Geometry_Engine: Remove Degrees() method for NurbsSurface

[pawelbaran]

Description:

BH.Engine.Geometry.Query.Degrees(this NurbsSurface surf) method does not return correct results when the first knot value does not have full multiplicity (Rhino wiki). Therefore, a new approach is proposed in this BHoM PR and #1298.

Test file:

Uploaded to SharePoint.

[epignatelli]

When does this happen? Why doesn't the nurbs knot vector have full multiplicity some times?

[pawelbaran]

I believe every surface closed by a periodic curve will be subject to that issue - an example has been added to the description of this issue.

[epignatelli]

Yeah, I am almost sure it is what @enarhi caught as well.

But then I think that making sure that Degrees returns a correct value also for periodic curve is the thing to fix. I'd avoid storing it in the object just because there is a bug in the Degrees method.
What do you think?

[pawelbaran]

From what I have found out, it is impossible to fix the bug because at the moment what we have is:

• total number of control points
• number of u knots
• number of v knots

In order to retrieve the degree in each direction we still need the number of control points in u and v - we end up with two unknowns in one equation: n = u * v

I am not an expert in the field though, so please be critical towards the above 🐒