[clinton/guile-figl.git] / upstream-doc / man2 / glCopyConvolutionFilter2D.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="glCopyConvolutionFilter2D">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glCopyConvolutionFilter2D</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glCopyConvolutionFilter2D</refname>
        <refpurpose>copy pixels into a two-dimensional convolution filter</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glCopyConvolutionFilter2D</function></funcdef>
                <paramdef>GLenum <parameter>target</parameter></paramdef>
                <paramdef>GLenum <parameter>internalformat</parameter></paramdef>
                <paramdef>GLint <parameter>x</parameter></paramdef>
                <paramdef>GLint <parameter>y</parameter></paramdef>
                <paramdef>GLsizei <parameter>width</parameter></paramdef>
                <paramdef>GLsizei <parameter>height</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>target</parameter></term>
            <listitem>
                <para>
                    Must be <constant>GL_CONVOLUTION_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>x</parameter></term>
            <term><parameter>y</parameter></term>
            <listitem>
                <para>
                    The window space coordinates of the lower-left coordinate of the
                    pixel array to copy.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>width</parameter></term>
            <listitem>
                <para>
                    The width of the pixel array to copy.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>height</parameter></term>
            <listitem>
                <para>
                    The height of the pixel array to copy.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glCopyConvolutionFilter2D</function> defines a two-dimensional convolution filter kernel with pixels
            from the current <constant>GL_READ_BUFFER</constant> (rather than from main memory,
            as is the case for <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>).
        </para>
        <para>
            The screen-aligned pixel rectangle with lower-left corner at (<parameter>x</parameter>,\ <parameter>y</parameter>),
            width <parameter>width</parameter> and height <parameter>height</parameter>
            is used to define the convolution filter. If any pixels within this
            region are
            outside the window that is associated with the GL context, the
            values obtained for those pixels are undefined.
        </para>
        <para>
            The pixels in the rectangle are processed
            exactly as if <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry> had been called with <emphasis>format</emphasis>
            set to RGBA, but the process stops just before final conversion.
            The R, G, B, and A components of each pixel are next scaled by the four
            2D <constant>GL_CONVOLUTION_FILTER_SCALE</constant> parameters and biased by the
            four 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_CONVOLUTION_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>
        <para>
        </para>
        <informaltable frame="topbot">
            <tgroup cols="7" align="left">
                <colspec colwidth="3*"/>
                <colspec colwidth="1*" align="center"/>
                <colspec colwidth="1*" align="center"/>
                <colspec colwidth="1*" align="center"/>
                <colspec colwidth="1*" align="center"/>
                <colspec colwidth="1.7*" align="center"/>
                <colspec colwidth="1.7*" 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_ALPHA</constant>
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                        A
                        </entry>
                        <entry align="center">
                        </entry>
                        <entry align="center">
                         
                        </entry>
                    </row>
                    <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.
        </para>
        <para>
            Pixel ordering is such that lower x screen coordinates correspond to
            lower <emphasis>i</emphasis> filter image coordinates, and lower y screen coordinates
            correspond to lower <emphasis>j</emphasis> filter image coordinates.
        </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>glCopyConvolutionFilter2D</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_CONVOLUTION_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_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_CONVOLUTION_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_CONVOLUTION_2D</constant> and name
            <constant>GL_MAX_CONVOLUTION_HEIGHT</constant>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glCopyConvolutionFilter2D</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>glGetConvolutionFilter</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <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="glCopyConvolutionFilter2D">
	5	<refmeta>
	6	<refmetainfo>
	7	<copyright>
	8	<year>1991-2006</year>
	9	<holder>Silicon Graphics, Inc.</holder>
	10	</copyright>
	11	</refmetainfo>
	12	<refentrytitle>glCopyConvolutionFilter2D</refentrytitle>
	13	<manvolnum>3G</manvolnum>
	14	</refmeta>
	15	<refnamediv>
	16	<refname>glCopyConvolutionFilter2D</refname>
	17	<refpurpose>copy pixels into a two-dimensional convolution filter</refpurpose>
	18	</refnamediv>
	19	<refsynopsisdiv><title>C Specification</title>
	20	<funcsynopsis>
	21	<funcprototype>
	22	<funcdef>void <function>glCopyConvolutionFilter2D</function></funcdef>
	23	<paramdef>GLenum <parameter>target</parameter></paramdef>
	24	<paramdef>GLenum <parameter>internalformat</parameter></paramdef>
	25	<paramdef>GLint <parameter>x</parameter></paramdef>
	26	<paramdef>GLint <parameter>y</parameter></paramdef>
	27	<paramdef>GLsizei <parameter>width</parameter></paramdef>
	28	<paramdef>GLsizei <parameter>height</parameter></paramdef>
	29	</funcprototype>
	30	</funcsynopsis>
	31	</refsynopsisdiv>
	32	<refsect1 id="parameters"><title>Parameters</title>
	33	<variablelist>
	34	<varlistentry>
	35	<term><parameter>target</parameter></term>
	36	<listitem>
	37	<para>
	38	Must be <constant>GL_CONVOLUTION_2D</constant>.
	39	</para>
	40	</listitem>
	41	</varlistentry>
	42	<varlistentry>
	43	<term><parameter>internalformat</parameter></term>
	44	<listitem>
	45	<para>
	46	The internal format of the convolution filter kernel.
	47	The allowable values are
	48	<constant>GL_ALPHA</constant>,
	49	<constant>GL_ALPHA4</constant>,
	50	<constant>GL_ALPHA8</constant>,
	51	<constant>GL_ALPHA12</constant>,
	52	<constant>GL_ALPHA16</constant>,
	53	<constant>GL_LUMINANCE</constant>,
	54	<constant>GL_LUMINANCE4</constant>,
	55	<constant>GL_LUMINANCE8</constant>,
	56	<constant>GL_LUMINANCE12</constant>,
	57	<constant>GL_LUMINANCE16</constant>,
	58	<constant>GL_LUMINANCE_ALPHA</constant>,
	59	<constant>GL_LUMINANCE4_ALPHA4</constant>,
	60	<constant>GL_LUMINANCE6_ALPHA2</constant>,
	61	<constant>GL_LUMINANCE8_ALPHA8</constant>,
	62	<constant>GL_LUMINANCE12_ALPHA4</constant>,
	63	<constant>GL_LUMINANCE12_ALPHA12</constant>,
	64	<constant>GL_LUMINANCE16_ALPHA16</constant>,
65	<constant>GL_INTENSITY</constant>,
66	<constant>GL_INTENSITY4</constant>,
67	<constant>GL_INTENSITY8</constant>,
68	<constant>GL_INTENSITY12</constant>,
69	<constant>GL_INTENSITY16</constant>,
70	<constant>GL_R3_G3_B2</constant>,
71	<constant>GL_RGB</constant>,
72	<constant>GL_RGB4</constant>,
73	<constant>GL_RGB5</constant>,
74	<constant>GL_RGB8</constant>,
75	<constant>GL_RGB10</constant>,
76	<constant>GL_RGB12</constant>,
77	<constant>GL_RGB16</constant>,
78	<constant>GL_RGBA</constant>,
79	<constant>GL_RGBA2</constant>,
80	<constant>GL_RGBA4</constant>,
81	<constant>GL_RGB5_A1</constant>,
82	<constant>GL_RGBA8</constant>,
83	<constant>GL_RGB10_A2</constant>,
84	<constant>GL_RGBA12</constant>, or
85	<constant>GL_RGBA16</constant>.
86	</para>
87	</listitem>
88	</varlistentry>
89	<varlistentry>
90	<term><parameter>x</parameter></term>
91	<term><parameter>y</parameter></term>
92	<listitem>
93	<para>
94	The window space coordinates of the lower-left coordinate of the
95	pixel array to copy.
96	</para>
97	</listitem>
98	</varlistentry>
99	<varlistentry>
100	<term><parameter>width</parameter></term>
101	<listitem>
102	<para>
103	The width of the pixel array to copy.
104	</para>
105	</listitem>
106	</varlistentry>
107	<varlistentry>
108	<term><parameter>height</parameter></term>
109	<listitem>
110	<para>
111	The height of the pixel array to copy.
112	</para>
113	</listitem>
114	</varlistentry>
115	</variablelist>
116	</refsect1>
117	<refsect1 id="description"><title>Description</title>
118	<para>
119	<function>glCopyConvolutionFilter2D</function> defines a two-dimensional convolution filter kernel with pixels
120	from the current <constant>GL_READ_BUFFER</constant> (rather than from main memory,
121	as is the case for <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>).
122	</para>
123	<para>
124	The screen-aligned pixel rectangle with lower-left corner at (<parameter>x</parameter>,\ <parameter>y</parameter>),
125	width <parameter>width</parameter> and height <parameter>height</parameter>
126	is used to define the convolution filter. If any pixels within this
127	region are
128	outside the window that is associated with the GL context, the
129	values obtained for those pixels are undefined.
130	</para>
131	<para>
132	The pixels in the rectangle are processed
133	exactly as if <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry> had been called with <emphasis>format</emphasis>
134	set to RGBA, but the process stops just before final conversion.
135	The R, G, B, and A components of each pixel are next scaled by the four
136	2D <constant>GL_CONVOLUTION_FILTER_SCALE</constant> parameters and biased by the
137	four 2D <constant>GL_CONVOLUTION_FILTER_BIAS</constant> parameters.
138	(The scale and bias parameters are set by <citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>
139	using the <constant>GL_CONVOLUTION_2D</constant> target and the names
140	<constant>GL_CONVOLUTION_FILTER_SCALE</constant> and <constant>GL_CONVOLUTION_FILTER_BIAS</constant>.
141	The parameters themselves are vectors of four values that are applied to red,
142	green, blue, and alpha, in that order.)
143	The R, G, B, and A values are not clamped to [0,1] at any time during this
144	process.
145	</para>
146	<para>
147	Each pixel is then converted to the internal format specified by
148	<parameter>internalformat</parameter>.
149	This conversion simply maps the component values of the pixel (R, G, B,
150	and A) to the values included in the internal format (red, green, blue,
151	alpha, luminance, and intensity). The mapping is as follows:
152	</para>
153	<para>
154	</para>
155	<informaltable frame="topbot">
156	<tgroup cols="7" align="left">
157	<colspec colwidth="3*"/>
158	<colspec colwidth="1*" align="center"/>
159	<colspec colwidth="1*" align="center"/>
160	<colspec colwidth="1*" align="center"/>
161	<colspec colwidth="1*" align="center"/>
162	<colspec colwidth="1.7*" align="center"/>
163	<colspec colwidth="1.7*" align="center"/>
164	<thead>
165	<row>
166	<entry rowsep="1" align="left"><emphasis role="bold">
167	Internal Format
168	</emphasis></entry>
169	<entry rowsep="1" align="center"><emphasis role="bold">
170	Red
171	</emphasis></entry>
172	<entry rowsep="1" align="center"><emphasis role="bold">
173	Green
174	</emphasis></entry>
175	<entry rowsep="1" align="center"><emphasis role="bold">
176	Blue
177	</emphasis></entry>
178	<entry rowsep="1" align="center"><emphasis role="bold">
179	Alpha
180	</emphasis></entry>
181	<entry rowsep="1" align="center"><emphasis role="bold">
182	Luminance
183	</emphasis></entry>
184	<entry rowsep="1" align="center"><emphasis role="bold">
185	Intensity
186	</emphasis></entry>
187	</row>
188	</thead>
189	<tbody>
190	<row>
191	<entry align="left">
192	<constant>GL_ALPHA</constant>
193	</entry>
194	<entry align="center">
195	</entry>
196	<entry align="center">
197	</entry>
198	<entry align="center">
199	</entry>
200	<entry align="center">
201	A
202	</entry>
203	<entry align="center">
204	</entry>
205	<entry align="center">
206
207	</entry>
208	</row>
209	<row>
210	<entry align="left">
211	<constant>GL_LUMINANCE</constant>
212	</entry>
213	<entry align="center">
214	</entry>
215	<entry align="center">
216	</entry>
217	<entry align="center">
218	</entry>
219	<entry align="center">
220	</entry>
221	<entry align="center">
222	R
223	</entry>
224	<entry align="center">
225
226	</entry>
227	</row>
228	<row>
229	<entry align="left">
230	<constant>GL_LUMINANCE_ALPHA</constant>
231	</entry>
232	<entry align="center">
233	</entry>
234	<entry align="center">
235	</entry>
236	<entry align="center">
237	</entry>
238	<entry align="center">
239	A
240	</entry>
241	<entry align="center">
242	R
243	</entry>
244	<entry align="center">
245
246	</entry>
247	</row>
248	<row>
249	<entry align="left">
250	<constant>GL_INTENSITY</constant>
251	</entry>
252	<entry align="center">
253	</entry>
254	<entry align="center">
255	</entry>
256	<entry align="center">
257	</entry>
258	<entry align="center">
259	</entry>
260	<entry align="center">
261	</entry>
262	<entry align="center">
263	R
264	</entry>
265	</row>
266	<row>
267	<entry align="left">
268	<constant>GL_RGB</constant>
269	</entry>
270	<entry align="center">
271	R
272	</entry>
273	<entry align="center">
274	G
275	</entry>
276	<entry align="center">
277	B
278	</entry>
279	<entry align="center">
280	</entry>
281	<entry align="center">
282	</entry>
283	<entry align="center">
284
285	</entry>
286	</row>
287	<row>
288	<entry align="left">
289	<constant>GL_RGBA</constant>
290	</entry>
291	<entry align="center">
292	R
293	</entry>
294	<entry align="center">
295	G
296	</entry>
297	<entry align="center">
298	B
299	</entry>
300	<entry align="center">
301	A
302	</entry>
303	<entry align="center">
304	</entry>
305	<entry align="center">
306
307	</entry>
308	</row>
309	</tbody>
310	</tgroup>
311	</informaltable>
312	<para>
313	The red, green, blue, alpha, luminance, and/or intensity components of
314	the resulting pixels are stored in floating-point rather than integer
315	format.
316	</para>
317	<para>
318	Pixel ordering is such that lower x screen coordinates correspond to
319	lower <emphasis>i</emphasis> filter image coordinates, and lower y screen coordinates
320	correspond to lower <emphasis>j</emphasis> filter image coordinates.
321	</para>
322	<para>
323	Note that after a convolution is performed, the resulting color
324	components are also scaled by their corresponding
325	<constant>GL_POST_CONVOLUTION_c_SCALE</constant> parameters and biased by their
326	corresponding <constant>GL_POST_CONVOLUTION_c_BIAS</constant> parameters (where
327	<emphasis>c</emphasis> takes on the values <emphasis role="bold">RED</emphasis>, <emphasis role="bold">GREEN</emphasis>, <emphasis role="bold">BLUE</emphasis>, and
328	<emphasis role="bold">ALPHA</emphasis>).
329	These parameters are set by <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>.
330	</para>
331	</refsect1>
332	<refsect1 id="notes"><title>Notes</title>
333	<para>
334	<function>glCopyConvolutionFilter2D</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
335	is called with an argument of <constant>GL_EXTENSIONS</constant>.
336	</para>
337	</refsect1>
338	<refsect1 id="errors"><title>Errors</title>
339	<para>
340	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
341	<constant>GL_CONVOLUTION_2D</constant>.
342	</para>
343	<para>
344	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not one of the
345	allowable values.
346	</para>
347	<para>
348	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> is less than zero or greater
349	than the maximum supported value.
350	This value may be queried with <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
351	using target <constant>GL_CONVOLUTION_2D</constant> and name
352	<constant>GL_MAX_CONVOLUTION_WIDTH</constant>.
353	</para>
354	<para>
355	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>height</parameter> is less than zero or greater
356	than the maximum supported value.
357	This value may be queried with <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
358	using target <constant>GL_CONVOLUTION_2D</constant> and name
359	<constant>GL_MAX_CONVOLUTION_HEIGHT</constant>.
360	</para>
361	<para>
362	<constant>GL_INVALID_OPERATION</constant> is generated if <function>glCopyConvolutionFilter2D</function> is executed
363	between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
364	execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
365	</para>
366	</refsect1>
367	<refsect1 id="associatedgets"><title>Associated Gets</title>
368	<para>
369	<citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glGetConvolutionFilter</refentrytitle></citerefentry>
370	</para>
371	</refsect1>
372	<refsect1 id="seealso"><title>See Also</title>
373	<para>
374	<citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>,
375	<citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>,
376	<citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>
377	</para>
378	</refsect1>
379	<refsect1 id="Copyright"><title>Copyright</title>
380	<para>
381	Copyright <trademark class="copyright"></trademark> 1991-2006
382	Silicon Graphics, Inc. This document is licensed under the SGI
383	Free Software B License. For details, see
384	<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
385	</para>
386	</refsect1>
387	</refentry>