Degree 1 bSplineSurface?

EvanReese

Is there a fundamental reason we can't make a degree 1 bSplineSurface? It could be handy to make some interesting faceted designs. It works in Rhino, and gives the result on the right.

S1mon

So in this case, Rhino is sampling the surface on the left to get points which are theoretically a series of knots in a degree-1 B-Splines (basically making a bunch of poly lines). 

How are you trying to construct the b-splines to build the b-splinesurface? Are you generating the sampled points?

EvanReese

I've not really started anything. I was just curious if it would work and found that for b-spline curves and surfaces in Onshape the minimum degree is 2 and wondered why. For my test, I just started with a grid of points and was able to generate degree 2+ surfaces, but get an error at degree 1.

S1mon

Interesting. You've probably seen this, but you can create degree-1 Béziers in sketcher (it will even let you make things parallel or perpendicular to them!).

It's unfortunate if you can't make a degree -1 surface. Of course you could make degree-2 curves (which are still lines) by adding a control points midway between the endpoints.

Are you trying to do this as one multi-span b-spline surface, or are you ok with making 64 surfaces and boolean-ing them together?

EvanReese

I'm not really trying to do anything in particular. I just thought it would be cool if it were possible, since I could use it to easily make something like a faceted loft tool, or a way to convert existing faces to a faceted version. If it can't be done this way, I don't expect to pursue it much more at the moment.