UF_BREP_spline_s (查看源代码)
 
定义在: uf_brep_types.h
 
也被称为：
 
概述
Contains data defining a non-uniform rational b-spline (NURBS) curve.
There are 4 values for each control point or pole: x, y, z and w. The
coordinates are weighted. The parameter values specify how much of
the spline is to be active, i.e. visible and used. They cannot be outside
the interval defined by the knot vector. The lowest allowed value is
knots[order-1]. The largest is knots[num_poles]. NURBS curves need not have
Bezier end conditions (be clamped).

The number of knots and poles, and the order are related as follows:
nknots = num_poles + order.


Data Members

num_poles
int
Number of control points or poles, i.e.,
poles[num_poles][4]

order
int
degree + 1 of the basis functions

is_rational
logical
Set according to whether the spline is rational:
True if the spline is rational, else false.

knots
double *
knots[num_poles+order]. If this is an output
structure then this member must be freed by
calling UF_free.

poles) [ 4 ]
double (*
control point vectors. If this is an output
structure, then this member must be freed by
calling UF_free.

start_param
double
smallest t value of curve's active region

end_param
double
largest t value of curve's active region