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. 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 enabled. To enable and disable two-dimensional texturing, call glEnable and glDisable with argument `GL_TEXTURE_2D`. To enable and disable texturing using cube-mapped texture, call glEnable and glDisable with argument `GL_TEXTURE_CUBE_MAP`.

`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 an extension-specified compressed-texture format. The `format` of the compressed texture image is selected by the GL implementation that compressed it (see glTexImage2D) and should be queried at the time the texture was compressed with glGetTexLevelParameter.

If a non-zero named buffer object is bound to the `GL_PIXEL_UNPACK_BUFFER` target (see glBindBuffer) while a texture image is specified, `data` is treated as a byte offset into the buffer object's data store.

## Notes

`glCompressedTexSubImage2D` is available only if the GL version is 1.3 or greater.

`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`, `GL_TEXTURE_CUBE_MAP_NEGATIVE_Z`, or `GL_PROXY_TEXTURE_CUBE_MAP` are available only if the GL version is 1.3 or greater.

## Errors

`GL_INVALID_ENUM` is generated if `format` is one of these generic compressed internal formats: `GL_COMPRESSED_ALPHA`, `GL_COMPRESSED_LUMINANCE`, `GL_COMPRESSED_LUMINANCE_ALPHA`, `GL_COMPRESSED_INTENSITY`, `GL_COMPRESSED_RGB`, `GL_COMPRESSED_RGBA`, `GL_COMPRESSED_SLUMINANCE`, `GL_COMPRESSED_SLUMINANCE_ALPHA`, `GL_COMPRESSED_SRGB`, `GL_COMPRESSED_SRGBA`, or `GL_COMPRESSED_SRGB_ALPHA`.

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

`GL_INVALID_OPERATION` is generated if a non-zero buffer object name is bound to the `GL_PIXEL_UNPACK_BUFFER` target and the buffer object's data store is currently mapped.

`GL_INVALID_OPERATION` is generated if a non-zero buffer object name is bound to the `GL_PIXEL_UNPACK_BUFFER` target and the data would be unpacked from the buffer object such that the memory reads required would exceed the data store size.

`GL_INVALID_OPERATION` is generated if `glCompressedTexSubImage2D` is executed between the execution of glBegin and the corresponding execution of glEnd.

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

glGetCompressedTexImage

glGet with argument `GL_TEXTURE_COMPRESSED`

glGet with argument `GL_PIXEL_UNPACK_BUFFER_BINDING`

glGetTexLevelParameter with arguments `GL_TEXTURE_INTERNAL_FORMAT` and `GL_TEXTURE_COMPRESSED_IMAGE_SIZE`

glIsEnabled with argument `GL_TEXTURE_2D` or `GL_TEXTURE_CUBE_MAP`

## See Also

glActiveTexture, glColorTable, glCompressedTexImage1D, glCompressedTexImage2D, glCompressedTexImage3D, glCompressedTexSubImage1D, glCompressedTexSubImage3D, glConvolutionFilter1D, glCopyPixels, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glDrawPixels, glMatrixMode, glPixelStore, glPixelTransfer, glTexEnv, glTexGen, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D, 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/.