# Splines/Surface/Continuity

Question asked by Jens Hartwich on Nov 3, 2015

Ii have some problems understanding SW Splines/Surface/Continuity in SW2014/15 Student Edition.

1)

Spline = B-Spline

Style Spline = Bézier-Spline

But what are surfaces? If i create a simple planar surface out of 4 Curves. Maybe 2 Splines and 2 Style Splines. The result will be ? A NURBS Surface?

2) Continuity Part1:

A Style Spline will always have one span/segment, which means the whole Spline is always G2.

A Spline can have more than one span, but he is also always G2.

But if i end a Style Spline or Spline and start a new Spline in the last Point, it will be G0. I can add tangentially for G1 or curvature for G2 by adding relationship between both Splines/StyleSplines.

Am i right?

3) Continuity Part2:

Can i add G3 or G4 to Splines/StyleSplines or Surfaces?

4) Continuity Part3:

Watching a Spline/StyleSpline i can see Continuity G0-G2, by activating Cirvature Comb. But its impossible to see G3 or higher?

Watching a Surface i can see Continuity G0-G2, by activating zebra stripes. But its impossible to see G3 or higher?

5) The Relationship and editing for Knots, Controllpoints (CVs), Degree (order +1), Edit Points (Though Points) and Spans/Segments.

For StyleSplines:

CVs = Degree + Span

Easy: Span = 1, Degree = I can read in Property Manager, CVs = I can count. Start and Endpoint are also CVs.

For Spline = B-Spline

This is a little bit complicated, cause i cant read out the degree of the B-Spline. I know that i need the number of knots(not equal to edit points) for calculating the degree. I know that activating the spline handle and moving the spline handle point, add more CVs to the Spline, while the number of edit points is the same. This will result in a higher degree, but whats about the number of knots? I know too, that relaxing the spline, aka activating Simplify Splines, will remove some CVs, so there will be a lower Degree. But whats about the knots? Can u clear this Relationship?

Thanks for clearing my problems and helping me out. Sorry for my bad english.