2003-2004 Silicon Graphics, Inc.
glCopyTexSubImage2D 3G
glCopyTexSubImage2D specify a two-dimensional texture subimage with pixels from the color buffer

## C Specification

void `glCopyTexSubImage2D` GLenum target GLint level GLint xoffset GLint yoffset GLint x GLint y GLsizei width GLsizei height

## Parameters

target

  Specifies the target texture. Must be `GL_TEXTURE_2D`.

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.

yoffset

  Specifies a texel offset in the y direction within the texture array.

x, y

  Specify the window coordinates of the lower left corner of the rectangular region of pixels to be copied.

width

  Specifies the width of the texture subimage.

height

  Specifies the height of the texture subimage.

## Description

`glCopyTexSubImage2D` replaces a rectangular portion of a two-dimensional texture image with pixels from the color buffer.

The screen-aligned pixel rectangle with lower left corner at ( x, y) and with width width and height height replaces the portion of the texture array with x indices xoffset through xoffset+width-1 , inclusive, and y indices yoffset through yoffset+height-1 , inclusive, at the mipmap level specified by level.

The pixels in the rectangle are processed the same way as with glCopyTexImage2D.

`glCopyTexSubImage2D` requires that the internal format of the currently bound texture is such that color buffer components can be dropped during conversion to the internal format, but new components cannot be added. For example, an `GL_RGB` color buffer can be used to create `GL_LUMINANCE` or `GL_RGB` textures, but not `GL_ALPHA`, `GL_LUMINANCE_ALPHA` or `GL_RGBA` textures.

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 color 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, height, or border parameters of the specified texture array or to texel values outside the specified subregion.

## Errors

`GL_INVALID_ENUM` is generated if target is not `GL_TEXTURE_2D`.

`GL_INVALID_OPERATION` is generated if the texture array has not been defined by a previous glTexImage2D or glCopyTexImage2D operation or if the internal format of the currently bound texture is not compatible with the color buffer format.

`GL_INVALID_VALUE` is generated if level is less than 0.

`GL_INVALID_VALUE` may be generated if level is greater than log 2 max , where max is the returned value of `GL_MAX_TEXTURE_SIZE`.

`GL_INVALID_VALUE` is generated if xoffset<0 , xoffset+width> w , yoffset<0 , or yoffset+height> h , where w is the texture width and h is the texture height.

## Associated Gets

glGet with argument `GL_MAX_TEXTURE_SIZE`

## See Also

glCompressedTexSubImage2D, glCopyTexImage2D, glGet, glTexEnv, glTexImage2D, glTexParameter, glTexSubImage2D

## Copyright

Copyright 2003-2004 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.