glCopyTexSubImage1DEXT(3G)     OpenGL Reference	    glCopyTexSubImage1DEXT(3G)



NAME
     glCopyTexSubImage1DEXT - copy pixels into a 1D texture subimage


C SPECIFICATION
     void glCopyTexSubImage1DEXT( GLenum target,
				  GLint	level,
				  GLint	xoffset,
				  GLint	x,
				  GLint	y,
				  GLsizei width	)


PARAMETERS
     target   The target texture.  Must	be GL_TEXTURE_1D

     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.

     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 pixel rectangle to be transferred to the
	      texture array.

DESCRIPTION
     glCopyTexSubImage1DEXT replaces a rectangular portion of a	two-
     dimensional texture image with pixels from	the current GL_READ_BUFFER
     (rather than from main memory, as is the case for glTexSubImage1DEXT).

     The screen-aligned	pixel rectangle	with lower-left	corner at (x, y),
     width width and height 1 replaces the portion of the texture array	with x
     indices xoffset through xoffset+width-1, inclusive. The destination
     rectangle in the texture array may	not include any	texels outside the
     texture array as it was originally	specified.

     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.

     It	is not an error	to specify a subtexture	with zero width, but such a
     specification has no effect.  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.



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glCopyTexSubImage1DEXT(3G)     OpenGL Reference	    glCopyTexSubImage1DEXT(3G)



NOTES
     glCopyTexSubImage1DEXT 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, or
     (xoffset+width)>(TEXTURE_WIDTH-TEXTURE_BORDER), where TEXTURE_WIDTH and
     TEXTURE_BORDER are	the state values of the	texture	image being modified.
     Note that TEXTURE_WIDTH includes twice the	border width.

     GL_INVALID_VALUE is generated if width is negative.

     GL_INVALID_OPERATION is generated when the	texture	array has not been
     defined by	a previous glTexImage1D	(or equivalent)	operation.

     GL_INVALID_OPERATION is generated if glCopyTexSubImage1DEXT is executed
     between the execution of glBegin and the corresponding execution of
     glEnd.

ASSOCIATED GETS
     glGetTexImage


MACHINE	DEPENDENCIES
     glCopyTexSubImage1DEXT 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.








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glCopyTexSubImage1DEXT(3G)     OpenGL Reference	    glCopyTexSubImage1DEXT(3G)



SEE ALSO
     glTexImage1D, glTexSubImage1DEXT, glCopyPixels.





















































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