glViewport(3)

NAME

       glViewport - set the viewport

C SPECIFICATION

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

       delim $$

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 nor-
       malized  device coordinates to window coordinates.  Let ($x sub nd$, $y
       sub nd$) be normalized device coordinates.  Then the window coordinates
       ($x sub w$, $y sub w$) are computed as follows:

        x sub w ~=~ ( x sub nd ~+~ 1 ) left ( "width" over 2 right ) ~+~ "x"

        y sub w ~=~ ( y sub nd ~+~ 1 ) left ( "height" over 2 right ) ~+~ "y"

Viewport  width and height are silently clamped to a range that depends on the

implementation. To query this range, call glGet with argument

GL_MAX_VIEWPORT_DIMS.

ERRORS

       GL_INVALID_VALUE is generated if either width or height is negative.

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

ASSOCIATED GETS

       glGet with argument GL_VIEWPORT
       glGet with argument GL_MAX_VIEWPORT_DIMS

SEE ALSO

       glDepthRange(3G)

                                                                GLVIEWPORT(3G)