Provided by: opengl-4-man-doc_1.0~svn33624-1_all 
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 │
├─────────────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
│ Function │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
│ / │ │ │ │ │ │ │ │ │ │ │ │ │
│ 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)