upstream-man-pages/man2/glGetSeparableFilter.xml

   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="glGetSeparableFilter">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glGetSeparableFilter</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glGetSeparableFilter</refname>
  17         <refpurpose>get separable convolution filter kernel images</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glGetSeparableFilter</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>row</parameter></paramdef>
  27                 <paramdef>GLvoid * <parameter>column</parameter></paramdef>
  28                 <paramdef>GLvoid * <parameter>span</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                     The separable filter to be retrieved.
  39                     Must be
  40                     <constant>GL_SEPARABLE_2D</constant>.
  41                 </para>
  42             </listitem>
  43         </varlistentry>
  44         <varlistentry>
  45             <term><parameter>format</parameter></term>
  46             <listitem>
  47                 <para>
  48                     Format of the output images.
  49                     Must be one of
  50                     <constant>GL_RED</constant>,
  51                     <constant>GL_GREEN</constant>,
  52                     <constant>GL_BLUE</constant>,
  53                     <constant>GL_ALPHA</constant>,
  54                     <constant>GL_RGB</constant>,
  55                     <constant>GL_BGR</constant>
  56                     <constant>GL_RGBA</constant>,
  57                     <constant>GL_BGRA</constant>,
  58                     <constant>GL_LUMINANCE</constant>, or
  59                     <constant>GL_LUMINANCE_ALPHA</constant>.
  60                 </para>
  61             </listitem>
  62         </varlistentry>
  63         <varlistentry>
  64             <term><parameter>type</parameter></term>
  65             <listitem>
  66                 <para>
  67                     Data type of components in the output images.
  68                     Symbolic constants
  69                     <constant>GL_UNSIGNED_BYTE</constant>,
  70                     <constant>GL_BYTE</constant>,
  71                     <constant>GL_BITMAP</constant>,
  72                     <constant>GL_UNSIGNED_SHORT</constant>,
  73                     <constant>GL_SHORT</constant>,
  74                     <constant>GL_UNSIGNED_INT</constant>,
  75                     <constant>GL_INT</constant>,
  76                     <constant>GL_FLOAT</constant>,
  77                     <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
  78                     <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
  79                     <constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
  80                     <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
  81                     <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
  82                     <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
  83                     <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
  84                     <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
  85                     <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
  86                     <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
  87                     <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and
  88                     <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
  89                     are accepted.
  90                 </para>
  91             </listitem>
  92         </varlistentry>
  93         <varlistentry>
  94             <term><parameter>row</parameter></term>
  95             <listitem>
  96                 <para>
  97                     Pointer to storage for the row filter image.
  98                 </para>
  99             </listitem>
 100         </varlistentry>
 101         <varlistentry>
 102             <term><parameter>column</parameter></term>
 103             <listitem>
 104                 <para>
 105                     Pointer to storage for the column filter image.
 106                 </para>
 107             </listitem>
 108         </varlistentry>
 109         <varlistentry>
 110             <term><parameter>span</parameter></term>
 111             <listitem>
 112                 <para>
 113                     Pointer to storage for the span filter image (currently unused).
 114                 </para>
 115             </listitem>
 116         </varlistentry>
 117         </variablelist>
 118     </refsect1>
 119     <refsect1 id="description"><title>Description</title>
 120         <para>
 121             <function>glGetSeparableFilter</function> returns the two one-dimensional filter kernel images for the
 122             current separable 2D convolution filter.
 123             The row image is placed in <parameter>row</parameter> and the column image is placed in
 124             <parameter>column</parameter> according to the specifications in <parameter>format</parameter> and <parameter>type</parameter>.
 125             (In the current implementation, <parameter>span</parameter> is not affected in any way.)
 126             No pixel transfer operations are performed on the images, but the relevant
 127             pixel storage modes are applied.
 128         </para>
 129         <para>
 130             If a non-zero named buffer object is bound to the <constant>GL_PIXEL_PACK_BUFFER</constant> target
 131             (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a separable convolution filter is
 132             requested, <parameter>row</parameter>, <parameter>column</parameter>, and <parameter>span</parameter> are treated as a byte offset into the buffer object's data store.
 133         </para>
 134         <para>
 135             Color components that are present in <parameter>format</parameter> but not included in the
 136             internal format of the filters are returned as zero.
 137             The assignments of internal color components to the components of <parameter>format</parameter>
 138             are as follows:
 139         </para>
 140         <para>
 141         </para>
 142         <informaltable frame="topbot">
 143             <tgroup cols="2" align="left">
 144                 <colspec align="center"/>
 145                 <colspec align="center"/>
 146                 <thead>
 147                     <row>
 148                         <entry rowsep="1" align="center"><emphasis role="bold">
 149                         Internal Component
 150                         </emphasis></entry>
 151                         <entry rowsep="1" align="center"><emphasis role="bold">
 152                         Resulting Component
 153                         </emphasis></entry>
 154                     </row>
 155                 </thead>
 156                 <tbody>
 157                     <row>
 158                         <entry align="left">
 159                         Red
 160                         </entry>
 161                         <entry align="left">
 162                         Red
 163                         </entry>
 164                     </row>
 165                     <row>
 166                         <entry align="left">
 167                         Green
 168                         </entry>
 169                         <entry align="left">
 170                         Green
 171                         </entry>
 172                     </row>
 173                     <row>
 174                         <entry align="left">
 175                         Blue
 176                         </entry>
 177                         <entry align="left">
 178                         Blue
 179                         </entry>
 180                     </row>
 181                     <row>
 182                         <entry align="left">
 183                         Alpha
 184                         </entry>
 185                         <entry align="left">
 186                         Alpha
 187                         </entry>
 188                     </row>
 189                     <row>
 190                         <entry align="left">
 191                         Luminance
 192                         </entry>
 193                         <entry align="left">
 194                         Red
 195                         </entry>
 196                     </row>
 197                     <row>
 198                         <entry align="left">
 199                         Intensity
 200                         </entry>
 201                         <entry align="left">
 202                         Red
 203                         </entry>
 204                     </row>
 205                 </tbody>
 206             </tgroup>
 207         </informaltable>
 208         <para>
 209         </para>
 210     </refsect1>
 211     <refsect1 id="notes"><title>Notes</title>
 212         <para>
 213             <function>glGetSeparableFilter</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
 214             is called with an argument of <constant>GL_EXTENSIONS</constant>.
 215         </para>
 216         <para>
 217             Non-separable 2D filters must be retrieved with <citerefentry><refentrytitle>glGetConvolutionFilter</refentrytitle></citerefentry>.
 218         </para>
 219     </refsect1>
 220     <refsect1 id="errors"><title>Errors</title>
 221         <para>
 222             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not <constant>GL_SEPARABLE_2D</constant>.
 223         </para>
 224         <para>
 225             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>format</parameter> is not one of the allowable
 226             values.
 227         </para>
 228         <para>
 229             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not one of the allowable
 230             values.
 231         </para>
 232         <para>
 233             <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>type</parameter> is one of
 234             <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
 235             <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
 236             <constant>GL_UNSIGNED_SHORT_5_6_5</constant>, or
 237             <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>
 238             and <parameter>format</parameter> is not <constant>GL_RGB</constant>.
 239         </para>
 240         <para>
 241             <constant>GL_INVALID_OPERATION</constant> is generated if <parameter>type</parameter> is one of
 242             <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
 243             <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
 244             <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
 245             <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
 246             <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
 247             <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
 248             <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, or
 249             <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>
 250             and <parameter>format</parameter> is neither <constant>GL_RGBA</constant> nor <constant>GL_BGRA</constant>.
 251         </para>
 252         <para>
 253             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 254             <constant>GL_PIXEL_PACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
 255         </para>
 256         <para>
 257             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 258             <constant>GL_PIXEL_PACK_BUFFER</constant> target and the data would be packed to the buffer
 259             object such that the memory writes required would exceed the data store size.
 260         </para>
 261         <para>
 262             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 263             <constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>row</parameter> or <parameter>column</parameter> is not evenly divisible
 264             into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>.
 265         </para>
 266         <para>
 267             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetSeparableFilter</function> is executed
 268             between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
 269             execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 270         </para>
 271     </refsect1>
 272     <refsect1 id="associatedgets"><title>Associated Gets</title>
 273         <para>
 274             <citerefentry><refentrytitle>glGetConvolutionParameter</refentrytitle></citerefentry>
 275         </para>
 276         <para>
 277             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_PACK_BUFFER_BINDING</constant>
 278         </para>
 279     </refsect1>
 280     <refsect1 id="seealso"><title>See Also</title>
 281         <para>
 282             <citerefentry><refentrytitle>glGetConvolutionFilter</refentrytitle></citerefentry>,
 283             <citerefentry><refentrytitle>glConvolutionParameter</refentrytitle></citerefentry>,
 284             <citerefentry><refentrytitle>glSeparableFilter2D</refentrytitle></citerefentry>
 285         </para>
 286     </refsect1>
 287     <refsect1 id="Copyright"><title>Copyright</title>
 288         <para>
 289             Copyright <trademark class="copyright"></trademark> 1991-2006
 290             Silicon Graphics, Inc. This document is licensed under the SGI
 291             Free Software B License. For details, see
 292             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 293         </para>
 294     </refsect1>
 295 </refentry>