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glGetTexImage(3G)					     glGetTexImage(3G)

NAME
       glGetTexImage - return a texture image

SYNOPSIS
       void glGetTexImage(
	       GLenum target,
	       GLint level,
	       GLenum format,
	       GLenum type,
	       GLvoid *pixels );

PARAMETERS
       Specifies  which	 texture  is  to  be obtained.	GL_TEXTURE_1D, GL_TEX‐
       TURE_2D, and GL_TEXTURE_3D are accepted.	 Specifies the level-of-detail
       number  of the desired image. Level 0 is the base image level.  Level n
       is the nth mipmap reduction image.  Specifies a pixel  for the returned
       data.  The  supported  formats are GL_RED, GL_GREEN, GL_BLUE, GL_ALPHA,
       GL_RGB, GL_BGR, GL_RGBA, GL_BGRA, GL_LUMINANCE, and GL_LUMINANCE_ALPHA.
       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,	 GL_FLOAT,     GL_UNSIGNED_BYTE_3_3_2,
       GL_UNSIGNED_BYTE_2_3_3_REV,		      GL_UNSIGNED_SHORT_5_6_5,
       GL_UNSIGNED_SHORT_5_6_5_REV,		    GL_UNSIGNED_SHORT_4_4_4_4,
       GL_UNSIGNED_SHORT_4_4_4_4_REV,		    GL_UNSIGNED_SHORT_5_5_5_1,
       GL_UNSIGNED_SHORT_1_5_5_5_REV,		      GL_UNSIGNED_INT_8_8_8_8,
       GL_UNSIGNED_INT_8_8_8_8_REV,	 GL_UNSIGNED_INT_10_10_10_2,	   and
       GL_UNSIGNED_INT_2_10_10_10_REV.	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),	 glTexImage2D()	 (GL_TEXTURE_2D),  or	glTexImage3D()
       (GL_TEXTURE_3D).	  level	 specifies  the	 level-of-detail number of the
       desired image.  format and type specify the  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
       internal 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(), with the exception that no  pixel  transfer
       operations  are	performed,  when called with the same format and type,
       with x and y set to 0, width set to the	width  of  the	texture	 image
       (including  border  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.

       When the GL_ARB_multitexture extension  is  supported,  glGetTexImage()
       returns the texture image for the active texture unit.

       The     types	GL_UNSIGNED_BYTE_3_3_2,	   GL_UNSIGNED_BYTE_2_3_3_REV,
       GL_UNSIGNED_SHORT_5_6_5,			  GL_UNSIGNED_SHORT_5_6_5_REV,
       GL_UNSIGNED_SHORT_4_4_4_4,		GL_UNSIGNED_SHORT_4_4_4_4_REV,
       GL_UNSIGNED_SHORT_5_5_5_1,		GL_UNSIGNED_SHORT_1_5_5_5_REV,
       GL_UNSIGNED_INT_8_8_8_8,			  GL_UNSIGNED_INT_8_8_8_8_REV,
       GL_UNSIGNED_INT_10_10_10_2,  GL_UNSIGNED_INT_2_10_10_10_REV,  and   the
       formats GL_BGR, and GL_BGRA are available only if the GL version is 1.2
       or greater.

ERRORS
       GL_INVALID_ENUM is generated if target,	format,	 or  type  is  not  an
       accepted 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().

       GL_INVALID_OPERATION    is    returned	 if    type    is    one    of
       GL_UNSIGNED_BYTE_3_3_2,			   GL_UNSIGNED_BYTE_2_3_3_REV,
       GL_UNSIGNED_SHORT_5_6_5, or GL_UNSIGNED_SHORT_5_6_5_REV and  format  is
       not GL_RGB.

       GL_INVALID_OPERATION    is    returned	 if    type    is    one    of
       GL_UNSIGNED_SHORT_4_4_4_4,		GL_UNSIGNED_SHORT_4_4_4_4_REV,
       GL_UNSIGNED_SHORT_5_5_5_1,		GL_UNSIGNED_SHORT_1_5_5_5_REV,
       GL_UNSIGNED_INT_8_8_8_8,			  GL_UNSIGNED_INT_8_8_8_8_REV,
       GL_UNSIGNED_INT_10_10_10_2, or GL_UNSIGNED_INT_2_10_10_10_REV, and for‐
       mat is neither GL_RGBA or GL_BGRA.

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_INTERNALFORMAT
       glGet() with arguments GL_PACK_ALIGNMENT and others

SEE ALSO
       glActiveTextureARB(3), glDrawPixels(3),	glReadPixels(3),  glTexEnv(3),
       glTexGen(3),  glTexImage1D(3), glTexImage2D(3), glTexImage3D(3), glTex‐
       SubImage1D(3),  glTexSubImage2D(3),  glTexSubImage3D(3),	  glTexParame‐
       ter(3)

							     glGetTexImage(3G)
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