glPixelZoom function

Article
02/10/2021

The glPixelZoom function specifies the pixel zoom factors.

Syntax

void WINAPI glPixelZoom(
   GLfloat xfactor,
   GLfloat yfactor
);

Parameters

xfactor: The x zoom factor for pixel write operations.
yfactor: The y zoom factor for pixel write operations.

Return value

This function does not return a value.

Error codes

The following error code can be retrieved by the glGetError function.

Name	Meaning
GL_INVALID_OPERATION	The function was called between a call to glBegin and the corresponding call to glEnd.

Remarks

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

Equation showing the locations where pixels are candidates for replacement.

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.

The following functions retrieve information related to glPixelZoom:

glGet with argument GL_ZOOM_X

glGet with argument GL_ZOOM_Y

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Gl.h
Library	Opengl32.lib
DLL	Opengl32.dll