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<refentry id= "glCompressedTexImage1D" >
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<refentryinfo >
<copyright >
<year > 1991-2006</year>
<holder > Silicon Graphics, Inc.</holder>
</copyright>
<copyright >
<year > 2011-2013</year>
<holder > Khronos Group</holder>
</copyright>
</refentryinfo>
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<refmeta >
<refentrytitle > glCompressedTexImage1D</refentrytitle>
<manvolnum > 3G</manvolnum>
</refmeta>
<refnamediv >
<refname > glCompressedTexImage1D</refname>
<refpurpose > specify a one-dimensional texture image in a compressed format</refpurpose>
</refnamediv>
<refsynopsisdiv > <title > C Specification</title>
<funcsynopsis >
<funcprototype >
<funcdef > void <function > glCompressedTexImage1D</function> </funcdef>
<paramdef > GLenum <parameter > target</parameter> </paramdef>
<paramdef > GLint <parameter > level</parameter> </paramdef>
<paramdef > GLenum <parameter > internalformat</parameter> </paramdef>
<paramdef > GLsizei <parameter > width</parameter> </paramdef>
<paramdef > GLint <parameter > border</parameter> </paramdef>
<paramdef > GLsizei <parameter > imageSize</parameter> </paramdef>
<paramdef > const GLvoid * <parameter > data</parameter> </paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id= "parameters" > <title > Parameters</title>
<variablelist >
<varlistentry >
<term > <parameter > target</parameter> </term>
<listitem >
<para >
Specifies the target texture.
Must be <constant > GL_TEXTURE_1D</constant> or <constant > GL_PROXY_TEXTURE_1D</constant> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > level</parameter> </term>
<listitem >
<para >
Specifies the level-of-detail number.
Level 0 is the base image level.
Level <emphasis > n</emphasis> is the <emphasis > n</emphasis> th mipmap reduction image.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > internalformat</parameter> </term>
<listitem >
<para >
Specifies the format of the compressed image data stored at address <parameter > data</parameter> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > width</parameter> </term>
<listitem >
<para >
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Specifies the width of the texture image.
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All implementations support texture images that are at least 64 texels wide. The height of the 1D texture image is 1.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > border</parameter> </term>
<listitem >
<para >
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This value must be 0.
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</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > imageSize</parameter> </term>
<listitem >
<para >
Specifies the number of unsigned bytes of image data starting at the address specified by <parameter > data</parameter> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > data</parameter> </term>
<listitem >
<para >
Specifies a pointer to the compressed image data in memory.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id= "description" > <title > Description</title>
<para >
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Texturing allows elements of an image array to be read by shaders.
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</para>
<para >
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<function > glCompressedTexImage1D</function> loads a previously defined, and retrieved, compressed
one-dimensional texture image if <parameter > target</parameter> is <constant > GL_TEXTURE_1D</constant>
(see <citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> ).
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</para>
<para >
If <parameter > target</parameter> is <constant > GL_PROXY_TEXTURE_1D</constant> , no data is read from <parameter > data</parameter> , but
all of the texture image state is recalculated, checked for consistency, and checked against the implementation's capabilities. If the implementation cannot handle a texture of the requested texture size, it sets all of the image state to 0, but does not generate an error (see <citerefentry > <refentrytitle > glGetError</refentrytitle> </citerefentry> ). To query for an entire mipmap array, use an image array level greater than or equal to 1.
</para>
<para >
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<parameter > internalformat</parameter> must be an extension-specified compressed-texture format.
When a texture is loaded with
<citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> using a generic compressed texture format
(e.g., <constant > GL_COMPRESSED_RGB</constant> ) the GL selects from one of
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its extensions supporting compressed textures. In order to load the
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compressed texture image using <function > glCompressedTexImage1D</function> , query the compressed texture image's size and
format using <citerefentry > <refentrytitle > glGetTexLevelParameter</refentrytitle> </citerefentry> .
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</para>
<para >
If a non-zero named buffer object is bound to the <constant > GL_PIXEL_UNPACK_BUFFER</constant> target
(see <citerefentry > <refentrytitle > glBindBuffer</refentrytitle> </citerefentry> ) while a texture image is
specified, <parameter > data</parameter> is treated as a byte offset into the buffer object's data store.
</para>
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<para >
If the compressed data are arranged into fixed-size blocks of texels, the pixel
storage modes can be used to select a sub-rectangle from a larger containing rectangle.
These pixel storage modes operate in the same way as they do for <citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> .
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In the following description, denote by
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > s</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation> ,
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > w</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation> ,
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > h</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation> , and
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > d</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
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the values of pixel storage modes <constant > GL_UNPACK_COMPRESSED_BLOCK_SIZE</constant> ,
<constant > GL_UNPACK_COMPRESSED_BLOCK_WIDTH</constant> , <constant > GL_UNPACK_COMPRESSED_BLOCK_HEIGHT</constant> ,
and <constant > GL_UNPACK_COMPRESSED_BLOCK_DEPTH</constant> , respectively.
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<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > s</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
is the compressed block size in bytes;
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > w</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation> ,
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > h</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation> , and
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > d</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
are the compressed block width, height, and depth in pixels.
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</para>
<para >
By default the pixel storage modes <constant > GL_UNPACK_ROW_LENGTH</constant> ,
<constant > GL_UNPACK_SKIP_ROWS</constant> , <constant > GL_UNPACK_SKIP_PIXELS</constant> ,
<constant > GL_UNPACK_IMAGE_HEIGHT</constant> and <constant > GL_UNPACK_SKIP_IMAGES</constant>
are ignored for compressed images. To enable <constant > GL_UNPACK_SKIP_PIXELS</constant>
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and <constant > GL_UNPACK_ROW_LENGTH</constant> ,
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > s</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
and
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > w</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
must both be non-zero.
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To also enable <constant > GL_UNPACK_SKIP_ROWS</constant> and <constant > GL_UNPACK_IMAGE_HEIGHT</constant> ,
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<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > h</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
must be non-zero.
To also enable <constant > GL_UNPACK_SKIP_IMAGES</constant> ,
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > d</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
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must be non-zero. All parameters must be consistent with the compressed format to produce the desired results.
</para>
<para >
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When selecting a sub-rectangle from a compressed image,
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<itemizedlist >
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<listitem >
<para >
the value of <constant > GL_UNPACK_SKIP_PIXELS</constant> must be a multiple of
<inlineequation >
<mml:math > <mml:mrow > <mml:msub > <mml:mi > b</mml:mi> <mml:mi > w</mml:mi> </mml:msub> </mml:mrow> </mml:math>
</inlineequation>
</para>
</listitem>
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</itemizedlist>
</para>
<para >
<parameter > imageSize</parameter> must be equal to:
</para>
<para >
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<inlineequation >
<mml:math display = 'block' >
<mml:mrow >
<mml:msub >
<mml:mi > b</mml:mi>
<mml:mi > s</mml:mi>
</mml:msub>
<mml:mo lspace= '2px' rspace= '2px' > × </mml:mo>
<mml:mfenced open = '⌈' close = '⌉' >
<mml:mfrac >
<mml:mi > width</mml:mi>
<mml:msub >
<mml:mi > b</mml:mi>
<mml:mi > w</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math>
</inlineequation>
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</para>
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</refsect1>
<refsect1 id= "errors" > <title > Errors</title>
<para >
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<constant > GL_INVALID_ENUM</constant> is generated if <parameter > internalformat</parameter> is not
a supported specific compressed internal formats, or is one of the generic
compressed internal formats:
<constant > GL_COMPRESSED_RED</constant> ,
<constant > GL_COMPRESSED_RG</constant> ,
<constant > GL_COMPRESSED_RGB</constant> ,
<constant > GL_COMPRESSED_RGBA</constant> .
<constant > GL_COMPRESSED_SRGB</constant> , or
<constant > GL_COMPRESSED_SRGB_ALPHA</constant> .
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</para>
<para >
<constant > GL_INVALID_VALUE</constant> is generated if <parameter > imageSize</parameter> is not consistent with
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the format, dimensions, and contents of the specified compressed image data.
</para>
<para >
<constant > GL_INVALID_VALUE</constant> is generated if <parameter > border</parameter> is not 0.
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</para>
<para >
<constant > GL_INVALID_OPERATION</constant> is generated if parameter combinations are not
supported by the specific compressed internal format as specified in the
specific texture compression extension.
</para>
<para >
<constant > GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
<constant > GL_PIXEL_UNPACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
</para>
<para >
<constant > GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
<constant > GL_PIXEL_UNPACK_BUFFER</constant> target and the data would be unpacked from the buffer
object such that the memory reads required would exceed the data store size.
</para>
<para >
Undefined results, including abnormal program termination, are generated if
<parameter > data</parameter> is not encoded in a manner consistent with the extension
specification defining the internal compression format.
</para>
</refsect1>
<refsect1 id= "associatedgets" > <title > Associated Gets</title>
<para >
<citerefentry > <refentrytitle > glGetCompressedTexImage</refentrytitle> </citerefentry>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_TEXTURE_COMPRESSED</constant>
</para>
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<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_NUM_COMPRESSED_TEXTURE_FORMATS</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_COMPRESSED_TEXTURE_FORMATS</constant>
</para>
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<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGetTexLevelParameter</refentrytitle> </citerefentry> with arguments <constant > GL_TEXTURE_INTERNAL_FORMAT</constant>
and <constant > GL_TEXTURE_COMPRESSED_IMAGE_SIZE</constant>
</para>
</refsect1>
<refsect1 id= "seealso" > <title > See Also</title>
<para >
<citerefentry > <refentrytitle > glActiveTexture</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCopyTexImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCopyTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCopyTexSubImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCopyTexSubImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCopyTexSubImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glPixelStore</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexSubImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexSubImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexSubImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexParameter</refentrytitle> </citerefentry>
</para>
</refsect1>
<refsect1 id= "Copyright" > <title > Copyright</title>
<para >
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Copyright <trademark class= "copyright" > </trademark> 1991-2006 Silicon Graphics, Inc.
Copyright <trademark class= "copyright" > </trademark> 2011-2013 Khronos Group.
This document is licensed under the SGI
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Free Software B License. For details, see
<ulink url= "http://oss.sgi.com/projects/FreeB/" > http://oss.sgi.com/projects/FreeB/</ulink> .
</para>
</refsect1>
</refentry>
