OpenGL man pages
glPixelZoom - specify the pixel zoom factors
void glPixelZoom( GLfloat xfactor,
GLfloat yfactor )
xfactor, yfactor Specify the x and y zoom factors for pixel write
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
(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
Fri Dec 6 11:18:03 EST 1996
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