Name

PBSC3C − Specifies the 3D nonuniform B-spline curve 3 with color primitive. 

Operating States: PHOP, ∗, STOP, ∗
PHIGS PLUS function
Creates a structure element

Syntax

PBSC3C (SORD, NKA, KNOTS, PARL, RTYPE, NCP, PXA, PYA, PZA, PWA,
CSCLDR, CSCREC)

Argument    Data Type      Access    Description
---------------------------------------------------------------------------
SORD        Integer        Read      Order of the curve
NKA         Integer        Read      Number of knots
KNOTS(NKA)  Array of       Read      Knots
            reals
PARL(2)     Real           Read      Parameter range limits (minimum,
                                     maximum)
RTYPE       Integer        Read      Rationality
NCP         Integer        Read      Number of control points
PXA(NCP),   Real           Read      Control points
PYA(NCP),                            in modeling coordinates
PZA(NCP),
PWA(NCP)
CSCLDR      Integer        Read      Number of array elements used in CSCREC
CSCREC      Character ∗80  Read      Data record for the color spline curve
(CSCLDR)
--------------------------------------------------------------------------

Constants

Defined Argument    Constant     Description
---------------------------------------------------------------------------
RTYPE               PRAT         Rational (4D) control points
                    PNRAT        Nonrational (3D) control points
--------------------------------------------------------------------------

Description

PBSC3C specifies the three-dimensional nonuniform B-spline curve 3 with color primitive, a primitive consisting of a curve determined by connecting points. 

Depending on the current edit mode, this function either inserts the new structure element directly after the element indicated by the pointer or replaces the element indicated by the pointer.  The pointer then points to the new nonuniform B-spline curve 3 with color element. 

During structure traversal, the polyline set 3 with data primitive attributes provide additional data.  Digital PHIGS computes the curve approximation criteria and draws a nonuniform B-spline curve 3. The following are important considerations when using this function:

•The spline order must be a positive integer.  The knots must form an increasing sequence of numbers. 

•The type parameter may have the enumerated value PRAT or PNRAT. 

•The PARL argument specifies over what range Digital PHIGS evaluates the B-spline curve.  The minimum value must be less than or equal to the maximum value. 

•At structure traversal, PHIGS draws a nonuniform B-spline curve primitive with the attributes used by polyline set 3 with data, and the current curve approximation criteria.  It uses these for values specified in PARL. 

The number of control points must be at least as large as the spline order. The number of control points plus the spline order must equal the number of knots. 

If Digital PHIGS is in immediate mode, it performs this function immediately, but the function does not create a structure element. 

Digital PHIGS Version 3.1 does not support this function.

See PPCSC and PUCSC for a description of the data record. 

See Also

PADS
PQCVF
PSCAC
PSDCI
PSHRID
PSIASF
PSLN
PSLWSC
PSPKID
PSPLC
PSPLCI
PSPLI
PSPLSM
PSVWI