Hi David - from a presentation that Dale Lear gave us a while back:
Curves that give exact matches when using Loft, ExtrudeCrv, and Revolve to make SubDs are called SubDFriendly.
SubDFriendly curves are:
- NURBS
- degree 3
- uniform
- non-rational
- natural or periodic
Friendly curves have zero end curvature.
Because it is very easy to mess up these end conditions, the SubDFriendly curves hide those two “extra” points.
HTH,
-wim