NURBS
The NURBS (nonuniform rational B-spline) curve is defined by expandable arrays of knots, weights, and control points.
Figure 245. Cubic NURBS Curve
Data Format:
degree Degree of the basis function
params[] Array of knots
weights[] Array of weights for rational
NURBS, otherwise NULL.
c_pnts[][3] Array of control points
params[] Array of knots
weights[] Array of weights for rational
NURBS, otherwise NULL.
c_pnts[][3] Array of control points
Definition:
k = degree of basis function
N = (number of knots) - (degree) - 2
w = weights
C = control points (x, y, z) * w
B = basis functions
By this equation, the number of control points equals N+1.
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