glCopyTexSubImage3DEXT(3G)     OpenGL Reference	    glCopyTexSubImage3DEXT(3G)



NAME
     glCopyTexSubImage3DEXT - copy pixels into a 3D texture subimage


C SPECIFICATION
     void glCopyTexSubImage3DEXT( GLenum target,
				  GLint	level,
				  GLint	xoffset,
				  GLint	yoffset,
				  GLint	zoffset,
				  GLint	x,
				  GLint	y,
				  GLsizei width,
				  GLsizei height )


PARAMETERS
     target   The target texture.  Must	be GL_TEXTURE_3D_EXT

     level    The level-of-detail number.  Level 0 is the base image level.
	      Level n is the nth mipmap	reduction image.

     xoffset  A	texel offset in	the x direction	within the texture array.

     yoffset  A	texel offset in	the y direction	within the texture array.

     zoffset  A	texel offset in	the z direction	within the texture array.

     x	      The x coordinate of the lower-left corner	of the pixel rectangle
	      to be transferred	to the texture array.

     y	      The y coordinate of the lower-left corner	of the pixel rectangle
	      to be transferred	to the texture array.

     width    The width	of the texture subimage.

     height   The height of the	texture	subimage.

DESCRIPTION
     glCopyTexSubImage3DEXT replaces a rectangular portion of a	three-
     dimensional texture image with pixels from	the current GL_READ_BUFFER
     (rather than from main memory, as is the case for glTexSubImage3DEXT).

     The screen-aligned	pixel rectangle	with lower-left	corner at (x, y)
     having width width	and height height replaces the rectangular area	of the
     S-T slice located at zoffset with	x indices xoffset through
     xoffset+width-1, inclusive, and y indices yoffset through
     yoffset+height-1, inclusive (But, see discussion of GL_INTERLACE_SGIX
     below).






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glCopyTexSubImage3DEXT(3G)     OpenGL Reference	    glCopyTexSubImage3DEXT(3G)



     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	GL_INTERLACE_SGIX is enabled, then every other row of the destination
     texture is	skipped. That is, only rows (0,2,4,...)	of the S-T slice
     (where the	border is considered part of the slice)	are defined. A
     complete video frame may be assembled in a	slice of the texture array by
     invoking glCopyTexSubImage3DEXT on	two consecutive	video fields, with
     yoffset values that differ	by one.

     The pixels	in the rectangle are processed exactly as if glCopyPixels 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.

     If	any of the pixels within the specified rectangle of the	current
     GL_READ_BUFFER are	outside	the read window	associated with	the current
     rendering context,	then the values	obtained for those pixels are
     undefined.

NOTES
     glCopyTexSubImage3DEXT is part of the EXT_copy_texture extension.	See
     glIntro for more information about	using extensions.

ERRORS
     GL_INVALID_ENUM is	generated when target is not one of the	allowable
     values.

     GL_INVALID_VALUE is generated if level is less than zero or greater than
     log2(max),	where max is the returned value	of GL_MAX_TEXTURE_SIZE.

     GL_INVALID_VALUE is generated if xoffset<-TEXTURE_BORDER,
     (xoffset+width)>(TEXTURE_WIDTH-TEXTURE_BORDER), yoffset<-TEXTURE_BORDER,
     (yoffset+interlacexheight)>(TEXTURE_HEIGHT-TEXTURE_BORDER), or if
     zoffset<-TEXTURE_BORDER.  Where TEXTURE_WIDTH, TEXTURE_HEIGHT, and
     TEXTURE_BORDER are	the state values of the	texture	image being modified,
     and interlace is 1	if GL_INTERLACE_SGIX is	disabled and 2 otherwise.
     Note that TEXTURE_WIDTH and TEXTURE_HEIGHT	include	twice the border
     width.

     GL_INVALID_VALUE is generated if width or height is negative.

     GL_INVALID_OPERATION is generated when the	texture	array has not been
     defined by	a previous glTexImage3D	(or equivalent)	operation.

     GL_INVALID_OPERATION is generated if glCopyTexSubImage3DEXT is executed
     between the execution of glBegin and the corresponding execution of
     glEnd.




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glCopyTexSubImage3DEXT(3G)     OpenGL Reference	    glCopyTexSubImage3DEXT(3G)



ASSOCIATED GETS
     glGetTexImage


MACHINE	DEPENDENCIES
     glCopyTexSubImage3DEXT is not supported on	RealityEngine, RealityEngine2,
     and VTX systems.

     On	InfiniteReality	systems, the width of the image	to be transferred to
     texture memory must be a multiple of 8.  This constraint will be lifted
     in	a future release, though transfers that	are a multiple of 8 in length
     will have somewhat	higher performance than	other transfers.

     Texture borders are not supported on InfiniteReality systems.  They will
     be	supported in a future release, however,	they will require large
     amounts of	texture	memory.	 Whenever possible, applications should	use
     borderless	textures and GL_CLAMP_TO_EDGE_SGIS wrap	mode.

     On	High Impact and	Maximum	Impact systems,	if the right side of the image
     to	be transferred to texture memory is not	the right side of the texture,
     then its index must be a multiple of 32, where index = xoffset+width.
     Otherwise it will generate	a GL_INVALID_VALUE error.

     The SGIX_interlace	extension is supported only on InfiniteReality systems
     and on RealityEngine, RealityEngine2, and VTX systems.


SEE ALSO
     glTexImage3D, glTexSubImage3DEXT, glCopyPixels.


























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