TKE_NURBS_Curve

Opcode

ASCII

N

Hexadecimal

4E

Decimal

78

Operands

Byte options, Byte degree, Long control_count, (
control_count)xPoint control_points, [(control_count)xFloat weights],
[(control_count+degree+1)xFloat knots],
[Float start], [Float end]

options

bitmask indicating which options are present

degree

degree of the curve

control_count

number of control points in the curve

control_points

control_count triplets of x, y, z data

weights

control_count weight factors

knots

control_count + degree + 1 knot values

start

parametric start point (0-1, default 0)

end

parametric end point (0-1, default 1)

Notes

Standard NURBS curve definition. Curve is inserted into the currently opened segment.

The parametric start and end points are defined to range from zero to one, which is different from some solid modelers. Solid modelling kernels typically parameterize their curves with respect to the given knot vector.

Any fields that can be left unspecified have default values: 0 for start, 1 for end, linearly increasing values for knot (i.e. [0,1,2,3,4,5,6,7…]) and uniform weights (i.e. [1,1,1,1,1…]).

Option flags

0001

Weights are specified

0002

Knots are specified

0004

Start is specified

0008

End is specified