upstream-man-pages/man4/xhtml/glPixelStore.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
   3 <!-- saved from url=(0013)about:internet -->
   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 - OpenGL 4 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><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"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glPixelStoref</b>(</code></td><td>GLenum  </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLfloat  </td><td><var class="pdparam">param</var><code>)</code>;</td></tr></table></div><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glPixelStorei</b>(</code></td><td>GLenum  </td><td><var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">param</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>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" lang="en" xml:lang="en"><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 href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a> as well as the unpacking of
  29             texture patterns (see <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
  30             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>, <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>, <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
  31             <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>, <a href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>),
  32             <a href="glCompressedTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage1D</span></span></a>, <a href="glCompressedTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>,
  33             <a href="glCompressedTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage3D</span></span></a>, <a href="glCompressedTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage1D</span></span></a>,
  34             <a href="glCompressedTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage2D</span></span></a> or <a href="glCompressedTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage1D</span></span></a>.
  35         </p><p>
  36             <em class="parameter"><code>pname</code></em> is a symbolic constant indicating the parameter to be set, and
  37             <em class="parameter"><code>param</code></em> is the new value.  Six of the twelve storage parameters affect
  38             how pixel data is returned to client memory.
  39             They are as follows:
  40         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_PACK_SWAP_BYTES</code></span></dt><dd><p>
  41                         If true,
  42                         byte ordering for multibyte color components,
  43                         depth components,
  44                         or stencil indices
  45                         is reversed.
  46                         That is,
  47                         if a four-byte component consists of bytes
  48                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  49
  50                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  51                             <mml:mn>0</mml:mn>
  52                             </mml:msub>
  53                         </mml:math>,
  54                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  55
  56                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  57                             <mml:mn>1</mml:mn>
  58                             </mml:msub>
  59                         </mml:math>,
  60                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  61
  62                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  63                             <mml:mn>2</mml:mn>
  64                             </mml:msub>
  65                         </mml:math>,
  66                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  67
  68                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  69                             <mml:mn>3</mml:mn>
  70                             </mml:msub>
  71                         </mml:math>,
  72                         it is stored in memory as
  73                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  74
  75                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  76                             <mml:mn>3</mml:mn>
  77                             </mml:msub>
  78                         </mml:math>,
  79                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  80
  81                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  82                             <mml:mn>2</mml:mn>
  83                             </mml:msub>
  84                         </mml:math>,
  85                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  86
  87                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  88                             <mml:mn>1</mml:mn>
  89                             </mml:msub>
  90                         </mml:math>,
  91                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  92
  93                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
  94                             <mml:mn>0</mml:mn>
  95                             </mml:msub>
  96                         </mml:math>
  97                         if <code class="constant">GL_PACK_SWAP_BYTES</code> is true.
  98                         <code class="constant">GL_PACK_SWAP_BYTES</code> has no effect on the memory order of components
  99                         within a pixel,
 100                         only on the order of bytes within components or indices.
 101                         For example,
 102                         the three components of a <code class="constant">GL_RGB</code> format pixel are always stored with
 103                         red first,
 104                         green second,
 105                         and blue third,
 106                         regardless of the value of <code class="constant">GL_PACK_SWAP_BYTES</code>.
 107                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_LSB_FIRST</code></span></dt><dd><p>
 108                         If true,
 109                         bits are ordered within a byte from least significant to most significant;
 110                         otherwise,
 111                         the first bit in each byte is the most significant one.
 112                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_ROW_LENGTH</code></span></dt><dd><p>
 113                         If greater than 0,
 114                         <code class="constant">GL_PACK_ROW_LENGTH</code> defines the number of pixels in a row.
 115                         If the first pixel of a row is placed at location
 116                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 117                         in memory,
 118                         then the location of the first pixel of the next row is obtained by skipping
 119                     </p><p>
 120                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 121
 122                             <mml:mrow>
 123                                 <mml:mi mathvariant="italic">k</mml:mi>
 124                                 <mml:mo>=</mml:mo>
 125                                 <mml:mfenced open="{" close="">
 126                                     <mml:mrow>
 127                                         <mml:mtable>
 128                                             <mml:mtr><mml:mtd>
 129                                                 <mml:mrow>
 130                                                     <mml:mi mathvariant="italic">n</mml:mi>
 131                                                     <mml:mo>⁢</mml:mo>
 132                                                     <mml:mi mathvariant="italic">l</mml:mi>
 133                                                 </mml:mrow>
 134                                             </mml:mtd></mml:mtr>
 135                                             <mml:mtr><mml:mtd>
 136                                                 <mml:mrow>
 137                                                     <mml:mfenced open="" close="">
 138                                                         <mml:mfrac>
 139                                                             <mml:mi mathvariant="italic">a</mml:mi>
 140                                                             <mml:mi mathvariant="italic">s</mml:mi>
 141                                                         </mml:mfrac>
 142                                                     </mml:mfenced>
 143                                                     <mml:mo>⁢</mml:mo>
 144                                                     <mml:mfenced open="&#x2308;" close="&#x2309;">
 145                                                         <mml:mfrac>
 146                                                             <mml:mfenced open="" close="">
 147                                                                 <mml:mrow>
 148                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 149                                                                     <mml:mo>⁢</mml:mo>
 150                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 151                                                                     <mml:mo>⁢</mml:mo>
 152                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 153                                                                 </mml:mrow>
 154                                                             </mml:mfenced>
 155                                                             <mml:mi mathvariant="italic">a</mml:mi>
 156                                                         </mml:mfrac>
 157                                                     </mml:mfenced>
 158                                                 </mml:mrow>
 159                                             </mml:mtd></mml:mtr>
 160                                         </mml:mtable>
 161                                         <mml:mo>⁢</mml:mo>
 162                                         <mml:mtable>
 163                                             <mml:mtr><mml:mtd>
 164                                                 <mml:mrow>
 165                                                     <mml:mi mathvariant="italic">s</mml:mi>
 166                                                     <mml:mo>&gt;=</mml:mo>
 167                                                     <mml:mi mathvariant="italic">a</mml:mi>
 168                                                 </mml:mrow>
 169                                             </mml:mtd></mml:mtr>
 170                                             <mml:mtr><mml:mtd>
 171                                                 <mml:mrow>
 172                                                     <mml:mi mathvariant="italic">s</mml:mi>
 173                                                     <mml:mo>&lt;</mml:mo>
 174                                                     <mml:mi mathvariant="italic">a</mml:mi>
 175                                                 </mml:mrow>
 176                                             </mml:mtd></mml:mtr>
 177                                         </mml:mtable>
 178                                     </mml:mrow>
 179                                 </mml:mfenced>
 180                             </mml:mrow>
 181                         </mml:math></div><p>
 182                     </p><p>
 183                         components or indices,
 184                         where
 185                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 186                         is the number of components or indices in a pixel,
 187                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 188                         is the number of pixels in a row
 189                         (<code class="constant">GL_PACK_ROW_LENGTH</code> if it is greater than 0,
 190                         the
 191                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 192                         argument to the pixel routine otherwise),
 193                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 194                         is the value of <code class="constant">GL_PACK_ALIGNMENT</code>, and
 195                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 196                         is the size, in bytes, of a single component
 197                         (if
 198                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 199
 200                             <mml:mrow>
 201                                 <mml:mi mathvariant="italic">a</mml:mi>
 202                                 <mml:mo>&lt;</mml:mo>
 203                                 <mml:mi mathvariant="italic">s</mml:mi>
 204                             </mml:mrow>
 205                         </mml:math>,
 206                         then it is as if
 207                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 208
 209                             <mml:mrow>
 210                                 <mml:mi mathvariant="italic">a</mml:mi>
 211                                 <mml:mo>=</mml:mo>
 212                                 <mml:mi mathvariant="italic">s</mml:mi>
 213                             </mml:mrow>
 214                         </mml:math>).
 215                         In the case of 1-bit values,
 216                         the location of the next row is obtained by skipping
 217                     </p><p>
 218                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 219
 220                             <mml:mrow>
 221                                 <mml:mi mathvariant="italic">k</mml:mi>
 222                                 <mml:mo>=</mml:mo>
 223                                 <mml:mrow>
 224                                     <mml:mn>8</mml:mn>
 225                                     <mml:mo>⁢</mml:mo>
 226                                     <mml:mi mathvariant="italic">a</mml:mi>
 227                                     <mml:mo>⁢</mml:mo>
 228                                     <mml:mfenced open="&#x2308;" close="&#x2309;">
 229                                         <mml:mfrac>
 230                                             <mml:mfenced open="" close="">
 231                                                 <mml:mrow>
 232                                                     <mml:mi mathvariant="italic">n</mml:mi>
 233                                                     <mml:mo>⁢</mml:mo>
 234                                                     <mml:mi mathvariant="italic">l</mml:mi>
 235                                                 </mml:mrow>
 236                                             </mml:mfenced>
 237                                             <mml:mfenced open="" close="">
 238                                                 <mml:mrow>
 239                                                     <mml:mn>8</mml:mn>
 240                                                     <mml:mo>⁢</mml:mo>
 241                                                     <mml:mi mathvariant="italic">a</mml:mi>
 242                                                 </mml:mrow>
 243                                             </mml:mfenced>
 244                                         </mml:mfrac>
 245                                     </mml:mfenced>
 246                                 </mml:mrow>
 247                             </mml:mrow>
 248                         </mml:math>
 249                     </p><p>
 250                         components or indices.
 251                     </p><p>
 252                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 253                         red,
 254                         green,
 255                         blue,
 256                         alpha,
 257                         and depth.
 258                         Storage format <code class="constant">GL_RGB</code>,
 259                         for example,
 260                         has three components per pixel:
 261                         first red,
 262                         then green,
 263                         and finally blue.
 264                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_IMAGE_HEIGHT</code></span></dt><dd><p>
 265                         If greater than 0,
 266                         <code class="constant">GL_PACK_IMAGE_HEIGHT</code> defines the number of pixels in an image
 267                         three-dimensional texture volume, where ``image'' is defined by all pixels
 268                         sharing the same third dimension index.
 269                         If the first pixel of a row is placed at location
 270                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 271                         in memory,
 272                         then the location of the first pixel of the next row is obtained by skipping
 273                     </p><p>
 274                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 275
 276                             <mml:mrow>
 277                                 <mml:mi mathvariant="italic">k</mml:mi>
 278                                 <mml:mo>=</mml:mo>
 279                                 <mml:mfenced open="{" close="">
 280                                     <mml:mrow>
 281                                         <mml:mtable>
 282                                             <mml:mtr><mml:mtd>
 283                                                 <mml:mrow>
 284                                                     <mml:mi mathvariant="italic">n</mml:mi>
 285                                                     <mml:mo>⁢</mml:mo>
 286                                                     <mml:mi mathvariant="italic">l</mml:mi>
 287                                                     <mml:mo>⁢</mml:mo>
 288                                                     <mml:mi mathvariant="italic">h</mml:mi>
 289                                                 </mml:mrow>
 290                                             </mml:mtd></mml:mtr>
 291                                             <mml:mtr><mml:mtd>
 292                                                 <mml:mrow>
 293                                                     <mml:mfenced open="" close="">
 294                                                         <mml:mfrac>
 295                                                             <mml:mi mathvariant="italic">a</mml:mi>
 296                                                             <mml:mi mathvariant="italic">s</mml:mi>
 297                                                         </mml:mfrac>
 298                                                     </mml:mfenced>
 299                                                     <mml:mo>⁢</mml:mo>
 300                                                     <mml:mfenced open="&#x2308;" close="&#x2309;">
 301                                                         <mml:mfrac>
 302                                                             <mml:mfenced open="" close="">
 303                                                                 <mml:mrow>
 304                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 305                                                                     <mml:mo>⁢</mml:mo>
 306                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 307                                                                     <mml:mo>⁢</mml:mo>
 308                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 309                                                                     <mml:mo>⁢</mml:mo>
 310                                                                     <mml:mi mathvariant="italic">h</mml:mi>
 311                                                                 </mml:mrow>
 312                                                             </mml:mfenced>
 313                                                             <mml:mi mathvariant="italic">a</mml:mi>
 314                                                         </mml:mfrac>
 315                                                     </mml:mfenced>
 316                                                 </mml:mrow>
 317                                             </mml:mtd></mml:mtr>
 318                                         </mml:mtable>
 319                                         <mml:mo>⁢</mml:mo>
 320                                         <mml:mtable>
 321                                             <mml:mtr><mml:mtd>
 322                                                 <mml:mrow>
 323                                                     <mml:mi mathvariant="italic">s</mml:mi>
 324                                                     <mml:mo>&gt;=</mml:mo>
 325                                                     <mml:mi mathvariant="italic">a</mml:mi>
 326                                                 </mml:mrow>
 327                                             </mml:mtd></mml:mtr>
 328                                             <mml:mtr><mml:mtd>
 329                                                 <mml:mrow>
 330                                                     <mml:mi mathvariant="italic">s</mml:mi>
 331                                                     <mml:mo>&lt;</mml:mo>
 332                                                     <mml:mi mathvariant="italic">a</mml:mi>
 333                                                 </mml:mrow>
 334                                             </mml:mtd></mml:mtr>
 335                                         </mml:mtable>
 336                                     </mml:mrow>
 337                                 </mml:mfenced>
 338                             </mml:mrow>
 339                         </mml:math></div><p>
 340                     </p><p>
 341                         components or indices, where
 342                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 343                         is the number of components or indices
 344                         in a pixel,
 345                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 346                         is the number of pixels in a row
 347                         (<code class="constant">GL_PACK_ROW_LENGTH</code> if it is greater than 0, the
 348                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 349                         argument to <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> otherwise),
 350                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math>
 351                         is the number of
 352                         rows in a pixel image (<code class="constant">GL_PACK_IMAGE_HEIGHT</code> if it is greater than
 353                         0, the
 354                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">height</mml:mi></mml:math>
 355                         argument to the <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> routine otherwise),
 356                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 357                         is the value of
 358                         <code class="constant">GL_PACK_ALIGNMENT</code>, and
 359                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 360                         is the size, in bytes, of a single
 361                         component (if
 362                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 363
 364                             <mml:mrow>
 365                                 <mml:mi mathvariant="italic">a</mml:mi>
 366                                 <mml:mo>&lt;</mml:mo>
 367                                 <mml:mi mathvariant="italic">s</mml:mi>
 368                             </mml:mrow>
 369                         </mml:math>,
 370                         then it is as if
 371                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 372
 373                             <mml:mrow>
 374                                 <mml:mi mathvariant="italic">a</mml:mi>
 375                                 <mml:mo>=</mml:mo>
 376                                 <mml:mi mathvariant="italic">s</mml:mi>
 377                             </mml:mrow>
 378                         </mml:math>).
 379                     </p><p>
 380                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 381                         red,
 382                         green,
 383                         blue,
 384                         alpha,
 385                         and depth.
 386                         Storage format <code class="constant">GL_RGB</code>,
 387                         for example,
 388                         has three components per pixel:
 389                         first red,
 390                         then green,
 391                         and finally blue.
 392                     </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>
 393                         These values are provided as a convenience to the programmer;
 394                         they provide no functionality that cannot be duplicated simply by
 395                         incrementing the pointer passed to <a href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>.
 396                         Setting <code class="constant">GL_PACK_SKIP_PIXELS</code> to
 397                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>
 398                         is equivalent to incrementing
 399                         the pointer by
 400                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 401
 402                             <mml:mrow>
 403                                 <mml:mi mathvariant="italic">i</mml:mi>
 404                                 <mml:mo>⁢</mml:mo>
 405                                 <mml:mi mathvariant="italic">n</mml:mi>
 406                             </mml:mrow>
 407                         </mml:math>
 408                         components or indices,
 409                         where
 410                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 411                         is the number of components or indices in each pixel.
 412                         Setting <code class="constant">GL_PACK_SKIP_ROWS</code> to
 413                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>
 414                         is equivalent to incrementing
 415                         the pointer by
 416                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 417
 418                             <mml:mrow>
 419                                 <mml:mi mathvariant="italic">j</mml:mi>
 420                                 <mml:mo>⁢</mml:mo>
 421                                 <mml:mi mathvariant="italic">m</mml:mi>
 422                             </mml:mrow>
 423                         </mml:math>
 424                         components or indices,
 425                         where
 426                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">m</mml:mi></mml:math>
 427                         is the number of components or indices per row,
 428                         as just computed in the <code class="constant">GL_PACK_ROW_LENGTH</code> section.
 429                         Setting <code class="constant">GL_PACK_SKIP_IMAGES</code> to
 430                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">k</mml:mi></mml:math>
 431                         is equivalent to incrementing
 432                         the pointer by
 433                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 434
 435                             <mml:mrow>
 436                                 <mml:mi mathvariant="italic">k</mml:mi>
 437                                 <mml:mo>⁢</mml:mo>
 438                                 <mml:mi mathvariant="italic">p</mml:mi>
 439                             </mml:mrow>
 440                         </mml:math>,
 441                         where
 442                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 443                         is the number of components or indices
 444                         per image, as computed in the <code class="constant">GL_PACK_IMAGE_HEIGHT</code> section.
 445                     </p></dd><dt><span class="term"><code class="constant">GL_PACK_ALIGNMENT</code></span></dt><dd><p>
 446                         Specifies the alignment requirements for the start of each pixel row in memory.
 447                         The allowable values are
 448                         1 (byte-alignment),
 449                         2 (rows aligned to even-numbered bytes),
 450                         4 (word-alignment), and
 451                         8 (rows start on double-word boundaries).
 452                     </p></dd></dl></div><p>
 453             The other six of the twelve storage parameters affect how pixel data is
 454             read from client memory.
 455             These values are significant for
 456             <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 457             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 458             <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
 459             <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
 460             <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>, and
 461             <a href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>
 462         </p><p>
 463             They are as follows:
 464         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_UNPACK_SWAP_BYTES</code></span></dt><dd><p>
 465                         If true,
 466                         byte ordering for multibyte color components,
 467                         depth components,
 468                         or stencil indices
 469                         is reversed.
 470                         That is,
 471                         if a four-byte component consists of bytes
 472                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 473
 474                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 475                             <mml:mn>0</mml:mn>
 476                             </mml:msub>
 477                         </mml:math>,
 478                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 479
 480                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 481                             <mml:mn>1</mml:mn>
 482                             </mml:msub>
 483                         </mml:math>,
 484                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 485
 486                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 487                             <mml:mn>2</mml:mn>
 488                             </mml:msub>
 489                         </mml:math>,
 490                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 491
 492                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 493                             <mml:mn>3</mml:mn>
 494                             </mml:msub>
 495                         </mml:math>,
 496                         it is taken from memory as
 497                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 498
 499                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 500                             <mml:mn>3</mml:mn>
 501                             </mml:msub>
 502                         </mml:math>,
 503                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 504
 505                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 506                             <mml:mn>2</mml:mn>
 507                             </mml:msub>
 508                         </mml:math>,
 509                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 510
 511                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 512                             <mml:mn>1</mml:mn>
 513                             </mml:msub>
 514                         </mml:math>,
 515                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 516
 517                             <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
 518                             <mml:mn>0</mml:mn>
 519                             </mml:msub>
 520                         </mml:math>
 521                         if <code class="constant">GL_UNPACK_SWAP_BYTES</code> is true.
 522                         <code class="constant">GL_UNPACK_SWAP_BYTES</code> has no effect on the memory order of components
 523                         within a pixel,
 524                         only on the order of bytes within components or indices.
 525                         For example,
 526                         the three components of a <code class="constant">GL_RGB</code> format pixel are always stored with
 527                         red first,
 528                         green second,
 529                         and blue third,
 530                         regardless of the value of <code class="constant">GL_UNPACK_SWAP_BYTES</code>.
 531                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_LSB_FIRST</code></span></dt><dd><p>
 532                         If true,
 533                         bits are ordered within a byte from least significant to most significant;
 534                         otherwise,
 535                         the first bit in each byte is the most significant one.
 536                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_ROW_LENGTH</code></span></dt><dd><p>
 537                         If greater than 0,
 538                         <code class="constant">GL_UNPACK_ROW_LENGTH</code> defines the number of pixels in a row.
 539                         If the first pixel of a row is placed at location
 540                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 541                         in memory,
 542                         then the location of the first pixel of the next row is obtained by skipping
 543                     </p><p>
 544                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 545
 546                             <mml:mrow>
 547                                 <mml:mi mathvariant="italic">k</mml:mi>
 548                                 <mml:mo>=</mml:mo>
 549                                 <mml:mfenced open="{" close="">
 550                                     <mml:mrow>
 551                                         <mml:mtable>
 552                                             <mml:mtr><mml:mtd>
 553                                                 <mml:mrow>
 554                                                     <mml:mi mathvariant="italic">n</mml:mi>
 555                                                     <mml:mo>⁢</mml:mo>
 556                                                     <mml:mi mathvariant="italic">l</mml:mi>
 557                                                 </mml:mrow>
 558                                             </mml:mtd></mml:mtr>
 559                                             <mml:mtr><mml:mtd>
 560                                                 <mml:mrow>
 561                                                     <mml:mfenced open="" close="">
 562                                                         <mml:mfrac>
 563                                                             <mml:mi mathvariant="italic">a</mml:mi>
 564                                                             <mml:mi mathvariant="italic">s</mml:mi>
 565                                                         </mml:mfrac>
 566                                                     </mml:mfenced>
 567                                                     <mml:mo>⁢</mml:mo>
 568                                                     <mml:mfenced open="&#x2308;" close="&#x2309;">
 569                                                         <mml:mfrac>
 570                                                             <mml:mfenced open="" close="">
 571                                                                 <mml:mrow>
 572                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 573                                                                     <mml:mo>⁢</mml:mo>
 574                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 575                                                                     <mml:mo>⁢</mml:mo>
 576                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 577                                                                 </mml:mrow>
 578                                                             </mml:mfenced>
 579                                                             <mml:mi mathvariant="italic">a</mml:mi>
 580                                                         </mml:mfrac>
 581                                                     </mml:mfenced>
 582                                                 </mml:mrow>
 583                                             </mml:mtd></mml:mtr>
 584                                         </mml:mtable>
 585                                         <mml:mo>⁢</mml:mo>
 586                                         <mml:mtable>
 587                                             <mml:mtr><mml:mtd>
 588                                                 <mml:mrow>
 589                                                     <mml:mi mathvariant="italic">s</mml:mi>
 590                                                     <mml:mo>&gt;=</mml:mo>
 591                                                     <mml:mi mathvariant="italic">a</mml:mi>
 592                                                 </mml:mrow>
 593                                             </mml:mtd></mml:mtr>
 594                                             <mml:mtr><mml:mtd>
 595                                                 <mml:mrow>
 596                                                     <mml:mi mathvariant="italic">s</mml:mi>
 597                                                     <mml:mo>&lt;</mml:mo>
 598                                                     <mml:mi mathvariant="italic">a</mml:mi>
 599                                                 </mml:mrow>
 600                                             </mml:mtd></mml:mtr>
 601                                         </mml:mtable>
 602                                     </mml:mrow>
 603                                 </mml:mfenced>
 604                             </mml:mrow>
 605                         </mml:math></div><p>
 606                     </p><p>
 607                         components or indices,
 608                         where
 609                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 610                         is the number of components or indices in a pixel,
 611                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 612                         is the number of pixels in a row
 613                         (<code class="constant">GL_UNPACK_ROW_LENGTH</code> if it is greater than 0,
 614                         the
 615                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 616                         argument to the pixel routine otherwise),
 617                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 618                         is the value of <code class="constant">GL_UNPACK_ALIGNMENT</code>, and
 619                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 620                         is the size, in bytes, of a single component
 621                         (if
 622                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 623
 624                             <mml:mrow>
 625                                 <mml:mi mathvariant="italic">a</mml:mi>
 626                                 <mml:mo>&lt;</mml:mo>
 627                                 <mml:mi mathvariant="italic">s</mml:mi>
 628                             </mml:mrow>
 629                         </mml:math>,
 630                         then it is as if
 631                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 632
 633                             <mml:mrow>
 634                                 <mml:mi mathvariant="italic">a</mml:mi>
 635                                 <mml:mo>=</mml:mo>
 636                                 <mml:mi mathvariant="italic">s</mml:mi>
 637                             </mml:mrow>
 638                         </mml:math>).
 639                         In the case of 1-bit values,
 640                         the location of the next row is obtained by skipping
 641                     </p><p>
 642                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 643
 644                             <mml:mrow>
 645                                 <mml:mi mathvariant="italic">k</mml:mi>
 646                                 <mml:mo>=</mml:mo>
 647                                 <mml:mrow>
 648                                     <mml:mn>8</mml:mn>
 649                                     <mml:mo>⁢</mml:mo>
 650                                     <mml:mi mathvariant="italic">a</mml:mi>
 651                                     <mml:mo>⁢</mml:mo>
 652                                     <mml:mfenced open="&#x2308;" close="&#x2309;">
 653                                         <mml:mfrac>
 654                                             <mml:mfenced open="" close="">
 655                                                 <mml:mrow>
 656                                                     <mml:mi mathvariant="italic">n</mml:mi>
 657                                                     <mml:mo>⁢</mml:mo>
 658                                                     <mml:mi mathvariant="italic">l</mml:mi>
 659                                                 </mml:mrow>
 660                                             </mml:mfenced>
 661                                             <mml:mfenced open="" close="">
 662                                                 <mml:mrow>
 663                                                     <mml:mn>8</mml:mn>
 664                                                     <mml:mo>⁢</mml:mo>
 665                                                     <mml:mi mathvariant="italic">a</mml:mi>
 666                                                 </mml:mrow>
 667                                             </mml:mfenced>
 668                                         </mml:mfrac>
 669                                     </mml:mfenced>
 670                                 </mml:mrow>
 671                             </mml:mrow>
 672                         </mml:math>
 673                     </p><p>
 674                         components or indices.
 675                     </p><p>
 676                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 677                         red,
 678                         green,
 679                         blue,
 680                         alpha,
 681                         and depth.
 682                         Storage format <code class="constant">GL_RGB</code>,
 683                         for example,
 684                         has three components per pixel:
 685                         first red,
 686                         then green,
 687                         and finally blue.
 688                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_IMAGE_HEIGHT</code></span></dt><dd><p>
 689                         If greater than 0,
 690                         <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code> defines the number of pixels in an image of
 691                         a three-dimensional texture volume.  Where ``image'' is defined by all
 692                         pixel sharing the same third dimension index.
 693                         If the first pixel of a row is placed at location
 694                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">p</mml:mi></mml:math>
 695                         in memory,
 696                         then the location of the first pixel of the next row is obtained by skipping
 697                     </p><p>
 698                         </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 699
 700                             <mml:mrow>
 701                                 <mml:mi mathvariant="italic">k</mml:mi>
 702                                 <mml:mo>=</mml:mo>
 703                                 <mml:mfenced open="{" close="">
 704                                     <mml:mrow>
 705                                         <mml:mtable>
 706                                             <mml:mtr><mml:mtd>
 707                                                 <mml:mrow>
 708                                                     <mml:mi mathvariant="italic">n</mml:mi>
 709                                                     <mml:mo>⁢</mml:mo>
 710                                                     <mml:mi mathvariant="italic">l</mml:mi>
 711                                                     <mml:mo>⁢</mml:mo>
 712                                                     <mml:mi mathvariant="italic">h</mml:mi>
 713                                                 </mml:mrow>
 714                                             </mml:mtd></mml:mtr>
 715                                             <mml:mtr><mml:mtd>
 716                                                 <mml:mrow>
 717                                                     <mml:mfenced open="" close="">
 718                                                         <mml:mfrac>
 719                                                             <mml:mi mathvariant="italic">a</mml:mi>
 720                                                             <mml:mi mathvariant="italic">s</mml:mi>
 721                                                         </mml:mfrac>
 722                                                     </mml:mfenced>
 723                                                     <mml:mo>⁢</mml:mo>
 724                                                     <mml:mfenced open="&#x2308;" close="&#x2309;">
 725                                                         <mml:mfrac>
 726                                                             <mml:mfenced open="" close="">
 727                                                                 <mml:mrow>
 728                                                                     <mml:mi mathvariant="italic">s</mml:mi>
 729                                                                     <mml:mo>⁢</mml:mo>
 730                                                                     <mml:mi mathvariant="italic">n</mml:mi>
 731                                                                     <mml:mo>⁢</mml:mo>
 732                                                                     <mml:mi mathvariant="italic">l</mml:mi>
 733                                                                     <mml:mo>⁢</mml:mo>
 734                                                                     <mml:mi mathvariant="italic">h</mml:mi>
 735                                                                 </mml:mrow>
 736                                                             </mml:mfenced>
 737                                                             <mml:mi mathvariant="italic">a</mml:mi>
 738                                                         </mml:mfrac>
 739                                                     </mml:mfenced>
 740                                                 </mml:mrow>
 741                                             </mml:mtd></mml:mtr>
 742                                         </mml:mtable>
 743                                         <mml:mo>⁢</mml:mo>
 744                                         <mml:mtable>
 745                                             <mml:mtr><mml:mtd>
 746                                                 <mml:mrow>
 747                                                     <mml:mi mathvariant="italic">s</mml:mi>
 748                                                     <mml:mo>&gt;=</mml:mo>
 749                                                     <mml:mi mathvariant="italic">a</mml:mi>
 750                                                 </mml:mrow>
 751                                             </mml:mtd></mml:mtr>
 752                                             <mml:mtr><mml:mtd>
 753                                                 <mml:mrow>
 754                                                     <mml:mi mathvariant="italic">s</mml:mi>
 755                                                     <mml:mo>&lt;</mml:mo>
 756                                                     <mml:mi mathvariant="italic">a</mml:mi>
 757                                                 </mml:mrow>
 758                                             </mml:mtd></mml:mtr>
 759                                         </mml:mtable>
 760                                     </mml:mrow>
 761                                 </mml:mfenced>
 762                             </mml:mrow>
 763                         </mml:math></div><p>
 764                     </p><p>
 765                         components or indices,
 766                         where
 767                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 768                         is the number of components or indices in a pixel,
 769                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">l</mml:mi></mml:math>
 770                         is the number of pixels in a row
 771                         (<code class="constant">GL_UNPACK_ROW_LENGTH</code> if it is greater than 0,
 772                         the
 773                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">width</mml:mi></mml:math>
 774                         argument to <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> otherwise),
 775                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">h</mml:mi></mml:math>
 776                         is the number of rows in an image (<code class="constant">GL_UNPACK_IMAGE_HEIGHT</code> if
 777                         it is greater than 0, the
 778                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">height</mml:mi></mml:math>
 779                         argument to <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> otherwise),
 780                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">a</mml:mi></mml:math>
 781                         is the value of <code class="constant">GL_UNPACK_ALIGNMENT</code>, and
 782                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 783                         is the size, in bytes, of a single component
 784                         (if
 785                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 786
 787                             <mml:mrow>
 788                                 <mml:mi mathvariant="italic">a</mml:mi>
 789                                 <mml:mo>&lt;</mml:mo>
 790                                 <mml:mi mathvariant="italic">s</mml:mi>
 791                             </mml:mrow>
 792                         </mml:math>,
 793                         then it is as if
 794                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 795
 796                             <mml:mrow>
 797                                 <mml:mi mathvariant="italic">a</mml:mi>
 798                                 <mml:mo>=</mml:mo>
 799                                 <mml:mi mathvariant="italic">s</mml:mi>
 800                             </mml:mrow>
 801                         </mml:math>).
 802                     </p><p>
 803                         The word <span class="emphasis"><em>component</em></span> in this description refers to the nonindex values
 804                         red,
 805                         green,
 806                         blue,
 807                         alpha,
 808                         and depth.
 809                         Storage format <code class="constant">GL_RGB</code>,
 810                         for example,
 811                         has three components per pixel:
 812                         first red,
 813                         then green,
 814                         and finally blue.
 815                     </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>
 816                         These values are provided as a convenience to the programmer;
 817                         they provide no functionality that cannot be duplicated by
 818                         incrementing the pointer passed to
 819                         <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 820                         <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 821                         <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a> or
 822                         <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>.
 823                         Setting <code class="constant">GL_UNPACK_SKIP_PIXELS</code> to
 824                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>
 825                         is equivalent to incrementing
 826                         the pointer by
 827                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 828
 829                             <mml:mrow>
 830                                 <mml:mi mathvariant="italic">i</mml:mi>
 831                                 <mml:mo>⁢</mml:mo>
 832                                 <mml:mi mathvariant="italic">n</mml:mi>
 833                             </mml:mrow>
 834                         </mml:math>
 835                         components or indices,
 836                         where
 837                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 838                         is the number of components or indices in each pixel.
 839                         Setting <code class="constant">GL_UNPACK_SKIP_ROWS</code> to
 840                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>
 841                         is equivalent to incrementing
 842                         the pointer by
 843                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 844
 845                             <mml:mrow>
 846                                 <mml:mi mathvariant="italic">j</mml:mi>
 847                                 <mml:mo>⁢</mml:mo>
 848                                 <mml:mi mathvariant="italic">k</mml:mi>
 849                             </mml:mrow>
 850                         </mml:math>
 851                         components or indices,
 852                         where
 853                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">k</mml:mi></mml:math>
 854                         is the number of components or indices per row,
 855                         as just computed in the <code class="constant">GL_UNPACK_ROW_LENGTH</code> section.
 856                     </p></dd><dt><span class="term"><code class="constant">GL_UNPACK_ALIGNMENT</code></span></dt><dd><p>
 857                         Specifies the alignment requirements for the start of each pixel row in memory.
 858                         The allowable values are
 859                         1 (byte-alignment),
 860                         2 (rows aligned to even-numbered bytes),
 861                         4 (word-alignment), and
 862                         8 (rows start on double-word boundaries).
 863                     </p></dd></dl></div><p>
 864             The following table gives the type,
 865             initial value,
 866             and range of valid values for each storage parameter
 867             that can be set with <code class="function">glPixelStore</code>.
 868         </p><p>
 869         </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>
 870                         <em class="parameter"><code>pname</code></em>
 871                         </strong></span></th><th align="center"><span class="bold"><strong>
 872                         Type
 873                         </strong></span></th><th align="center"><span class="bold"><strong>
 874                         Initial Value
 875                         </strong></span></th><th align="center"><span class="bold"><strong>
 876                         Valid Range
 877                         </strong></span></th></tr></thead><tbody><tr><td align="left">
 878                         <code class="constant">GL_PACK_SWAP_BYTES</code>
 879                         </td><td align="center">
 880                         boolean
 881                         </td><td align="center">
 882                         false
 883                         </td><td align="center">
 884                         true or false
 885                         </td></tr><tr><td align="left">
 886                         <code class="constant">GL_PACK_LSB_FIRST</code>
 887                         </td><td align="center">
 888                         boolean
 889                         </td><td align="center">
 890                         false
 891                         </td><td align="center">
 892                         true or false
 893                         </td></tr><tr><td align="left">
 894                         <code class="constant">GL_PACK_ROW_LENGTH</code>
 895                         </td><td align="center">
 896                         integer
 897                         </td><td align="center">
 898                         0
 899                         </td><td align="center">
 900                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 901
 902                             <mml:mfenced open="[" close=")">
 903                                 <mml:mn>0</mml:mn>
 904                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 905                             </mml:mfenced>
 906                         </mml:math>
 907                         </td></tr><tr><td align="left">
 908                         <code class="constant">GL_PACK_IMAGE_HEIGHT</code>
 909                         </td><td align="center">
 910                         integer
 911                         </td><td align="center">
 912                         0
 913                         </td><td align="center">
 914                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 915
 916                             <mml:mfenced open="[" close=")">
 917                                 <mml:mn>0</mml:mn>
 918                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 919                             </mml:mfenced>
 920                         </mml:math>
 921                         </td></tr><tr><td align="left">
 922                         <code class="constant">GL_PACK_SKIP_ROWS</code>
 923                         </td><td align="center">
 924                         integer
 925                         </td><td align="center">
 926                         0
 927                         </td><td align="center">
 928                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 929
 930                             <mml:mfenced open="[" close=")">
 931                                 <mml:mn>0</mml:mn>
 932                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 933                             </mml:mfenced>
 934                         </mml:math>
 935                         </td></tr><tr><td align="left">
 936                         <code class="constant">GL_PACK_SKIP_PIXELS</code>
 937                         </td><td align="center">
 938                         integer
 939                         </td><td align="center">
 940                         0
 941                         </td><td align="center">
 942                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 943
 944                             <mml:mfenced open="[" close=")">
 945                                 <mml:mn>0</mml:mn>
 946                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 947                             </mml:mfenced>
 948                         </mml:math>
 949                         </td></tr><tr><td align="left">
 950                         <code class="constant">GL_PACK_SKIP_IMAGES</code>
 951                         </td><td align="center">
 952                         integer
 953                         </td><td align="center">
 954                         0
 955                         </td><td align="center">
 956                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 957
 958                             <mml:mfenced open="[" close=")">
 959                                 <mml:mn>0</mml:mn>
 960                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 961                             </mml:mfenced>
 962                         </mml:math>
 963                         </td></tr><tr><td align="left">
 964                         <code class="constant">GL_PACK_ALIGNMENT</code>
 965                         </td><td align="center">
 966                         integer
 967                         </td><td align="center">
 968                         4
 969                         </td><td align="center">
 970                         1, 2, 4, or 8
 971                         </td></tr><tr><td align="left">
 972                         <code class="constant">GL_UNPACK_SWAP_BYTES</code>
 973                         </td><td align="center">
 974                         boolean
 975                         </td><td align="center">
 976                         false
 977                         </td><td align="center">
 978                         true or false
 979                         </td></tr><tr><td align="left">
 980                         <code class="constant">GL_UNPACK_LSB_FIRST</code>
 981                         </td><td align="center">
 982                         boolean
 983                         </td><td align="center">
 984                         false
 985                         </td><td align="center">
 986                         true or false
 987                         </td></tr><tr><td align="left">
 988                         <code class="constant">GL_UNPACK_ROW_LENGTH</code>
 989                         </td><td align="center">
 990                         integer
 991                         </td><td align="center">
 992                         0
 993                         </td><td align="center">
 994                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 995
 996                             <mml:mfenced open="[" close=")">
 997                                 <mml:mn>0</mml:mn>
 998                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
 999                             </mml:mfenced>
1000                         </mml:math>
1001                         </td></tr><tr><td align="left">
1002                         <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code>
1003                         </td><td align="center">
1004                         integer
1005                         </td><td align="center">
1006                         0
1007                         </td><td align="center">
1008                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1009
1010                             <mml:mfenced open="[" close=")">
1011                                 <mml:mn>0</mml:mn>
1012                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1013                             </mml:mfenced>
1014                         </mml:math>
1015                         </td></tr><tr><td align="left">
1016                         <code class="constant">GL_UNPACK_SKIP_ROWS</code>
1017                         </td><td align="center">
1018                         integer
1019                         </td><td align="center">
1020                         0
1021                         </td><td align="center">
1022                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1023
1024                             <mml:mfenced open="[" close=")">
1025                                 <mml:mn>0</mml:mn>
1026                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1027                             </mml:mfenced>
1028                         </mml:math>
1029                         </td></tr><tr><td align="left">
1030                         <code class="constant">GL_UNPACK_SKIP_PIXELS</code>
1031                         </td><td align="center">
1032                         integer
1033                         </td><td align="center">
1034                         0
1035                         </td><td align="center">
1036                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1037
1038                             <mml:mfenced open="[" close=")">
1039                                 <mml:mn>0</mml:mn>
1040                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1041                             </mml:mfenced>
1042                         </mml:math>
1043                         </td></tr><tr><td align="left">
1044                         <code class="constant">GL_UNPACK_SKIP_IMAGES</code>
1045                         </td><td align="center">
1046                         integer
1047                         </td><td align="center">
1048                         0
1049                         </td><td align="center">
1050                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
1051
1052                             <mml:mfenced open="[" close=")">
1053                                 <mml:mn>0</mml:mn>
1054                                 <mml:infinity definitionURL="" encoding=""></mml:infinity>
1055                             </mml:mfenced>
1056                         </mml:math>
1057                         </td></tr><tr><td align="left">
1058                         <code class="constant">GL_UNPACK_ALIGNMENT</code>
1059                         </td><td align="center">
1060                         integer
1061                         </td><td align="center">
1062                         4
1063                         </td><td align="center">
1064                         1, 2, 4, or 8
1065                         </td></tr></tbody></table></div><p>
1066             <code class="function">glPixelStoref</code> can be used to set any pixel store parameter.
1067             If the parameter type is boolean,
1068             then if <em class="parameter"><code>param</code></em> is 0,
1069             the parameter is false;
1070             otherwise it is set to true.
1071             If <em class="parameter"><code>pname</code></em> is a integer type parameter,
1072             <em class="parameter"><code>param</code></em> is rounded to the nearest integer.
1073         </p><p>
1074             Likewise, <code class="function">glPixelStorei</code> can also be used to set any of the
1075             pixel store parameters.
1076             Boolean parameters are set to false if <em class="parameter"><code>param</code></em> is 0 and true otherwise.
1077         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
1078             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>pname</code></em> is not an accepted value.
1079         </p><p>
1080             <code class="constant">GL_INVALID_VALUE</code> is generated if a negative row length,
1081             pixel skip,
1082             or row skip value is specified,
1083             or if alignment is specified as other than 1, 2, 4, or 8.
1084         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
1085             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SWAP_BYTES</code>
1086         </p><p>
1087             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_LSB_FIRST</code>
1088         </p><p>
1089             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_ROW_LENGTH</code>
1090         </p><p>
1091             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_IMAGE_HEIGHT</code>
1092         </p><p>
1093             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SKIP_ROWS</code>
1094         </p><p>
1095             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SKIP_PIXELS</code>
1096         </p><p>
1097             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_SKIP_IMAGES</code>
1098         </p><p>
1099             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PACK_ALIGNMENT</code>
1100         </p><p>
1101             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SWAP_BYTES</code>
1102         </p><p>
1103             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_LSB_FIRST</code>
1104         </p><p>
1105             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_ROW_LENGTH</code>
1106         </p><p>
1107             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_IMAGE_HEIGHT</code>
1108         </p><p>
1109             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SKIP_ROWS</code>
1110         </p><p>
1111             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SKIP_PIXELS</code>
1112         </p><p>
1113             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_SKIP_IMAGES</code>
1114         </p><p>
1115             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_UNPACK_ALIGNMENT</code>
1116         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
1117             <a href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
1118             <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
1119             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
1120             <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
1121             <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
1122             <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,
1123             <a href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>,
1124             <a href="glCompressedTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage1D</span></span></a>,
1125             <a href="glCompressedTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>,
1126             <a href="glCompressedTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage3D</span></span></a>,
1127             <a href="glCompressedTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage1D</span></span></a>,
1128             <a href="glCompressedTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage2D</span></span></a>,
1129             <a href="glCompressedTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage1D</span></span></a>.
1130         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
1131             Copyright <span class="trademark"></span>© 1991-2006
1132             Silicon Graphics, Inc. <span class="trademark"></span>© 2011
1133             Khronos Group. This document is licensed under the SGI
1134             Free Software B License. For details, see
1135             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
1136         </p></div></div></body></html>