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 > > > ________________________________ > Windows Live Messenger på mobilen. Hold kontakten hvor som helst når som > helst. > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
