|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 the texel offset within the texture array.|
|x, y||Specify the window coordinates of the left corner of the row of pixels to be copied.|
|width||Specifies the width of the texture subimage.|
glCopyTexSubImage1D replaces a portion of a one-dimensional texture image with pixels from the current GL_READ_BUFFER (rather than from main memory, as is the case for glTexSubImage1D).
The screen-aligned pixel row with left corner at (x, y), and with length width replaces the portion of the texture array with x indices xoffset through xoffset + width - 1, inclusive. The destination in the texture array may not include any texels outside the texture array as it was originally specified.
The pixels in the row 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 textures 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 row 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.
No change is made to the internalformat, width, or border parameters of the specified texture array or to texel values outside the specified subregion.
glCopyTexSubImage1D is available only if the GL version is 1.1 or greater.
Texturing has no effect in color index mode.
glPixelStore and glPixelTransfer modes affect texture images in exactly the way they affect glDrawPixels.
GL_INVALID_ENUM is generated if target is not GL_TEXTURE_1D.
GL_INVALID_OPERATION is generated if the texture array has not been defined by a previous glTexImage1D or glCopyTexImage1D operation.
GL_INVALID_VALUE is generated if level is less than 0.
GL_INVALID_VALUE may be generated if level>log2 max, where max is the returned value of GL_MAX_TEXTURE_SIZE.
GL_INVALID_VALUE is generated if y < -b or if width < -b, where b is the border width of the texture array.
GL_INVALID_VALUE is generated if xoffset < -b, or (xoffset + width) > (w-b), where w is the GL_TEXTURE_WIDTH, and b is the GL_TEXTURE_BORDER of the texture image being modified. Note that w includes twice the border width.
glIsEnabled with argument GL_TEXTURE_1D
glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage2D, glPixelStore, glPixelTransfer, glTexEnv, glTexGen, glTexImage1D, glTexImage2D, glTexParameter, glTexSubImage1D, glTexSubImage2D