viewport(3G)

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

C SPECIFICATION
     void viewport(Screencoord left, Screencoord right, Screencoord bottom, Screencoord 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
     viewport 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 perspective 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
     -getgdesc(GD_XPMAX) to 2*getgdesc(GD_XPMAX).  The valid range for bottom,
     and top is -getgdesc(GD_YPMAX) to 2*getgdesc(GD_YPMAX).  The maximum
     width and height is 2K.

     viewport also loads the screenmask.

SEE ALSO
     scrmask, getviewport, popviewport, pushviewport

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