Hi Christian, You can use osg::PixelBufferObject to assist with transferring data to and from the GPU. However, to hide the cost of the wait for rendering pipeline to flush and the transfer back it's best to double buffer and read the previous frames result. Without doing the double buffer there is little benefit over just doing a standard glReadPixels. The OpenSceneGraph/osgscreencapture example illustrates the use of PBO's including buffering.
However, it sounds like you want to result during the same frame so the double buffering trick won't be applicable and you'll be stuck with a hit for waiting for the GPU's rendering pipeline to complete and then do the transfer, this round trip is very expensive and PBO's can only smooth the edges a little, they can't make it cheap. By far the best way is to keep all the data on the GPU and do the processing you require on the GPU using shaders/compute shaders/OpenCL/CUDA, only passing the minimum amount of data if any back to the GPU. Robert. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
