## Name

glCompressedTexSubImage2D, glCompressedTextureSubImage2D — 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`)`;

`void glCompressedTextureSubImage2D(` | GLuint texture,
| GLint level,
| GLint xoffset,
| GLint yoffset,
| GLsizei width,
| GLsizei height,
| GLenum format,
| GLsizei imageSize,
| const void *data`)`;

## Parameters

`target`

  Specifies the target to which the texture is bound for `glCompressedTexSubImage2D` function. Must be `GL_TEXTURE_1D_ARRAY`, `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`.

`texture`

  Specifies the texture object name for `glCompressedTextureSubImage2D` function.

`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 allows elements of an image array to be read by shaders.

`glCompressedTexSubImage2D` and `glCompressedTextureSubImage2D` redefine 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.

`internalformat` must be a known compressed image format (such as `GL_RGTC`) or 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.

## Errors

`GL_INVALID_ENUM` is generated if `internalformat` is of the generic compressed internal formats: `GL_COMPRESSED_RED`, `GL_COMPRESSED_RG`, `GL_COMPRESSED_RGB`, `GL_COMPRESSED_RGBA`. `GL_COMPRESSED_SRGB`, or `GL_COMPRESSED_SRGB_ALPHA`.

`GL_INVALID_ENUM` is generated by `glCompressedTexSubImage2D` if `target` is `GL_TEXTURE_RECTANGLE` or `GL_PROXY_TEXTURE_RECTANGLE`.

`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 by `glCompressedTextureSubImage2D` if `texture` is not the name of an existing texture object.

`GL_INVALID_OPERATION` is generated by `glCompressedTextureSubImage2D` if the effective target is `GL_TEXTURE_RECTANGLE`.

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`

## Version Support

| OpenGL Version
--- | ---
Function / Feature Name | 2.0 | 2.1 | 3.0 | 3.1 | 3.2 | 3.3 | 4.0 | 4.1 | 4.2 | 4.3 | 4.4 | 4.5
`glCompressedTexSubImage2D` | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔ | ✔
`glCompressedTextureSubImage2D` | - | - | - | - | - | - | - | - | - | - | - | ✔

## See Also

glActiveTexture, glCompressedTexImage1D, glCompressedTexImage2D, glCompressedTexImage3D, glCompressedTexSubImage1D, glCompressedTexSubImage3D, glCopyTexImage1D, glCopyTexImage2D, glCopyTexSubImage1D, glCopyTexSubImage2D, glCopyTexSubImage3D, glPixelStore, glTexImage2D, glTexImage3D, glTexSubImage1D, glTexSubImage2D, glTexSubImage3D, glTexParameter

## Copyright

Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.