glPixelZoom - specify the pixel zoom factors
GLfloat 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 cdot xfactor, yr + m .
yfactor) (xr + (n+1) . 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.
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
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