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)