viewport(3G)							  viewport(3G)

NAME    [Toc]    [Back]

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

C SPECIFICATION    [Toc]    [Back]

     void viewport(Screencoord left, Screencoord right,	Screencoord bottom, Screencoord	top)

PARAMETERS    [Toc]    [Back]

     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    [Toc]    [Back]

     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    [Toc]    [Back]

     scrmask, getviewport, popviewport,	pushviewport

NOTE    [Toc]    [Back]

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


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