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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="glGetConvolutionFilter"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glGetConvolutionFilter</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glGetConvolutionFilter</refname> | |
17 | <refpurpose>get current 1D or 2D convolution filter kernel</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glGetConvolutionFilter</function></funcdef> | |
23 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
24 | <paramdef>GLenum <parameter>format</parameter></paramdef> | |
25 | <paramdef>GLenum <parameter>type</parameter></paramdef> | |
26 | <paramdef>GLvoid * <parameter>image</parameter></paramdef> | |
27 | </funcprototype> | |
28 | </funcsynopsis> | |
29 | </refsynopsisdiv> | |
30 | <refsect1 id="parameters"><title>Parameters</title> | |
31 | <variablelist> | |
32 | <varlistentry> | |
33 | <term><parameter>target</parameter></term> | |
34 | <listitem> | |
35 | <para> | |
36 | The filter to be retrieved. | |
37 | Must be one of | |
38 | <constant>GL_CONVOLUTION_1D</constant> or | |
39 | <constant>GL_CONVOLUTION_2D</constant>. | |
40 | </para> | |
41 | </listitem> | |
42 | </varlistentry> | |
43 | <varlistentry> | |
44 | <term><parameter>format</parameter></term> | |
45 | <listitem> | |
46 | <para> | |
47 | Format of the output image. | |
48 | Must be one of | |
49 | <constant>GL_RED</constant>, | |
50 | <constant>GL_GREEN</constant>, | |
51 | <constant>GL_BLUE</constant>, | |
52 | <constant>GL_ALPHA</constant>, | |
53 | <constant>GL_RGB</constant>, | |
54 | <constant>GL_BGR</constant>, | |
55 | <constant>GL_RGBA</constant>, | |
56 | <constant>GL_BGRA</constant>, | |
57 | <constant>GL_LUMINANCE</constant>, or | |
58 | <constant>GL_LUMINANCE_ALPHA</constant>. | |
59 | </para> | |
60 | </listitem> | |
61 | </varlistentry> | |
62 | <varlistentry> | |
63 | <term><parameter>type</parameter></term> | |
64 | <listitem> | |
65 | <para> | |
66 | Data type of components in the output image. | |
67 | Symbolic constants | |
68 | <constant>GL_UNSIGNED_BYTE</constant>, | |
69 | <constant>GL_BYTE</constant>, | |
70 | <constant>GL_BITMAP</constant>, | |
71 | <constant>GL_UNSIGNED_SHORT</constant>, | |
72 | <constant>GL_SHORT</constant>, | |
73 | <constant>GL_UNSIGNED_INT</constant>, | |
74 | <constant>GL_INT</constant>, | |
75 | <constant>GL_FLOAT</constant>, | |
76 | <constant>GL_UNSIGNED_BYTE_3_3_2</constant>, | |
77 | <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>, | |
78 | <constant>GL_UNSIGNED_SHORT_5_6_5</constant>, | |
79 | <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>, | |
80 | <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>, | |
81 | <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>, | |
82 | <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>, | |
83 | <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>, | |
84 | <constant>GL_UNSIGNED_INT_8_8_8_8</constant>, | |
85 | <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>, | |
86 | <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and | |
87 | <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant> | |
88 | are accepted. | |
89 | </para> | |
90 | </listitem> | |
91 | </varlistentry> | |
92 | <varlistentry> | |
93 | <term><parameter>image</parameter></term> | |
94 | <listitem> | |
95 | <para> | |
96 | Pointer to storage for the output image. | |
97 | </para> | |
98 | </listitem> | |
99 | </varlistentry> | |
100 | </variablelist> | |
101 | </refsect1> | |
102 | <refsect1 id="description"><title>Description</title> | |
103 | <para> | |
104 | <function>glGetConvolutionFilter</function> returns the current 1D or 2D convolution filter kernel as an image. | |
105 | The one- or two-dimensional image is placed in <parameter>image</parameter> according to the | |
106 | specifications in <parameter>format</parameter> and <parameter>type</parameter>. | |
107 | No pixel transfer operations are performed on this image, but the relevant | |
108 | pixel storage modes are applied. | |
109 | </para> | |
110 | <para> | |
111 | If a non-zero named buffer object is bound to the <constant>GL_PIXEL_PACK_BUFFER</constant> target | |
112 | (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a convolution filter is | |
113 | requested, <parameter>image</parameter> is treated as a byte offset into the buffer object's data store. | |
114 | </para> | |
115 | <para> | |
116 | Color components that are present in <parameter>format</parameter> but not included in the | |
117 | internal format of the filter are returned as zero. | |
118 | The assignments of internal color components to the components of <parameter>format</parameter> | |
119 | are as follows. | |
120 | </para> | |
121 | <informaltable frame="topbot"> | |
122 | <tgroup cols="2" align="left"> | |
123 | <colspec/> | |
124 | <colspec/> | |
125 | <thead> | |
126 | <row> | |
127 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
128 | Internal Component | |
129 | </emphasis></entry> | |
130 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
131 | Resulting Component | |
132 | </emphasis></entry> | |
133 | </row> | |
134 | </thead> | |
135 | <tbody> | |
136 | <row> | |
137 | <entry align="left"> | |
138 | Red | |
139 | </entry> | |
140 | <entry align="left"> | |
141 | Red | |
142 | </entry> | |
143 | </row> | |
144 | <row> | |
145 | <entry align="left"> | |
146 | Green | |
147 | </entry> | |
148 | <entry align="left"> | |
149 | Green | |
150 | </entry> | |
151 | </row> | |
152 | <row> | |
153 | <entry align="left"> | |
154 | Blue | |
155 | </entry> | |
156 | <entry align="left"> | |
157 | Blue | |
158 | </entry> | |
159 | </row> | |
160 | <row> | |
161 | <entry align="left"> | |
162 | Alpha | |
163 | </entry> | |
164 | <entry align="left"> | |
165 | Alpha | |
166 | </entry> | |
167 | </row> | |
168 | <row> | |
169 | <entry align="left"> | |
170 | Luminance | |
171 | </entry> | |
172 | <entry align="left"> | |
173 | Red | |
174 | </entry> | |
175 | </row> | |
176 | <row> | |
177 | <entry align="left"> | |
178 | Intensity | |
179 | </entry> | |
180 | <entry align="left"> | |
181 | Red | |
182 | </entry> | |
183 | </row> | |
184 | </tbody> | |
185 | </tgroup> | |
186 | </informaltable> | |
187 | <para> | |
188 | </para> | |
189 | </refsect1> | |
190 | <refsect1 id="notes"><title>Notes</title> | |
191 | <para> | |
192 | <function>glGetConvolutionFilter</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry> | |
193 | is called with an argument of <constant>GL_EXTENSIONS</constant>. | |
194 | </para> | |
195 | <para> | |
196 | The current separable 2D filter must be retrieved with | |
197 | <citerefentry><refentrytitle>glGetSeparableFilter</refentrytitle></citerefentry> rather than <function>glGetConvolutionFilter</function>. | |
198 | </para> | |
199 | </refsect1> | |
200 | <refsect1 id="errors"><title>Errors</title> | |
201 | <para> | |
202 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not one of the allowable | |
203 | values. | |
204 | </para> | |
205 | <para> | |
206 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>format</parameter> is not one of the allowable | |
207 | values. | |
208 | </para> | |
209 | <para> | |
210 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not one of the allowable | |
211 | values. | |
212 | </para> | |
213 | <para> | |
214 | <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>type</parameter> is one of | |
215 | <constant>GL_UNSIGNED_BYTE_3_3_2</constant>, | |
216 | <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>, | |
217 | <constant>GL_UNSIGNED_SHORT_5_6_5</constant>, or | |
218 | <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant> | |
219 | and <parameter>format</parameter> is not <constant>GL_RGB</constant>. | |
220 | </para> | |
221 | <para> | |
222 | <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>type</parameter> is one of | |
223 | <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>, | |
224 | <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>, | |
225 | <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>, | |
226 | <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>, | |
227 | <constant>GL_UNSIGNED_INT_8_8_8_8</constant>, | |
228 | <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>, | |
229 | <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, or | |
230 | <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant> | |
231 | and <parameter>format</parameter> is neither <constant>GL_RGBA</constant> nor <constant>GL_BGRA</constant>. | |
232 | </para> | |
233 | <para> | |
234 | <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the | |
235 | <constant>GL_PIXEL_PACK_BUFFER</constant> target and the buffer object's data store is currently mapped. | |
236 | </para> | |
237 | <para> | |
238 | <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the | |
239 | <constant>GL_PIXEL_PACK_BUFFER</constant> target and the data would be packed to the buffer | |
240 | object such that the memory writes required would exceed the data store size. | |
241 | </para> | |
242 | <para> | |
243 | <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the | |
244 | <constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>image</parameter> is not evenly divisible | |
245 | into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>. | |
246 | </para> | |
247 | <para> | |
248 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetConvolutionFilter</function> is executed | |
249 | between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding | |
250 | execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
251 | </para> | |
252 | </refsect1> | |
253 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
254 | <para> | |
255 | <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry> | |
256 | </para> | |
257 | <para> | |
258 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_PACK_BUFFER_BINDING</constant> | |
259 | </para> | |
260 | </refsect1> | |
261 | <refsect1 id="seealso"><title>See Also</title> | |
262 | <para> | |
263 | <citerefentry><refentrytitle>glGetSeparableFilter</refentrytitle></citerefentry>, | |
264 | <citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>, | |
265 | <citerefentry><refentrytitle>glConvolutionFilter1D</refentrytitle></citerefentry>, | |
266 | <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry> | |
267 | </para> | |
268 | </refsect1> | |
269 | <refsect1 id="Copyright"><title>Copyright</title> | |
270 | <para> | |
271 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
272 | Silicon Graphics, Inc. This document is licensed under the SGI | |
273 | Free Software B License. For details, see | |
274 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
275 | </para> | |
276 | </refsect1> | |
277 | </refentry> |