Here's an initial test of octree-based cutting simulation:
If you turn up the resolution to eleven, where it starts to be useful and not so grainy, the calculation of the tool-swept volume, which we subtract from the stock at each move, becomes too slow.
See also octree operations.
Download a short clip with a depth=10 tree: OUTPUT (it's also on youtube, but a 2s clip on youtube doesn't work very well: http://www.youtube.com/watch?v=G0RYS9FcqR0)
some screenshots:
http://en.wikipedia.org/wiki/Marching_cubes
there's now version 2 of this here:
http://www.anderswallin.net/2010/08/opencamlib-machining-simulation-v-2/