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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="glConvolutionParameter"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glConvolutionParameter</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glConvolutionParameter</refname> | |
17 | <refpurpose>set convolution parameters</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glConvolutionParameterf</function></funcdef> | |
23 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
24 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
25 | <paramdef>GLfloat <parameter>params</parameter></paramdef> | |
26 | </funcprototype> | |
27 | </funcsynopsis> | |
28 | <funcsynopsis> | |
29 | <funcprototype> | |
30 | <funcdef>void <function>glConvolutionParameteri</function></funcdef> | |
31 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
32 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
33 | <paramdef>GLint <parameter>params</parameter></paramdef> | |
34 | </funcprototype> | |
35 | </funcsynopsis> | |
36 | </refsynopsisdiv> | |
37 | <!-- eqn: ignoring delim $$ --> | |
38 | <para> | |
39 | </para> | |
40 | <refsect1 id="parameters"><title>Parameters</title> | |
41 | <variablelist> | |
42 | <varlistentry> | |
43 | <term><parameter>target</parameter></term> | |
44 | <listitem> | |
45 | <para> | |
46 | The target for the convolution parameter. | |
47 | Must be one of | |
48 | <constant>GL_CONVOLUTION_1D</constant>, | |
49 | <constant>GL_CONVOLUTION_2D</constant>, or | |
50 | <constant>GL_SEPARABLE_2D</constant>. | |
51 | </para> | |
52 | </listitem> | |
53 | </varlistentry> | |
54 | <varlistentry> | |
55 | <term><parameter>pname</parameter></term> | |
56 | <listitem> | |
57 | <para> | |
58 | The parameter to be set. | |
59 | Must be | |
60 | <constant>GL_CONVOLUTION_BORDER_MODE</constant>. | |
61 | </para> | |
62 | </listitem> | |
63 | </varlistentry> | |
64 | <varlistentry> | |
65 | <term><parameter>params</parameter></term> | |
66 | <listitem> | |
67 | <para> | |
68 | The parameter value. | |
69 | Must be one of | |
70 | <constant>GL_REDUCE</constant>, <constant>GL_CONSTANT_BORDER</constant>, <constant>GL_REPLICATE_BORDER</constant>. | |
71 | </para> | |
72 | <para> | |
73 | </para> | |
74 | </listitem> | |
75 | </varlistentry> | |
76 | </variablelist> | |
77 | </refsect1> | |
78 | <refsynopsisdiv><title>C Specification</title> | |
79 | <funcsynopsis> | |
80 | <funcprototype> | |
81 | <funcdef>void <function>glConvolutionParameterfv</function></funcdef> | |
82 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
83 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
84 | <paramdef>const GLfloat * <parameter>params</parameter></paramdef> | |
85 | </funcprototype> | |
86 | </funcsynopsis> | |
87 | <funcsynopsis> | |
88 | <funcprototype> | |
89 | <funcdef>void <function>glConvolutionParameteriv</function></funcdef> | |
90 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
91 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
92 | <paramdef>const GLint * <parameter>params</parameter></paramdef> | |
93 | </funcprototype> | |
94 | </funcsynopsis> | |
95 | </refsynopsisdiv> | |
96 | <para> | |
97 | </para> | |
98 | <refsect1 id="parameters2"><title>Parameters</title> | |
99 | <variablelist> | |
100 | <varlistentry> | |
101 | <term><parameter>target</parameter></term> | |
102 | <listitem> | |
103 | <para> | |
104 | The target for the convolution parameter. | |
105 | Must be one of | |
106 | <constant>GL_CONVOLUTION_1D</constant>, | |
107 | <constant>GL_CONVOLUTION_2D</constant>, or | |
108 | <constant>GL_SEPARABLE_2D</constant>. | |
109 | </para> | |
110 | </listitem> | |
111 | </varlistentry> | |
112 | <varlistentry> | |
113 | <term><parameter>pname</parameter></term> | |
114 | <listitem> | |
115 | <para> | |
116 | The parameter to be set. | |
117 | Must be one of | |
118 | <constant>GL_CONVOLUTION_BORDER_MODE</constant>, | |
119 | <constant>GL_CONVOLUTION_BORDER_COLOR</constant>, | |
120 | <constant>GL_CONVOLUTION_FILTER_SCALE</constant>, or | |
121 | <constant>GL_CONVOLUTION_FILTER_BIAS</constant>. | |
122 | </para> | |
123 | </listitem> | |
124 | </varlistentry> | |
125 | <varlistentry> | |
126 | <term><parameter>params</parameter></term> | |
127 | <listitem> | |
128 | <para> | |
129 | The parameter value. | |
130 | If <parameter>pname</parameter>v is <constant>GL_CONVOLUTION_BORDER_MODE</constant>, <parameter>params</parameter>v must be one of | |
131 | <constant>GL_REDUCE</constant>, <constant>GL_CONSTANT_BORDER</constant>, or <constant>GL_REPLICATE_BORDER</constant>. | |
132 | Otherwise, must be a vector of four values (for red, green, blue, and alpha, | |
133 | respectively) to be used for | |
134 | scaling (when <parameter>pname</parameter>v is <constant>GL_CONVOLUTION_FILTER_SCALE</constant>), or | |
135 | biasing (when <parameter>pname</parameter>v is <constant>GL_CONVOLUTION_FILTER_BIAS</constant>) a convolution | |
136 | filter kernel or setting the constant border color (when <parameter>pname</parameter>v is | |
137 | <constant>GL_CONVOLUTION_BORDER_COLOR</constant>. | |
138 | </para> | |
139 | </listitem> | |
140 | </varlistentry> | |
141 | </variablelist> | |
142 | </refsect1> | |
143 | <refsect1 id="description"><title>Description</title> | |
144 | <para> | |
145 | <function>glConvolutionParameter</function> sets the value of a convolution parameter. | |
146 | </para> | |
147 | <para> | |
148 | <parameter>target</parameter> selects the convolution filter to be affected: | |
149 | <constant>GL_CONVOLUTION_1D</constant>, | |
150 | <constant>GL_CONVOLUTION_2D</constant>, or | |
151 | <constant>GL_SEPARABLE_2D</constant> | |
152 | for the 1D, 2D, or separable 2D filter, respectively. | |
153 | </para> | |
154 | <para> | |
155 | <parameter>pname</parameter> selects the parameter to be changed. | |
156 | <constant>GL_CONVOLUTION_FILTER_SCALE</constant> and <constant>GL_CONVOLUTION_FILTER_BIAS</constant> | |
157 | affect the definition of the convolution filter kernel; see | |
158 | <citerefentry><refentrytitle>glConvolutionFilter1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>, and | |
159 | <citerefentry><refentrytitle>glSeparableFilter2D</refentrytitle></citerefentry> for details. | |
160 | In these cases, <parameter>params</parameter>v is an array of four values to be applied to | |
161 | red, green, blue, and alpha values, respectively. The initial value for | |
162 | <constant>GL_CONVOLUTION_FILTER_SCALE</constant> is (1, 1, 1, 1), and the initial value | |
163 | for <constant>GL_CONVOLUTION_FILTER_BIAS</constant> is (0, 0, 0, 0). | |
164 | </para> | |
165 | <para> | |
166 | A <parameter>pname</parameter> value of <constant>GL_CONVOLUTION_BORDER_MODE</constant> controls the | |
167 | convolution border mode. The accepted modes are: | |
168 | </para> | |
169 | <variablelist> | |
170 | <varlistentry> | |
171 | <term><constant>GL_REDUCE</constant></term> | |
172 | <listitem> | |
173 | <para> | |
174 | The image resulting from convolution is | |
175 | smaller than the source image. | |
176 | If the filter width is | |
177 | <inlineequation><mml:math><mml:mi mathvariant="italic">Wf</mml:mi></mml:math></inlineequation> | |
178 | and height is | |
179 | <inlineequation><mml:math><mml:mi mathvariant="italic">Hf</mml:mi></mml:math></inlineequation>, | |
180 | and the source image width is | |
181 | <inlineequation><mml:math><mml:mi mathvariant="italic">Ws</mml:mi></mml:math></inlineequation> | |
182 | and height is | |
183 | <inlineequation><mml:math><mml:mi mathvariant="italic">Hs</mml:mi></mml:math></inlineequation>, | |
184 | then the convolved image width will be | |
185 | <inlineequation><mml:math> | |
186 | <!-- eqn: Ws - Wf + 1:--> | |
187 | <mml:mrow> | |
188 | <mml:mi mathvariant="italic">Ws</mml:mi> | |
189 | <mml:mo>-</mml:mo> | |
190 | <mml:mi mathvariant="italic">Wf</mml:mi> | |
191 | <mml:mo>+</mml:mo> | |
192 | <mml:mn>1</mml:mn> | |
193 | </mml:mrow> | |
194 | </mml:math></inlineequation> | |
195 | and height | |
196 | will be | |
197 | <inlineequation><mml:math> | |
198 | <!-- eqn: Hs - Hf + 1:--> | |
199 | <mml:mrow> | |
200 | <mml:mi mathvariant="italic">Hs</mml:mi> | |
201 | <mml:mo>-</mml:mo> | |
202 | <mml:mi mathvariant="italic">Hf</mml:mi> | |
203 | <mml:mo>+</mml:mo> | |
204 | <mml:mn>1</mml:mn> | |
205 | </mml:mrow> | |
206 | </mml:math></inlineequation>. | |
207 | (If this reduction would generate an image with zero or negative width | |
208 | and/or height, the output is simply null, with no error generated.) | |
209 | The coordinates of the image resulting from convolution are zero | |
210 | through | |
211 | <inlineequation><mml:math> | |
212 | <!-- eqn: Ws - Wf:--> | |
213 | <mml:mrow> | |
214 | <mml:mi mathvariant="italic">Ws</mml:mi> | |
215 | <mml:mo>-</mml:mo> | |
216 | <mml:mi mathvariant="italic">Wf</mml:mi> | |
217 | </mml:mrow> | |
218 | </mml:math></inlineequation> | |
219 | in width and zero through | |
220 | <inlineequation><mml:math> | |
221 | <!-- eqn: Hs - Hf:--> | |
222 | <mml:mrow> | |
223 | <mml:mi mathvariant="italic">Hs</mml:mi> | |
224 | <mml:mo>-</mml:mo> | |
225 | <mml:mi mathvariant="italic">Hf</mml:mi> | |
226 | </mml:mrow> | |
227 | </mml:math></inlineequation> | |
228 | in | |
229 | height. | |
230 | </para> | |
231 | </listitem> | |
232 | </varlistentry> | |
233 | <varlistentry> | |
234 | <term><constant>GL_CONSTANT_BORDER</constant></term> | |
235 | <listitem> | |
236 | <para> | |
237 | The image resulting from convolution is the same size as the source image, and | |
238 | processed as if the source image were surrounded by pixels with their color | |
239 | specified by the <constant>GL_CONVOLUTION_BORDER_COLOR</constant>. | |
240 | </para> | |
241 | </listitem> | |
242 | </varlistentry> | |
243 | <varlistentry> | |
244 | <term><constant>GL_REPLICATE_BORDER</constant></term> | |
245 | <listitem> | |
246 | <para> | |
247 | The image resulting from convolution is the same size as the source image, and | |
248 | processed as if the outermost pixel on the border of the source image were | |
249 | replicated. | |
250 | </para> | |
251 | </listitem> | |
252 | </varlistentry> | |
253 | </variablelist> | |
254 | </refsect1> | |
255 | <refsect1 id="notes"><title>Notes</title> | |
256 | <para> | |
257 | <function>glConvolutionParameter</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry> | |
258 | is called with an argument of <constant>GL_EXTENSIONS</constant>. | |
259 | </para> | |
260 | <para> | |
261 | In cases where errors can result from the specification of invalid | |
262 | image dimensions, it is the dimensions after convolution that are | |
263 | tested, not the dimensions of the source image. | |
264 | For example, <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry> requires power-of-two image size. | |
265 | When <constant>GL_REDUCE</constant> border mode is in effect, | |
266 | the source image must be larger than the final power-of-two size | |
267 | by one less than the size of the 1D filter kernel. | |
268 | </para> | |
269 | </refsect1> | |
270 | <refsect1 id="errors"><title>Errors</title> | |
271 | <para> | |
272 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not one of the allowable | |
273 | values. | |
274 | </para> | |
275 | <para> | |
276 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is not one of the allowable | |
277 | values. | |
278 | </para> | |
279 | <para> | |
280 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is | |
281 | <constant>GL_CONVOLUTION_BORDER_MODE</constant> and <parameter>params</parameter> is not one of | |
282 | <constant>GL_REDUCE</constant>, <constant>GL_CONSTANT_BORDER</constant>, or <constant>GL_REPLICATE_BORDER</constant>. | |
283 | </para> | |
284 | <para> | |
285 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glConvolutionParameter</function> is executed | |
286 | between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding | |
287 | execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
288 | </para> | |
289 | </refsect1> | |
290 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
291 | <para> | |
292 | <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry> | |
293 | </para> | |
294 | </refsect1> | |
295 | <refsect1 id="seealso"><title>See Also</title> | |
296 | <para> | |
297 | <citerefentry><refentrytitle>glConvolutionFilter1D</refentrytitle></citerefentry>, | |
298 | <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>, | |
299 | <citerefentry><refentrytitle>glSeparableFilter2D</refentrytitle></citerefentry>, | |
300 | <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry> | |
301 | </para> | |
302 | </refsect1> | |
303 | <refsect1 id="Copyright"><title>Copyright</title> | |
304 | <para> | |
305 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
306 | Silicon Graphics, Inc. This document is licensed under the SGI | |
307 | Free Software B License. For details, see | |
308 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
309 | </para> | |
310 | </refsect1> | |
311 | </refentry> |