glPixelZoom.3gl

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

See Also

  glCopyPixels,	glDrawPixels

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Last Edited: Tue May 23, 1995

AFV