POP_MATRIX(3G)

NAME

pop_matrix − remove matrix from the top of the matrix stack.

SYNOPSIS

C SYNTAX

void pop_matrix(fildes);
int fildes;
void pop_matrix2d(fildes,xform2);
int fildes;
float xform2[3][2];
void pop_matrix3d(fildes,xform3);
int fildes;
float xform3[4][4];

FORTRAN77 SYNTAX

    See Language Dependencies Below
         subroutine pop_matrix(fildes)
        integer*4 fildes
         subroutine pop_matrix2d(fildes,xform2)
        integer*4 fildes
        real xform2(2,3)
          subroutine pop_matrix3d(fildes,xform3)
        integer*4 fildes
        real xform3(4,4)

PASCAL SYNTAX

type
two_d_xform = array [1..3][1..2] of real;
three_d_xform = array [1..4][1..4] of real;
procedure pop_matrix(fildes:integer);
procedure pop_matrix2d(fildes:integer;
var xform:two_d_xform);
procedure pop_matrix3d(fildes:integer;
var xform:three_d_xform);

HP-UX COMPATIBILITY

Level: HP-UX/STANDARD

Origin: HP

DESCRIPTION

INPUT PARAMETERS

fildes
is an integer file descriptor returned by gopen when an I/O path to a graphic device is opened.

OUTPUT PARAMETERS

xform2
is a 3x2 (2-Dimensional) matrix.
xform3
is a 4x4 (3-Dimensional) matrix.

DISCUSSION

The top matrix on the matrix stack is called the current transformation matrix.

The pop_matrix procedure removes the top matrix from the matrix stack and throws it away.

The pop_matrix2d and pop_matrix3d procedures remove the top matrix from the matrix stack, concatenates it with the inverse of the current vdc-to-device unit transformation matrix and stores the result in either xform2 or xform3 . The new current transformation matrix is the next matrix on the matrix stack.

The vdc-to-device unit transformation matrix cannot be popped or replaced using matrix functions. It can be changed using vdc_extent, viewport_justification, set_p1_p2, or mapping_mode. If there is only one matrix (the vdc-to-device unit transformation matrix) in the matrix stack, pop_matrix will generate a warning.

Internally to Starbase, all matrices are maintained in 3D (4x4) form, so pop_matrix2d must shrink the current transformation matrix down before returning it.

LANGUAGE DEPENDENCIES

FORTRAN77
A transposition of array rows and columns is required due to the manner in which FORTRAN77 stores arrays.

DEFAULTS

After gopen the current transformation matrix is the vdc-to-device unit transformation matrix.

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