PSSAC(3g) — Subroutines

Name

PSSAC − Indicates the minimum quality desired for the approximation of the surface’s geometry.

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

Old Syntax

DSSAC (APRXTP, LDR, DATREC)

Argument       Data Type      Access    Description
---------------------------------------------------------------------------
APRXTP         Integer        Read      Approximation criteria type
LDR            Integer        Read      Length of the data record
DATREC(LDR)    Array of       Read      Data record
               character ∗80
---------------------------------------------------------------------------

New Syntax

PSSAC (ACRI, LDR, DATREC)

Argument       Data Type      Access    Description
---------------------------------------------------------------------------
ACRI           Integer        Read      Curve approximation criteria type
LDR            Integer        Read      Length of the data record
DATREC(LDR)    Array of       Read      Data record
               character ∗80
---------------------------------------------------------------------------

Constants

Defined Argument      Constant      Description
---------------------------------------------------------------------------
ACRI                  PWDSA         Workstation-dependent method
                      PCBKSA        Constant parametric subdivision
                                    between knots
                      PCSWSA        Chordal size, in world coordinates
                      PCSNSA        Chordal size, in normalized projection
                                    coordinates
                      PCSDSA        Chordal size, in device coordinates
                      PCDWSA        Planar deviation, in world coordinates
                      PCDNSA        Planar deviation, in normalized
                                    projection coordinates
                      PCDDSA        Planar deviation, in device
                                    coordinates
                      PRWSA         Relative, in world coordinates
                      PRNSA         Relative, in normalized projection
                                    coordinates
                      PRDSA         Relative, in device coordinates
                      DCSDSA        Constant subdivision (non-PEX only)
                      DIDSA         Implementation-dependent method
                                    (PEX only)
---------------------------------------------------------------------------

Description

PSSAC indicates the minimum quality desired for the approximation of the surface’s geometry. When you specify two approximation values, the first applies to the u parameter, and the second applies to the v parameter.

Depending on the 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 set surface approximation criteria element.

During structure traversal, if the specified approximation type is undefined, Digital PHIGS uses type 1.

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

The new function syntax conforms to the ISO Fortran standard. Digital recommends that you code using the new function syntax.

Data Record Information

If ACRI is PWDSA, there is no data record.

If ACRI is PCBKSA or DCSDSA, the data record has the following format:

INTEGER IL   = 2     Number of integer values
INTEGER IA(1)        Number of subdivisions between knots in u
INTEGER IA(2)        Number of subdivisions between knots in v
        RL   = 0
        RA   = ()
        SL   = 0
        LSTR = ()
        STR = ()

If ACRI is PCSWSA, PCSNSA, or PCSDSA, the data record has the following format:

        IL    = 0
        IA    = ()
INTEGER RL    = 2    Number of real elements
REAL    RA(1) =      u approximation value
REAL    RA(2) =      v approximation value
        SL    = 0
        LSTR = ()
        STR   = ()

If ACRI is PPDWSA, PPDNSA, PPDDSA, PRWSA, PRNSA, or PRDSA, the data record has the following format:

        IL   = 0
        IA   = ()
INTEGER RL   = 1     Number of real elements
REAL    RA   = (1)   Approximation value
        SL   = 0
        LSTR = ()
        STR = ()

If ACRI is DIDSA, the data record has the following format:

        IL    = 0
        IA    = 0
        RL    = 2    Number of reals
        RA(1) =      U approximation value
        RA(2) =      V approximation value
        SL    = 0
        LSTR = ()
        STR   = ()

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