1991-2006
Silicon Graphics, Inc.
glViewport
3G

# 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 pixels. 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 normalized device coordinates to window coordinates. Let x nd y nd be normalized device coordinates. Then the window coordinates x w y w are computed as follows:

x w = x nd + 1 &it; width 2 + x

y w = y nd + 1 &it; 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 `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

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.