Name

PSVWR3 − Defines an index and the values of its associated entry for the workstation view table. 

Operating States: PHOP, WSOP, ∗, ∗
PHIGS standard function

Syntax

PSVWR3 (WKID, VIEWI, VWORMT, VWMPMT, VWCPLM, XYCLPI, BCLIPI, FCLIPI)

Argument       Data Type      Access    Description
---------------------------------------------------------------------------
WKID           Integer        Read      Workstation identifier
VIEWI          Integer        Read      View index
VWORMT(4,4)    Array of       Read      View orientation matrix
               reals
VMMPMT(4,4)    Array of       Read      View mapping matrix
               reals
VWCPLM(6)      Array of       Read      View clipping limits, in
               reals                    normalized projection coordinates
                                        (XMIN, XMAX, YMIN, YMAX, ZMIN, ZMAX)
XYCLPI         Integer        Read      xy-clipping indicator
BCLIPI         Integer        Read      Back clipping indicator
FCLIPI         Integer        Read      Front clipping indicator
---------------------------------------------------------------------------

Constants

Defined Argument       Constant        Description
---------------------------------------------------------------------------
XYCLPI                 PNCLIP          Clipping disabled
BCLIPI,                PCLIP           Clipping enabled
FCLIPI
---------------------------------------------------------------------------

Description

PSVWR3 allows you to create or redefine an index and the values of its associated entry for the workstation view table. The two specified matrices and the specified view clipping limits make up the three stages of viewing. 

The specified index value must be greater than 0.  The 0 index and its associated table entry values are predefined by Digital PHIGS and cannot be changed. 

The index entry 0 in each view table is illustrated in the hardcopy and Bookreader versions of the documentation. 

The elements of a view table entry are:

•View orientation matrix

Positions, rotates, or otherwise transforms homogeneous coordinate points in world coordinate units to orient information with respect to right-left, top-bottom, and front-back.  This orientation establishes the view reference coordinate system.  The PEVOM3 function generates the value for this input argument, as output to that function’s view orientation matrix argument.  The view orientation matrix is a 4 x 4 matrix. 

•View mapping matrix

Represents transformations of oriented information, such as perspective and parallel viewing transformation.  The view mapping matrix transforms points in view reference coordinates to points in the normalized projection coordinate system. The PEVMM3 function generates the value for this input argument as output to that function’s view mapping matrix argument. The view mapping matrix is a 4 x 4 matrix. 

The view mapping matrix is not the only place in the transformation pipeline in which such mapping operations occur, nor is the view mapping matrix limited to performing such operations.  See Getting Started with DEC PHIGS for more information on the view mapping matrix. 

•View clipping limits

Specifies the region of normalized projection coordinate space in which visible data may appear when clipping is turned on and when clipping defined by the workstation window is ignored.  To create the view clipping matrix, you specify six values in the order XMIN, XMAX, YMIN, YMAX, ZMIN, ZMAX. 

The XMIN and YMIN values must be less than the XMAX and YMAX values, respectively.  The ZMIN value must be less than or equal to the ZMAX value. 

The six values define a rectangular parallelepiped that is oriented such that its edges are parallel to the normalized projection coordinate axes. 

•xy-clipping indicator

Controls the clipping against the planes defined by XMIN, XMAX, YMIN, and YMAX.  It is set to one of two values of the enumerated data
  PCLIP or PNCLIP. If the xy-clipping indicator value is PNCLIP, the region of normalized projection coordinate space in which visible data can appear is unlimited in x and y. 

•Back-clipping indicator

Controls the clipping against the ZMIN plane.  It is set to one of two values of the enumerated data type: PCLIP or PNCLIP.  If the back-clipping indicator value is PNCLIP, the region of normalized projection coordinate space in which visible data can appear is unlimited in the negative z direction. 

•Front-clipping indicator

Controls the clipping against the ZMAX plane.  It is set to one of two values of the enumerated data type: PCLIP or PNCLIP.  If the front-clipping indicator value is PNCLIP, the region of normalized projection coordinate space in which visible data can appear is unlimited in the positive z direction. 

The PSVWR3 function has the following effects:

•Values are set for the specified view in these workstation state list entries:

•Requested view orientation matrix

•Requested view mapping matrix

•Requested view clipping limits

•Requested xy-clipping indicator

•Requested back-clipping indicator

•Requested front-clipping indicator

The function updates requested entries, rather than current entries, because the visual effect of setting a view table entry may be deferred. 

•The viewing transformation update state entry in the workstation state list is set to PENDING on the specified workstation. 

The next time the workstation is updated, the following actions occur:

•The corresponding current values for the specified view in the workstation state list are set to the requested entry values specified in this function. 

•The viewing transformation update state entry in the workstation state list is set to NOTPENDING. 
 

See Also

PEVMM3
PEVOM3
PQVWR
PSVWI
PSVWR
PSVTIP
PUWK