GLPIXELZOOM

Section: Misc. Reference Manual Pages (3G)
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NAME

glPixelZoom - specify the pixel zoom factors

C SPECIFICATION

void glPixelZoom( GLfloat xfactor,


                    GLfloat yfactor )

delim $$

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 $m$th row and $n$th column of the pixel rectangle, then pixels whose centers are in the rectangle with corners at

($xr ~+~ n cdot "xfactor"$, $yr ~+~ m cdot "yfactor"$)

($xr ~+~ (n+1) cdot "xfactor"$, $yr ~+~ (m+1) cdot "yfactor"$)

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