Well this is a revision from two posts back. I implemented the simulation code the way I planned, and the glue, etc.; but the trouble is there are tens of thousands of calls to the code that links the simulation to the lua code. It's messy.
I don't know if the simulation code itself is, after all, going to be useful. But I have decided to take the soundable () class out of lua; the basis for putting it in lua instead of C++ was that it was simple enough and wouldn't suck up any CPU. Well, the profiler is telling me that no matter how I try and slice this one, it's sucking up a lot of CPU. So out it goes!