Hi Robert,
I see a drop from 60fps to 30 fps in the osgPreRender example, when I switch
from frame buffer to frame buffer object.
I am going to try to run that example on some different hardware/drivers to see
if this happens only on some of them.
Viggo
> Date: Wed, 13 Aug 2008 17:31:28 +0100
> From: [EMAIL PROTECTED]
> To: [email protected]
> Subject: Re: [osg-users] Frame-rate issue on RTT
>
> Hi Viggo,
>
> I haven't yet seen performance delta's between rendering scenes to a
> frame buffer and a frame buffer object, but my own testing is rather
> limited to Linux and Nvidia these data, which an occasional foray on
> the Mac.
>
> There is plenty unsaid about your setup that could be causing the
> performance delta, there is a chance that it is just the FBO that is
> push the OpenGL driver on to a slow path, but also just as much chance
> that something else is the cause.
>
> In general I'd say 20fps frame rate is very poor and needs to be
> addressed before other areas such as FBOs are looked at. You need to
> start by looking at what is the bottlenecks - CPU, GPU etc. The
> osgviewer stats can help reveal this.
>
> Robert.
>
> On Wed, Aug 13, 2008 at 2:55 PM, Viggo Løvli <[EMAIL PROTECTED]> wrote:
> > Hi,
> >
> > I have seen a strange thing about framerate...
> >
> > I have a complex city where I have 20fps (not optimized yet)...
> >
> > I set the following:
> > - Render target implementation = osg::Camera::FRAME_BUFFER
> > - I attach a RGBA buffer that is the same size as the frame-buffer.
> > Result:
> > - Framerate stays at 20fps.
> > - Colors are written to the frame-buffer.
> > - Colors are also written to the RGBA surface I attached to the camera.
> > - I thus have 20fps and two copies of my scene-image.
> >
> > I set the following:
> > - Render target implementation = osg::Camera::FRAME_BUFFER_OBJECT
> > - I attach a RGBA buffer that is the same size as the frame-buffer.
> > Result:
> > - Framerate drops to 10fps.
> > - Colors are written to the RGBA surface I attached to the camera.
> > - Nothing is written to the frame-buffer.
> > - I thus have 10fps and only one copy of the scene-image.
> >
> > So, one mode give me more data, and high framerate while the other mode give
> > me less data and lower framerate. This sounds odd.
> >
> > Another test:
> > - Render target implementation = osg::Camera::FRAME_BUFFER_OBJECT
> > - I attach a RGBA buffer that is the same size as the frame-buffer.
> > - I attach another RGBA buffer that is the same size as the frame-buffer.
> > - I set up the pixel-shaders to output some extra data from the scene to
> > the second buffer.
> > Result:
> > - Framerate stays at 10fps.
> > - Colors are written to the RGBA surface I attached to the camera.
> > - The second buffer gets the data I wrote to it.
> > - Nothing is written to the frame-buffer.
> > - I thus have 10fps and two copies of the scene-image.
> >
> > My conclusion:
> > - I assume that setting FRAME_BUFFER_OBJECT means that the hardware
> > change to some kind of pipeline that is much slower than normal.
> > - (I am using a NVIDIA Quadro FX 1500 card).
> >
> > And my question to you:
> > - Does anybody know if my conclusion is all that is to it, or is there
> > something I can do that will speed up things?
> >
> > Regards,
> > Viggo
> >
> >
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