[osg-users] Supporting multiple frame rates

Buckley, Bob CTR MDA/DES bob.buckley.ctr at mda.mil
Thu Apr 28 15:24:40 PDT 2011


Overlay buffer comes to mind given the selection and clearing control.
But, if I remember right, they are limited to color index mode.
Newer hardware of the day may allow RGB mode.

We did this type of multiplexing with Performer years ago, but with different windows.
We rendered the scene at a full 60 Hz and alternated HUD insets at 30hz.
Much easier than trying to do it on the same canvas.

Bob Buckley
Principal Software Engineer
Raytheon

-----Original Message-----
From: osg-users-bounces at lists.openscenegraph.org [mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Brad Huber
Sent: Thursday, April 28, 2011 9:40 AM
To: osg-users at lists.openscenegraph.org
Subject: [osg-users] Supporting multiple frame rates

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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