glGetCompressedTexImage man page on Darwin
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GLGETCOMPRESSEDTEXIM(3G) OpenGL 3.3 GLGETCOMPRESSEDTEXIM(3G)
NAME
glGetCompressedTexImage - return a compressed texture image
C SPECIFICATION
void glGetCompressedTexImage(GLenum target, GLint lod, GLvoid * img);
PARAMETERS
target
Specifies which texture is to be obtained. GL_TEXTURE_1D,
GL_TEXTURE_2D, GL_TEXTURE_3D, 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 are accepted.
lod
Specifies the level-of-detail number of the desired image. Level 0
is the base image level. Level n is the nth mipmap reduction image.
img
Returns the compressed texture image.
DESCRIPTION
glGetCompressedTexImage returns the compressed texture image associated
with target and lod into img. img should be an array of
GL_TEXTURE_COMPRESSED_IMAGE_SIZE bytes. target specifies whether the
desired texture image was one specified by glTexImage1D()
(GL_TEXTURE_1D), glTexImage2D() (GL_TEXTURE_2D or any of
GL_TEXTURE_CUBE_MAP_*), or glTexImage3D() (GL_TEXTURE_3D). 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, img 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, then 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_VALUE is generated if lod is less than zero or greater than
the maximum number of LODs permitted by the implementation.
GL_INVALID_OPERATION is generated if glGetCompressedTexImage 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 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
SEE ALSO
glActiveTexture(), glCompressedTexImage1D(), glCompressedTexImage2D(),
glCompressedTexImage3D(), glCompressedTexSubImage1D(),
glCompressedTexSubImage2D(), glCompressedTexSubImage3D(),
glReadPixels(), glTexImage1D(), glTexImage2D(), glTexImage3D(),
glTexParameter(), glTexSubImage1D(), glTexSubImage2D(),
glTexSubImage3D()
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/.
OpenGL 3.3 03/08/2011 GLGETCOMPRESSEDTEXIM(3G)
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