glViewport
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## Name

glViewport — set the viewport

## C Specification

`void `glViewport`` | `(` | `GLint `x`, GLint `y`, GLsizei `width`, GLsizei `height`);`

## Python Specification

``glViewport`` | `(` | ``x`, `y`, `width`, `height`) → `None``

## 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`

## See Also

glDepthRange

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