Curvature continuous box using splines

[cloughna]

I am trying to make a curvature continuous "box" shaped cut using splines. A quick sketch looks like this.

As you can see, the control polygon is constrained so that it is a perfect square. However, the spline is obviously not curvature continuous

If i try to do it by defining interpolation points, I get a different result, but still not perfect.


See the upper left (among others)?

Is there a clean way to do this? I know I can set a c2 condition in SW, but I see no option for that in WF3.

Any insights will be greatly appreciated.

 

[dewme5]

Without trying it, my suggestion would be more points, and setting tangents. Instead of a point on the center line, there should be a point at both ends of the straight, and then one in the middle of the curve. making for 12 points total.

 

[cloughna]

Wouldn't setting tangents only give me tangency and, by definition, not curvature continuousness? 12 points seems like an awful lot for a nice smooth curve.

I will give it a shot though, thanks.

 

[dewme5]

Here is a quick rendition of it. If I wanted to really control it, I would create construction lines to dictate the point in the center of the arcs.