'\" t
.\"     Title: glGetCompressedTexImage
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/>
.\"      Date: 05/30/2012
.\"    Manual: [FIXME: manual]
.\"    Source: [FIXME: source]
.\"  Language: English
.\"
.TH "GLGETCOMPRESSEDTEXIM" "3G" "05/30/2012" "[FIXME: source]" "[FIXME: manual]"
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.SH "NAME"
glGetCompressedTexImage \- return a compressed texture image
.SH "C SPECIFICATION"
.HP \w'void\ glGetCompressedTexImage('u
.BI "void glGetCompressedTexImage(GLenum\ " "target" ", GLint\ " "lod" ", GLvoid\ *\ " "img" ");"
.SH "PARAMETERS"
.PP
\fItarget\fR
.RS 4
Specifies which texture is to be obtained\&.
\fBGL_TEXTURE_1D\fR,
\fBGL_TEXTURE_2D\fR,
\fBGL_TEXTURE_3D\fR,
\fBGL_TEXTURE_CUBE_MAP_POSITIVE_X\fR,
\fBGL_TEXTURE_CUBE_MAP_NEGATIVE_X\fR,
\fBGL_TEXTURE_CUBE_MAP_POSITIVE_Y\fR,
\fBGL_TEXTURE_CUBE_MAP_NEGATIVE_Y\fR,
\fBGL_TEXTURE_CUBE_MAP_POSITIVE_Z\fR, and
\fBGL_TEXTURE_CUBE_MAP_NEGATIVE_Z\fR
are accepted\&.
.RE
.PP
\fIlod\fR
.RS 4
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\&.
.RE
.PP
\fIimg\fR
.RS 4
Returns the compressed texture image\&.
.RE
.SH "DESCRIPTION"
.PP

\fBglGetCompressedTexImage\fR
returns the compressed texture image associated with
\fItarget\fR
and
\fIlod\fR
into
\fIimg\fR\&.
\fIimg\fR
should be an array of
\fBGL_TEXTURE_COMPRESSED_IMAGE_SIZE\fR
bytes\&.
\fItarget\fR
specifies whether the desired texture image was one specified by
\fBglTexImage1D\fR()
(\fBGL_TEXTURE_1D\fR),
\fBglTexImage2D\fR()
(\fBGL_TEXTURE_2D\fR
or any of
\fBGL_TEXTURE_CUBE_MAP_*\fR), or
\fBglTexImage3D\fR()
(\fBGL_TEXTURE_3D\fR)\&.
\fIlod\fR
specifies the level\-of\-detail number of the desired image\&.
.PP
If a non\-zero named buffer object is bound to the
\fBGL_PIXEL_PACK_BUFFER\fR
target (see
\fBglBindBuffer\fR()) while a texture image is requested,
\fIimg\fR
is treated as a byte offset into the buffer object\*(Aqs data store\&.
.PP
To minimize errors, first verify that the texture is compressed by calling
\fBglGetTexLevelParameter\fR()
with argument
\fBGL_TEXTURE_COMPRESSED\fR\&. If the texture is compressed, then determine the amount of memory required to store the compressed texture by calling
\fBglGetTexLevelParameter\fR()
with argument
\fBGL_TEXTURE_COMPRESSED_IMAGE_SIZE\fR\&. Finally, retrieve the internal format of the texture by calling
\fBglGetTexLevelParameter\fR()
with argument
\fBGL_TEXTURE_INTERNAL_FORMAT\fR\&. 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
\fItarget\fR
textures\&.
.SH "ERRORS"
.PP

\fBGL_INVALID_VALUE\fR
is generated if
\fIlod\fR
is less than zero or greater than the maximum number of LODs permitted by the implementation\&.
.PP

\fBGL_INVALID_OPERATION\fR
is generated if
\fBglGetCompressedTexImage\fR
is used to retrieve a texture that is in an uncompressed internal format\&.
.PP

\fBGL_INVALID_OPERATION\fR
is generated if a non\-zero buffer object name is bound to the
\fBGL_PIXEL_PACK_BUFFER\fR
target and the buffer object\*(Aqs data store is currently mapped\&.
.PP

\fBGL_INVALID_OPERATION\fR
is generated if a non\-zero buffer object name is bound to the
\fBGL_PIXEL_PACK_BUFFER\fR
target and the data would be packed to the buffer object such that the memory writes required would exceed the data store size\&.
.SH "ASSOCIATED GETS"
.PP

\fBglGetTexLevelParameter\fR()
with argument
\fBGL_TEXTURE_COMPRESSED\fR
.PP

\fBglGetTexLevelParameter\fR()
with argument
\fBGL_TEXTURE_COMPRESSED_IMAGE_SIZE\fR
.PP

\fBglGetTexLevelParameter\fR()
with argument
\fBGL_TEXTURE_INTERNAL_FORMAT\fR
.PP

\fBglGet\fR()
with argument
\fBGL_PIXEL_PACK_BUFFER_BINDING\fR
.SH "SEE ALSO"
.PP

\fBglActiveTexture\fR(),
\fBglCompressedTexImage1D\fR(),
\fBglCompressedTexImage2D\fR(),
\fBglCompressedTexImage3D\fR(),
\fBglCompressedTexSubImage1D\fR(),
\fBglCompressedTexSubImage2D\fR(),
\fBglCompressedTexSubImage3D\fR(),
\fBglReadPixels\fR(),
\fBglTexImage1D\fR(),
\fBglTexImage2D\fR(),
\fBglTexImage3D\fR(),
\fBglTexParameter\fR(),
\fBglTexSubImage1D\fR(),
\fBglTexSubImage2D\fR(),
\fBglTexSubImage3D\fR()
.SH "COPYRIGHT"
.PP
Copyright
\(co
1991\-2006 Silicon Graphics, Inc\&. This document is licensed under the SGI Free Software B License\&. For details, see
\m[blue]\fBhttp://oss\&.sgi\&.com/projects/FreeB/\fR\m[]\&.