glPixelZoom -	specify	the pixel zoom factors

glPixelZoom
	glPixelZoom(xfactor, yfactor) -> None

void glPixelZoom( GLfloat xfactor,
                  GLfloat yfactor )

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

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.

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

glGet	with argument GL_ZOOM_X
glGet	with argument GL_ZOOM_Y

glCopyPixels,	glDrawPixels