Nurbs turns itself to polyline? Is this normal?

Hi All.
I feel like a noob because i don’t see/understand where this is coming from and I’d thank any explanation.
I work with degree1-planar-closed-nurbs. I move their vertices and… they become degree1-planar-closed-polylines!

I mistakedly assumed that when I rebuilt a nurbs with degree 1 it would convert to a polyline.
That I can understand that was a misconception of mine but this automatic transformation?? Rhino should at least give the user a warning, right?

Is this really a problem? What’s the practical difference?

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They are the same geometry essentially in that case. Polyline just calculates more efficiently and saves resources vs a degree 1 nurbs curve. Same result geometrically made a different way behind the scenes.

I´m working with a certain plugin, Topologic that transforms the geometry in a special type of topological objects. The thing is it turns nurbs (wich are single objects) into “edges” and polylines (which are composite objects) into “wires” which are a composite of edges.
So even if both objects have the same geometrical results, they are indeed NOT the same and thus, I think we can expect Rhino to give us a warning.

Hello - Can you use ToNurbs before handing the polylines to the plugin?


Yes, my concern is not in the conversion. I already solved it once I knew what was happening.
My concern is that my beloved Rhino didn´t warn me of the conversion that was happening when I was just moving a vertex.