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3 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glCopyConvolutionFilter2D</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glCopyConvolutionFilter2D"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glCopyConvolutionFilter2D — copy pixels into a two-dimensional convolution filter</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glCopyConvolutionFilter2D</b>(</code></td><td>GLenum </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLenum </td><td><var class="pdparam">internalformat</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">x</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">y</var>, </td></tr><tr><td> </td><td>GLsizei </td><td><var class="pdparam">width</var>, </td></tr><tr><td> </td><td>GLsizei </td><td><var class="pdparam">height</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>target</code></em></span></dt><dd><p> | |
4 | Must be <code class="constant">GL_CONVOLUTION_2D</code>. | |
5 | </p></dd><dt><span class="term"><em class="parameter"><code>internalformat</code></em></span></dt><dd><p> | |
6 | The internal format of the convolution filter kernel. | |
7 | The allowable values are | |
8 | <code class="constant">GL_ALPHA</code>, | |
9 | <code class="constant">GL_ALPHA4</code>, | |
10 | <code class="constant">GL_ALPHA8</code>, | |
11 | <code class="constant">GL_ALPHA12</code>, | |
12 | <code class="constant">GL_ALPHA16</code>, | |
13 | <code class="constant">GL_LUMINANCE</code>, | |
14 | <code class="constant">GL_LUMINANCE4</code>, | |
15 | <code class="constant">GL_LUMINANCE8</code>, | |
16 | <code class="constant">GL_LUMINANCE12</code>, | |
17 | <code class="constant">GL_LUMINANCE16</code>, | |
18 | <code class="constant">GL_LUMINANCE_ALPHA</code>, | |
19 | <code class="constant">GL_LUMINANCE4_ALPHA4</code>, | |
20 | <code class="constant">GL_LUMINANCE6_ALPHA2</code>, | |
21 | <code class="constant">GL_LUMINANCE8_ALPHA8</code>, | |
22 | <code class="constant">GL_LUMINANCE12_ALPHA4</code>, | |
23 | <code class="constant">GL_LUMINANCE12_ALPHA12</code>, | |
24 | <code class="constant">GL_LUMINANCE16_ALPHA16</code>, | |
25 | <code class="constant">GL_INTENSITY</code>, | |
26 | <code class="constant">GL_INTENSITY4</code>, | |
27 | <code class="constant">GL_INTENSITY8</code>, | |
28 | <code class="constant">GL_INTENSITY12</code>, | |
29 | <code class="constant">GL_INTENSITY16</code>, | |
30 | <code class="constant">GL_R3_G3_B2</code>, | |
31 | <code class="constant">GL_RGB</code>, | |
32 | <code class="constant">GL_RGB4</code>, | |
33 | <code class="constant">GL_RGB5</code>, | |
34 | <code class="constant">GL_RGB8</code>, | |
35 | <code class="constant">GL_RGB10</code>, | |
36 | <code class="constant">GL_RGB12</code>, | |
37 | <code class="constant">GL_RGB16</code>, | |
38 | <code class="constant">GL_RGBA</code>, | |
39 | <code class="constant">GL_RGBA2</code>, | |
40 | <code class="constant">GL_RGBA4</code>, | |
41 | <code class="constant">GL_RGB5_A1</code>, | |
42 | <code class="constant">GL_RGBA8</code>, | |
43 | <code class="constant">GL_RGB10_A2</code>, | |
44 | <code class="constant">GL_RGBA12</code>, or | |
45 | <code class="constant">GL_RGBA16</code>. | |
46 | </p></dd><dt><span class="term"><em class="parameter"><code>x</code></em>, </span><span class="term"><em class="parameter"><code>y</code></em></span></dt><dd><p> | |
47 | The window space coordinates of the lower-left coordinate of the | |
48 | pixel array to copy. | |
49 | </p></dd><dt><span class="term"><em class="parameter"><code>width</code></em></span></dt><dd><p> | |
50 | The width of the pixel array to copy. | |
51 | </p></dd><dt><span class="term"><em class="parameter"><code>height</code></em></span></dt><dd><p> | |
52 | The height of the pixel array to copy. | |
53 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
54 | <code class="function">glCopyConvolutionFilter2D</code> defines a two-dimensional convolution filter kernel with pixels | |
55 | from the current <code class="constant">GL_READ_BUFFER</code> (rather than from main memory, | |
56 | as is the case for <a class="citerefentry" href="glConvolutionFilter2D.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionFilter2D</span></span></a>). | |
57 | </p><p> | |
58 | The screen-aligned pixel rectangle with lower-left corner at (<em class="parameter"><code>x</code></em>,\ <em class="parameter"><code>y</code></em>), | |
59 | width <em class="parameter"><code>width</code></em> and height <em class="parameter"><code>height</code></em> | |
60 | is used to define the convolution filter. If any pixels within this | |
61 | region are | |
62 | outside the window that is associated with the GL context, the | |
63 | values obtained for those pixels are undefined. | |
64 | </p><p> | |
65 | The pixels in the rectangle are processed | |
66 | exactly as if <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a> had been called with <span class="emphasis"><em>format</em></span> | |
67 | set to RGBA, but the process stops just before final conversion. | |
68 | The R, G, B, and A components of each pixel are next scaled by the four | |
69 | 2D <code class="constant">GL_CONVOLUTION_FILTER_SCALE</code> parameters and biased by the | |
70 | four 2D <code class="constant">GL_CONVOLUTION_FILTER_BIAS</code> parameters. | |
71 | (The scale and bias parameters are set by <a class="citerefentry" href="glConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionParameter</span></span></a> | |
72 | using the <code class="constant">GL_CONVOLUTION_2D</code> target and the names | |
73 | <code class="constant">GL_CONVOLUTION_FILTER_SCALE</code> and <code class="constant">GL_CONVOLUTION_FILTER_BIAS</code>. | |
74 | The parameters themselves are vectors of four values that are applied to red, | |
75 | green, blue, and alpha, in that order.) | |
76 | The R, G, B, and A values are not clamped to [0,1] at any time during this | |
77 | process. | |
78 | </p><p> | |
79 | Each pixel is then converted to the internal format specified by | |
80 | <em class="parameter"><code>internalformat</code></em>. | |
81 | This conversion simply maps the component values of the pixel (R, G, B, | |
82 | and A) to the values included in the internal format (red, green, blue, | |
83 | alpha, luminance, and intensity). The mapping is as follows: | |
84 | </p><p> | |
85 | </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> | |
86 | Internal Format | |
87 | </strong></span></th><th align="center"><span class="bold"><strong> | |
88 | Red | |
89 | </strong></span></th><th align="center"><span class="bold"><strong> | |
90 | Green | |
91 | </strong></span></th><th align="center"><span class="bold"><strong> | |
92 | Blue | |
93 | </strong></span></th><th align="center"><span class="bold"><strong> | |
94 | Alpha | |
95 | </strong></span></th><th align="center"><span class="bold"><strong> | |
96 | Luminance | |
97 | </strong></span></th><th align="center"><span class="bold"><strong> | |
98 | Intensity | |
99 | </strong></span></th></tr></thead><tbody><tr><td align="left"> | |
100 | <code class="constant">GL_ALPHA</code> | |
101 | </td><td align="center"> | |
102 | </td><td align="center"> | |
103 | </td><td align="center"> | |
104 | </td><td align="center"> | |
105 | A | |
106 | </td><td align="center"> | |
107 | </td><td align="center"> | |
108 | ||
109 | </td></tr><tr><td align="left"> | |
110 | <code class="constant">GL_LUMINANCE</code> | |
111 | </td><td align="center"> | |
112 | </td><td align="center"> | |
113 | </td><td align="center"> | |
114 | </td><td align="center"> | |
115 | </td><td align="center"> | |
116 | R | |
117 | </td><td align="center"> | |
118 | ||
119 | </td></tr><tr><td align="left"> | |
120 | <code class="constant">GL_LUMINANCE_ALPHA</code> | |
121 | </td><td align="center"> | |
122 | </td><td align="center"> | |
123 | </td><td align="center"> | |
124 | </td><td align="center"> | |
125 | A | |
126 | </td><td align="center"> | |
127 | R | |
128 | </td><td align="center"> | |
129 | ||
130 | </td></tr><tr><td align="left"> | |
131 | <code class="constant">GL_INTENSITY</code> | |
132 | </td><td align="center"> | |
133 | </td><td align="center"> | |
134 | </td><td align="center"> | |
135 | </td><td align="center"> | |
136 | </td><td align="center"> | |
137 | </td><td align="center"> | |
138 | R | |
139 | </td></tr><tr><td align="left"> | |
140 | <code class="constant">GL_RGB</code> | |
141 | </td><td align="center"> | |
142 | R | |
143 | </td><td align="center"> | |
144 | G | |
145 | </td><td align="center"> | |
146 | B | |
147 | </td><td align="center"> | |
148 | </td><td align="center"> | |
149 | </td><td align="center"> | |
150 | ||
151 | </td></tr><tr><td align="left"> | |
152 | <code class="constant">GL_RGBA</code> | |
153 | </td><td align="center"> | |
154 | R | |
155 | </td><td align="center"> | |
156 | G | |
157 | </td><td align="center"> | |
158 | B | |
159 | </td><td align="center"> | |
160 | A | |
161 | </td><td align="center"> | |
162 | </td><td align="center"> | |
163 | ||
164 | </td></tr></tbody></table></div><p> | |
165 | The red, green, blue, alpha, luminance, and/or intensity components of | |
166 | the resulting pixels are stored in floating-point rather than integer | |
167 | format. | |
168 | </p><p> | |
169 | Pixel ordering is such that lower x screen coordinates correspond to | |
170 | lower <span class="emphasis"><em>i</em></span> filter image coordinates, and lower y screen coordinates | |
171 | correspond to lower <span class="emphasis"><em>j</em></span> filter image coordinates. | |
172 | </p><p> | |
173 | Note that after a convolution is performed, the resulting color | |
174 | components are also scaled by their corresponding | |
175 | <code class="constant">GL_POST_CONVOLUTION_c_SCALE</code> parameters and biased by their | |
176 | corresponding <code class="constant">GL_POST_CONVOLUTION_c_BIAS</code> parameters (where | |
177 | <span class="emphasis"><em>c</em></span> takes on the values <span class="bold"><strong>RED</strong></span>, <span class="bold"><strong>GREEN</strong></span>, <span class="bold"><strong>BLUE</strong></span>, and | |
178 | <span class="bold"><strong>ALPHA</strong></span>). | |
179 | These parameters are set by <a class="citerefentry" href="glPixelTransfer.xml"><span class="citerefentry"><span class="refentrytitle">glPixelTransfer</span></span></a>. | |
180 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> | |
181 | <code class="function">glCopyConvolutionFilter2D</code> is present only if <code class="code">ARB_imaging</code> is returned when <a class="citerefentry" href="glGetString.xml"><span class="citerefentry"><span class="refentrytitle">glGetString</span></span></a> | |
182 | is called with an argument of <code class="constant">GL_EXTENSIONS</code>. | |
183 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
184 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not | |
185 | <code class="constant">GL_CONVOLUTION_2D</code>. | |
186 | </p><p> | |
187 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>internalformat</code></em> is not one of the | |
188 | allowable values. | |
189 | </p><p> | |
190 | <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>width</code></em> is less than zero or greater | |
191 | than the maximum supported value. | |
192 | This value may be queried with <a class="citerefentry" href="glGetConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionParameter</span></span></a> | |
193 | using target <code class="constant">GL_CONVOLUTION_2D</code> and name | |
194 | <code class="constant">GL_MAX_CONVOLUTION_WIDTH</code>. | |
195 | </p><p> | |
196 | <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>height</code></em> is less than zero or greater | |
197 | than the maximum supported value. | |
198 | This value may be queried with <a class="citerefentry" href="glGetConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionParameter</span></span></a> | |
199 | using target <code class="constant">GL_CONVOLUTION_2D</code> and name | |
200 | <code class="constant">GL_MAX_CONVOLUTION_HEIGHT</code>. | |
201 | </p><p> | |
202 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glCopyConvolutionFilter2D</code> is executed | |
203 | between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding | |
204 | execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>. | |
205 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
206 | <a class="citerefentry" href="glGetConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionParameter</span></span></a>, <a class="citerefentry" href="glGetConvolutionFilter.xml"><span class="citerefentry"><span class="refentrytitle">glGetConvolutionFilter</span></span></a> | |
207 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
208 | <a class="citerefentry" href="glConvolutionFilter2D.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionFilter2D</span></span></a>, | |
209 | <a class="citerefentry" href="glConvolutionParameter.xml"><span class="citerefentry"><span class="refentrytitle">glConvolutionParameter</span></span></a>, | |
210 | <a class="citerefentry" href="glPixelTransfer.xml"><span class="citerefentry"><span class="refentrytitle">glPixelTransfer</span></span></a> | |
211 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
212 | Copyright <span class="trademark"></span>© 1991-2006 | |
213 | Silicon Graphics, Inc. This document is licensed under the SGI | |
214 | Free Software B License. For details, see | |
215 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
216 | </p></div></div></body></html> |