This is something that I have yet to look into. I'm currently
busy making many enhancements to 3dSurf2Vol. But I will try to
evaluate it in the reasonably near future.
One option would be to compute the angle difference between the
two rays (the normal, and the one connecting the node pair) for
each node. At any rate, the node normals won't be quite precise
either, as each node's normal is the average of the normals of
those triangles including that node.
This is one of the functions I want put into 3dSurfCalc, once I,
um, actually write the program. Coming soon to a theater near you...
- rick