Example: NURBS Data Format
The system defines the NURBS (nonuniform rational B-spline) curve by expandable arrays of knots, weights, and control points. The following illustration shows a Cubic NURBS Curve.
Data format:
degree
Degree of the basis function
params[]
Array of knots
weights[]
Array of weights for rational NURBS; otherwise, NULL or 1.0 for polynomial b-spline.
c_pnts[][3]
Array of control points
Definition:
k = degree of basis function

N = number of knots, degree -2

wi = weights

Ci = control points (x, y, z) * wi

Bi,k = basis functions
By this equation, the number of control points equals N+1.