first question), then goes through each
>> GraphicsContext and calls runOperations. Where I get lost is, where
>> are the operations for the GraphicsContext defined and added, that
>> actually end up doing the work of rendering the drawables?
>>
>> Any direction in this case would clear a lot up for me, thanks,
>>
>> Dan
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>>
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