1991-2006
Silicon Graphics, Inc.
glCompressedTexImage2D
3G

# glCompressedTexImage2D

specify a two-dimensional texture image in a compressed format

## C Specification

                    void glCompressedTexImage2D
                    GLenum target
                    GLint level
                    GLenum internalformat
                    GLsizei width
                    GLsizei height
                    GLint border
                    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.

`internalformat`

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

`width`

  Specifies the width of the texture image. All implementations support 2D texture images that are at least 64 texels wide and cube-mapped texture images that are at least 16 texels wide.

`height`

  Specifies the height of the texture image. All implementations support 2D texture images that are at least 64 texels high and cube-mapped texture images that are at least 16 texels high.

`border`

  Specifies the width of the border. Must be 0.

`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.

`glCompressedTexImage2D` defines a two-dimensional texture image or cube-map texture image using compressed image data from client memory. The texture image is decoded according to the extension specification defining the specified `internalformat`. OpenGL ES defines no specific compressed texture formats, but does provide a mechanism to obtain symbolic constants for such formats provided by extensions. The number of compressed texture formats supported can be obtained by querying the value of `GL_NUM_COMPRESSED_TEXTURE_FORMATS`. The list of specific compressed texture formats supported can be obtained by querying the value of `GL_COMPRESSED_TEXTURE_FORMATS`.

## Notes

A GL implementation may choose to store the texture array at any internal resolution it chooses.

`glCompressedTexImage2D` 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 `internalformat` 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 &it; 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 `width` or `height` is less than 0 or greater than `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 `border` is not 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 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, glCompressedTexSubImage2D, 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/.