1991-2006 Silicon Graphics, Inc.
glCompressedTexSubImage2D 3G
glCompressedTexSubImage2D specify a two-dimensional texture subimage in a compressed format

## 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 of the active texture unit. Must be `GL_TEXTURE_2D`, `GL_TEXTURE_CUBE_MAP_POSITIVE_X`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_X`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Y`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Y`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Z`, or `GL_TEXTURE_CUBE_MAP_NEGATIVE_Z`.

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.

width

  Specifies the width of the texture subimage.

height

  Specifies the height of the texture subimage.

format

  Specifies the format of the compressed image data stored at address data.

imageSize

  Specifies the number of unsigned bytes of image data starting at the address specified by data.

data

  Specifies a pointer to the compressed image data in memory.

## Description

Texturing maps a portion of a specified texture image onto each graphical primitive for which texturing is active. Texturing is active when the current fragment shader or vertex shader makes use of built-in texture lookup functions.

`glCompressedTexSubImage2D` redefines a contiguous subregion of an existing two-dimensional texture image. The texels referenced by data replace the portion of the existing texture array with x indices xoffset and xoffset + width - 1 , and the 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 width of 0, but such a specification has no effect.

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

## Notes

`glCompressedTexSubImage2D` specifies a two-dimensional or cube-map texture for the current texture unit, specified with glActiveTexture.

## Errors

`GL_INVALID_ENUM` is generated if target is not `GL_TEXTURE_2D`, `GL_TEXTURE_CUBE_MAP_POSITIVE_X`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_X`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Y`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Y`, `GL_TEXTURE_CUBE_MAP_POSITIVE_Z`, or `GL_TEXTURE_CUBE_MAP_NEGATIVE_Z`.

`GL_INVALID_ENUM` is generated if format is not a supported format returned in `GL_COMPRESSED_TEXTURE_FORMATS`.

`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` when target is `GL_TEXTURE_2D` or `GL_MAX_CUBE_MAP_TEXTURE_SIZE` when target is not `GL_TEXTURE_2D`.

`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_VALUE` is generated if imageSize is not consistent with the format, dimensions, and contents of the specified compressed image data.

`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` or `GL_MAX_CUBE_MAP_TEXTURE_SIZE`

## See Also

glActiveTexture, glCompressedTexImage2D, glCopyTexImage2D, glCopyTexSubImage2D, glTexImage2D, glTexSubImage2D, glTexParameter

## Copyright

Copyright 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.