gluScaleImage.3gl

Name

  gluScaleImage	- scale	an image to an arbitrary size

C Specification

  int gluScaleImage( GLenum format,

		     GLint widthin,

		     GLint heightin,

		     GLenum typein,

		     const void	*datain,

		     GLint widthout,

		     GLint heightout,

		     GLenum typeout,

		     void *dataout )

Parameters

  format     Specifies the format of the pixel data.  The following symbolic

	     values are	valid: GL_COLOR_INDEX, GL_STENCIL_INDEX,

	     GL_DEPTH_COMPONENT, GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA, GL_RGB,

	     GL_RGBA, GL_LUMINANCE, and	GL_LUMINANCE_ALPHA.



  widthin, heightin

	     Specify the width and height, respectively, of the	source image

	     that is scaled.



  typein     Specifies the data	type for datain. Must be one of

	     GL_UNSIGNED_BYTE, GL_BYTE,	GL_BITMAP, GL_UNSIGNED_SHORT,

	     GL_SHORT, GL_UNSIGNED_INT,	GL_INT,	or GL_FLOAT.



  datain     Specifies a pointer to the	source image.



  widthout, heightout

	     Specify the width and height, respectively, of the	destination

	     image.



  typeout    Specifies the data	type for dataout. Must be one of

	     GL_UNSIGNED_BYTE, GL_BYTE,	GL_BITMAP, GL_UNSIGNED_SHORT,

	     GL_SHORT, GL_UNSIGNED_INT,	GL_INT,	or GL_FLOAT.



  dataout    Specifies a pointer to the	destination image.

Description

  gluScaleImage	scales a pixel image using the appropriate pixel store modes

  to unpack data from the source image and pack	data into the destination

  image.



  When shrinking an image, gluScaleImage uses a	box filter to sample the

  source image and create pixels for the destination image.  When magnifying

  an image, the	pixels from the	source image are linearly interpolated to

  create the destination image.



  A return value of zero indicates success, otherwise a	GLU error code is

  returned indicating what the problem was (see	gluErrorString).



  Please refer to the glReadPixels reference page for a	description of the

  acceptable values for	the format, typein, and	typeout	parameters.

See Also

  glDrawPixels,	glReadPixels, gluBuild1DMipmaps, gluBuild2DMipmaps,

  gluErrorString

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Last Edited: Mon, May 22, 1995

AFV