hammax wrote: ↑
Sat Jun 02, 2018 4:42 pm
… sorry to contradict.
I experienced this behavior since some time and it's the cause for me, not to use Periodic Sketcher-BSpline.
I rather take a normal BSpline and connect starting and endpoint via tangential poles at each side.
It is never a problem to contradict. I think there is some kind of misunderstanding or bug. Let's try to understand each other:
1. You are not complaining that the extruded part has a seed. You accept it will have a seed, like circles do, but you complain about the position of the seed:
This shows a periodic b-spline, a normal b-spline and a circle.
a. All of them generate a seed.
b. The seed is where the start and end points of the period shape meet.
c. In the circle, care has been taken that no point is shown in the sketcher at this point. In the periodic B-Spline it should be possible to do this as well.
2. From a mathematical/geometric point of view a normal b-spline has a starting point that coincides in position with the first knot and first pole and an endpoint which coincides in position with the last knot and last pole. This is because the first knot multiplicity is made to be the degree. See a (4) in the normal b-spline. A periodic b-spline has a (1) multiplicity on each knot. Such a b-spline has a starting point coinciding with the first knot and an endpoint coinciding with the last point. However, there is no pole at that position!!
https://www.globalspec.com/reference/61 ... ine-curves
3. What is exactly irritating. I mean, which effect do you have in your normal CAD operations where this causes disturbance?
Another way you have to know if a point is a knot or not, is to look for "points" in the Elements Widget of the sketcher, if there are no "Points" what you see is part of the edge itself.