[osg-users] Supporting multiple frame rates

Farshid Lashkari flashk at gmail.com
Thu Apr 28 09:06:03 PDT 2011


Hi Brad,

I haven't tried this myself, but it might work. Create a separate
context/thread that renders the scene to a texture. Once it finishes
rendering, use the NV_copy_image extension (
http://developer.download.nvidia.com/opengl/specs/GL_NV_copy_image.txt) to
copy the image into the main context containing the HUD. I haven't used the
NV_copy_image extension myself, but from my understanding it allows copying
texture data between different contexts. I'm not sure if ATI has a similar
extension.

Cheers,
Farshid

On Thu, Apr 28, 2011 at 8:39 AM, Brad Huber <bradh at procerus.com> wrote:

> Hello,
>
>
>
> We currently have an OSG based application which renders at 30-60+ fps on
> our development hardware with discrete gpus.  Unfortunately we have to be
> able to  deploy on a wide range of hardware including stuff that is
> significantly less capable (Intel GPUs, etc).  On some of these slower
> platforms we are seeing framerates that are 10-15 fps.  This is actually ok
> for us with one exception, live video.
>
>
>
> We show live video in the scene graph (for now strictly in the HUD).  We
> have a requirement to make the video render at native speed (~30 fps).  I am
> looking for a way to make the HUD/video render at 30 fps and let the rest of
> the scene graph render at a floating rate (whatever the machine can handle).
>
>
>
> How might this be accomplished?  Since this is a HUD, obviously it must
> ultimately render to the same graphics context, however it doesn’t really
> need to respect the depth buffer, etc of the rest of the scene (it should
> always render on top).
>
>
>
> PS Should I be thinking about render to texture?
>
>
>
> Related threads I came across:
>
> http://forum.openscenegraph.org/viewtopic.php?t=7858
>
>
> http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/2008-January/006000.html
>
> http://forum.openscenegraph.org/viewtopic.php?t=7117
>
>
>
> Thanks
>
> -Brad
>
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> osg-users at lists.openscenegraph.org
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>
>
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