Hi Jean-Paul,

> I never quite understood before what the “Maintain Tangent”
> option did. I had tried tu use it but I saw no noticeable
> difference. Now I know (at least I think I know…)

Yeah it won't have an effect in just any sweep, the conditions need to be right for it to be able to be used, like the profile needs to be planar and if there is more than one profile they have to all share a same tangent direction where they touch the rails.

Also if you have exactly symmetrical rails then it would not really do anything because in that case the profile also slides along each rail in equal distances with each step.

It's when the 2 rails are different in shape and length that the profile will tend to twist as it is moved by sliding along the rails since the "slide distance" on each side is different in that case, except not with "Maintain tangent".

Maybe it should have been called "parallel planes" instead.


> Is this a kind of thing that would make smooth deformations
> easier for NURBS objects? Is it on the wish list for MoI ?

Yes, it would help to kind of squish objects around. It is on the wish list for MoI but I'm not sure when it will happen. It is difficult to make it work on a solid that has joined edges and still keep the edges stay connected in the deformed result, especially when the joined edges are trim edges that are located somewhere internal to the underlying surface rather than a natural surface edge.

- Michael