GLVIEWPORT(3G)                                                  GLVIEWPORT(3G)



NAME
       glViewport - set the viewport


C SPECIFICATION
       void glViewport( GLint x,
                        GLint y,
                        GLsizei width,
                        GLsizei height )


PARAMETERS
       x, y Specify  the  lower left corner of the viewport rectangle, in pix-
            els. The initial value is (0,0).

       width, height
            Specify the width and height of the viewport.  When a  GL  context
            is  first  attached  to  a window, width and height are set to the
            dimensions of that window.

DESCRIPTION
       glViewport specifies the affine transformation of x and y from  normal-
       ized  device coordinates to window coordinates.  Let (xnd, ynd) be nor-
       malized device coordinates.  Then the window coordinates (xw,  yw)  are
       computed as follows:

                             xw = (xnd]1) (width/2) ] x

                             yw = (ynd]1) (height/2) ] y


       Viewport  width and height are silently clamped to a range that depends
       on the implementation.  To query this range, call glGet  with  argument
       GLMAXVIEWPORTDIMS.

ERORS
       GLINVALIDVALUE is generated if either width or height is negative.

       GLINVALIDOPERATION is generated if glViewport is executed between the
       execution of glBegin and the corresponding execution of glEnd.

ASOCIATED GETS
       glGet with argument GLVIEWPORT
       glGet with argument GLMAXVIEWPORTDIMS

SEE ALSO
       glDepthRange



                                                                GLVIEWPORT(3G)