Hi Danny, actually although the NX generated one looks great at a first glance it actually has some problems in it.
It seems to be constructed with a different technique of kind of sliding out the control points for the ends of sweep segments.
But that technique has produced some areas where the control points have been slid backwards so that the created surface is a badly formed self-intersecting one.
Here's a zoom in to one problem area:
Note that the surface in that spot has a sudden abrupt 180 degree hook in it:
If you turn on surface control points you can see what has happened, there were several straight sections coming up to the miter, and then it produced the miter by shifting control points around, but that caused the end of the surface to come partly back over one of the previous straight sections:
The other short segment has the same kind of problem.
That particular technique that is being used there works pretty good if the sweep path is not very tightly bent in that zone near the miter (because tightly bent ones will have numerous control points all over it), and if the miter angles are smaller so that they don't shift the points back over a previous section so much.
There is another possible technique which is to kind of place in slanted profile curves at the corners of each miter spot and use those as profiles for the sweep. Rhino actually seems to have a somewhat new option for that called "untrimmed miters" which works pretty good for this case but does not work well for more bendy paths.
That would probably be a good option to have in Sweep in MoI too though. But that kind of produces a different kind of problem where creating a surface between angled profiles makes for some variation in the "tube thickness" because the sweep profile has a kind of angular turn to it as it moves along the path, similar to the example in this previous post:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3546.6
So anyway as you can see it is not really an easy problem to solve, even NX / Parasolid did not get it right... and I think that may be due to it actually being a geometric impossibility to have exact constant tube thickness and also exactly meeting miters on non-planar curved segments like this.
- Michael
