# 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.

## Associated Gets

glGet with argument GL_VIEWPORT

glGet with argument GL_MAX_VIEWPORT_DIMS

## Version Support

OpenGL Version
Function / Feature Name 2.0 2.1 3.0 3.1 3.2 3.3 4.0 4.1 4.2 4.3 4.4 4.5
glViewport