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<HTML><BODY><PRE>     <STRONG>NAME</STRONG>	  <STRONG>glCopyTexSubImage2D</STRONG> -	copy a two-dimensional texture	  subimage     <STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>	  void <STRONG>glCopyTexSubImage2D</STRONG>( GLenum <EM>target</EM>,				    GLint <EM>level</EM>,				    GLint <EM>xoffset</EM>,				    GLint <EM>yoffset</EM>,				    GLint <EM>x</EM>,				    GLint <EM>y</EM>,				    GLsizei <EM>width</EM>,				    GLsizei <EM>height</EM> )     <STRONG>PARAMETERS</STRONG>	  <EM>target</EM>   Specifies the target	texture.  Must be		   <STRONG>GL_TEXTURE_2D</STRONG>	  <EM>level</EM>	   Specifies the level-of-detail number.  Level	0 is		   the base image level.  Level	<EM>n</EM> is the <EM>n</EM>th mipmap		   reduction image.	  <EM>xoffset</EM>  Specifies a texel offset in the x direction within		   the texture array.	  <EM>yoffset</EM>  Specifies a texel offset in the y direction within		   the texture array.	  <EM>x</EM>, <EM>y</EM>	   Specify the window coordinates of the lower left		   corner of the rectangular region of pixels to be		   copied.	  <EM>width</EM>	   Specifies the width of the texture subimage.	  <EM>height</EM>   Specifies the height	of the texture subimage.     <STRONG>DESCRIPTION</STRONG>	  <STRONG>glCopyTexSubImage2D</STRONG> replaces a rectangular portion of	a	  two-dimensional texture image	with pixels from the current	  <STRONG>GL_READ_BUFFER</STRONG> (rather than from main	memory,	as is the case	  for <STRONG>glTexSubImage2D</STRONG>).	  The screen-aligned pixel rectangle with lower	left corner at	  (<EM>x</EM>, <EM>y</EM>) and with width	<EM>width</EM> and height <EM>height</EM>	replaces the	  portion of the texture array with x indices <EM>xoffset</EM> through	  <EM>xoffset</EM> + <EM>width</EM> - 1, inclusive, and y	indices	<EM>yoffset</EM>	  through <EM>yoffset</EM> + <EM>height</EM> - 1,	inclusive, at the mipmap level	  specified by <EM>level</EM>.	  The pixels in	the rectangle are processed exactly as if	  <STRONG>glCopyPixels</STRONG> had been	called,	but the	process	stops just	  before final conversion.  At this point, all pixel component	  values are clamped to	the range [0, 1] and then converted to	  the texture's	internal format	for storage in the texel	  array.	  The destination rectangle in the texture array may not	  include any texels outside the texture array as it was	  originally specified.	 It is not an error to specify a	  subtexture with zero width or	height,	but such a	  specification	has no effect.	  If any of the	pixels within the specified rectangle of the	  current <STRONG>GL_READ_BUFFER</STRONG> are outside the read window	  associated with the current rendering	context, then the	  values obtained for those pixels are undefined.	  No change is made to the <EM>internalformat</EM>, <EM>width</EM>, <EM>height</EM>, or	  <EM>border</EM> parameters of the specified texture array or to texel	  values outside the specified subregion.     <STRONG>NOTES</STRONG>	  <STRONG>glCopyTexSubImage2D</STRONG> is available only	if the GL version is	  1.1 or greater.	  Texturing has	no effect in color index mode.	  <STRONG>glPixelStore</STRONG> and <STRONG>glPixelTransfer</STRONG> modes affect	texture	images	  in exactly the way they affect <STRONG>glDrawPixels</STRONG>.     <STRONG>ERRORS</STRONG>	  <STRONG>GL_INVALID_ENUM</STRONG> is generated if <EM>target</EM> is not	<STRONG>GL_TEXTURE_2D</STRONG>.	  <STRONG>GL_INVALID_OPERATION</STRONG> is generated if the texture array has	  not been defined by a	previous <STRONG>glTexImage2D</STRONG> or	  <STRONG>glCopyTexImage2D</STRONG> operation.	  <STRONG>GL_INVALID_VALUE</STRONG> is generated	if <EM>level</EM> is less than 0.	  <STRONG>GL_INVALID_VALUE</STRONG> may be generated if <EM>level</EM> is	greater	than	  log max, where max is	the returned value of	  <STRONG>GL_MAX_TEXTURE_SIZE</STRONG>.	  <STRONG>GL_INVALID_VALUE</STRONG> is generated	if <EM>x</EM> &lt;	-b or if <EM>y</EM> &lt;  -b,	  where	b is the border	width of the texture array.	  <STRONG>GL_INVALID_VALUE</STRONG> is generated	if xoffset &lt; -b,	  (<EM>xoffset</EM> + <EM>width</EM>) &gt; (w - b), <EM>yoffset</EM> &lt;  -b, or	  (<EM>yoffset</EM> + <EM>height</EM>) &gt; (h - b),	where w	is the	  <STRONG>GL_TEXTURE_WIDTH</STRONG>, h is the  <STRONG>GL_TEXTURE_HEIGHT</STRONG>, and b is the	  <STRONG>GL_TEXTURE_BORDER</STRONG> of the texture image being modified.  Note	  that w and h include twice the border	width.	  <STRONG>GL_INVALID_OPERATION</STRONG> is generated if <STRONG>glCopyTexSubImage2D</STRONG> is	  executed between the execution of <STRONG>glBegin</STRONG> and	the	  corresponding	execution of <STRONG>glEnd</STRONG>.     <STRONG>ASSOCIATED</STRONG>	<STRONG>GETS</STRONG>	  <STRONG>glGetTexImage</STRONG>	  <STRONG>glIsEnabled</STRONG> with argument <STRONG>GL_TEXTURE_2D</STRONG>     <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>	  <STRONG>glCopyPixels</STRONG>,	<STRONG>glCopyTexImage1D</STRONG>, <STRONG>glCopyTexImage2D</STRONG>,	  <STRONG>glCopyTexSubImage1D</STRONG>, <STRONG>glPixelStore</STRONG>, <STRONG>glPixelTransfer</STRONG>,	  <STRONG>glTexEnv</STRONG>, <STRONG>glTexGen</STRONG>, <STRONG>glTexImage1D</STRONG>, <STRONG>glTexImage2D</STRONG>,	  <STRONG>glTexParameter</STRONG>, <STRONG>glTexSubImage1D</STRONG>, <STRONG>glTexSubImage2D</STRONG></PRE></BODY></HTML>
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