glTexSubImage1DEXT(3G)	       OpenGL Reference		glTexSubImage1DEXT(3G)



NAME
     glTexSubImage1DEXT	- specify a one-dimensional texture subimage


C SPECIFICATION
     void glTexSubImage1DEXT( GLenum target,
			      GLint level,
			      GLint xoffset,
			      GLsizei width,
			      GLenum format,
			      GLenum type,
			      const GLvoid *pixels )


PARAMETERS
     target   Specifies	the target texture.  Must be GL_TEXTURE_1D.

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

     xoffset  Specifies	a texel	offset in the x	direction within the texture
	      array.

     width    Specifies	the width of the texture subimage.

     format   Specifies	the format of the pixel	data.  The following symbolic
	      values are accepted:  GL_COLOR_INDEX, GL_RED, GL_GREEN, GL_BLUE,
	      GL_ALPHA,	GL_RGB,	GL_RGBA, GL_ABGR_EXT, GL_LUMINANCE, and
	      GL_LUMINANCE_ALPHA.

     type     Specifies	the data type of the pixel data.  The following
	      symbolic values are accepted:  GL_UNSIGNED_BYTE, GL_BYTE,
	      GL_BITMAP, GL_UNSIGNED_SHORT, GL_SHORT, GL_UNSIGNED_INT, GL_INT,
	      GL_FLOAT,	GL_UNSIGNED_BYTE_3_3_2_EXT,
	      GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
	      GL_UNSIGNED_INT_8_8_8_8_EXT, and GL_UNSIGNED_INT_10_10_10_2_EXT.

     pixels   Specifies	a pointer to the image data in memory.


DESCRIPTION
     Texturing maps a portion of a specified texture image onto	each graphical
     primitive for which texturing is enabled.	One-dimensional	texturing is
     enabled and disabled using	glEnable and glDisable with argument
     GL_TEXTURE_1D.

     glTexSubImage1DEXT	redefines a contiguous subregion of an existing	one-
     dimensional texture array.	 The texels referenced by pixels replace the
     portion of	the existing texture array with	x indices xoffset and
     xoffset+width-1, inclusive.  This region may not include any texels
     outside the range of the texture array as it was originally specified.
     It	is not an error	to specify a subtexture	with zero width, but such a



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glTexSubImage1DEXT(3G)	       OpenGL Reference		glTexSubImage1DEXT(3G)



     specification has no effect.

NOTES
     Texturing has no effect in	color index mode.

     glPixelStore and glPixelTransfer modes affect texture images in exactly
     the way they affect glDrawPixels.

     glTexSubImage1DEXT	is part	of the EXT_subtexture extension.

     If	type is	set to GL_UNSIGNED_BYTE_3_3_2_EXT,
     GL_UNSIGNED_SHORT_4_4_4_4_EXT, GL_UNSIGNED_SHORT_5_5_5_1_EXT,
     GL_UNSIGNED_INT_8_8_8_8_EXT, or GL_UNSIGNED_INT_10_10_10_2_EXT and	the
     EXT_packed_pixels extension is not	supported then a GL_INVALID_ENUM error
     is	generated.

     See glIntro for more information on using extensions.

ERRORS
     GL_INVALID_ENUM is	generated when target is not GL_TEXTURE_1D.

     GL_INVALID_OPERATION is generated when the	texture	image has not been
     defined by	a previous glTexImage1D	operation.

     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 if
     (xoffset+width)>(TEXTURE_WIDTH-TEXTURE_BORDER), where TEXTURE_WIDTH is
     the width of the image being modified and TEXTURE_BORDER is the border
     width of the image	being modified.	 Note that TEXTURE_WIDTH includes
     twice the border width.

     GL_INVALID_ENUM is	generated when format is not an	accepted format
     constant. Format constants	other than GL_STENCIL_INDEX and
     GL_DEPTH_COMPONENT	are accepted.

     GL_INVALID_ENUM is	generated when type is not a type constant.

     GL_INVALID_ENUM is	generated if type is GL_BITMAP and format is not
     GL_COLOR_INDEX.

     GL_INVALID_OPERATION is generated if glTexSubImage1DEXT is	executed
     between the execution of glBegin and the corresponding execution of
     glEnd.

ASSOCIATED GETS
     glGetTexImage
     glIsEnabled with argument GL_TEXTURE_1D






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glTexSubImage1DEXT(3G)	       OpenGL Reference		glTexSubImage1DEXT(3G)



MACHINE	DEPENDENCIES
     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.

     The EXT_packed_pixels extension is	not supported on RealityEngine,
     RealityEngine2, and VTX systems; it will be supported on High Impact and
     Maximum Impact systems in a future	release.

     glTexSubImage1DEXT	is not supported on RealityEngine, RealityEngine2, and
     VTX systems.

     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.


SEE ALSO
     glDrawPixels, glFog, glPixelStore,	glPixelTransfer, glTexEnv, glTexGen,
     glTexImage1D, glTexParameter.




























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