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# docs.GL

OpenGL 4
OpenGL 3
OpenGL 2
OpenGL ES 3
OpenGL ES 2

# glViewport

## 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 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 ⁢ width 2 + x

y w = y nd + 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 `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`

## Tutorials

## See Also

glDepthRange

## Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/.

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