.TH viewport 3 "R1c" "Silicon Graphics"
.SH NAME
.I viewport
- allocate an area of the screen for an image
.SH SYNOPSIS
.nf
.TP \w'FORTRAN\ \ \ 'u
C
.B "viewport(left, right, bottom, top)"
.B "Screencoord left, right, bottom, top;"
.IP 
.TP \w'FORTRAN\ \ \ 'u
FORTRAN
.B "subroutine viewpo(left, right, bottom, top)"
.B "integer*2 left, right, bottom, top"
.IP 
.TP \w'FORTRAN\ \ \ 'u
Pascal
.B "procedure viewport(left, right, bottom, top: Screencoord);"
.sp
.SH DESCRIPTION
The first step in defining the mapping from world coordinates to
screen coordinates is to choose an area of the screen to display an
image.  This area is called the \f2viewport\f1 and is specified in
screen coordinates.  
The arguments
to the \f2viewport\f1 command define a rectangular area on the screen by
the left, right, bottom, and top coordinates.  This command also loads the 
screen mask.
.SH "SEE ALSO"
.I scrmask, getviewport, popviewport, pushviewport