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NAME

       glGetCompressedTexImage, glGetnCompressedTexImage, glGetCompressedTextureImage - return a
       compressed texture image

C SPECIFICATION

       void glGetCompressedTexImage(GLenum target, GLint level, GLvoid * pixels);

       void glGetnCompressedTexImage(GLenum target, GLint level, GLsizei bufSize, void *pixels);

       void glGetCompressedTextureImage(GLuint texture, GLint level, GLsizei bufSize,
                                        void *pixels);

PARAMETERS

       target
           Specifies the target to which the texture is bound for glGetCompressedTexImage and
           glGetnCompressedTexImage functions.  GL_TEXTURE_1D, GL_TEXTURE_1D_ARRAY,
           GL_TEXTURE_2D, GL_TEXTURE_2D_ARRAY, GL_TEXTURE_3D, GL_TEXTURE_CUBE_MAP_ARRAY,
           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, and GL_TEXTURE_CUBE_MAP_NEGATIVE_Z,
           GL_TEXTURE_RECTANGLE are accepted.

       texture
           Specifies the texture object name for glGetCompressedTextureImage function.

       level
           Specifies the level-of-detail number of the desired image. Level 0 is the base image
           level. Level $n$ is the $n$-th mipmap reduction image.

       bufSize
           Specifies the size of the buffer pixels for glGetCompressedTextureImage and
           glGetnCompressedTexImage functions.

       pixels
           Returns the compressed texture image.

DESCRIPTION

       glGetCompressedTexImage and glGetnCompressedTexImage return the compressed texture image
       associated with target and lod into pixels.  glGetCompressedTextureImage serves the same
       purpose, but instead of taking a texture target, it takes the ID of the texture object.
       pixels should be an array of bufSize bytes for glGetnCompresedTexImage and
       glGetCompressedTextureImage functions, and of GL_TEXTURE_COMPRESSED_IMAGE_SIZE bytes in
       case of glGetCompressedTexImage. If the actual data takes less space than bufSize, the
       remaining bytes will not be touched.  target specifies the texture target, to which the
       texture the data the function should extract the data from is bound to.  lod specifies the
       level-of-detail number of the desired image.

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

       To minimize errors, first verify that the texture is compressed by calling
       glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED. If the texture is
       compressed, you can determine the amount of memory required to store the compressed
       texture by calling glGetTexLevelParameter() with argument
       GL_TEXTURE_COMPRESSED_IMAGE_SIZE. Finally, retrieve the internal format of the texture by
       calling glGetTexLevelParameter() with argument GL_TEXTURE_INTERNAL_FORMAT. To store the
       texture for later use, associate the internal format and size with the retrieved texture
       image. These data can be used by the respective texture or subtexture loading routine used
       for loading target textures.

ERRORS

       GL_INVALID_OPERATION is generated by glGetCompressedTextureImage if texture is not the
       name of an existing texture object.

       GL_INVALID_VALUE is generated if level is less than zero or greater than the maximum
       number of LODs permitted by the implementation.

       GL_INVALID_OPERATION is generated if glGetCompressedTexImage, glGetnCompressedTexImage,
       and glGetCompressedTextureImage is used to retrieve a texture that is in an uncompressed
       internal format.

       GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to the
       GL_PIXEL_PACK_BUFFER target, the buffer storage was not initialized with glBufferStorage
       using GL_MAP_PERSISTENT_BIT flag, 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_PACK_BUFFER target and the data would be packed to the buffer object such that
       the memory writes required would exceed the data store size.

ASSOCIATED GETS

       glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED

       glGetTexLevelParameter() with argument GL_TEXTURE_COMPRESSED_IMAGE_SIZE

       glGetTexLevelParameter() with argument GL_TEXTURE_INTERNAL_FORMAT

       glGet() with argument GL_PIXEL_PACK_BUFFER_BINDING

VERSION SUPPORT

       ┌────────────────────────────┬───────────────────────────────────────────────────────────────────────┐
       │                            │                OpenGL Version                                         │
       ├────────────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │Function2.02.13.03.13.23.34.04.14.24.34.44.5 │
       │/                           │     │     │     │     │     │     │     │     │     │     │     │     │
       │Feature                     │     │     │     │     │     │     │     │     │     │     │     │     │
       │Name                        │     │     │     │     │     │     │     │     │     │     │     │     │
       ├────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │glGetCompressedTexImage     │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       ├────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │glGetCompressedTextureImage │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  ✔  │
       ├────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │glGetnCompressedTexImage    │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  ✔  │
       └────────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘

SEE ALSO

       glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage2D(),
       glCompressedTexImage3D(), glCompressedTexSubImage1D(), glCompressedTexSubImage2D(),
       glCompressedTexSubImage3D(), glReadPixels(), glTexImage1D(), glTexImage2D(),
       glTexImage3D(), glTexParameter(), glTexSubImage1D(), glTexSubImage2D(), glTexSubImage3D()

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://opencontent.org/openpub/.

COPYRIGHT

       Copyright © 1991-2006 Silicon Graphics, Inc.
       Copyright © 2010-2014 Khronos Group

[FIXME: source]                             01/03/2018                   GLGETCOMPRESSEDTEXIM(3G)