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 ⁢ 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/.