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GLGETTEXIMAGE()						       GLGETTEXIMAGE()

NAME
       glGetTexImage - return a	texture	image

C SPECIFICATION
       void glGetTexImage( GLenum target,
			   GLint level,
			   GLenum format,
			   GLenum type,
			   GLvoid *pixels )

       delim $$

PARAMETERS
       target  Specifies  which	 texture is to be obtained.  GL_TEXTURE_1D and
	       GL_TEXTURE_2D are accepted.

       level   Specifies the level-of-detail  number  of  the  desired	image.
	       Level 0 is the base image level.	 Level $n$ is the $n$th	mipmap
	       reduction image.

       format  Specifies a pixel format	for the	returned data.	The  supported
	       formats	 are  GL_RED,  GL_GREEN,  GL_BLUE,  GL_ALPHA,  GL_RGB,
	       GL_RGBA,	GL_LUMINANCE, and GL_LUMINANCE_ALPHA.

       type    Specifies a pixel type for the returned	data.	The  supported
	       types   are   GL_UNSIGNED_BYTE,	 GL_BYTE,   GL_UNSIGNED_SHORT,
	       GL_SHORT, GL_UNSIGNED_INT, GL_INT, and GL_FLOAT.

       pixels  Returns the texture image.  Should be a pointer to an array  of
	       the type	specified by type.

DESCRIPTION
       glGetTexImage  returns  a  texture image	into pixels.  target specifies
       whether the desired texture image  is  one  specified  by  glTexImage1D
       (GL_TEXTURE_1D)	or  by	glTexImage2D (GL_TEXTURE_2D).  level specifies
       the level-of-detail number of the desired image.	 format	and type spec-
       ify  the	format and type	of the desired image array.  See the reference
       pages glTexImage1D and glDrawPixels for a description of	the acceptable
       values for the format and type parameters, respectively.

       To understand the operation of glGetTexImage, consider the selected in-
       ternal four-component texture image to be an RGBA color buffer the size
       of  the	image.	 The  semantics	of glGetTexImage are then identical to
       those of	glReadPixels called with the same format and type, with	x  and
       y set to	0, width set to	the width of the texture image (including bor-
       der if one was specified), and height set to 1 for 1D images, or	to the
       height of the texture image (including border if	one was	specified) for
       2D images.  Because the internal	texture	image is an RGBA image,	 pixel
       formats	GL_COLOR_INDEX,	 GL_STENCIL_INDEX,  and	GL_DEPTH_COMPONENT are
       not accepted, and pixel type GL_BITMAP is not accepted.

       If the selected texture image does not  contain	four  components,  the
       following  mappings are applied.	 Single-component textures are treated
       as RGBA buffers with red	set to the single-component value,  green  set
       to  0,	blue set to 0, and alpha set to	1.  Two-component textures are
       treated as RGBA buffers with red	set to the value  of  component	 zero,
       alpha  set  to the value	of component one, and green and	blue set to 0.
       Finally,	three-component	textures are treated as	RGBA buffers with  red
       set  to	component zero,	green set to component one, blue set to	compo-
       nent two, and alpha set to 1.

       To determine the	required size of pixels, use glGetTexLevelParameter to
       determine  the dimensions of the	internal texture image,	then scale the
       required	number of pixels by the	storage	required for each pixel, based
       on  format and type.  Be	sure to	take the pixel storage parameters into
       account,	especially GL_PACK_ALIGNMENT.

NOTES
       If an error is generated, no change is made to the contents of pixels.

ERRORS
       GL_INVALID_ENUM is generated if target, format, or type is not  an  ac-
       cepted value.

       GL_INVALID_VALUE	is generated if	level is less than 0.

       GL_INVALID_VALUE	 may  be generated if level is greater than $log sub 2
       max$, where $max$ is the	returned value of GL_MAX_TEXTURE_SIZE.

       GL_INVALID_OPERATION is generated if glGetTexImage is executed  between
       the execution of	glBegin	and the	corresponding execution	of glEnd.

ASSOCIATED GETS
       glGetTexLevelParameter with argument GL_TEXTURE_WIDTH
       glGetTexLevelParameter with argument GL_TEXTURE_HEIGHT
       glGetTexLevelParameter with argument GL_TEXTURE_BORDER
       glGetTexLevelParameter with argument GL_TEXTURE_COMPONENTS
       glGet with arguments GL_PACK_ALIGNMENT and others

SEE ALSO
       glDrawPixels,  glReadPixels, glTexEnv, glTexGen,	glTexImage1D, glTexIm-
       age2D, glTexSubImage1D, glTexSubImage2D,	glTexParameter

							       GLGETTEXIMAGE()

NAME | C SPECIFICATION | PARAMETERS | DESCRIPTION | NOTES | ERRORS | ASSOCIATED GETS | SEE ALSO

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