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.	 Let, (xr, yr)
     be	the current raster position, and let interlace be either 1 or 2
     corresponding to whether GL_INTERLACE_SGIX	is enabled or not,
     respectively.  Then, during the execution of glDrawPixels or
     glCopyPixels, for a pixel that is in the mth row and nth column of	the
     source image, the destination pixels that are candidate for replacement
     are those whose centers are on the	bottom or left edge of,	or inside the
     rectangle with corners at
     (xr + n x xfactor,	yr + m x interlace x yfactor) and
     (xr + (n +	1) x xfactor,yr	+ (m x interlace + 1) x	yfactor)

     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
     and on RealityEngine, RealityEngine2, and VTX systems.


SEE ALSO
     glCopyPixels, glEnable, glDrawPixels.










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