viewpo(3G)

NAME
     viewpo - allocates a rectangular area of the window for an image

FORTRAN 77 SPECIFICATION
     subroutine viewpo(left, right, bottom, top)
     integer*4 left, right, bottom, top

PARAMETERS
     left     is the x coordinate of the viewport left side.

     right    is the x coordinate of the viewport right side.

     bottom   is the y coordinate of the viewport bottom.

     top      is the y coordinate of the viewport top.

DESCRIPTION
     viewpo specifies, in pixels, the area of the window that displays an
     image.  The viewport locations are specified relative to the lower-left
     corner of the window. Specifying the viewport is the first step in
     mapping world coordinates to screen coordinates.  The portion of world
     space that window, ortho, or perspe describes is mapped into the
     viewport.  left, right, bottom, and top coordinates define a rectangular
     area on the screen.

     When the system is not in feedback mode the rectangular area is
     restricted as follows.  The valid range for left, and right is
     -getgde(GDXPMAX) to 2*getgde(GDXPMAX).  The valid range for bottom, and
     top is -getgde(GDYPMAX) to 2*getgde(GDYPMAX).  The maximum width and
     height is 2K.

     viewpo also loads the screenmask.

SEE ALSO
     scrmas, getvie, popvie, pushvi

NOTE
     On the Personal Iris, if left is greater than right or bottom is greater
     than top, the screen displays a reflected image.