upstream-doc/man2/glColorTable.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="glColorTable">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glColorTable</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glColorTable</refname>
  17         <refpurpose>define a color lookup table</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glColorTable</function></funcdef>
  23                 <paramdef>GLenum <parameter>target</parameter></paramdef>
  24                 <paramdef>GLenum <parameter>internalformat</parameter></paramdef>
  25                 <paramdef>GLsizei <parameter>width</parameter></paramdef>
  26                 <paramdef>GLenum <parameter>format</parameter></paramdef>
  27                 <paramdef>GLenum <parameter>type</parameter></paramdef>
  28                 <paramdef>const GLvoid * <parameter>data</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 one of
  39                     <constant>GL_COLOR_TABLE</constant>,
  40                     <constant>GL_POST_CONVOLUTION_COLOR_TABLE</constant>,
  41                     <constant>GL_POST_COLOR_MATRIX_COLOR_TABLE</constant>,
  42                     <constant>GL_PROXY_COLOR_TABLE</constant>,
  43                     <constant>GL_PROXY_POST_CONVOLUTION_COLOR_TABLE</constant>,
  44                     or
  45                     <constant>GL_PROXY_POST_COLOR_MATRIX_COLOR_TABLE</constant>.
  46                 </para>
  47             </listitem>
  48         </varlistentry>
  49         <varlistentry>
  50             <term><parameter>internalformat</parameter></term>
  51             <listitem>
  52                 <para>
  53                     The internal format of the color table.
  54                     The allowable values are
  55                     <constant>GL_ALPHA</constant>,
  56                     <constant>GL_ALPHA4</constant>,
  57                     <constant>GL_ALPHA8</constant>,
  58                     <constant>GL_ALPHA12</constant>,
  59                     <constant>GL_ALPHA16</constant>,
  60                     <constant>GL_LUMINANCE</constant>,
  61                     <constant>GL_LUMINANCE4</constant>,
  62                     <constant>GL_LUMINANCE8</constant>,
  63                     <constant>GL_LUMINANCE12</constant>,
  64                     <constant>GL_LUMINANCE16</constant>,
  65                     <constant>GL_LUMINANCE_ALPHA</constant>,
  66                     <constant>GL_LUMINANCE4_ALPHA4</constant>,
  67                     <constant>GL_LUMINANCE6_ALPHA2</constant>,
  68                     <constant>GL_LUMINANCE8_ALPHA8</constant>,
  69                     <constant>GL_LUMINANCE12_ALPHA4</constant>,
  70                     <constant>GL_LUMINANCE12_ALPHA12</constant>,
  71                     <constant>GL_LUMINANCE16_ALPHA16</constant>,
  72                     <constant>GL_INTENSITY</constant>,
  73                     <constant>GL_INTENSITY4</constant>,
  74                     <constant>GL_INTENSITY8</constant>,
  75                     <constant>GL_INTENSITY12</constant>,
  76                     <constant>GL_INTENSITY16</constant>,
  77                     <constant>GL_R3_G3_B2</constant>,
  78                     <constant>GL_RGB</constant>,
  79                     <constant>GL_RGB4</constant>,
  80                     <constant>GL_RGB5</constant>,
  81                     <constant>GL_RGB8</constant>,
  82                     <constant>GL_RGB10</constant>,
  83                     <constant>GL_RGB12</constant>,
  84                     <constant>GL_RGB16</constant>,
  85                     <constant>GL_RGBA</constant>,
  86                     <constant>GL_RGBA2</constant>,
  87                     <constant>GL_RGBA4</constant>,
  88                     <constant>GL_RGB5_A1</constant>,
  89                     <constant>GL_RGBA8</constant>,
  90                     <constant>GL_RGB10_A2</constant>,
  91                     <constant>GL_RGBA12</constant>, and
  92                     <constant>GL_RGBA16</constant>.
  93                 </para>
  94             </listitem>
  95         </varlistentry>
  96         <varlistentry>
  97             <term><parameter>width</parameter></term>
  98             <listitem>
  99                 <para>
 100                     The number of entries in the color lookup table specified by <parameter>data</parameter>.
 101                 </para>
 102             </listitem>
 103         </varlistentry>
 104         <varlistentry>
 105             <term><parameter>format</parameter></term>
 106             <listitem>
 107                 <para>
 108                     The format of the pixel data in <parameter>data</parameter>.
 109                     The allowable values are
 110                     <constant>GL_RED</constant>,
 111                     <constant>GL_GREEN</constant>,
 112                     <constant>GL_BLUE</constant>,
 113                     <constant>GL_ALPHA</constant>,
 114                     <constant>GL_LUMINANCE</constant>,
 115                     <constant>GL_LUMINANCE_ALPHA</constant>,
 116                     <constant>GL_RGB</constant>,
 117                     <constant>GL_BGR</constant>,
 118                     <constant>GL_RGBA</constant>, and
 119                     <constant>GL_BGRA</constant>.
 120                 </para>
 121             </listitem>
 122         </varlistentry>
 123         <varlistentry>
 124             <term><parameter>type</parameter></term>
 125             <listitem>
 126                 <para>
 127                     The type of the pixel data in <parameter>data</parameter>.
 128                     The allowable values are
 129                     <constant>GL_UNSIGNED_BYTE</constant>,
 130                     <constant>GL_BYTE</constant>,
 131                     <constant>GL_UNSIGNED_SHORT</constant>,
 132                     <constant>GL_SHORT</constant>,
 133                     <constant>GL_UNSIGNED_INT</constant>,
 134                     <constant>GL_INT</constant>,
 135                     <constant>GL_FLOAT</constant>,
 136                     <constant>GL_UNSIGNED_BYTE_3_3_2</constant>,
 137                     <constant>GL_UNSIGNED_BYTE_2_3_3_REV</constant>,
 138                     <constant>GL_UNSIGNED_SHORT_5_6_5</constant>,
 139                     <constant>GL_UNSIGNED_SHORT_5_6_5_REV</constant>,
 140                     <constant>GL_UNSIGNED_SHORT_4_4_4_4</constant>,
 141                     <constant>GL_UNSIGNED_SHORT_4_4_4_4_REV</constant>,
 142                     <constant>GL_UNSIGNED_SHORT_5_5_5_1</constant>,
 143                     <constant>GL_UNSIGNED_SHORT_1_5_5_5_REV</constant>,
 144                     <constant>GL_UNSIGNED_INT_8_8_8_8</constant>,
 145                     <constant>GL_UNSIGNED_INT_8_8_8_8_REV</constant>,
 146                     <constant>GL_UNSIGNED_INT_10_10_10_2</constant>, and
 147                     <constant>GL_UNSIGNED_INT_2_10_10_10_REV</constant>.
 148                 </para>
 149             </listitem>
 150         </varlistentry>
 151         <varlistentry>
 152             <term><parameter>data</parameter></term>
 153             <listitem>
 154                 <para>
 155                     Pointer to a one-dimensional array of pixel data that is processed to
 156                     build the color table.
 157                 </para>
 158             </listitem>
 159         </varlistentry>
 160         </variablelist>
 161     </refsect1>
 162     <refsect1 id="description"><title>Description</title>
 163         <para>
 164             <function>glColorTable</function> may be used in two ways:
 165             to test the actual size and color resolution of a lookup table
 166             given a particular set of parameters,
 167             or to load the contents of a color lookup
 168             table.
 169             Use the targets <constant>GL_PROXY_*</constant> for the first case
 170             and the other targets for the second case.
 171         </para>
 172         <para>
 173             If a non-zero named buffer object is bound to the <constant>GL_PIXEL_UNPACK_BUFFER</constant> target
 174             (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a color table is
 175             specified, <parameter>data</parameter> is treated as a byte offset into the buffer object's data store.
 176         </para>
 177         <para>
 178             If <parameter>target</parameter> is <constant>GL_COLOR_TABLE</constant>,
 179             <constant>GL_POST_CONVOLUTION_COLOR_TABLE</constant>,
 180             or
 181             <constant>GL_POST_COLOR_MATRIX_COLOR_TABLE</constant>,
 182             <function>glColorTable</function> builds a color lookup table from an array of pixels.
 183             The pixel array specified by <parameter>width</parameter>, <parameter>format</parameter>, <parameter>type</parameter>, and <parameter>data</parameter>
 184             is extracted from memory and
 185             processed just as if <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry> were called, but processing
 186             stops after the final expansion to RGBA is completed.
 187         </para>
 188         <para>
 189             The four scale parameters and the four bias parameters that are defined
 190             for the table are then used to scale and bias the R, G, B, and A components
 191             of each pixel.
 192             (Use <function>glColorTableParameter</function> to set these scale and bias
 193             parameters.)
 194         </para>
 195         <para>
 196             Next, the R, G, B, and A values are clamped to the range
 197             <inlineequation><mml:math>
 198                 <!-- eqn: [0,1]:-->
 199                 <mml:mfenced open="[" close="]">
 200                     <mml:mn>0</mml:mn>
 201                     <mml:mn>1</mml:mn>
 202                 </mml:mfenced>
 203             </mml:math></inlineequation>.
 204             Each pixel is then converted to the internal format specified by
 205             <parameter>internalformat</parameter>.
 206             This conversion simply maps the component values of the pixel (R, G, B,
 207             and A) to the values included in the internal format (red, green, blue,
 208             alpha, luminance, and intensity).  The mapping is as follows:
 209         </para>
 210         <para>
 211         </para>
 212         <informaltable frame="topbot">
 213             <tgroup cols="7" align="left">
 214                 <colspec colwidth="3*" />
 215                 <colspec colwidth="1*" align="center"/>
 216                 <colspec colwidth="1*" align="center"/>
 217                 <colspec colwidth="1*" align="center"/>
 218                 <colspec colwidth="1*" align="center"/>
 219                 <colspec colwidth="1.5*" align="center"/>
 220                 <colspec colwidth="1.5*" align="center"/>
 221                 <thead>
 222                     <row>
 223                         <entry rowsep="1" align="left"><emphasis role="bold">
 224                         Internal Format
 225                         </emphasis></entry>
 226                         <entry rowsep="1" align="center"><emphasis role="bold">
 227                         Red
 228                         </emphasis></entry>
 229                         <entry rowsep="1" align="center"><emphasis role="bold">
 230                         Green
 231                         </emphasis></entry>
 232                         <entry rowsep="1" align="center"><emphasis role="bold">
 233                         Blue
 234                         </emphasis></entry>
 235                         <entry rowsep="1" align="center"><emphasis role="bold">
 236                         Alpha
 237                         </emphasis></entry>
 238                         <entry rowsep="1" align="center"><emphasis role="bold">
 239                         Luminance
 240                         </emphasis></entry>
 241                         <entry rowsep="1" align="center"><emphasis role="bold">
 242                         Intensity
 243                         </emphasis></entry>
 244                     </row>
 245                 </thead>
 246                 <tbody>
 247                     <row>
 248                         <entry align="left">
 249                         <constant>GL_ALPHA</constant>
 250                         </entry>
 251                         <entry align="center">
 252                         </entry>
 253                         <entry align="center">
 254                         </entry>
 255                         <entry align="center">
 256                         </entry>
 257                         <entry align="center">
 258                         A
 259                         </entry>
 260                         <entry align="center">
 261                         </entry>
 262                         <entry align="center">
 263
 264                         </entry>
 265                     </row>
 266                     <row>
 267                         <entry align="left">
 268                         <constant>GL_LUMINANCE</constant>
 269                         </entry>
 270                         <entry align="center">
 271                         </entry>
 272                         <entry align="center">
 273                         </entry>
 274                         <entry align="center">
 275                         </entry>
 276                         <entry align="center">
 277                         </entry>
 278                         <entry align="center">
 279                         R
 280                         </entry>
 281                         <entry align="center">
 282
 283                         </entry>
 284                     </row>
 285                     <row>
 286                         <entry align="left">
 287                         <constant>GL_LUMINANCE_ALPHA</constant>
 288                         </entry>
 289                         <entry align="center">
 290                         </entry>
 291                         <entry align="center">
 292                         </entry>
 293                         <entry align="center">
 294                         </entry>
 295                         <entry align="center">
 296                         A
 297                         </entry>
 298                         <entry align="center">
 299                         R
 300                         </entry>
 301                         <entry align="center">
 302
 303                         </entry>
 304                     </row>
 305                     <row>
 306                         <entry align="left">
 307                         <constant>GL_INTENSITY</constant>
 308                         </entry>
 309                         <entry align="center">
 310                         </entry>
 311                         <entry align="center">
 312                         </entry>
 313                         <entry align="center">
 314                         </entry>
 315                         <entry align="center">
 316                         </entry>
 317                         <entry align="center">
 318                         </entry>
 319                         <entry align="center">
 320                         R
 321                         </entry>
 322                     </row>
 323                     <row>
 324                         <entry align="left">
 325                         <constant>GL_RGB</constant>
 326                         </entry>
 327                         <entry align="center">
 328                         R
 329                         </entry>
 330                         <entry align="center">
 331                         G
 332                         </entry>
 333                         <entry align="center">
 334                         B
 335                         </entry>
 336                         <entry align="center">
 337                         </entry>
 338                         <entry align="center">
 339                         </entry>
 340                         <entry align="center">
 341
 342                         </entry>
 343                     </row>
 344                     <row>
 345                         <entry align="left">
 346                         <constant>GL_RGBA</constant>
 347                         </entry>
 348                         <entry align="center">
 349                         R
 350                         </entry>
 351                         <entry align="center">
 352                         G
 353                         </entry>
 354                         <entry align="center">
 355                         B
 356                         </entry>
 357                         <entry align="center">
 358                         A
 359                         </entry>
 360                         <entry align="center">
 361                         </entry>
 362                         <entry align="center">
 363
 364                         </entry>
 365                     </row>
 366                 </tbody>
 367             </tgroup>
 368         </informaltable>
 369         <para>
 370             Finally, the red, green, blue, alpha, luminance, and/or intensity components of
 371             the resulting pixels are stored in the color table.
 372             They form a one-dimensional table with indices in the range
 373             <inlineequation><mml:math>
 374                 <!-- eqn: [0, width-1]:-->
 375                 <mml:mfenced open="[" close="]">
 376                     <mml:mn>0</mml:mn>
 377                     <mml:mrow>
 378                         <mml:mi mathvariant="italic">width</mml:mi>
 379                         <mml:mo>-</mml:mo>
 380                         <mml:mn>1</mml:mn>
 381                     </mml:mrow>
 382                 </mml:mfenced>
 383             </mml:math></inlineequation>.
 384         </para>
 385         <para>
 386             If <parameter>target</parameter> is <constant>GL_PROXY_*</constant>,
 387             <function>glColorTable</function> recomputes and stores the values of the proxy color table's state
 388             variables
 389             <constant>GL_COLOR_TABLE_FORMAT</constant>,
 390             <constant>GL_COLOR_TABLE_WIDTH</constant>,
 391             <constant>GL_COLOR_TABLE_RED_SIZE</constant>,
 392             <constant>GL_COLOR_TABLE_GREEN_SIZE</constant>,
 393             <constant>GL_COLOR_TABLE_BLUE_SIZE</constant>,
 394             <constant>GL_COLOR_TABLE_ALPHA_SIZE</constant>,
 395             <constant>GL_COLOR_TABLE_LUMINANCE_SIZE</constant>, and
 396             <constant>GL_COLOR_TABLE_INTENSITY_SIZE</constant>.
 397             There is no effect on the image or state of any actual color table.
 398             If the specified color table is too large to be supported, then all the
 399             proxy state variables listed above are set to zero.
 400             Otherwise, the color table could be supported by <function>glColorTable</function>
 401             using the corresponding non-proxy target,
 402             and the proxy state variables are set as if that target were being defined.
 403         </para>
 404         <para>
 405             The proxy state variables can be retrieved by calling
 406             <citerefentry><refentrytitle>glGetColorTableParameter</refentrytitle></citerefentry> with a target of
 407             <constant>GL_PROXY_*</constant>.
 408             This allows the application to decide if a particular <function>glColorTable</function>
 409             command would succeed, and to determine what the resulting color table
 410             attributes would be.
 411         </para>
 412         <para>
 413             If a color table is enabled, and its width is non-zero, then its
 414             contents are used to replace a subset of the components of each RGBA
 415             pixel group, based on the internal format of the table.
 416         </para>
 417         <para>
 418             Each pixel group has color components (R, G, B, A)
 419             that are in the range
 420             <inlineequation><mml:math>
 421                 <!-- eqn: [0.0, 1.0]:-->
 422                 <mml:mfenced open="[" close="]">
 423                     <mml:mn>0.0</mml:mn>
 424                     <mml:mn>1.0</mml:mn>
 425                 </mml:mfenced>
 426             </mml:math></inlineequation>.
 427             The color components are rescaled to
 428             the size of the color lookup table to form an index.
 429             Then a subset of the components based on the internal format of the table are
 430             replaced by the table entry selected by that index.
 431             If the color components and contents of the table are represented as follows:
 432         </para>
 433         <para>
 434         </para>
 435         <informaltable frame="topbot">
 436             <tgroup cols="2" align="left">
 437                 <colspec align="center"/>
 438                 <colspec align="center"/>
 439                 <thead>
 440                     <row>
 441                         <entry rowsep="1" align="center"><emphasis role="bold">
 442                         Representation
 443                         </emphasis></entry>
 444                         <entry rowsep="1" align="center"><emphasis role="bold">
 445                         Meaning
 446                         </emphasis></entry>
 447                     </row>
 448                 </thead>
 449                 <tbody>
 450                     <row>
 451                         <entry align="center">
 452                         <code>r</code>
 453                         </entry>
 454                         <entry align="left">
 455                         Table index computed from <code>R</code>
 456                         </entry>
 457                     </row>
 458                     <row>
 459                         <entry align="center">
 460                         <code>g</code>
 461                         </entry>
 462                         <entry align="left">
 463                         Table index computed from <code>G</code>
 464                         </entry>
 465                     </row>
 466                     <row>
 467                         <entry align="center">
 468                         <code>b</code>
 469                         </entry>
 470                         <entry align="left">
 471                         Table index computed from <code>B</code>
 472                         </entry>
 473                     </row>
 474                     <row>
 475                         <entry align="center">
 476                         <code>a</code>
 477                         </entry>
 478                         <entry align="left">
 479                         Table index computed from <code>A</code>
 480                         </entry>
 481                     </row>
 482                     <row>
 483                         <entry align="center">
 484                         <code>L[i]</code>
 485                         </entry>
 486                         <entry align="left">
 487                         Luminance value at table index <code>i</code>
 488                         </entry>
 489                     </row>
 490                     <row>
 491                         <entry align="center">
 492                         <code>I[i]</code>
 493                         </entry>
 494                         <entry align="left">
 495                         Intensity value at table index <code>i</code>
 496                         </entry>
 497                     </row>
 498                     <row>
 499                         <entry align="center">
 500                         <code>R[i]</code>
 501                         </entry>
 502                         <entry align="left">
 503                         Red value at table index <code>i</code>
 504                         </entry>
 505                     </row>
 506                     <row>
 507                         <entry align="center">
 508                         <code>G[i]</code>
 509                         </entry>
 510                         <entry align="left">
 511                         Green value at table index <code>i</code>
 512                         </entry>
 513                     </row>
 514                     <row>
 515                         <entry align="center">
 516                         <code>B[i]</code>
 517                         </entry>
 518                         <entry align="left">
 519                         Blue value at table index <code>i</code>
 520                         </entry>
 521                     </row>
 522                     <row>
 523                         <entry align="center">
 524                         <code>A[i]</code>
 525                         </entry>
 526                         <entry align="left">
 527                         Alpha value at table index <code>i</code>
 528                         </entry>
 529                     </row>
 530                 </tbody>
 531             </tgroup>
 532         </informaltable>
 533         <para>
 534             then the result of color table lookup is as follows:
 535         </para>
 536         <para>
 537         </para>
 538         <informaltable frame="topbot">
 539             <tgroup cols="5" align="left">
 540                 <colspec colwidth="2*" />
 541                 <colspec colwidth="1*" colname="r"/>
 542                 <colspec colwidth="1*" colname="g"/>
 543                 <colspec colwidth="1*" colname="b"/>
 544                 <colspec colwidth="1*" colname="a"/>
 545                 <thead>
 546                     <row>
 547                         <entry align="left"><emphasis role="bold">
 548                         </emphasis></entry>
 549                         <entry namest="r" nameend="a" align="center"><emphasis role="bold">
 550                         Resulting Texture Components
 551                         </emphasis></entry>
 552                     </row>
 553                     <row>
 554                         <entry rowsep="1" align="left"><emphasis role="bold">
 555                         Table Internal Format
 556                         </emphasis></entry>
 557                         <entry rowsep="1" align="center"><emphasis role="bold">
 558                         R
 559                         </emphasis></entry>
 560                         <entry rowsep="1" align="center"><emphasis role="bold">
 561                         G
 562                         </emphasis></entry>
 563                         <entry rowsep="1" align="center"><emphasis role="bold">
 564                         B
 565                         </emphasis></entry>
 566                         <entry rowsep="1" align="center"><emphasis role="bold">
 567                         A
 568                         </emphasis></entry>
 569                     </row>
 570                 </thead>
 571                 <tbody>
 572                     <row>
 573                         <entry align="left">
 574                         <constant>GL_ALPHA</constant>
 575                         </entry>
 576                         <entry align="center">
 577                         <code>R</code>
 578                         </entry>
 579                         <entry align="center">
 580                         <code>G</code>
 581                         </entry>
 582                         <entry align="center">
 583                         <code>B</code>
 584                         </entry>
 585                         <entry align="center">
 586                         <code>A[a]</code>
 587                         </entry>
 588                     </row>
 589                     <row>
 590                         <entry align="left">
 591                         <constant>GL_LUMINANCE</constant>
 592                         </entry>
 593                         <entry align="center">
 594                         <code>L[r]</code>
 595                         </entry>
 596                         <entry align="center">
 597                         <code>L[g]</code>
 598                         </entry>
 599                         <entry align="center">
 600                         <code>L[b]</code>
 601                         </entry>
 602                         <entry align="center">
 603                         <code>At</code>
 604                         </entry>
 605                     </row>
 606                     <row>
 607                         <entry align="left">
 608                         <constant>GL_LUMINANCE_ALPHA</constant>
 609                         </entry>
 610                         <entry align="center">
 611                         <code>L[r]</code>
 612                         </entry>
 613                         <entry align="center">
 614                         <code>L[g]</code>
 615                         </entry>
 616                         <entry align="center">
 617                         <code>L[b]</code>
 618                         </entry>
 619                         <entry align="center">
 620                         <code>A[a]</code>
 621                         </entry>
 622                     </row>
 623                     <row>
 624                         <entry align="left">
 625                         <constant>GL_INTENSITY</constant>
 626                         </entry>
 627                         <entry align="center">
 628                         <code>I[r]</code>
 629                         </entry>
 630                         <entry align="center">
 631                         <code>I[g]</code>
 632                         </entry>
 633                         <entry align="center">
 634                         <code>I[b]</code>
 635                         </entry>
 636                         <entry align="center">
 637                         <code>I[a]</code>
 638                         </entry>
 639                     </row>
 640                     <row>
 641                         <entry align="left">
 642                         <constant>GL_RGB</constant>
 643                         </entry>
 644                         <entry align="center">
 645                         <code>R[r]</code>
 646                         </entry>
 647                         <entry align="center">
 648                         <code>G[g]</code>
 649                         </entry>
 650                         <entry align="center">
 651                         <code>B[b]</code>
 652                         </entry>
 653                         <entry align="center">
 654                         <code>A</code>
 655                         </entry>
 656                     </row>
 657                     <row>
 658                         <entry align="left">
 659                         <constant>GL_RGBA</constant>
 660                         </entry>
 661                         <entry align="center">
 662                         <code>R[r]</code>
 663                         </entry>
 664                         <entry align="center">
 665                         <code>G[g]</code>
 666                         </entry>
 667                         <entry align="center">
 668                         <code>B[b]</code>
 669                         </entry>
 670                         <entry align="center">
 671                         <code>A[a]</code>
 672                         </entry>
 673                     </row>
 674                 </tbody>
 675             </tgroup>
 676         </informaltable>
 677         <para>
 678             When <constant>GL_COLOR_TABLE</constant> is enabled, the colors resulting from
 679             the pixel map operation (if it is enabled) are mapped
 680             by the color lookup table before being passed to the convolution
 681             operation. The colors resulting from the convolution operation
 682             are modified by the post convolution color lookup table when
 683             <constant>GL_POST_CONVOLUTION_COLOR_TABLE</constant>
 684             is enabled. These modified colors are then sent to the color matrix operation.
 685             Finally, if <constant>GL_POST_COLOR_MATRIX_COLOR_TABLE</constant>
 686             is enabled, the colors resulting from the color matrix operation
 687             are mapped by the post color matrix color lookup table before being
 688             used by the histogram operation.
 689         </para>
 690         <para>
 691         </para>
 692     </refsect1>
 693     <refsect1 id="notes"><title>Notes</title>
 694         <para>
 695             <function>glColorTable</function> is present only if <code>ARB_imaging</code> is returned when <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
 696             is called with an argument of <constant>GL_EXTENSIONS</constant>.
 697         </para>
 698         <para>
 699             If <parameter>target</parameter> is set to <constant>GL_COLOR_TABLE</constant>,
 700             <constant>GL_POST_CONVOLUTION_COLOR_TABLE</constant>,
 701             or <constant>GL_POST_COLOR_MATRIX_COLOR_TABLE</constant>,
 702             then <parameter>width</parameter> must be a power of two or a <constant>GL_INVALID_VALUE</constant>
 703             error is generated.
 704         </para>
 705         <para>
 706         </para>
 707     </refsect1>
 708     <refsect1 id="errors"><title>Errors</title>
 709         <para>
 710             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not one of the allowable
 711             values.
 712         </para>
 713         <para>
 714             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>internalformat</parameter> is not one of the
 715             allowable values.
 716         </para>
 717         <para>
 718             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>format</parameter> is not one of the allowable
 719             values.
 720         </para>
 721         <para>
 722             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>type</parameter> is not one of the allowable
 723             values.
 724         </para>
 725         <para>
 726             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>width</parameter> is less than zero.
 727         </para>
 728         <para>
 729             <constant>GL_TABLE_TOO_LARGE</constant> is generated if the requested color table
 730             is too large to be supported by the implementation, and <parameter>target</parameter> is
 731             not a <constant>GL_PROXY_*</constant> target.
 732         </para>
 733         <para>
 734             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 735             <constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
 736         </para>
 737         <para>
 738             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 739             <constant>GL_PIXEL_UNPACK_BUFFER</constant> target and the data would be unpacked from the buffer
 740             object such that the memory reads required would exceed the data store size.
 741         </para>
 742         <para>
 743             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
 744             <constant>GL_PIXEL_UNPACK_BUFFER</constant> target and <parameter>data</parameter> is not evenly divisible
 745             into the number of bytes needed to store in memory a datum indicated by <parameter>type</parameter>.
 746         </para>
 747         <para>
 748             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glColorTable</function> is executed
 749             between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
 750             execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 751         </para>
 752     </refsect1>
 753     <refsect1 id="associatedgets"><title>Associated Gets</title>
 754         <para>
 755             <citerefentry><refentrytitle>glGetColorTableParameter</refentrytitle></citerefentry>
 756         </para>
 757         <para>
 758             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_UNPACK_BUFFER_BINDING</constant>
 759         </para>
 760     </refsect1>
 761     <refsect1 id="seealso"><title>See Also</title>
 762         <para>
 763             <citerefentry><refentrytitle>glColorSubTable</refentrytitle></citerefentry>,
 764             <function>glColorTableParameter</function>,
 765             <citerefentry><refentrytitle>glCopyColorTable</refentrytitle></citerefentry>,
 766             <citerefentry><refentrytitle>glCopyColorSubTable</refentrytitle></citerefentry>,
 767             <citerefentry><refentrytitle>glGetColorTable</refentrytitle></citerefentry>
 768         </para>
 769     </refsect1>
 770     <refsect1 id="Copyright"><title>Copyright</title>
 771         <para>
 772             Copyright <trademark class="copyright"></trademark> 1991-2006
 773             Silicon Graphics, Inc. This document is licensed under the SGI
 774             Free Software B License. For details, see
 775             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 776         </para>
 777     </refsect1>
 778 </refentry>