But finally, after doing some internet research and reading a variety of SKY-CLOUD technical papers, including those presented at SIGGRAPH, I finally realized that the way to do this was RIGHT UNDER MY NOSE! -That is- Microsoft Flight Simulator comes with GMAX 1.2- and Microsoft's own FS 2004 GamePack SDK. (You can ALSO download GMAX 1.2 and the FS2004 GamePack SDK for free- you don't need to have FS 2004 for this little experiment).