2003-2004 Silicon Graphics, Inc.
glCompressedTexSubImage2D 3G
glCompressedTexSubImage2D specify a two-dimensional compressed texture subimage

## C Specification

void `glCompressedTexSubImage2D` GLenum target GLint level GLint xoffset GLint yoffset GLsizei width GLsizei height GLenum format GLsizei imageSize const GLvoid * data

## Parameters

target

  Specifies the target texture. Must be `GL_TEXTURE_2D`.

level

  Specifies the level-of-detail number.

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.

width

  Specifies the width of the texture subimage.

height

  Specifies the height of the texture subimage.

format

  Specifies the format of the pixel data. Currently, there is no supported format.

imageSize

  Specifies the size of the compressed pixel data in bytes.

data

  Specifies a pointer to the compressed image data in memory.

## Description

`glCompressedTexSubImage2D` redefines a contiguous subregion of an existing two-dimensional compressed texture image. The texels referenced by pixels replace the portion of the existing texture array with x indices xoffset and xoffset+width-1 , inclusive, and y indices yoffset and yoffset+height-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 or height, but such a specification has no effect.

format must be the same compressed-texture format previously specified by glCompressedTexImage2D.

The required paletted formats do not allow subimage updates, but other formats defined by extensions may.

## Notes

glPixelStorei has no effect on compressed texture images.

`glCompressedTexSubImage2D` specifies the two-dimensional sub texture for the currently bound texture, specified with glBindTexture, and the current texture unit, specified with glActiveTexture.

## Errors

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

`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 width and h is the height of the texture image being modified.

`GL_INVALID_VALUE` is generated if width or height is less than 0.

`GL_INVALID_OPERATION` is generated if the texture array has not been defined by a previous glCompressedTexImage2D operation whose internalformat matches the format of `glCompressedTexSubImage2D`.

`GL_INVALID_OPERATION` is generated if parameter combinations are not supported by the specific compressed internal format as specified in the specific texture compression extension.

Undefined results, including abnormal program termination, are generated if data is not encoded in a manner consistent with the extension specification defining the internal compression format.

## Associated Gets

glGet with arguments `GL_NUM_COMPRESSED_TEXTURE_FORMATS` and `GL_COMPRESSED_TEXTURE_FORMATS`

glGet with argument `GL_MAX_TEXTURE_SIZE`

## See Also

glActiveTexture, glBindTexture, glCompressedTexImage2D, glCopyTexSubImage2D, glGet, glPixelStorei, glTexEnv, glTexParameter

## 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/.