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# docs.GL

OpenGL 3
OpenGL 2

# glPixelZoom

## Name

glPixelZoom — specify the pixel zoom factors

## C Specification

`void glPixelZoom(` | GLfloat | xfactor,
| GLfloat | yfactor`)`;

## Parameters

`xfactor`, `yfactor`

  Specify the x and y zoom factors for pixel write operations.

## Description

`glPixelZoom` specifies values for the x and y zoom factors. During the execution of glDrawPixels or glCopyPixels, if ( xr , yr ) is the current raster position, and a given element is in the mth row and nth column of the pixel rectangle, then pixels whose centers are in the rectangle with corners at

( xr + n · xfactor , yr + m · yfactor )

( xr + n + 1 · xfactor , yr + m + 1 · yfactor )

are candidates for replacement. Any pixel whose center lies on the bottom or left edge of this rectangular region is also modified.

Pixel zoom factors are not limited to positive values. Negative zoom factors reflect the resulting image about the current raster position.

## Errors

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

## Associated Gets

glGet with argument `GL_ZOOM_X`

glGet with argument `GL_ZOOM_Y`

## See Also

glCopyPixels, glDrawPixels

## 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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