convert to Periodic curve???

Replies to This Discussion

Permalink Reply by David Rutten on July 29, 2015 at 4:32am

It is not necessarily possible to convert a closed curve into a periodic curve. Periodic curves require changes to the control-points as well as the knot vector, so just changing the knots won't do it.

But why do you need a periodic curve?

Permalink Reply by Manuel Sotomayor Millan on July 29, 2015 at 4:49am

If the curve is Periodic it can be splitted In two subcurves, and they will be of type NurbsCurve.

If the curve is not Periodic and I split it in two segments, the segment containing the  point (t = 0) of the original curve is not a curve but a polycurve. This takes me to further problems if I use this curve for lofting a surface.

Changing the seam of the curve to one of the splitting points dos not solve it.

Thank you very much.

P.D. I know it is not necessarily possible but I am cutting a circle, so I assumed it would be possible.

Permalink Reply by David Rutten on July 29, 2015 at 7:15am

Changing the seam of the curve to one of the splitting points dos not solve it.

It doesn't work or it doesn't result in the correct result or?

What if you convert the PolyCurve to a nurbscurve using the ToNurbsCurve() method?

Permalink Reply by Manuel Sotomayor Millan on July 29, 2015 at 7:30am

Changing the seam of the curve to one of the splitting points dos not solve it.

It doesn't work or it doesn't result in the correct result or

It works but the curve still keeps the information on where the point(t=0) was in the original curve.

I already used the method to toNurbsCurve() but it does not solve it either.

When I use the curve for lofting it splits the curve at this point.

It looks like the support of RhinoCommon for curves with kinks and  surfaces is not enough for this. Theoretically a nurbscCurve/nurbsSurface can have a kink/edge by adjusting multiplicities of knots. I am not an expert of this but thought it could be done. Even though it is not my case to produce a nurbsSurface with  an edge, I am actually lofting portions of circles but they get splitted at the startpoint of the original circle.

Permalink Reply by nikos tzar on July 29, 2015 at 7:55am

I may be way off subject but, if this is about circles, couldn't you bypass the problem by drawing 2 arcs on top of each circle and using those for loft?

Permalink Reply by Manuel Sotomayor Millan on July 29, 2015 at 8:19am

Thanks nikos.

Yes I can work that around. Sometimes it is much easier.