[clinton/guile-figl.git] / upstream-doc / man2 / glSeparableFilter2D.xml

<?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="glSeparableFilter2D">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glSeparableFilter2D</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glSeparableFilter2D</refname>
        <refpurpose>define a separable two-dimensional convolution filter</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glSeparableFilter2D</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLenum <parameter>internalformat</parameter></paramdef>
                <paramdef>GLsizei <parameter>width</parameter></paramdef>
                <paramdef>GLsizei <parameter>height</parameter></paramdef>
                <paramdef>GLenum <parameter>format</parameter></paramdef>
                <paramdef>GLenum <parameter>type</parameter></paramdef>
                <paramdef>const GLvoid * <parameter>row</parameter></paramdef>
                <paramdef>const GLvoid * <parameter>column</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Must be <constant>GL_SEPARABLE_2D</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>internalformat</parameter></term>
            <listitem>
                <para>
                    The internal format of the convolution filter kernel.
                    The allowable values are
                    <constant>GL_ALPHA</constant>,
                    <constant>GL_ALPHA4</constant>,
                    <constant>GL_ALPHA8</constant>,
                    <constant>GL_ALPHA12</constant>,
                    <constant>GL_ALPHA16</constant>,
                    <constant>GL_LUMINANCE</constant>,
                    <constant>GL_LUMINANCE4</constant>,
                    <constant>GL_LUMINANCE8</constant>,
                    <constant>GL_LUMINANCE12</constant>,
                    <constant>GL_LUMINANCE16</constant>,
                    <constant>GL_LUMINANCE_ALPHA</constant>,
                    <constant>GL_LUMINANCE4_ALPHA4</constant>,
                    <constant>GL_LUMINANCE6_ALPHA2</constant>,
                    <constant>GL_LUMINANCE8_ALPHA8</constant>,
                    <constant>GL_LUMINANCE12_ALPHA4</constant>,
                    <constant>GL_LUMINANCE12_ALPHA12</constant>,
                    <constant>GL_LUMINANCE16_ALPHA16</constant>,
                    <constant>GL_INTENSITY</constant>,
                    <constant>GL_INTENSITY4</constant>,
                    <constant>GL_INTENSITY8</constant>,
                    <constant>GL_INTENSITY12</constant>,
                    <constant>GL_INTENSITY16</constant>,
                    <constant>GL_R3_G3_B2</constant>,
                    <constant>GL_RGB</constant>,
                    <constant>GL_RGB4</constant>,
                    <constant>GL_RGB5</constant>,
                    <constant>GL_RGB8</constant>,
                    <constant>GL_RGB10</constant>,
                    <constant>GL_RGB12</constant>,
                    <constant>GL_RGB16</constant>,
                    <constant>GL_RGBA</constant>,
                    <constant>GL_RGBA2</constant>,
                    <constant>GL_RGBA4</constant>,
                    <constant>GL_RGB5_A1</constant>,
                    <constant>GL_RGBA8</constant>,
                    <constant>GL_RGB10_A2</constant>,
                    <constant>GL_RGBA12</constant>, or
                    <constant>GL_RGBA16</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>width</parameter></term>
            <listitem>
                <para>
                    The number of elements in the pixel array referenced by <parameter>row</parameter>.
                    (This is the width of the separable filter kernel.)
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>height</parameter></term>
            <listitem>
                <para>
                    The number of elements in the pixel array referenced by <parameter>column</parameter>.
                    (This is the height of the separable filter kernel.)
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>format</parameter></term>
            <listitem>
                <para>
                    The format of the pixel data in <parameter>row</parameter> and <parameter>column</parameter>.
                    The allowable values are
                    <constant>GL_RED</constant>,
                    <constant>GL_GREEN</constant>,
                    <constant>GL_BLUE</constant>,
                    <constant>GL_ALPHA</constant>,
                    <constant>GL_RGB</constant>,
                    <constant>GL_BGR</constant>,
                    <constant>GL_RGBA</constant>,
                    <constant>GL_BGRA</constant>,
                    <constant>GL_INTENSITY</constant>,
                    <constant>GL_LUMINANCE</constant>, and
                    <constant>GL_LUMINANCE_ALPHA</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>type</parameter></term>
            <listitem>
                <para>
                    The type of the pixel data in <parameter>row</parameter> and <parameter>column</parameter>.
                    Symbolic constants
                    <constant>GL_UNSIGNED_BYTE</constant>,
                    <constant>GL_BYTE</constant>,
                    <constant>GL_BITMAP</constant>,
                    <constant>GL_UNSIGNED_SHORT</constant>,
                    <constant>GL_SHORT</constant>,
                    <constant>GL_UNSIGNED_INT</constant>,
                    <constant>GL_INT</constant>,
                    <constant>GL_FLOAT</constant>,
                    <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
                    <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
                    <constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
                    <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
                    <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
                    <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
                    <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
                    <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
                    <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
                    <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
                    <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and
                    <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
                    are accepted.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>row</parameter></term>
            <listitem>
                <para>
                    Pointer to a one-dimensional array of pixel data that is processed to
                    build the row filter kernel.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>column</parameter></term>
            <listitem>
                <para>
                    Pointer to a one-dimensional array of pixel data that is processed to
                    build the column filter kernel.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glSeparableFilter2D</function> builds a two-dimensional separable convolution filter kernel from
            two arrays of pixels.
        </para>
        <para>
            The pixel arrays specified by (<parameter>width</parameter>, <parameter>format</parameter>, <parameter>type</parameter>, <parameter>row</parameter>)
            and (<parameter>height</parameter>, <parameter>format</parameter>, <parameter>type</parameter>, <parameter>column</parameter>) are processed just as if
            they had been passed to <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>,
            but processing stops after the final expansion to RGBA is completed.
        </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 convolution filter is
            specified, <parameter>row</parameter> and <parameter>column</parameter> are treated as byte offsets into the buffer object's data store.
        </para>
        <para>
            Next, the R, G, B, and A components of all pixels in both arrays are scaled
            by the four separable 2D <constant>GL_CONVOLUTION_FILTER_SCALE</constant> parameters and
            biased by the four separable 2D <constant>GL_CONVOLUTION_FILTER_BIAS</constant> parameters.
            (The scale and bias parameters are set by <citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>
            using the <constant>GL_SEPARABLE_2D</constant> target and the names
            <constant>GL_CONVOLUTION_FILTER_SCALE</constant> and <constant>GL_CONVOLUTION_FILTER_BIAS</constant>.
            The parameters themselves are vectors of four values that are applied to red,
            green, blue, and alpha, in that order.)
            The R, G, B, and A values are not clamped to [0,1] at any time during this
            process.
        </para>
        <para>
            Each pixel is then converted to the internal format specified by
            <parameter>internalformat</parameter>.
            This conversion simply maps the component values of the pixel (R, G, B,
            and A) to the values included in the internal format (red, green, blue,
            alpha, luminance, and intensity).  The mapping is as follows:
        </para>
        <informaltable frame="topbot">
            <tgroup cols="7" align="left">
                <colspec colwidth="2.5*" />
                <colspec colwidth="1*" align="center"/>
                <colspec colwidth="1*"  align="center"/>
                <colspec colwidth="1*"  align="center"/>
                <colspec colwidth="1*"  align="center"/>
                <colspec colwidth="1.5*"  align="center"/>
                <colspec colwidth="1.5*"  align="center"/>
                <thead>
                    <row>
                        <entry rowsep="1" align="left"><emphasis role="bold">
                        Internal Format
                        </emphasis></entry>
                        <entry rowsep="1" align="center"><emphasis role="bold">
                        Red
                        </emphasis></entry>
                        <entry rowsep="1" align="center"><emphasis role="bold">
                        Green
                        </emphasis></entry>
                        <entry rowsep="1" align="center"><emphasis role="bold">
                        Blue
                        </emphasis></entry>
                        <entry rowsep="1" align="center"><emphasis role="bold">
                        Alpha
                        </emphasis></entry>
                        <entry rowsep="1" align="center"><emphasis role="bold">
                        Luminance
                        </emphasis></entry>
                        <entry rowsep="1" align="center"><emphasis role="bold">
                        Intensity
                        </emphasis></entry>
                    </row>
                </thead>
                <tbody>
                    <row>
                        <entry align="left">
                        <constant>GL_LUMINANCE</constant>
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        R
                        </entry>
                        <entry align="center">
                         
                        </entry>
                    </row>
                    <row>
                        <entry align="left">
                        <constant>GL_LUMINANCE_ALPHA</constant>
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        A
                        </entry>
                        <entry align="center">
                        R
                        </entry>
                        <entry align="center">
                         
                        </entry>
                    </row>
                    <row>
                        <entry align="left">
                        <constant>GL_INTENSITY</constant>
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        R
                        </entry>
                    </row>
                    <row>
                        <entry align="left">
                        <constant>GL_RGB</constant>
                        </entry>
                        <entry align="center">
                        R
                        </entry>
                        <entry align="center">
                        G
                        </entry>
                        <entry align="center">
                        B
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                         
                        </entry>
                    </row>
                    <row>
                        <entry align="left">
                        <constant>GL_RGBA</constant>
                        </entry>
                        <entry align="center">
                        R
                        </entry>
                        <entry align="center">
                        G
                        </entry>
                        <entry align="center">
                        B
                        </entry>
                        <entry align="center">
                        A
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                         
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </informaltable>
        <para>
            The red, green, blue, alpha, luminance, and/or intensity components of
            the resulting pixels are stored in floating-point rather than integer
            format.
            They form two one-dimensional filter kernel images.
            The row image is indexed by coordinate <emphasis>i</emphasis> starting at zero and
            increasing from left to right.
            Each location in the row image is derived from element <emphasis>i</emphasis> of <parameter>row</parameter>.
            The column image is indexed by coordinate <emphasis>j</emphasis> starting at zero
            and increasing from bottom to top.
            Each location in the column image is derived from element <emphasis>j</emphasis> of <parameter>column</parameter>.
        </para>
        <para>
            Note that after a convolution is performed, the resulting color
            components are also scaled by their corresponding
            <constant>GL_POST_CONVOLUTION_c_SCALE</constant> parameters and biased by their
            corresponding <constant>GL_POST_CONVOLUTION_c_BIAS</constant> parameters (where
            <emphasis>c</emphasis> takes on the values <emphasis role="bold">RED</emphasis>, <emphasis role="bold">GREEN</emphasis>, <emphasis role="bold">BLUE</emphasis>, and
            <emphasis role="bold">ALPHA</emphasis>).
            These parameters are set by <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            <function>glSeparableFilter2D</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
            is called with an argument of <constant>GL_EXTENSIONS</constant>.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
            <constant>GL_SEPARABLE_2D</constant>.
        </para>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not one of the
            allowable values.
        </para>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>format</parameter> is not one of the allowable
            values.
        </para>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not one of the allowable
            values.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> is less than zero or greater
            than the maximum supported value.
            This value may be queried with <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
            using target <constant>GL_SEPARABLE_2D</constant> and name
            <constant>GL_MAX_CONVOLUTION_WIDTH</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>height</parameter> is less than zero or greater
            than the maximum supported value.
            This value may be queried with <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
            using target <constant>GL_SEPARABLE_2D</constant> and name
            <constant>GL_MAX_CONVOLUTION_HEIGHT</constant>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>height</parameter> is one of
            <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
            <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
            <constant>GL_UNSIGNED_SHORT_5_6_5</constant>, or
            <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>
            and <parameter>format</parameter> is not <constant>GL_RGB</constant>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>height</parameter> is one of
            <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
            <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
            <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
            <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
            <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
            <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
            <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, or
            <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
            and <parameter>format</parameter> is neither <constant>GL_RGBA</constant> nor <constant>GL_BGRA</constant>.
        </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>
            <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 <parameter>row</parameter> or 
            <parameter>column</parameter> is not evenly divisible 
            into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glSeparableFilter2D</function> is executed
            between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
            execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glGetSeparableFilter</refentrytitle></citerefentry>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glConvolutionFilter1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            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>
Commit	Line	Data
7faf1d71 AW	1	<?xml version="1.0" encoding="UTF-8"?>
	2	<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
	3	"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
	4	<refentry id="glSeparableFilter2D">
	5	<refmeta>
	6	<refmetainfo>
	7	<copyright>
	8	<year>1991-2006</year>
	9	<holder>Silicon Graphics, Inc.</holder>
	10	</copyright>
	11	</refmetainfo>
	12	<refentrytitle>glSeparableFilter2D</refentrytitle>
	13	<manvolnum>3G</manvolnum>
	14	</refmeta>
	15	<refnamediv>
	16	<refname>glSeparableFilter2D</refname>
	17	<refpurpose>define a separable two-dimensional convolution filter</refpurpose>
	18	</refnamediv>
	19	<refsynopsisdiv><title>C Specification</title>
	20	<funcsynopsis>
	21	<funcprototype>
	22	<funcdef>void <function>glSeparableFilter2D</function></funcdef>
	23	<paramdef>GLenum <parameter>target</parameter></paramdef>
	24	<paramdef>GLenum <parameter>internalformat</parameter></paramdef>
	25	<paramdef>GLsizei <parameter>width</parameter></paramdef>
	26	<paramdef>GLsizei <parameter>height</parameter></paramdef>
	27	<paramdef>GLenum <parameter>format</parameter></paramdef>
	28	<paramdef>GLenum <parameter>type</parameter></paramdef>
	29	<paramdef>const GLvoid * <parameter>row</parameter></paramdef>
	30	<paramdef>const GLvoid * <parameter>column</parameter></paramdef>
	31	</funcprototype>
	32	</funcsynopsis>
	33	</refsynopsisdiv>
	34	<refsect1 id="parameters"><title>Parameters</title>
	35	<variablelist>
	36	<varlistentry>
	37	<term><parameter>target</parameter></term>
	38	<listitem>
	39	<para>
	40	Must be <constant>GL_SEPARABLE_2D</constant>.
	41	</para>
	42	</listitem>
	43	</varlistentry>
	44	<varlistentry>
	45	<term><parameter>internalformat</parameter></term>
	46	<listitem>
	47	<para>
	48	The internal format of the convolution filter kernel.
	49	The allowable values are
	50	<constant>GL_ALPHA</constant>,
	51	<constant>GL_ALPHA4</constant>,
	52	<constant>GL_ALPHA8</constant>,
	53	<constant>GL_ALPHA12</constant>,
	54	<constant>GL_ALPHA16</constant>,
	55	<constant>GL_LUMINANCE</constant>,
	56	<constant>GL_LUMINANCE4</constant>,
	57	<constant>GL_LUMINANCE8</constant>,
	58	<constant>GL_LUMINANCE12</constant>,
	59	<constant>GL_LUMINANCE16</constant>,
	60	<constant>GL_LUMINANCE_ALPHA</constant>,
	61	<constant>GL_LUMINANCE4_ALPHA4</constant>,
	62	<constant>GL_LUMINANCE6_ALPHA2</constant>,
	63	<constant>GL_LUMINANCE8_ALPHA8</constant>,
	64	<constant>GL_LUMINANCE12_ALPHA4</constant>,
65	<constant>GL_LUMINANCE12_ALPHA12</constant>,
66	<constant>GL_LUMINANCE16_ALPHA16</constant>,
67	<constant>GL_INTENSITY</constant>,
68	<constant>GL_INTENSITY4</constant>,
69	<constant>GL_INTENSITY8</constant>,
70	<constant>GL_INTENSITY12</constant>,
71	<constant>GL_INTENSITY16</constant>,
72	<constant>GL_R3_G3_B2</constant>,
73	<constant>GL_RGB</constant>,
74	<constant>GL_RGB4</constant>,
75	<constant>GL_RGB5</constant>,
76	<constant>GL_RGB8</constant>,
77	<constant>GL_RGB10</constant>,
78	<constant>GL_RGB12</constant>,
79	<constant>GL_RGB16</constant>,
80	<constant>GL_RGBA</constant>,
81	<constant>GL_RGBA2</constant>,
82	<constant>GL_RGBA4</constant>,
83	<constant>GL_RGB5_A1</constant>,
84	<constant>GL_RGBA8</constant>,
85	<constant>GL_RGB10_A2</constant>,
86	<constant>GL_RGBA12</constant>, or
87	<constant>GL_RGBA16</constant>.
88	</para>
89	</listitem>
90	</varlistentry>
91	<varlistentry>
92	<term><parameter>width</parameter></term>
93	<listitem>
94	<para>
95	The number of elements in the pixel array referenced by <parameter>row</parameter>.
96	(This is the width of the separable filter kernel.)
97	</para>
98	</listitem>
99	</varlistentry>
100	<varlistentry>
101	<term><parameter>height</parameter></term>
102	<listitem>
103	<para>
104	The number of elements in the pixel array referenced by <parameter>column</parameter>.
105	(This is the height of the separable filter kernel.)
106	</para>
107	</listitem>
108	</varlistentry>
109	<varlistentry>
110	<term><parameter>format</parameter></term>
111	<listitem>
112	<para>
113	The format of the pixel data in <parameter>row</parameter> and <parameter>column</parameter>.
114	The allowable values are
115	<constant>GL_RED</constant>,
116	<constant>GL_GREEN</constant>,
117	<constant>GL_BLUE</constant>,
118	<constant>GL_ALPHA</constant>,
119	<constant>GL_RGB</constant>,
120	<constant>GL_BGR</constant>,
121	<constant>GL_RGBA</constant>,
122	<constant>GL_BGRA</constant>,
123	<constant>GL_INTENSITY</constant>,
124	<constant>GL_LUMINANCE</constant>, and
125	<constant>GL_LUMINANCE_ALPHA</constant>.
126	</para>
127	</listitem>
128	</varlistentry>
129	<varlistentry>
130	<term><parameter>type</parameter></term>
131	<listitem>
132	<para>
133	The type of the pixel data in <parameter>row</parameter> and <parameter>column</parameter>.
134	Symbolic constants
135	<constant>GL_UNSIGNED_BYTE</constant>,
136	<constant>GL_BYTE</constant>,
137	<constant>GL_BITMAP</constant>,
138	<constant>GL_UNSIGNED_SHORT</constant>,
139	<constant>GL_SHORT</constant>,
140	<constant>GL_UNSIGNED_INT</constant>,
141	<constant>GL_INT</constant>,
142	<constant>GL_FLOAT</constant>,
143	<constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
144	<constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
145	<constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
146	<constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
147	<constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
148	<constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
149	<constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
150	<constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
151	<constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
152	<constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
153	<constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and
154	<constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
155	are accepted.
156	</para>
157	</listitem>
158	</varlistentry>
159	<varlistentry>
160	<term><parameter>row</parameter></term>
161	<listitem>
162	<para>
163	Pointer to a one-dimensional array of pixel data that is processed to
164	build the row filter kernel.
165	</para>
166	</listitem>
167	</varlistentry>
168	<varlistentry>
169	<term><parameter>column</parameter></term>
170	<listitem>
171	<para>
172	Pointer to a one-dimensional array of pixel data that is processed to
173	build the column filter kernel.
174	</para>
175	</listitem>
176	</varlistentry>
177	</variablelist>
178	</refsect1>
179	<refsect1 id="description"><title>Description</title>
180	<para>
181	<function>glSeparableFilter2D</function> builds a two-dimensional separable convolution filter kernel from
182	two arrays of pixels.
183	</para>
184	<para>
185	The pixel arrays specified by (<parameter>width</parameter>, <parameter>format</parameter>, <parameter>type</parameter>, <parameter>row</parameter>)
186	and (<parameter>height</parameter>, <parameter>format</parameter>, <parameter>type</parameter>, <parameter>column</parameter>) are processed just as if
187	they had been passed to <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>,
188	but processing stops after the final expansion to RGBA is completed.
189	</para>
190	<para>
191	If a non-zero named buffer object is bound to the <constant>GL_PIXEL_UNPACK_BUFFER</constant> target
192	(see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a convolution filter is
193	specified, <parameter>row</parameter> and <parameter>column</parameter> are treated as byte offsets into the buffer object's data store.
194	</para>
195	<para>
196	Next, the R, G, B, and A components of all pixels in both arrays are scaled
197	by the four separable 2D <constant>GL_CONVOLUTION_FILTER_SCALE</constant> parameters and
198	biased by the four separable 2D <constant>GL_CONVOLUTION_FILTER_BIAS</constant> parameters.
199	(The scale and bias parameters are set by <citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>
200	using the <constant>GL_SEPARABLE_2D</constant> target and the names
201	<constant>GL_CONVOLUTION_FILTER_SCALE</constant> and <constant>GL_CONVOLUTION_FILTER_BIAS</constant>.
202	The parameters themselves are vectors of four values that are applied to red,
203	green, blue, and alpha, in that order.)
204	The R, G, B, and A values are not clamped to [0,1] at any time during this
205	process.
206	</para>
207	<para>
208	Each pixel is then converted to the internal format specified by
209	<parameter>internalformat</parameter>.
210	This conversion simply maps the component values of the pixel (R, G, B,
211	and A) to the values included in the internal format (red, green, blue,
212	alpha, luminance, and intensity). The mapping is as follows:
213	</para>
214	<informaltable frame="topbot">
215	<tgroup cols="7" align="left">
216	<colspec colwidth="2.5*" />
217	<colspec colwidth="1*" align="center"/>
218	<colspec colwidth="1*" align="center"/>
219	<colspec colwidth="1*" align="center"/>
220	<colspec colwidth="1*" align="center"/>
221	<colspec colwidth="1.5*" align="center"/>
222	<colspec colwidth="1.5*" align="center"/>
223	<thead>
224	<row>
225	<entry rowsep="1" align="left"><emphasis role="bold">
226	Internal Format
227	</emphasis></entry>
228	<entry rowsep="1" align="center"><emphasis role="bold">
229	Red
230	</emphasis></entry>
231	<entry rowsep="1" align="center"><emphasis role="bold">
232	Green
233	</emphasis></entry>
234	<entry rowsep="1" align="center"><emphasis role="bold">
235	Blue
236	</emphasis></entry>
237	<entry rowsep="1" align="center"><emphasis role="bold">
238	Alpha
239	</emphasis></entry>
240	<entry rowsep="1" align="center"><emphasis role="bold">
241	Luminance
242	</emphasis></entry>
243	<entry rowsep="1" align="center"><emphasis role="bold">
244	Intensity
245	</emphasis></entry>
246	</row>
247	</thead>
248	<tbody>
249	<row>
250	<entry align="left">
251	<constant>GL_LUMINANCE</constant>
252	</entry>
253	<entry align="center">
254	</entry>
255	<entry align="center">
256	</entry>
257	<entry align="center">
258	</entry>
259	<entry align="center">
260	</entry>
261	<entry align="center">
262	R
263	</entry>
264	<entry align="center">
265
266	</entry>
267	</row>
268	<row>
269	<entry align="left">
270	<constant>GL_LUMINANCE_ALPHA</constant>
271	</entry>
272	<entry align="center">
273	</entry>
274	<entry align="center">
275	</entry>
276	<entry align="center">
277	</entry>
278	<entry align="center">
279	A
280	</entry>
281	<entry align="center">
282	R
283	</entry>
284	<entry align="center">
285
286	</entry>
287	</row>
288	<row>
289	<entry align="left">
290	<constant>GL_INTENSITY</constant>
291	</entry>
292	<entry align="center">
293	</entry>
294	<entry align="center">
295	</entry>
296	<entry align="center">
297	</entry>
298	<entry align="center">
299	</entry>
300	<entry align="center">
301	</entry>
302	<entry align="center">
303	R
304	</entry>
305	</row>
306	<row>
307	<entry align="left">
308	<constant>GL_RGB</constant>
309	</entry>
310	<entry align="center">
311	R
312	</entry>
313	<entry align="center">
314	G
315	</entry>
316	<entry align="center">
317	B
318	</entry>
319	<entry align="center">
320	</entry>
321	<entry align="center">
322	</entry>
323	<entry align="center">
324
325	</entry>
326	</row>
327	<row>
328	<entry align="left">
329	<constant>GL_RGBA</constant>
330	</entry>
331	<entry align="center">
332	R
333	</entry>
334	<entry align="center">
335	G
336	</entry>
337	<entry align="center">
338	B
339	</entry>
340	<entry align="center">
341	A
342	</entry>
343	<entry align="center">
344	</entry>
345	<entry align="center">
346
347	</entry>
348	</row>
349	</tbody>
350	</tgroup>
351	</informaltable>
352	<para>
353	The red, green, blue, alpha, luminance, and/or intensity components of
354	the resulting pixels are stored in floating-point rather than integer
355	format.
356	They form two one-dimensional filter kernel images.
357	The row image is indexed by coordinate <emphasis>i</emphasis> starting at zero and
358	increasing from left to right.
359	Each location in the row image is derived from element <emphasis>i</emphasis> of <parameter>row</parameter>.
360	The column image is indexed by coordinate <emphasis>j</emphasis> starting at zero
361	and increasing from bottom to top.
362	Each location in the column image is derived from element <emphasis>j</emphasis> of <parameter>column</parameter>.
363	</para>
364	<para>
365	Note that after a convolution is performed, the resulting color
366	components are also scaled by their corresponding
367	<constant>GL_POST_CONVOLUTION_c_SCALE</constant> parameters and biased by their
368	corresponding <constant>GL_POST_CONVOLUTION_c_BIAS</constant> parameters (where
369	<emphasis>c</emphasis> takes on the values <emphasis role="bold">RED</emphasis>, <emphasis role="bold">GREEN</emphasis>, <emphasis role="bold">BLUE</emphasis>, and
370	<emphasis role="bold">ALPHA</emphasis>).
371	These parameters are set by <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>.
372	</para>
373	</refsect1>
374	<refsect1 id="notes"><title>Notes</title>
375	<para>
376	<function>glSeparableFilter2D</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
377	is called with an argument of <constant>GL_EXTENSIONS</constant>.
378	</para>
379	</refsect1>
380	<refsect1 id="errors"><title>Errors</title>
381	<para>
382	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
383	<constant>GL_SEPARABLE_2D</constant>.
384	</para>
385	<para>
386	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not one of the
387	allowable values.
388	</para>
389	<para>
390	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>format</parameter> is not one of the allowable
391	values.
392	</para>
393	<para>
394	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not one of the allowable
395	values.
396	</para>
397	<para>
398	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> is less than zero or greater
399	than the maximum supported value.
400	This value may be queried with <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
401	using target <constant>GL_SEPARABLE_2D</constant> and name
402	<constant>GL_MAX_CONVOLUTION_WIDTH</constant>.
403	</para>
404	<para>
405	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>height</parameter> is less than zero or greater
406	than the maximum supported value.
407	This value may be queried with <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
408	using target <constant>GL_SEPARABLE_2D</constant> and name
409	<constant>GL_MAX_CONVOLUTION_HEIGHT</constant>.
410	</para>
411	<para>
412	<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>height</parameter> is one of
413	<constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
414	<constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
415	<constant>GL_UNSIGNED_SHORT_5_6_5</constant>, or
416	<constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>
417	and <parameter>format</parameter> is not <constant>GL_RGB</constant>.
418	</para>
419	<para>
420	<constant>GL_INVALID_OPERATION</constant> is generated if <parameter>height</parameter> is one of
421	<constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
422	<constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
423	<constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
424	<constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
425	<constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
426	<constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
427	<constant>GL_UNSIGNED_INT_10_10_10_2</constant>, or
428	<constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
429	and <parameter>format</parameter> is neither <constant>GL_RGBA</constant> nor <constant>GL_BGRA</constant>.
430	</para>
431	<para>
432	<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
433	<constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
434	</para>
435	<para>
436	<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
437	<constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the data would be unpacked from the buffer
438	object such that the memory reads required would exceed the data store size.
439	</para>
440	<para>
441	<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
442	<constant>GL_PIXEL_UNPACK_BUFFER</constant> target and <parameter>row</parameter> or
443	<parameter>column</parameter> is not evenly divisible
444	into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>.
445	</para>
446	<para>
447	<constant>GL_INVALID_OPERATION</constant> is generated if <function>glSeparableFilter2D</function> is executed
448	between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
449	execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
450	</para>
451	</refsect1>
452	<refsect1 id="associatedgets"><title>Associated Gets</title>
453	<para>
454	<citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glGetSeparableFilter</refentrytitle></citerefentry>
455	</para>
456	<para>
457	<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
458	</para>
459	</refsect1>
460	<refsect1 id="seealso"><title>See Also</title>
461	<para>
462	<citerefentry><refentrytitle>glConvolutionFilter1D</refentrytitle></citerefentry>,
463	<citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>,
464	<citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>,
465	<citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>
466	</para>
467	</refsect1>
468	<refsect1 id="Copyright"><title>Copyright</title>
469	<para>
470	Copyright <trademark class="copyright"></trademark> 1991-2006
471	Silicon Graphics, Inc. This document is licensed under the SGI
472	Free Software B License. For details, see
473	<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
474	</para>
475	</refsect1>
476	</refentry>