upstream-man-pages/man3/xhtml/glPixelStore.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
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   4 <?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" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glPixelStore</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div class="refentry" title="glPixelStore"><a id="glPixelStore"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glPixelStore — set pixel storage modes</p></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glPixelStoref</b>(</code></td><td>GLenum <var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLfloat <var class="pdparam">param</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glPixelStorei</b>(</code></td><td>GLenum <var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLint <var class="pdparam">param</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>pname</code></em></span></dt><dd><p>
   5                     Specifies the symbolic name of the parameter to be set.
   6                     Six values affect the packing of pixel data into memory:
   7                     <code class="constant">GL_PACK_SWAP_BYTES</code>,
   8                     <code class="constant">GL_PACK_LSB_FIRST</code>,
   9                     <code class="constant">GL_PACK_ROW_LENGTH</code>,
  10                     <code class="constant">GL_PACK_IMAGE_HEIGHT</code>,
  11                     <code class="constant">GL_PACK_SKIP_PIXELS</code>,
  12                     <code class="constant">GL_PACK_SKIP_ROWS</code>,
  13                     <code class="constant">GL_PACK_SKIP_IMAGES</code>, and
  14                     <code class="constant">GL_PACK_ALIGNMENT</code>.
  15                     Six more affect the unpacking of pixel data <span class="emphasis"><em>from</em></span> memory:
  16                     <code class="constant">GL_UNPACK_SWAP_BYTES</code>,
  17                     <code class="constant">GL_UNPACK_LSB_FIRST</code>,
  18                     <code class="constant">GL_UNPACK_ROW_LENGTH</code>,
  19                     <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code>,
  20                     <code class="constant">GL_UNPACK_SKIP_PIXELS</code>,
  21                     <code class="constant">GL_UNPACK_SKIP_ROWS</code>,
  22                     <code class="constant">GL_UNPACK_SKIP_IMAGES</code>, and
  23                     <code class="constant">GL_UNPACK_ALIGNMENT</code>.
  24                 </p></dd><dt><span class="term"><em class="parameter"><code>param</code></em></span></dt><dd><p>
  25                     Specifies the value that <em class="parameter"><code>pname</code></em> is set to.
  26                 </p></dd></dl></div></div><div class="refsect1" title="Description"><a id="description"></a><h2>Description</h2><p>
  27             <code class="function">glPixelStore</code> sets pixel storage modes that affect the operation of subsequent
  28             <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a> as well as the unpacking of
  29             texture patterns (see <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
  30             <a class="citerefentry" href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>, <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>, <a class="citerefentry" href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
  31             <a class="citerefentry" href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>, <a class="citerefentry" href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>).
  32         </p><p>
  33             <em class="parameter"><code>pname</code></em> is a symbolic constant indicating the parameter to be set, and
  34             <em class="parameter"><code>param</code></em> is the new value.  Six of the twelve storage parameters affect
  35             how pixel data is returned to client memory.
  36             They are as follows:
  37         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_PACK_SWAP_BYTES</code></span></dt><dd><p>
  38                         If true,
  39                         byte ordering for multibyte color components,
  40                         depth components,
  41                         or stencil indices
  42                         is reversed.
  43                         That is,
  44                         if a four-byte component consists of bytes
  45                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  46
  47                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  48                             <mml:mn>0</mml:mn>
  49                             </mml:msub>
  50                         </mml:math>,
  51                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  52
  53                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  54                             <mml:mn>1</mml:mn>
  55                             </mml:msub>
  56                         </mml:math>,
  57                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  58
  59                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  60                             <mml:mn>2</mml:mn>
  61                             </mml:msub>
  62                         </mml:math>,
  63                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  64
  65                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  66                             <mml:mn>3</mml:mn>
  67                             </mml:msub>
  68                         </mml:math>,
  69                         it is stored in memory as
  70                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  71
  72                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  73                             <mml:mn>3</mml:mn>
  74                             </mml:msub>
  75                         </mml:math>,
  76                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  77
  78                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  79                             <mml:mn>2</mml:mn>
  80                             </mml:msub>
  81                         </mml:math>,
  82                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  83
  84                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  85                             <mml:mn>1</mml:mn>
  86                             </mml:msub>
  87                         </mml:math>,
  88                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  89
  90                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  91                             <mml:mn>0</mml:mn>
  92                             </mml:msub>
  93                         </mml:math>
  94                         if <code class="constant">GL_PACK_SWAP_BYTES</code> is true.
  95                         <code class="constant">GL_PACK_SWAP_BYTES</code> has no effect on the memory order of components
  96                         within a pixel,
  97                         only on the order of bytes within components or indices.
  98                         For example,
  99                         the three components of a <code class="constant">GL_RGB</code> format pixel are always stored with
 100                         red first,
 101                         green second,
 102                         and blue third,
 103                         regardless of the value of <code class="constant">GL_PACK_SWAP_BYTES</code>.
 104                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_LSB_FIRST</code></span></dt><dd><p>
 105                         If true,
 106                         bits are ordered within a byte from least significant to most significant;
 107                         otherwise,
 108                         the first bit in each byte is the most significant one.
 109                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_ROW_LENGTH</code></span></dt><dd><p>
 110                         If greater than 0,
 111                         <code class="constant">GL_PACK_ROW_LENGTH</code> defines the number of pixels in a row.
 112                         If the first pixel of a row is placed at location
 113                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 114                         in memory,
 115                         then the location of the first pixel of the next row is obtained by skipping
 116                     </p><p>
 117                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 118
 119                             <mml:mrow>
 120                                 <mml:mi mathvariant="italic">k</mml:mi>
 121                                 <mml:mo>=</mml:mo>
 122                                 <mml:mfenced open="{" close="">
 123                                     <mml:mrow>
 124                                         <mml:mtable>
 125                                             <mml:mtr><mml:mtd>
 126                                                 <mml:mrow>
 127                                                     <mml:mi mathvariant="italic">n</mml:mi>
 128                                                     <mml:mo>⁢</mml:mo>
 129                                                     <mml:mi mathvariant="italic">l</mml:mi>
 130                                                 </mml:mrow>
 131                                             </mml:mtd></mml:mtr>
 132                                             <mml:mtr><mml:mtd>
 133                                                 <mml:mrow>
 134                                                     <mml:mfenced open="" close="">
 135                                                         <mml:mfrac>
 136                                                             <mml:mi mathvariant="italic">a</mml:mi>
 137                                                             <mml:mi mathvariant="italic">s</mml:mi>
 138                                                         </mml:mfrac>
 139                                                     </mml:mfenced>
 140                                                     <mml:mo>⁢</mml:mo>
 141                                                     <mml:mfenced open="⌈" close="⌉">
 142                                                         <mml:mfrac>
 143                                                             <mml:mfenced open="" close="">
 144                                                                 <mml:mrow>
 145                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 146                                                                     <mml:mo>⁢</mml:mo>
 147                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 148                                                                     <mml:mo>⁢</mml:mo>
 149                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 150                                                                 </mml:mrow>
 151                                                             </mml:mfenced>
 152                                                             <mml:mi mathvariant="italic">a</mml:mi>
 153                                                         </mml:mfrac>
 154                                                     </mml:mfenced>
 155                                                 </mml:mrow>
 156                                             </mml:mtd></mml:mtr>
 157                                         </mml:mtable>
 158                                         <mml:mo>⁢</mml:mo>
 159                                         <mml:mtable>
 160                                             <mml:mtr><mml:mtd>
 161                                                 <mml:mrow>
 162                                                     <mml:mi mathvariant="italic">s</mml:mi>
 163                                                     <mml:mo>&gt;=</mml:mo>
 164                                                     <mml:mi mathvariant="italic">a</mml:mi>
 165                                                 </mml:mrow>
 166                                             </mml:mtd></mml:mtr>
 167                                             <mml:mtr><mml:mtd>
 168                                                 <mml:mrow>
 169                                                     <mml:mi mathvariant="italic">s</mml:mi>
 170                                                     <mml:mo>&lt;</mml:mo>
 171                                                     <mml:mi mathvariant="italic">a</mml:mi>
 172                                                 </mml:mrow>
 173                                             </mml:mtd></mml:mtr>
 174                                         </mml:mtable>
 175                                     </mml:mrow>
 176                                 </mml:mfenced>
 177                             </mml:mrow>
 178                         </mml:math></div><p>
 179                     </p><p>
 180                         components or indices,
 181                         where
 182                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 183                         is the number of components or indices in a pixel,
 184                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 185                         is the number of pixels in a row
 186                         (<code class="constant">GL_PACK_ROW_LENGTH</code> if it is greater than 0,
 187                         the
 188                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 189                         argument to the pixel routine otherwise),
 190                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 191                         is the value of <code class="constant">GL_PACK_ALIGNMENT</code>, and
 192                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 193                         is the size, in bytes, of a single component
 194                         (if
 195                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 196
 197                             <mml:mrow>
 198                                 <mml:mi mathvariant="italic">a</mml:mi>
 199                                 <mml:mo>&lt;</mml:mo>
 200                                 <mml:mi mathvariant="italic">s</mml:mi>
 201                             </mml:mrow>
 202                         </mml:math>,
 203                         then it is as if
 204                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 205
 206                             <mml:mrow>
 207                                 <mml:mi mathvariant="italic">a</mml:mi>
 208                                 <mml:mo>=</mml:mo>
 209                                 <mml:mi mathvariant="italic">s</mml:mi>
 210                             </mml:mrow>
 211                         </mml:math>).
 212                         In the case of 1-bit values,
 213                         the location of the next row is obtained by skipping
 214                     </p><p>
 215                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 216
 217                             <mml:mrow>
 218                                 <mml:mi mathvariant="italic">k</mml:mi>
 219                                 <mml:mo>=</mml:mo>
 220                                 <mml:mrow>
 221                                     <mml:mn>8</mml:mn>
 222                                     <mml:mo>⁢</mml:mo>
 223                                     <mml:mi mathvariant="italic">a</mml:mi>
 224                                     <mml:mo>⁢</mml:mo>
 225                                     <mml:mfenced open="⌈" close="⌉">
 226                                         <mml:mfrac>
 227                                             <mml:mfenced open="" close="">
 228                                                 <mml:mrow>
 229                                                     <mml:mi mathvariant="italic">n</mml:mi>
 230                                                     <mml:mo>⁢</mml:mo>
 231                                                     <mml:mi mathvariant="italic">l</mml:mi>
 232                                                 </mml:mrow>
 233                                             </mml:mfenced>
 234                                             <mml:mfenced open="" close="">
 235                                                 <mml:mrow>
 236                                                     <mml:mn>8</mml:mn>
 237                                                     <mml:mo>⁢</mml:mo>
 238                                                     <mml:mi mathvariant="italic">a</mml:mi>
 239                                                 </mml:mrow>
 240                                             </mml:mfenced>
 241                                         </mml:mfrac>
 242                                     </mml:mfenced>
 243                                 </mml:mrow>
 244                             </mml:mrow>
 245                         </mml:math>
 246                     </p><p>
 247                         components or indices.
 248                     </p><p>
 249                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 250                         red,
 251                         green,
 252                         blue,
 253                         alpha,
 254                         and depth.
 255                         Storage format <code class="constant">GL_RGB</code>,
 256                         for example,
 257                         has three components per pixel:
 258                         first red,
 259                         then green,
 260                         and finally blue.
 261                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_IMAGE_HEIGHT</code></span></dt><dd><p>
 262                         If greater than 0,
 263                         <code class="constant">GL_PACK_IMAGE_HEIGHT</code> defines the number of pixels in an image
 264                         three-dimensional texture volume, where ``image'' is defined by all pixels
 265                         sharing the same third dimension index.
 266                         If the first pixel of a row is placed at location
 267                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 268                         in memory,
 269                         then the location of the first pixel of the next row is obtained by skipping
 270                     </p><p>
 271                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 272
 273                             <mml:mrow>
 274                                 <mml:mi mathvariant="italic">k</mml:mi>
 275                                 <mml:mo>=</mml:mo>
 276                                 <mml:mfenced open="{" close="">
 277                                     <mml:mrow>
 278                                         <mml:mtable>
 279                                             <mml:mtr><mml:mtd>
 280                                                 <mml:mrow>
 281                                                     <mml:mi mathvariant="italic">n</mml:mi>
 282                                                     <mml:mo>⁢</mml:mo>
 283                                                     <mml:mi mathvariant="italic">l</mml:mi>
 284                                                     <mml:mo>⁢</mml:mo>
 285                                                     <mml:mi mathvariant="italic">h</mml:mi>
 286                                                 </mml:mrow>
 287                                             </mml:mtd></mml:mtr>
 288                                             <mml:mtr><mml:mtd>
 289                                                 <mml:mrow>
 290                                                     <mml:mfenced open="" close="">
 291                                                         <mml:mfrac>
 292                                                             <mml:mi mathvariant="italic">a</mml:mi>
 293                                                             <mml:mi mathvariant="italic">s</mml:mi>
 294                                                         </mml:mfrac>
 295                                                     </mml:mfenced>
 296                                                     <mml:mo>⁢</mml:mo>
 297                                                     <mml:mfenced open="⌈" close="⌉">
 298                                                         <mml:mfrac>
 299                                                             <mml:mfenced open="" close="">
 300                                                                 <mml:mrow>
 301                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 302                                                                     <mml:mo>⁢</mml:mo>
 303                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 304                                                                     <mml:mo>⁢</mml:mo>
 305                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 306                                                                     <mml:mo>⁢</mml:mo>
 307                                                                     <mml:mi mathvariant="italic">h</mml:mi>
 308                                                                 </mml:mrow>
 309                                                             </mml:mfenced>
 310                                                             <mml:mi mathvariant="italic">a</mml:mi>
 311                                                         </mml:mfrac>
 312                                                     </mml:mfenced>
 313                                                 </mml:mrow>
 314                                             </mml:mtd></mml:mtr>
 315                                         </mml:mtable>
 316                                         <mml:mo>⁢</mml:mo>
 317                                         <mml:mtable>
 318                                             <mml:mtr><mml:mtd>
 319                                                 <mml:mrow>
 320                                                     <mml:mi mathvariant="italic">s</mml:mi>
 321                                                     <mml:mo>&gt;=</mml:mo>
 322                                                     <mml:mi mathvariant="italic">a</mml:mi>
 323                                                 </mml:mrow>
 324                                             </mml:mtd></mml:mtr>
 325                                             <mml:mtr><mml:mtd>
 326                                                 <mml:mrow>
 327                                                     <mml:mi mathvariant="italic">s</mml:mi>
 328                                                     <mml:mo>&lt;</mml:mo>
 329                                                     <mml:mi mathvariant="italic">a</mml:mi>
 330                                                 </mml:mrow>
 331                                             </mml:mtd></mml:mtr>
 332                                         </mml:mtable>
 333                                     </mml:mrow>
 334                                 </mml:mfenced>
 335                             </mml:mrow>
 336                         </mml:math></div><p>
 337                     </p><p>
 338                         components or indices, where
 339                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 340                         is the number of components or indices
 341                         in a pixel,
 342                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 343                         is the number of pixels in a row
 344                         (<code class="constant">GL_PACK_ROW_LENGTH</code> if it is greater than 0, the
 345                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 346                         argument to <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> otherwise),
 347                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math>
 348                         is the number of
 349                         rows in a pixel image (<code class="constant">GL_PACK_IMAGE_HEIGHT</code> if it is greater than
 350                         0, the
 351                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">height</mml:mi></mml:math>
 352                         argument to the <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> routine otherwise),
 353                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 354                         is the value of
 355                         <code class="constant">GL_PACK_ALIGNMENT</code>, and
 356                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 357                         is the size, in bytes, of a single
 358                         component (if
 359                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 360
 361                             <mml:mrow>
 362                                 <mml:mi mathvariant="italic">a</mml:mi>
 363                                 <mml:mo>&lt;</mml:mo>
 364                                 <mml:mi mathvariant="italic">s</mml:mi>
 365                             </mml:mrow>
 366                         </mml:math>,
 367                         then it is as if
 368                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 369
 370                             <mml:mrow>
 371                                 <mml:mi mathvariant="italic">a</mml:mi>
 372                                 <mml:mo>=</mml:mo>
 373                                 <mml:mi mathvariant="italic">s</mml:mi>
 374                             </mml:mrow>
 375                         </mml:math>).
 376                     </p><p>
 377                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 378                         red,
 379                         green,
 380                         blue,
 381                         alpha,
 382                         and depth.
 383                         Storage format <code class="constant">GL_RGB</code>,
 384                         for example,
 385                         has three components per pixel:
 386                         first red,
 387                         then green,
 388                         and finally blue.
 389                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_SKIP_PIXELS</code>, <code class="constant">GL_PACK_SKIP_ROWS</code>, and <code class="constant">GL_PACK_SKIP_IMAGES</code></span></dt><dd><p>
 390                         These values are provided as a convenience to the programmer;
 391                         they provide no functionality that cannot be duplicated simply by
 392                         incrementing the pointer passed to <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>.
 393                         Setting <code class="constant">GL_PACK_SKIP_PIXELS</code> to
 394                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>
 395                         is equivalent to incrementing
 396                         the pointer by
 397                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 398
 399                             <mml:mrow>
 400                                 <mml:mi mathvariant="italic">i</mml:mi>
 401                                 <mml:mo>⁢</mml:mo>
 402                                 <mml:mi mathvariant="italic">n</mml:mi>
 403                             </mml:mrow>
 404                         </mml:math>
 405                         components or indices,
 406                         where
 407                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 408                         is the number of components or indices in each pixel.
 409                         Setting <code class="constant">GL_PACK_SKIP_ROWS</code> to
 410                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>
 411                         is equivalent to incrementing
 412                         the pointer by
 413                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 414
 415                             <mml:mrow>
 416                                 <mml:mi mathvariant="italic">j</mml:mi>
 417                                 <mml:mo>⁢</mml:mo>
 418                                 <mml:mi mathvariant="italic">m</mml:mi>
 419                             </mml:mrow>
 420                         </mml:math>
 421                         components or indices,
 422                         where
 423                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">m</mml:mi></mml:math>
 424                         is the number of components or indices per row,
 425                         as just computed in the <code class="constant">GL_PACK_ROW_LENGTH</code> section.
 426                         Setting <code class="constant">GL_PACK_SKIP_IMAGES</code> to
 427                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">k</mml:mi></mml:math>
 428                         is equivalent to incrementing
 429                         the pointer by
 430                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 431
 432                             <mml:mrow>
 433                                 <mml:mi mathvariant="italic">k</mml:mi>
 434                                 <mml:mo>⁢</mml:mo>
 435                                 <mml:mi mathvariant="italic">p</mml:mi>
 436                             </mml:mrow>
 437                         </mml:math>,
 438                         where
 439                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 440                         is the number of components or indices
 441                         per image, as computed in the <code class="constant">GL_PACK_IMAGE_HEIGHT</code> section.
 442                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_ALIGNMENT</code></span></dt><dd><p>
 443                         Specifies the alignment requirements for the start of each pixel row in memory.
 444                         The allowable values are
 445                         1 (byte-alignment),
 446                         2 (rows aligned to even-numbered bytes),
 447                         4 (word-alignment), and
 448                         8 (rows start on double-word boundaries).
 449                     </p></dd></dl></div><p>
 450             The other six of the twelve storage parameters affect how pixel data is
 451             read from client memory.
 452             These values are significant for
 453             <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 454             <a class="citerefentry" href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 455             <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
 456             <a class="citerefentry" href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
 457             <a class="citerefentry" href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>, and
 458             <a class="citerefentry" href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>
 459         </p><p>
 460             They are as follows:
 461         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_UNPACK_SWAP_BYTES</code></span></dt><dd><p>
 462                         If true,
 463                         byte ordering for multibyte color components,
 464                         depth components,
 465                         or stencil indices
 466                         is reversed.
 467                         That is,
 468                         if a four-byte component consists of bytes
 469                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 470
 471                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 472                             <mml:mn>0</mml:mn>
 473                             </mml:msub>
 474                         </mml:math>,
 475                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 476
 477                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 478                             <mml:mn>1</mml:mn>
 479                             </mml:msub>
 480                         </mml:math>,
 481                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 482
 483                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 484                             <mml:mn>2</mml:mn>
 485                             </mml:msub>
 486                         </mml:math>,
 487                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 488
 489                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 490                             <mml:mn>3</mml:mn>
 491                             </mml:msub>
 492                         </mml:math>,
 493                         it is taken from memory as
 494                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 495
 496                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 497                             <mml:mn>3</mml:mn>
 498                             </mml:msub>
 499                         </mml:math>,
 500                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 501
 502                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 503                             <mml:mn>2</mml:mn>
 504                             </mml:msub>
 505                         </mml:math>,
 506                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 507
 508                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 509                             <mml:mn>1</mml:mn>
 510                             </mml:msub>
 511                         </mml:math>,
 512                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 513
 514                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 515                             <mml:mn>0</mml:mn>
 516                             </mml:msub>
 517                         </mml:math>
 518                         if <code class="constant">GL_UNPACK_SWAP_BYTES</code> is true.
 519                         <code class="constant">GL_UNPACK_SWAP_BYTES</code> has no effect on the memory order of components
 520                         within a pixel,
 521                         only on the order of bytes within components or indices.
 522                         For example,
 523                         the three components of a <code class="constant">GL_RGB</code> format pixel are always stored with
 524                         red first,
 525                         green second,
 526                         and blue third,
 527                         regardless of the value of <code class="constant">GL_UNPACK_SWAP_BYTES</code>.
 528                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_LSB_FIRST</code></span></dt><dd><p>
 529                         If true,
 530                         bits are ordered within a byte from least significant to most significant;
 531                         otherwise,
 532                         the first bit in each byte is the most significant one.
 533                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_ROW_LENGTH</code></span></dt><dd><p>
 534                         If greater than 0,
 535                         <code class="constant">GL_UNPACK_ROW_LENGTH</code> defines the number of pixels in a row.
 536                         If the first pixel of a row is placed at location
 537                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 538                         in memory,
 539                         then the location of the first pixel of the next row is obtained by skipping
 540                     </p><p>
 541                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 542
 543                             <mml:mrow>
 544                                 <mml:mi mathvariant="italic">k</mml:mi>
 545                                 <mml:mo>=</mml:mo>
 546                                 <mml:mfenced open="{" close="">
 547                                     <mml:mrow>
 548                                         <mml:mtable>
 549                                             <mml:mtr><mml:mtd>
 550                                                 <mml:mrow>
 551                                                     <mml:mi mathvariant="italic">n</mml:mi>
 552                                                     <mml:mo>⁢</mml:mo>
 553                                                     <mml:mi mathvariant="italic">l</mml:mi>
 554                                                 </mml:mrow>
 555                                             </mml:mtd></mml:mtr>
 556                                             <mml:mtr><mml:mtd>
 557                                                 <mml:mrow>
 558                                                     <mml:mfenced open="" close="">
 559                                                         <mml:mfrac>
 560                                                             <mml:mi mathvariant="italic">a</mml:mi>
 561                                                             <mml:mi mathvariant="italic">s</mml:mi>
 562                                                         </mml:mfrac>
 563                                                     </mml:mfenced>
 564                                                     <mml:mo>⁢</mml:mo>
 565                                                     <mml:mfenced open="⌈" close="⌉">
 566                                                         <mml:mfrac>
 567                                                             <mml:mfenced open="" close="">
 568                                                                 <mml:mrow>
 569                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 570                                                                     <mml:mo>⁢</mml:mo>
 571                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 572                                                                     <mml:mo>⁢</mml:mo>
 573                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 574                                                                 </mml:mrow>
 575                                                             </mml:mfenced>
 576                                                             <mml:mi mathvariant="italic">a</mml:mi>
 577                                                         </mml:mfrac>
 578                                                     </mml:mfenced>
 579                                                 </mml:mrow>
 580                                             </mml:mtd></mml:mtr>
 581                                         </mml:mtable>
 582                                         <mml:mo>⁢</mml:mo>
 583                                         <mml:mtable>
 584                                             <mml:mtr><mml:mtd>
 585                                                 <mml:mrow>
 586                                                     <mml:mi mathvariant="italic">s</mml:mi>
 587                                                     <mml:mo>&gt;=</mml:mo>
 588                                                     <mml:mi mathvariant="italic">a</mml:mi>
 589                                                 </mml:mrow>
 590                                             </mml:mtd></mml:mtr>
 591                                             <mml:mtr><mml:mtd>
 592                                                 <mml:mrow>
 593                                                     <mml:mi mathvariant="italic">s</mml:mi>
 594                                                     <mml:mo>&lt;</mml:mo>
 595                                                     <mml:mi mathvariant="italic">a</mml:mi>
 596                                                 </mml:mrow>
 597                                             </mml:mtd></mml:mtr>
 598                                         </mml:mtable>
 599                                     </mml:mrow>
 600                                 </mml:mfenced>
 601                             </mml:mrow>
 602                         </mml:math></div><p>
 603                     </p><p>
 604                         components or indices,
 605                         where
 606                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 607                         is the number of components or indices in a pixel,
 608                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 609                         is the number of pixels in a row
 610                         (<code class="constant">GL_UNPACK_ROW_LENGTH</code> if it is greater than 0,
 611                         the
 612                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 613                         argument to the pixel routine otherwise),
 614                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 615                         is the value of <code class="constant">GL_UNPACK_ALIGNMENT</code>, and
 616                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 617                         is the size, in bytes, of a single component
 618                         (if
 619                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 620
 621                             <mml:mrow>
 622                                 <mml:mi mathvariant="italic">a</mml:mi>
 623                                 <mml:mo>&lt;</mml:mo>
 624                                 <mml:mi mathvariant="italic">s</mml:mi>
 625                             </mml:mrow>
 626                         </mml:math>,
 627                         then it is as if
 628                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 629
 630                             <mml:mrow>
 631                                 <mml:mi mathvariant="italic">a</mml:mi>
 632                                 <mml:mo>=</mml:mo>
 633                                 <mml:mi mathvariant="italic">s</mml:mi>
 634                             </mml:mrow>
 635                         </mml:math>).
 636                         In the case of 1-bit values,
 637                         the location of the next row is obtained by skipping
 638                     </p><p>
 639                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 640
 641                             <mml:mrow>
 642                                 <mml:mi mathvariant="italic">k</mml:mi>
 643                                 <mml:mo>=</mml:mo>
 644                                 <mml:mrow>
 645                                     <mml:mn>8</mml:mn>
 646                                     <mml:mo>⁢</mml:mo>
 647                                     <mml:mi mathvariant="italic">a</mml:mi>
 648                                     <mml:mo>⁢</mml:mo>
 649                                     <mml:mfenced open="⌈" close="⌉">
 650                                         <mml:mfrac>
 651                                             <mml:mfenced open="" close="">
 652                                                 <mml:mrow>
 653                                                     <mml:mi mathvariant="italic">n</mml:mi>
 654                                                     <mml:mo>⁢</mml:mo>
 655                                                     <mml:mi mathvariant="italic">l</mml:mi>
 656                                                 </mml:mrow>
 657                                             </mml:mfenced>
 658                                             <mml:mfenced open="" close="">
 659                                                 <mml:mrow>
 660                                                     <mml:mn>8</mml:mn>
 661                                                     <mml:mo>⁢</mml:mo>
 662                                                     <mml:mi mathvariant="italic">a</mml:mi>
 663                                                 </mml:mrow>
 664                                             </mml:mfenced>
 665                                         </mml:mfrac>
 666                                     </mml:mfenced>
 667                                 </mml:mrow>
 668                             </mml:mrow>
 669                         </mml:math>
 670                     </p><p>
 671                         components or indices.
 672                     </p><p>
 673                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 674                         red,
 675                         green,
 676                         blue,
 677                         alpha,
 678                         and depth.
 679                         Storage format <code class="constant">GL_RGB</code>,
 680                         for example,
 681                         has three components per pixel:
 682                         first red,
 683                         then green,
 684                         and finally blue.
 685                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_IMAGE_HEIGHT</code></span></dt><dd><p>
 686                         If greater than 0,
 687                         <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code> defines the number of pixels in an image of
 688                         a three-dimensional texture volume.  Where ``image'' is defined by all
 689                         pixel sharing the same third dimension index.
 690                         If the first pixel of a row is placed at location
 691                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 692                         in memory,
 693                         then the location of the first pixel of the next row is obtained by skipping
 694                     </p><p>
 695                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 696
 697                             <mml:mrow>
 698                                 <mml:mi mathvariant="italic">k</mml:mi>
 699                                 <mml:mo>=</mml:mo>
 700                                 <mml:mfenced open="{" close="">
 701                                     <mml:mrow>
 702                                         <mml:mtable>
 703                                             <mml:mtr><mml:mtd>
 704                                                 <mml:mrow>
 705                                                     <mml:mi mathvariant="italic">n</mml:mi>
 706                                                     <mml:mo>⁢</mml:mo>
 707                                                     <mml:mi mathvariant="italic">l</mml:mi>
 708                                                     <mml:mo>⁢</mml:mo>
 709                                                     <mml:mi mathvariant="italic">h</mml:mi>
 710                                                 </mml:mrow>
 711                                             </mml:mtd></mml:mtr>
 712                                             <mml:mtr><mml:mtd>
 713                                                 <mml:mrow>
 714                                                     <mml:mfenced open="" close="">
 715                                                         <mml:mfrac>
 716                                                             <mml:mi mathvariant="italic">a</mml:mi>
 717                                                             <mml:mi mathvariant="italic">s</mml:mi>
 718                                                         </mml:mfrac>
 719                                                     </mml:mfenced>
 720                                                     <mml:mo>⁢</mml:mo>
 721                                                     <mml:mfenced open="⌈" close="⌉">
 722                                                         <mml:mfrac>
 723                                                             <mml:mfenced open="" close="">
 724                                                                 <mml:mrow>
 725                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 726                                                                     <mml:mo>⁢</mml:mo>
 727                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 728                                                                     <mml:mo>⁢</mml:mo>
 729                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 730                                                                     <mml:mo>⁢</mml:mo>
 731                                                                     <mml:mi mathvariant="italic">h</mml:mi>
 732                                                                 </mml:mrow>
 733                                                             </mml:mfenced>
 734                                                             <mml:mi mathvariant="italic">a</mml:mi>
 735                                                         </mml:mfrac>
 736                                                     </mml:mfenced>
 737                                                 </mml:mrow>
 738                                             </mml:mtd></mml:mtr>
 739                                         </mml:mtable>
 740                                         <mml:mo>⁢</mml:mo>
 741                                         <mml:mtable>
 742                                             <mml:mtr><mml:mtd>
 743                                                 <mml:mrow>
 744                                                     <mml:mi mathvariant="italic">s</mml:mi>
 745                                                     <mml:mo>&gt;=</mml:mo>
 746                                                     <mml:mi mathvariant="italic">a</mml:mi>
 747                                                 </mml:mrow>
 748                                             </mml:mtd></mml:mtr>
 749                                             <mml:mtr><mml:mtd>
 750                                                 <mml:mrow>
 751                                                     <mml:mi mathvariant="italic">s</mml:mi>
 752                                                     <mml:mo>&lt;</mml:mo>
 753                                                     <mml:mi mathvariant="italic">a</mml:mi>
 754                                                 </mml:mrow>
 755                                             </mml:mtd></mml:mtr>
 756                                         </mml:mtable>
 757                                     </mml:mrow>
 758                                 </mml:mfenced>
 759                             </mml:mrow>
 760                         </mml:math></div><p>
 761                     </p><p>
 762                         components or indices,
 763                         where
 764                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 765                         is the number of components or indices in a pixel,
 766                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 767                         is the number of pixels in a row
 768                         (<code class="constant">GL_UNPACK_ROW_LENGTH</code> if it is greater than 0,
 769                         the
 770                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 771                         argument to <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> otherwise),
 772                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math>
 773                         is the number of rows in an image (<code class="constant">GL_UNPACK_IMAGE_HEIGHT</code> if
 774                         it is greater than 0, the
 775                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">height</mml:mi></mml:math>
 776                         argument to <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> otherwise),
 777                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 778                         is the value of <code class="constant">GL_UNPACK_ALIGNMENT</code>, and
 779                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 780                         is the size, in bytes, of a single component
 781                         (if
 782                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 783
 784                             <mml:mrow>
 785                                 <mml:mi mathvariant="italic">a</mml:mi>
 786                                 <mml:mo>&lt;</mml:mo>
 787                                 <mml:mi mathvariant="italic">s</mml:mi>
 788                             </mml:mrow>
 789                         </mml:math>,
 790                         then it is as if
 791                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 792
 793                             <mml:mrow>
 794                                 <mml:mi mathvariant="italic">a</mml:mi>
 795                                 <mml:mo>=</mml:mo>
 796                                 <mml:mi mathvariant="italic">s</mml:mi>
 797                             </mml:mrow>
 798                         </mml:math>).
 799                     </p><p>
 800                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 801                         red,
 802                         green,
 803                         blue,
 804                         alpha,
 805                         and depth.
 806                         Storage format <code class="constant">GL_RGB</code>,
 807                         for example,
 808                         has three components per pixel:
 809                         first red,
 810                         then green,
 811                         and finally blue.
 812                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_SKIP_PIXELS</code> and <code class="constant">GL_UNPACK_SKIP_ROWS</code></span></dt><dd><p>
 813                         These values are provided as a convenience to the programmer;
 814                         they provide no functionality that cannot be duplicated by
 815                         incrementing the pointer passed to
 816                         <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 817                         <a class="citerefentry" href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 818                         <a class="citerefentry" href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a> or
 819                         <a class="citerefentry" href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>.
 820                         Setting <code class="constant">GL_UNPACK_SKIP_PIXELS</code> to
 821                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>
 822                         is equivalent to incrementing
 823                         the pointer by
 824                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 825
 826                             <mml:mrow>
 827                                 <mml:mi mathvariant="italic">i</mml:mi>
 828                                 <mml:mo>⁢</mml:mo>
 829                                 <mml:mi mathvariant="italic">n</mml:mi>
 830                             </mml:mrow>
 831                         </mml:math>
 832                         components or indices,
 833                         where
 834                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 835                         is the number of components or indices in each pixel.
 836                         Setting <code class="constant">GL_UNPACK_SKIP_ROWS</code> to
 837                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>
 838                         is equivalent to incrementing
 839                         the pointer by
 840                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 841
 842                             <mml:mrow>
 843                                 <mml:mi mathvariant="italic">j</mml:mi>
 844                                 <mml:mo>⁢</mml:mo>
 845                                 <mml:mi mathvariant="italic">k</mml:mi>
 846                             </mml:mrow>
 847                         </mml:math>
 848                         components or indices,
 849                         where
 850                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">k</mml:mi></mml:math>
 851                         is the number of components or indices per row,
 852                         as just computed in the <code class="constant">GL_UNPACK_ROW_LENGTH</code> section.
 853                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_ALIGNMENT</code></span></dt><dd><p>
 854                         Specifies the alignment requirements for the start of each pixel row in memory.
 855                         The allowable values are
 856                         1 (byte-alignment),
 857                         2 (rows aligned to even-numbered bytes),
 858                         4 (word-alignment), and
 859                         8 (rows start on double-word boundaries).
 860                     </p></dd></dl></div><p>
 861             The following table gives the type,
 862             initial value,
 863             and range of valid values for each storage parameter
 864             that can be set with <code class="function">glPixelStore</code>.
 865         </p><p>
 866         </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left"><span class="bold"><strong>
 867                         <em class="parameter"><code>pname</code></em>
 868                         </strong></span></th><th align="center"><span class="bold"><strong>
 869                         Type
 870                         </strong></span></th><th align="center"><span class="bold"><strong>
 871                         Initial Value
 872                         </strong></span></th><th align="center"><span class="bold"><strong>
 873                         Valid Range
 874                         </strong></span></th></tr></thead><tbody><tr><td align="left">
 875                         <code class="constant">GL_PACK_SWAP_BYTES</code>
 876                         </td><td align="center">
 877                         boolean
 878                         </td><td align="center">
 879                         false
 880                         </td><td align="center">
 881                         true or false
 882                         </td></tr><tr><td align="left">
 883                         <code class="constant">GL_PACK_LSB_FIRST</code>
 884                         </td><td align="center">
 885                         boolean
 886                         </td><td align="center">
 887                         false
 888                         </td><td align="center">
 889                         true or false
 890                         </td></tr><tr><td align="left">
 891                         <code class="constant">GL_PACK_ROW_LENGTH</code>
 892                         </td><td align="center">
 893                         integer
 894                         </td><td align="center">
 895                         0
 896                         </td><td align="center">
 897                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 898
 899                             <mml:mfenced open="[" close=")">
 900                                 <mml:mn>0</mml:mn>
 901                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 902                             </mml:mfenced>
 903                         </mml:math>
 904                         </td></tr><tr><td align="left">
 905                         <code class="constant">GL_PACK_IMAGE_HEIGHT</code>
 906                         </td><td align="center">
 907                         integer
 908                         </td><td align="center">
 909                         0
 910                         </td><td align="center">
 911                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 912
 913                             <mml:mfenced open="[" close=")">
 914                                 <mml:mn>0</mml:mn>
 915                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 916                             </mml:mfenced>
 917                         </mml:math>
 918                         </td></tr><tr><td align="left">
 919                         <code class="constant">GL_PACK_SKIP_ROWS</code>
 920                         </td><td align="center">
 921                         integer
 922                         </td><td align="center">
 923                         0
 924                         </td><td align="center">
 925                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 926
 927                             <mml:mfenced open="[" close=")">
 928                                 <mml:mn>0</mml:mn>
 929                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 930                             </mml:mfenced>
 931                         </mml:math>
 932                         </td></tr><tr><td align="left">
 933                         <code class="constant">GL_PACK_SKIP_PIXELS</code>
 934                         </td><td align="center">
 935                         integer
 936                         </td><td align="center">
 937                         0
 938                         </td><td align="center">
 939                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 940
 941                             <mml:mfenced open="[" close=")">
 942                                 <mml:mn>0</mml:mn>
 943                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 944                             </mml:mfenced>
 945                         </mml:math>
 946                         </td></tr><tr><td align="left">
 947                         <code class="constant">GL_PACK_SKIP_IMAGES</code>
 948                         </td><td align="center">
 949                         integer
 950                         </td><td align="center">
 951                         0
 952                         </td><td align="center">
 953                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 954
 955                             <mml:mfenced open="[" close=")">
 956                                 <mml:mn>0</mml:mn>
 957                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 958                             </mml:mfenced>
 959                         </mml:math>
 960                         </td></tr><tr><td align="left">
 961                         <code class="constant">GL_PACK_ALIGNMENT</code>
 962                         </td><td align="center">
 963                         integer
 964                         </td><td align="center">
 965                         4
 966                         </td><td align="center">
 967                         1, 2, 4, or 8
 968                         </td></tr><tr><td align="left">
 969                         <code class="constant">GL_UNPACK_SWAP_BYTES</code>
 970                         </td><td align="center">
 971                         boolean
 972                         </td><td align="center">
 973                         false
 974                         </td><td align="center">
 975                         true or false
 976                         </td></tr><tr><td align="left">
 977                         <code class="constant">GL_UNPACK_LSB_FIRST</code>
 978                         </td><td align="center">
 979                         boolean
 980                         </td><td align="center">
 981                         false
 982                         </td><td align="center">
 983                         true or false
 984                         </td></tr><tr><td align="left">
 985                         <code class="constant">GL_UNPACK_ROW_LENGTH</code>
 986                         </td><td align="center">
 987                         integer
 988                         </td><td align="center">
 989                         0
 990                         </td><td align="center">
 991                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 992
 993                             <mml:mfenced open="[" close=")">
 994                                 <mml:mn>0</mml:mn>
 995                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 996                             </mml:mfenced>
 997                         </mml:math>
 998                         </td></tr><tr><td align="left">
 999                         <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code>
1000                         </td><td align="center">
1001                         integer
1002                         </td><td align="center">
1003                         0
1004                         </td><td align="center">
1005                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1006
1007                             <mml:mfenced open="[" close=")">
1008                                 <mml:mn>0</mml:mn>
1009                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1010                             </mml:mfenced>
1011                         </mml:math>
1012                         </td></tr><tr><td align="left">
1013                         <code class="constant">GL_UNPACK_SKIP_ROWS</code>
1014                         </td><td align="center">
1015                         integer
1016                         </td><td align="center">
1017                         0
1018                         </td><td align="center">
1019                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1020
1021                             <mml:mfenced open="[" close=")">
1022                                 <mml:mn>0</mml:mn>
1023                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1024                             </mml:mfenced>
1025                         </mml:math>
1026                         </td></tr><tr><td align="left">
1027                         <code class="constant">GL_UNPACK_SKIP_PIXELS</code>
1028                         </td><td align="center">
1029                         integer
1030                         </td><td align="center">
1031                         0
1032                         </td><td align="center">
1033                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1034
1035                             <mml:mfenced open="[" close=")">
1036                                 <mml:mn>0</mml:mn>
1037                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1038                             </mml:mfenced>
1039                         </mml:math>
1040                         </td></tr><tr><td align="left">
1041                         <code class="constant">GL_UNPACK_SKIP_IMAGES</code>
1042                         </td><td align="center">
1043                         integer
1044                         </td><td align="center">
1045                         0
1046                         </td><td align="center">
1047                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1048
1049                             <mml:mfenced open="[" close=")">
1050                                 <mml:mn>0</mml:mn>
1051                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1052                             </mml:mfenced>
1053                         </mml:math>
1054                         </td></tr><tr><td align="left">
1055                         <code class="constant">GL_UNPACK_ALIGNMENT</code>
1056                         </td><td align="center">
1057                         integer
1058                         </td><td align="center">
1059                         4
1060                         </td><td align="center">
1061                         1, 2, 4, or 8
1062                         </td></tr></tbody></table></div><p>
1063             <code class="function">glPixelStoref</code> can be used to set any pixel store parameter.
1064             If the parameter type is boolean,
1065             then if <em class="parameter"><code>param</code></em> is 0,
1066             the parameter is false;
1067             otherwise it is set to true.
1068             If <em class="parameter"><code>pname</code></em> is a integer type parameter,
1069             <em class="parameter"><code>param</code></em> is rounded to the nearest integer.
1070         </p><p>
1071             Likewise, <code class="function">glPixelStorei</code> can also be used to set any of the
1072             pixel store parameters.
1073             Boolean parameters are set to false if <em class="parameter"><code>param</code></em> is 0 and true otherwise.
1074         </p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2>Errors</h2><p>
1075             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>pname</code></em> is not an accepted value.
1076         </p><p>
1077             <code class="constant">GL_INVALID_VALUE</code> is generated if a negative row length,
1078             pixel skip,
1079             or row skip value is specified,
1080             or if alignment is specified as other than 1, 2, 4, or 8.
1081         </p></div><div class="refsect1" title="Associated Gets"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
1082             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SWAP_BYTES</code>
1083         </p><p>
1084             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_LSB_FIRST</code>
1085         </p><p>
1086             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_ROW_LENGTH</code>
1087         </p><p>
1088             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_IMAGE_HEIGHT</code>
1089         </p><p>
1090             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SKIP_ROWS</code>
1091         </p><p>
1092             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SKIP_PIXELS</code>
1093         </p><p>
1094             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SKIP_IMAGES</code>
1095         </p><p>
1096             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_ALIGNMENT</code>
1097         </p><p>
1098             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SWAP_BYTES</code>
1099         </p><p>
1100             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_LSB_FIRST</code>
1101         </p><p>
1102             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_ROW_LENGTH</code>
1103         </p><p>
1104             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code>
1105         </p><p>
1106             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SKIP_ROWS</code>
1107         </p><p>
1108             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SKIP_PIXELS</code>
1109         </p><p>
1110             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SKIP_IMAGES</code>
1111         </p><p>
1112             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_ALIGNMENT</code>
1113         </p></div><div class="refsect1" title="See Also"><a id="seealso"></a><h2>See Also</h2><p>
1114             <a class="citerefentry" href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
1115             <a class="citerefentry" href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
1116             <a class="citerefentry" href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
1117             <a class="citerefentry" href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
1118             <a class="citerefentry" href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
1119             <a class="citerefentry" href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,
1120             <a class="citerefentry" href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>
1121         </p></div><div class="refsect1" title="Copyright"><a id="Copyright"></a><h2>Copyright</h2><p>
1122             Copyright <span class="trademark"></span>© 1991-2006
1123             Silicon Graphics, Inc. This document is licensed under the SGI
1124             Free Software B License. For details, see
1125             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
1126         </p></div></div></body></html>