An open question: does SDL encapsulate enough glx/wgl/mac os features to support pbuffers and multiple rendering contexts in a platform independent way?
an nvidia engineer told me pbufs don't work on osx yet. he sent me these links for a linux/windows pbuffer abstraction:
http://cvs1.nvidia.com/DEMOS/OpenGL/inc/shared/pbuffer.h http://cvs1.nvidia.com/DEMOS/OpenGL/src/shared/pbuffer.cpp http://cvs1.nvidia.com/DEMOS/OpenGL/src/simple_pbuffer/
it seems the platform dependent things can be tucked away nicely, likewize for ordinary rendering contexts (windows). wgl also supports direct render to texture, without the pbuffer intermediate. as for sdl, i really don't know. i do know that there are some issues with sdl on osx you should be aware of, namely it requires the entry point of your program to be wrapped in objC code, which would require a serious workaround or a patch to pd.
tom