Merrily hacking away after reading Cyril Crassin'sthesis and finally have my first screenshot that looks like something. This is coded in C and GLSL only so far. It's a sparse oct-tree voxel based volume raycasting routine. It *really* hammers the GPU, but amazingly at 1024x768 this pulls somewhere over 20fps on my Nvidia GT520. At 1920x1200 it runs around 5fps. Considering this is the first version I'm rather pleased with myself. I've got it building on Windows and Linux.