glPixelZoom(3G) OpenGL Reference glPixelZoom(3G)NAME
glPixelZoom - specify the pixel zoom factors
C SPECIFICATION
void glPixelZoom( GLfloat xfactor,
GLfloat yfactor )
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 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.
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
glGet with argument GL_INTERLACE_SGIX
MACHINE DEPENDENCIES
The SGIX_interlace extension is supported only on InfiniteReality
systems, on RealityEngine, RealityEngine2, and VTX systems, on Octane2
VPro systems, and on O2 systems.
On InfiniteReality systems, the absolute values of the zoom factors must
be strictly less than 128. If not, they are clamped and GL_INVALID_VALUE
is generated.
Pixel zoom factors are snapped to fixed point precision on O2 systems,
Indy and XL systems, XS, XZ, Elan, and Extreme systems. glGet will
return these values.
Page 1
glPixelZoom(3G) OpenGL Reference glPixelZoom(3G)SEE ALSO
glCopyPixels, glEnable, glDrawPixels.
Page 2
