Hi Jonah - it took me about 1 minute to come up with the attached simple example. This boolean union with shared surfaces and edges is calculated fine here in the current MoI beta, but fails in Rhino 4.0 (Eval, version 11-Jun-2007).

Strangely, it works fine in Rhino 3.0, so it seems to be an area where there has been some regressions. I don't doubt that they will eventually be able to tune it up, but this simple example should prove that others are not exaggerating above.


Boolean operations are proving to be a particularly strong area in MoI, both in reliability of calculations as well as interface. The ability to have solids and curves interact directly can save extra steps in many simple construction scenarios.

- Michael