I control the update rate of slave cameras by inserting them into the scene
graph as needed. In my PostDrawCallback for the camera I can remove the
camera again when I do not require further updates.

This way, I can do on-demand updates of my simulation (we're doing 4G and
5G radio coverage computations in OpenGL)

Christian


2014-10-01 9:50 GMT+02:00 Robert Osfield <robert.osfi...@gmail.com>:

> Hi Julien,
>
> From what you've written is next to impossible to know what you actually
> mean.  What is a "full GPU policy"?  I don't know.  Perhaps others do.
>
> And when you talk about frame rate control, again I don't know what you
> mean in this context.
>
> The general meaning of frame rate control is how you manage the the call
> to viewer.frame() within your frame loop.  However, the way you use the
> expression doesn't at all seem to fit this normal usage.
>
> I remain perplexed, I'm sure others will be too.
>
> Robert.
>
> On 1 October 2014 08:32, Julien Valentin <julienvalenti...@gmail.com>
> wrote:
>
>> Thanks Robert for you quick reply,
>> and excuse my lack of precision for a problem that is to long to explain
>> in details. I've just tried to be generic in my question thinking:
>> "There surely are people that encountered this problem with realtime
>> environment mapping"
>>
>> So my personal not generic problem is:
>> I'm doing a gpu flow simulation in osg. I'm using a multiscale aproach
>> and use a full GPU policy in order to determine which LOD to target.
>>
>> The osg model of this policy is based on the classic render to texture
>> pattern:
>>
>> Code:
>>
>> camera->setComputeNearFarMode(osg::Camera::DO_NOT_COMPUTE_NEAR_FAR);
>> camera->setRenderOrder(osg::Camera::PRE_RENDER);
>> camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
>> camera->setProjectionMatrix(osg::Matrix::ortho2D(0, 1, 0, 1));
>> camera->setViewport(0, 0, _resolution.x(), _resolution.y());
>> texture->setTextureSize(_resolution.x(), _resolution.y(),
>> _resolution.z());
>> camera->attach(osg::Camera::COLOR_BUFFER0, texture.get(), 0,
>> osg::Camera::FACE_CONTROLLED_BY_GEOMETRY_SHADER);
>>
>>
>>
>> This policy is quite expensive(implies reduction of the whole volume so a
>> lot of osg::Cameras) and don't have to be process each frame so I would
>> like to control its framerate.
>>
>> As I don't use any geometry(but a quad), LOD can't be an escape and as
>> the result of the frame control my entire simulation, I can't degrade the
>> quality.
>>
>>
>>
>>
>> robertosfield wrote:
>> > Hi Julien,
>> >
>> > There are whole range of different ways to load balance, what route is
>> best will depend entirely on the nature of your data and your
>> requirements.  All we know so far is that it's "expensive", done off
>> screeen and doesn't need to be high quality.  The generality of the
>> problems means we can't provide any specific advice.
>> >
>> >
>> > The most general way to load balance with scene graphs is to use Level
>> of Detail nodes, LOD's - these need to be built into your scene graph when
>> you create it. You can use the view's Camera's LODScale to adjust the which
>> level of LOD child is selected for each view.
>> >
>> >
>> > Whether LOD's at all appropriate for you particular usage case I
>> absolutely cannot say as I really know next to nothing about the problem
>> you are trying to solve.  As I mentioned that are plenty of other ways of
>> manage the load but I'm not about to write a book for you based on no
>> information. If you want help you'll need to be specific and not wave your
>> arms vaguely around, please tell us what you scene graph consistents of and
>> the nature of the rendering you are wanting.
>> >
>> >
>> > Robert.
>> >
>> >
>> >
>> >
>> >
>> >
>> > On 30 September 2014 15:02, Julien Valentin < ()> wrote:
>> >
>> > > Hi,
>> > > I'm doing a lot of offscreen renderings that are very expensive and
>> "not so important" for the image to appears good.
>> > > What would be the best way in order to limit the rendering framerate
>> of these in order have more time for "more important" rendering?
>> > >
>> > > My idea was to override a geometry and control the rendering to the
>> framebuffer with a timer in it, but if there's a more convenient way to do
>> this i would be glad to know it
>> > > Thank you!
>> > >
>> > > Cheers,
>> > > Julien
>> > >
>> > > ------------------
>> > > Read this topic online here:
>> > > http://forum.openscenegraph.org/viewtopic.php?p=61212#61212 (
>> http://forum.openscenegraph.org/viewtopic.php?p=61212#61212)
>> > >
>> > >
>> > >
>> > >
>> > >
>> > > _______________________________________________
>> > > osg-users mailing list
>> > >  ()
>> > >
>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> (
>> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>> )
>> > >
>> >
>> >
>> >  ------------------
>> > Post generated by Mail2Forum
>>
>>
>> ------------------
>> Read this topic online here:
>> http://forum.openscenegraph.org/viewtopic.php?p=61221#61221
>>
>>
>>
>>
>>
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