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<?xml version="1.0" encoding="UTF-8"?>
< !DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
<refentry id= "glPixelStore" >
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<refentryinfo >
<copyright >
<year > 1991-2006</year>
<holder > Silicon Graphics, Inc.</holder>
</copyright>
<copyright >
<year > 2010-2013</year>
<holder > Khronos Group</holder>
</copyright>
</refentryinfo>
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<refmeta >
<refentrytitle > glPixelStore</refentrytitle>
<manvolnum > 3G</manvolnum>
</refmeta>
<refnamediv >
<refname > glPixelStore</refname>
<refpurpose > set pixel storage modes</refpurpose>
</refnamediv>
<refsynopsisdiv > <title > C Specification</title>
<funcsynopsis >
<funcprototype >
<funcdef > void <function > glPixelStoref</function> </funcdef>
<paramdef > GLenum <parameter > pname</parameter> </paramdef>
<paramdef > GLfloat <parameter > param</parameter> </paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis >
<funcprototype >
<funcdef > void <function > glPixelStorei</function> </funcdef>
<paramdef > GLenum <parameter > pname</parameter> </paramdef>
<paramdef > GLint <parameter > param</parameter> </paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id= "parameters" > <title > Parameters</title>
<variablelist >
<varlistentry >
<term > <parameter > pname</parameter> </term>
<listitem >
<para >
Specifies the symbolic name of the parameter to be set.
Six values affect the packing of pixel data into memory:
<constant > GL_PACK_SWAP_BYTES</constant> ,
<constant > GL_PACK_LSB_FIRST</constant> ,
<constant > GL_PACK_ROW_LENGTH</constant> ,
<constant > GL_PACK_IMAGE_HEIGHT</constant> ,
<constant > GL_PACK_SKIP_PIXELS</constant> ,
<constant > GL_PACK_SKIP_ROWS</constant> ,
<constant > GL_PACK_SKIP_IMAGES</constant> , and
<constant > GL_PACK_ALIGNMENT</constant> .
Six more affect the unpacking of pixel data <emphasis > from</emphasis> memory:
<constant > GL_UNPACK_SWAP_BYTES</constant> ,
<constant > GL_UNPACK_LSB_FIRST</constant> ,
<constant > GL_UNPACK_ROW_LENGTH</constant> ,
<constant > GL_UNPACK_IMAGE_HEIGHT</constant> ,
<constant > GL_UNPACK_SKIP_PIXELS</constant> ,
<constant > GL_UNPACK_SKIP_ROWS</constant> ,
<constant > GL_UNPACK_SKIP_IMAGES</constant> , and
<constant > GL_UNPACK_ALIGNMENT</constant> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > param</parameter> </term>
<listitem >
<para >
Specifies the value that <parameter > pname</parameter> is set to.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id= "description" > <title > Description</title>
<para >
<function > glPixelStore</function> sets pixel storage modes that affect the operation of subsequent
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<citerefentry > <refentrytitle > glReadPixels</refentrytitle> </citerefentry> as well as the unpacking of
texture patterns (see <citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> ,
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<citerefentry > <refentrytitle > glTexImage2D</refentrytitle> </citerefentry> , <citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> , <citerefentry > <refentrytitle > glTexSubImage1D</refentrytitle> </citerefentry> ,
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<citerefentry > <refentrytitle > glTexSubImage2D</refentrytitle> </citerefentry> , <citerefentry > <refentrytitle > glTexSubImage3D</refentrytitle> </citerefentry> ),
<citerefentry > <refentrytitle > glCompressedTexImage1D</refentrytitle> </citerefentry> , <citerefentry > <refentrytitle > glCompressedTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexImage3D</refentrytitle> </citerefentry> , <citerefentry > <refentrytitle > glCompressedTexSubImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage2D</refentrytitle> </citerefentry> or <citerefentry > <refentrytitle > glCompressedTexSubImage1D</refentrytitle> </citerefentry> .
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</para>
<para >
<parameter > pname</parameter> is a symbolic constant indicating the parameter to be set, and
<parameter > param</parameter> is the new value. Six of the twelve storage parameters affect
how pixel data is returned to client memory.
They are as follows:
</para>
<variablelist >
<varlistentry >
<term > <constant > GL_PACK_SWAP_BYTES</constant> </term>
<listitem >
<para >
If true,
byte ordering for multibyte color components,
depth components,
or stencil indices
is reversed.
That is,
if a four-byte component consists of bytes
<inlineequation > <mml:math >
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<!-- eqn: b sub 0: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 0</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 1: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 1</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 2: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 2</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 3: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 3</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
it is stored in memory as
<inlineequation > <mml:math >
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<!-- eqn: b sub 3: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 3</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 2: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 2</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 1: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 1</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 0: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 0</mml:mn>
</mml:msub>
</mml:math> </inlineequation>
if <constant > GL_PACK_SWAP_BYTES</constant> is true.
<constant > GL_PACK_SWAP_BYTES</constant> has no effect on the memory order of components
within a pixel,
only on the order of bytes within components or indices.
For example,
the three components of a <constant > GL_RGB</constant> format pixel are always stored with
red first,
green second,
and blue third,
regardless of the value of <constant > GL_PACK_SWAP_BYTES</constant> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_PACK_LSB_FIRST</constant> </term>
<listitem >
<para >
If true,
bits are ordered within a byte from least significant to most significant;
otherwise,
the first bit in each byte is the most significant one.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_PACK_ROW_LENGTH</constant> </term>
<listitem >
<para >
If greater than 0,
<constant > GL_PACK_ROW_LENGTH</constant> defines the number of pixels in a row.
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If the first pixel of a row is placed at location
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > p</mml:mi> </mml:math> </inlineequation>
in memory,
then the location of the first pixel of the next row is obtained by skipping
</para>
<para >
<informalequation > <mml:math >
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<!-- eqn: k = left { lpile { n l above {a over s} left ceiling { s n l } over a right ceiling} lpile {s >= a above s < a }: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > =</mml:mo>
<mml:mfenced open= "{" close= "" >
<mml:mrow >
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mfenced open= "" close= "" >
<mml:mfrac >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mfrac>
</mml:mfenced>
<mml:mo > ⁢ </mml:mo>
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<mml:mfenced open= "⌈" close= "⌉" >
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<mml:mfrac >
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
</mml:mrow>
</mml:mfenced>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
<mml:mo > ⁢ </mml:mo>
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > > =</mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:math> </informalequation>
</para>
<para >
components or indices,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > n</mml:mi> </mml:math> </inlineequation>
is the number of components or indices in a pixel,
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > l</mml:mi> </mml:math> </inlineequation>
is the number of pixels in a row
(<constant > GL_PACK_ROW_LENGTH</constant> if it is greater than 0,
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the
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > width</mml:mi> </mml:math> </inlineequation>
argument to the pixel routine otherwise),
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > a</mml:mi> </mml:math> </inlineequation>
is the value of <constant > GL_PACK_ALIGNMENT</constant> , and
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > s</mml:mi> </mml:math> </inlineequation>
is the size, in bytes, of a single component
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(if
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<inlineequation > <mml:math >
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<!-- eqn: a < s: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ,
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then it is as if
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<inlineequation > <mml:math >
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<!-- eqn: a = s: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > =</mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ).
In the case of 1-bit values,
the location of the next row is obtained by skipping
</para>
<para >
<inlineequation > <mml:math >
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<!-- eqn: k = 8 a left ceiling { n l } over { 8 a } right ceiling: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mn > 8</mml:mn>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > ⁢ </mml:mo>
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<mml:mfenced open= "⌈" close= "⌉" >
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<mml:mfrac >
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
</mml:mrow>
</mml:mfenced>
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mn > 8</mml:mn>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mfenced>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
</para>
<para >
components or indices.
</para>
<para >
The word <emphasis > component</emphasis> in this description refers to the nonindex values
red,
green,
blue,
alpha,
and depth.
Storage format <constant > GL_RGB</constant> ,
for example,
has three components per pixel:
first red,
then green,
and finally blue.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_PACK_IMAGE_HEIGHT</constant> </term>
<listitem >
<para >
If greater than 0,
<constant > GL_PACK_IMAGE_HEIGHT</constant> defines the number of pixels in an image
three-dimensional texture volume, where ``image'' is defined by all pixels
sharing the same third dimension index.
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If the first pixel of a row is placed at location
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > p</mml:mi> </mml:math> </inlineequation>
in memory,
then the location of the first pixel of the next row is obtained by skipping
</para>
<para >
<informalequation > <mml:math >
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<!-- eqn: k = left { lpile { n l h above {a over s} left ceiling { s n l h } over a right ceiling} lpile {s >= a above s < a }: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > =</mml:mo>
<mml:mfenced open= "{" close= "" >
<mml:mrow >
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > h</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mfenced open= "" close= "" >
<mml:mfrac >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mfrac>
</mml:mfenced>
<mml:mo > ⁢ </mml:mo>
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<mml:mfenced open= "⌈" close= "⌉" >
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<mml:mfrac >
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > h</mml:mi>
</mml:mrow>
</mml:mfenced>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
<mml:mo > ⁢ </mml:mo>
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > > =</mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:math> </informalequation>
</para>
<para >
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components or indices, where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > n</mml:mi> </mml:math> </inlineequation>
is the number of components or indices
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in a pixel,
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > l</mml:mi> </mml:math> </inlineequation>
is the number of pixels in a row
(<constant > GL_PACK_ROW_LENGTH</constant> if it is greater than 0, the
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > width</mml:mi> </mml:math> </inlineequation>
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argument to <citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> otherwise),
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > h</mml:mi> </mml:math> </inlineequation>
is the number of
rows in a pixel image (<constant > GL_PACK_IMAGE_HEIGHT</constant> if it is greater than
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0, the
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > height</mml:mi> </mml:math> </inlineequation>
argument to the <citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> routine otherwise),
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > a</mml:mi> </mml:math> </inlineequation>
is the value of
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<constant > GL_PACK_ALIGNMENT</constant> , and
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > s</mml:mi> </mml:math> </inlineequation>
is the size, in bytes, of a single
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component (if
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<inlineequation > <mml:math >
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<!-- eqn: a < s: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ,
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then it is as if
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<inlineequation > <mml:math >
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<!-- eqn: a = s: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > =</mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ).
</para>
<para >
The word <emphasis > component</emphasis> in this description refers to the nonindex values
red,
green,
blue,
alpha,
and depth.
Storage format <constant > GL_RGB</constant> ,
for example,
has three components per pixel:
first red,
then green,
and finally blue.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_PACK_SKIP_PIXELS</constant> , <constant > GL_PACK_SKIP_ROWS</constant> , and <constant > GL_PACK_SKIP_IMAGES</constant> </term>
<listitem >
<para >
These values are provided as a convenience to the programmer;
they provide no functionality that cannot be duplicated simply by
incrementing the pointer passed to <citerefentry > <refentrytitle > glReadPixels</refentrytitle> </citerefentry> .
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Setting <constant > GL_PACK_SKIP_PIXELS</constant> to
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > i</mml:mi> </mml:math> </inlineequation>
is equivalent to incrementing
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the pointer by
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<inlineequation > <mml:math >
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<!-- eqn: i n: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > i</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > n</mml:mi>
</mml:mrow>
</mml:math> </inlineequation>
components or indices,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > n</mml:mi> </mml:math> </inlineequation>
is the number of components or indices in each pixel.
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Setting <constant > GL_PACK_SKIP_ROWS</constant> to
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > j</mml:mi> </mml:math> </inlineequation>
is equivalent to incrementing
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the pointer by
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<inlineequation > <mml:math >
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<!-- eqn: j m: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > j</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > m</mml:mi>
</mml:mrow>
</mml:math> </inlineequation>
components or indices,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > m</mml:mi> </mml:math> </inlineequation>
is the number of components or indices per row,
as just computed in the <constant > GL_PACK_ROW_LENGTH</constant> section.
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Setting <constant > GL_PACK_SKIP_IMAGES</constant> to
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > k</mml:mi> </mml:math> </inlineequation>
is equivalent to incrementing
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the pointer by
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<inlineequation > <mml:math >
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<!-- eqn: k p: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > p</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > p</mml:mi> </mml:math> </inlineequation>
is the number of components or indices
per image, as computed in the <constant > GL_PACK_IMAGE_HEIGHT</constant> section.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_PACK_ALIGNMENT</constant> </term>
<listitem >
<para >
Specifies the alignment requirements for the start of each pixel row in memory.
The allowable values are
1 (byte-alignment),
2 (rows aligned to even-numbered bytes),
4 (word-alignment), and
8 (rows start on double-word boundaries).
</para>
</listitem>
</varlistentry>
</variablelist>
<para >
The other six of the twelve storage parameters affect how pixel data is
read from client memory.
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These values are significant for
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<citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexSubImage1D</refentrytitle> </citerefentry> ,
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<citerefentry > <refentrytitle > glTexSubImage2D</refentrytitle> </citerefentry> , and
<citerefentry > <refentrytitle > glTexSubImage3D</refentrytitle> </citerefentry>
2009-03-08 00:46:58 +00:00
</para>
<para >
They are as follows:
</para>
<variablelist >
<varlistentry >
<term > <constant > GL_UNPACK_SWAP_BYTES</constant> </term>
<listitem >
<para >
If true,
byte ordering for multibyte color components,
depth components,
or stencil indices
is reversed.
That is,
if a four-byte component consists of bytes
<inlineequation > <mml:math >
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<!-- eqn: b sub 0: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 0</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 1: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 1</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 2: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 2</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 3: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 3</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
it is taken from memory as
<inlineequation > <mml:math >
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<!-- eqn: b sub 3: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 3</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 2: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 2</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 1: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 1</mml:mn>
</mml:msub>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
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<!-- eqn: b sub 0: -->
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<mml:msub > <mml:mi mathvariant= "italic" > b</mml:mi>
<mml:mn > 0</mml:mn>
</mml:msub>
</mml:math> </inlineequation>
if <constant > GL_UNPACK_SWAP_BYTES</constant> is true.
<constant > GL_UNPACK_SWAP_BYTES</constant> has no effect on the memory order of components
within a pixel,
only on the order of bytes within components or indices.
For example,
the three components of a <constant > GL_RGB</constant> format pixel are always stored with
red first,
green second,
and blue third,
regardless of the value of <constant > GL_UNPACK_SWAP_BYTES</constant> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_UNPACK_LSB_FIRST</constant> </term>
<listitem >
<para >
If true,
bits are ordered within a byte from least significant to most significant;
otherwise,
the first bit in each byte is the most significant one.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_UNPACK_ROW_LENGTH</constant> </term>
<listitem >
<para >
If greater than 0,
<constant > GL_UNPACK_ROW_LENGTH</constant> defines the number of pixels in a row.
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If the first pixel of a row is placed at location
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > p</mml:mi> </mml:math> </inlineequation>
in memory,
then the location of the first pixel of the next row is obtained by skipping
</para>
<para >
<informalequation > <mml:math >
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<!-- eqn: k = left { lpile { n l above {a over s} left ceiling { s n l } over a right ceiling } lpile { s >= a above s < a }: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > =</mml:mo>
<mml:mfenced open= "{" close= "" >
<mml:mrow >
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mfenced open= "" close= "" >
<mml:mfrac >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mfrac>
</mml:mfenced>
<mml:mo > ⁢ </mml:mo>
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<mml:mfenced open= "⌈" close= "⌉" >
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<mml:mfrac >
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
</mml:mrow>
</mml:mfenced>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
<mml:mo > ⁢ </mml:mo>
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > > =</mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:math> </informalequation>
</para>
<para >
components or indices,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > n</mml:mi> </mml:math> </inlineequation>
is the number of components or indices in a pixel,
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > l</mml:mi> </mml:math> </inlineequation>
is the number of pixels in a row
(<constant > GL_UNPACK_ROW_LENGTH</constant> if it is greater than 0,
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the
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > width</mml:mi> </mml:math> </inlineequation>
argument to the pixel routine otherwise),
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > a</mml:mi> </mml:math> </inlineequation>
is the value of <constant > GL_UNPACK_ALIGNMENT</constant> , and
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > s</mml:mi> </mml:math> </inlineequation>
is the size, in bytes, of a single component
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(if
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<inlineequation > <mml:math >
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<!-- eqn: a < s: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ,
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then it is as if
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<inlineequation > <mml:math >
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<!-- eqn: a = s: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > =</mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ).
In the case of 1-bit values,
the location of the next row is obtained by skipping
</para>
<para >
<inlineequation > <mml:math >
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<!-- eqn: k = 8 a left ceiling { n l } over { 8 a } right ceiling: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mn > 8</mml:mn>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > ⁢ </mml:mo>
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<mml:mfenced open= "⌈" close= "⌉" >
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<mml:mfrac >
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
</mml:mrow>
</mml:mfenced>
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mn > 8</mml:mn>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mfenced>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
</para>
<para >
components or indices.
</para>
<para >
The word <emphasis > component</emphasis> in this description refers to the nonindex values
red,
green,
blue,
alpha,
and depth.
Storage format <constant > GL_RGB</constant> ,
for example,
has three components per pixel:
first red,
then green,
and finally blue.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_UNPACK_IMAGE_HEIGHT</constant> </term>
<listitem >
<para >
If greater than 0,
<constant > GL_UNPACK_IMAGE_HEIGHT</constant> defines the number of pixels in an image of
a three-dimensional texture volume. Where ``image'' is defined by all
pixel sharing the same third dimension index.
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If the first pixel of a row is placed at location
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > p</mml:mi> </mml:math> </inlineequation>
in memory,
then the location of the first pixel of the next row is obtained by skipping
</para>
<para >
<informalequation > <mml:math >
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<!-- eqn: k = left { lpile { n l h above {a over s} left ceiling { s n l h } over a right ceiling } lpile { s >= a above s < a }: -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mo > =</mml:mo>
<mml:mfenced open= "{" close= "" >
<mml:mrow >
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > h</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mfenced open= "" close= "" >
<mml:mfrac >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mfrac>
</mml:mfenced>
<mml:mo > ⁢ </mml:mo>
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<mml:mfenced open= "⌈" close= "⌉" >
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<mml:mfrac >
<mml:mfenced open= "" close= "" >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > n</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > l</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > h</mml:mi>
</mml:mrow>
</mml:mfenced>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
<mml:mo > ⁢ </mml:mo>
<mml:mtable >
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > > =</mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
<mml:mtr > <mml:mtd >
<mml:mrow >
<mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > a</mml:mi>
</mml:mrow>
</mml:mtd> </mml:mtr>
</mml:mtable>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:math> </informalequation>
</para>
<para >
components or indices,
2013-11-03 11:43:50 +00:00
where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > n</mml:mi> </mml:math> </inlineequation>
is the number of components or indices in a pixel,
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > l</mml:mi> </mml:math> </inlineequation>
is the number of pixels in a row
(<constant > GL_UNPACK_ROW_LENGTH</constant> if it is greater than 0,
2013-11-03 11:43:50 +00:00
the
2009-03-08 00:46:58 +00:00
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > width</mml:mi> </mml:math> </inlineequation>
argument to <citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> otherwise),
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > h</mml:mi> </mml:math> </inlineequation>
is the number of rows in an image (<constant > GL_UNPACK_IMAGE_HEIGHT</constant> if
2013-11-03 11:43:50 +00:00
it is greater than 0, the
2009-03-08 00:46:58 +00:00
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > height</mml:mi> </mml:math> </inlineequation>
argument to <citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> otherwise),
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > a</mml:mi> </mml:math> </inlineequation>
is the value of <constant > GL_UNPACK_ALIGNMENT</constant> , and
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > s</mml:mi> </mml:math> </inlineequation>
is the size, in bytes, of a single component
2013-11-03 11:43:50 +00:00
(if
2009-03-08 00:46:58 +00:00
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: a < s: -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > < </mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ,
2013-11-03 11:43:50 +00:00
then it is as if
2009-03-08 00:46:58 +00:00
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: a = s: -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > a</mml:mi>
<mml:mo > =</mml:mo>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:mrow>
</mml:math> </inlineequation> ).
</para>
<para >
The word <emphasis > component</emphasis> in this description refers to the nonindex values
red,
green,
blue,
alpha,
and depth.
Storage format <constant > GL_RGB</constant> ,
for example,
has three components per pixel:
first red,
then green,
and finally blue.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_UNPACK_SKIP_PIXELS</constant> and <constant > GL_UNPACK_SKIP_ROWS</constant> </term>
<listitem >
<para >
These values are provided as a convenience to the programmer;
they provide no functionality that cannot be duplicated by
incrementing the pointer passed to
<citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage2D</refentrytitle> </citerefentry> ,
2010-11-21 14:34:29 +00:00
<citerefentry > <refentrytitle > glTexSubImage1D</refentrytitle> </citerefentry> or
<citerefentry > <refentrytitle > glTexSubImage2D</refentrytitle> </citerefentry> .
2013-11-03 11:43:50 +00:00
Setting <constant > GL_UNPACK_SKIP_PIXELS</constant> to
2009-03-08 00:46:58 +00:00
<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > i</mml:mi> </mml:math> </inlineequation>
is equivalent to incrementing
2013-11-03 11:43:50 +00:00
the pointer by
2009-03-08 00:46:58 +00:00
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: i n: -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > i</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > n</mml:mi>
</mml:mrow>
</mml:math> </inlineequation>
components or indices,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > n</mml:mi> </mml:math> </inlineequation>
is the number of components or indices in each pixel.
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Setting <constant > GL_UNPACK_SKIP_ROWS</constant> to
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > j</mml:mi> </mml:math> </inlineequation>
is equivalent to incrementing
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the pointer by
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<inlineequation > <mml:math >
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<!-- eqn: j k: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > j</mml:mi>
<mml:mo > ⁢ </mml:mo>
<mml:mi mathvariant= "italic" > k</mml:mi>
</mml:mrow>
</mml:math> </inlineequation>
components or indices,
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where
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<inlineequation > <mml:math > <mml:mi mathvariant= "italic" > k</mml:mi> </mml:math> </inlineequation>
is the number of components or indices per row,
as just computed in the <constant > GL_UNPACK_ROW_LENGTH</constant> section.
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <constant > GL_UNPACK_ALIGNMENT</constant> </term>
<listitem >
<para >
Specifies the alignment requirements for the start of each pixel row in memory.
The allowable values are
1 (byte-alignment),
2 (rows aligned to even-numbered bytes),
4 (word-alignment), and
8 (rows start on double-word boundaries).
</para>
</listitem>
</varlistentry>
</variablelist>
<para >
The following table gives the type,
initial value,
and range of valid values for each storage parameter
that can be set with <function > glPixelStore</function> .
</para>
<para >
</para>
<informaltable frame= "topbot" >
<tgroup cols= "4" align= "left" >
<colspec colwidth= "2.5*" />
<colspec colwidth= "1*" align= "center" />
<colspec colwidth= "1*" align= "center" />
<colspec colwidth= "2*" align= "center" />
<thead >
<row >
<entry rowsep= "1" align= "left" > <emphasis role= "bold" >
<parameter > pname</parameter>
</emphasis> </entry>
<entry rowsep= "1" align= "center" > <emphasis role= "bold" >
Type
</emphasis> </entry>
<entry rowsep= "1" align= "center" > <emphasis role= "bold" >
Initial Value
</emphasis> </entry>
<entry rowsep= "1" align= "center" > <emphasis role= "bold" >
Valid Range
</emphasis> </entry>
</row>
</thead>
<tbody >
<row >
<entry align= "left" >
<constant > GL_PACK_SWAP_BYTES</constant>
</entry>
<entry align= "center" >
boolean
</entry>
<entry align= "center" >
false
</entry>
<entry align= "center" >
true or false
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_LSB_FIRST</constant>
</entry>
<entry align= "center" >
boolean
</entry>
<entry align= "center" >
false
</entry>
<entry align= "center" >
true or false
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_ROW_LENGTH</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_IMAGE_HEIGHT</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0, \(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_SKIP_ROWS</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_SKIP_PIXELS</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_SKIP_IMAGES</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_PACK_ALIGNMENT</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
4
</entry>
<entry align= "center" >
1, 2, 4, or 8
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_SWAP_BYTES</constant>
</entry>
<entry align= "center" >
boolean
</entry>
<entry align= "center" >
false
</entry>
<entry align= "center" >
true or false
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_LSB_FIRST</constant>
</entry>
<entry align= "center" >
boolean
</entry>
<entry align= "center" >
false
</entry>
<entry align= "center" >
true or false
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_ROW_LENGTH</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_IMAGE_HEIGHT</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_SKIP_ROWS</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_SKIP_PIXELS</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_SKIP_IMAGES</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
0
</entry>
<entry align= "center" >
<inlineequation > <mml:math >
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<!-- eqn: left [ 0,\(if right ): -->
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<mml:mfenced open= "[" close= ")" >
<mml:mn > 0</mml:mn>
<mml:infinity />
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_UNPACK_ALIGNMENT</constant>
</entry>
<entry align= "center" >
integer
</entry>
<entry align= "center" >
4
</entry>
<entry align= "center" >
1, 2, 4, or 8
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para >
<function > glPixelStoref</function> can be used to set any pixel store parameter.
If the parameter type is boolean,
then if <parameter > param</parameter> is 0,
the parameter is false;
otherwise it is set to true.
If <parameter > pname</parameter> is a integer type parameter,
<parameter > param</parameter> is rounded to the nearest integer.
</para>
<para >
Likewise, <function > glPixelStorei</function> can also be used to set any of the
pixel store parameters.
Boolean parameters are set to false if <parameter > param</parameter> is 0 and true otherwise.
</para>
</refsect1>
<refsect1 id= "errors" > <title > Errors</title>
<para >
<constant > GL_INVALID_ENUM</constant> is generated if <parameter > pname</parameter> is not an accepted value.
</para>
<para >
<constant > GL_INVALID_VALUE</constant> is generated if a negative row length,
pixel skip,
or row skip value is specified,
or if alignment is specified as other than 1, 2, 4, or 8.
</para>
</refsect1>
<refsect1 id= "associatedgets" > <title > Associated Gets</title>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_SWAP_BYTES</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_LSB_FIRST</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_ROW_LENGTH</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_IMAGE_HEIGHT</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_SKIP_ROWS</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_SKIP_PIXELS</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_SKIP_IMAGES</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_PACK_ALIGNMENT</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_SWAP_BYTES</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_LSB_FIRST</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_ROW_LENGTH</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_IMAGE_HEIGHT</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_SKIP_ROWS</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_SKIP_PIXELS</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_SKIP_IMAGES</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_UNPACK_ALIGNMENT</constant>
</para>
</refsect1>
<refsect1 id= "seealso" > <title > See Also</title>
<para >
<citerefentry > <refentrytitle > glReadPixels</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexSubImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glTexSubImage2D</refentrytitle> </citerefentry> ,
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<citerefentry > <refentrytitle > glTexSubImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexImage3D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage1D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage2D</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glCompressedTexSubImage1D</refentrytitle> </citerefentry> .
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</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> 2010-2013 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>
