upstream-man-pages/man2/xhtml/glMap1.xml

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   3 <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glMap1</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glMap1"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glMap1 — define a one-dimensional evaluator</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">glMap1f</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLfloat  </td><td><var class="pdparam">u1</var>, </td></tr><tr><td> </td><td>GLfloat  </td><td><var class="pdparam">u2</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">stride</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">order</var>, </td></tr><tr><td> </td><td>const GLfloat *  </td><td><var class="pdparam">points</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">glMap1d</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLdouble  </td><td><var class="pdparam">u1</var>, </td></tr><tr><td> </td><td>GLdouble  </td><td><var class="pdparam">u2</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">stride</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">order</var>, </td></tr><tr><td> </td><td>const GLdouble *  </td><td><var class="pdparam">points</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>target</code></em></span></dt><dd><p>
   4                     Specifies the kind of values that are generated by the evaluator.
   5                     Symbolic constants
   6                     <code class="constant">GL_MAP1_VERTEX_3</code>,
   7                     <code class="constant">GL_MAP1_VERTEX_4</code>,
   8                     <code class="constant">GL_MAP1_INDEX</code>,
   9                     <code class="constant">GL_MAP1_COLOR_4</code>,
  10                     <code class="constant">GL_MAP1_NORMAL</code>,
  11                     <code class="constant">GL_MAP1_TEXTURE_COORD_1</code>,
  12                     <code class="constant">GL_MAP1_TEXTURE_COORD_2</code>,
  13                     <code class="constant">GL_MAP1_TEXTURE_COORD_3</code>, and
  14                     <code class="constant">GL_MAP1_TEXTURE_COORD_4</code> are accepted.
  15                 </p></dd><dt><span class="term"><em class="parameter"><code>u1</code></em>, </span><span class="term"><em class="parameter"><code>u2</code></em></span></dt><dd><p>
  16                     Specify a linear mapping of
  17                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">u</mml:mi></mml:math>,
  18                     as presented to <a class="citerefentry" href="glEvalCoord1.xml"><span class="citerefentry"><span class="refentrytitle">glEvalCoord1</span></span></a>,
  19                     to
  20                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  21
  22                         <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
  23                     </mml:math>,
  24                     the variable that is evaluated by the equations specified by this command.
  25                 </p></dd><dt><span class="term"><em class="parameter"><code>stride</code></em></span></dt><dd><p>
  26                     Specifies the number of floats or doubles between
  27                     the beginning of one control point and the beginning of the next one
  28                     in the data structure referenced in <em class="parameter"><code>points</code></em>.
  29                     This allows control points to be embedded in arbitrary data structures.
  30                     The only constraint is that the values for a particular control point
  31                     must occupy contiguous memory locations.
  32                 </p></dd><dt><span class="term"><em class="parameter"><code>order</code></em></span></dt><dd><p>
  33                     Specifies the number of control points.
  34                     Must be positive.
  35                 </p></dd><dt><span class="term"><em class="parameter"><code>points</code></em></span></dt><dd><p>
  36                     Specifies a pointer to the array of control points.
  37                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  38             Evaluators provide a way to use polynomial or rational polynomial mapping
  39             to produce vertices,
  40             normals,
  41             texture coordinates,
  42             and colors.
  43             The values produced by an evaluator are sent to further stages
  44             of GL processing just as if they had been presented using
  45             <a class="citerefentry" href="glVertex.xml"><span class="citerefentry"><span class="refentrytitle">glVertex</span></span></a>,
  46             <a class="citerefentry" href="glNormal.xml"><span class="citerefentry"><span class="refentrytitle">glNormal</span></span></a>,
  47             <a class="citerefentry" href="glTexCoord.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord</span></span></a>, and
  48             <a class="citerefentry" href="glColor.xml"><span class="citerefentry"><span class="refentrytitle">glColor</span></span></a> commands,
  49             except that the generated values do not update the current normal,
  50             texture coordinates,
  51             or color.
  52         </p><p>
  53             All polynomial or rational polynomial splines of any degree
  54             (up to the maximum degree supported by the GL implementation)
  55             can be described using evaluators.
  56             These include almost all splines used in computer graphics: B-splines,
  57             Bezier curves, Hermite splines, and so on.
  58         </p><p>
  59             Evaluators define curves based on Bernstein polynomials.
  60             Define
  61             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  62
  63                 <mml:mrow>
  64                     <mml:mi mathvariant="italic">p</mml:mi>
  65                     <mml:mo>⁡</mml:mo>
  66                     <mml:mfenced open="(" close=")">
  67                         <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
  68                     </mml:mfenced>
  69                 </mml:mrow>
  70             </mml:math>
  71             as
  72         </p><p>
  73             </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  74
  75                 <mml:mrow>
  76                     <mml:mrow>
  77                         <mml:mi mathvariant="italic">p</mml:mi>
  78                         <mml:mo>⁡</mml:mo>
  79                         <mml:mfenced open="(" close=")">
  80                             <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
  81                         </mml:mfenced>
  82                     </mml:mrow>
  83                     <mml:mo>=</mml:mo>
  84                     <mml:mrow>
  85                         <mml:munderover>
  86                             <mml:mo>Σ</mml:mo>
  87                             <mml:mrow>
  88                                 <mml:mi mathvariant="italic">i</mml:mi>
  89                                 <mml:mo>=</mml:mo>
  90                                 <mml:mn>0</mml:mn>
  91                             </mml:mrow>
  92                             <mml:mi mathvariant="italic">n</mml:mi>
  93                         </mml:munderover>
  94                         <mml:mrow>
  95                             <mml:mrow>
  96                                 <mml:msup><mml:mfenced open="" close="">
  97                                     <mml:msub><mml:mi mathvariant="italic">B</mml:mi>
  98                                     <mml:mi mathvariant="italic">i</mml:mi>
  99                                     </mml:msub>
 100                                 </mml:mfenced>
 101                                 <mml:mi mathvariant="italic">n</mml:mi>
 102                                 </mml:msup>
 103                                 <mml:mo>⁡</mml:mo>
 104                                 <mml:mfenced open="(" close=")">
 105                                     <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 106                                 </mml:mfenced>
 107                             </mml:mrow>
 108                             <mml:mo>⁢</mml:mo>
 109                             <mml:msub><mml:mi mathvariant="italic">R</mml:mi>
 110                             <mml:mi mathvariant="italic">i</mml:mi>
 111                             </mml:msub>
 112                         </mml:mrow>
 113                     </mml:mrow>
 114                 </mml:mrow>
 115             </mml:math></div><p>
 116         </p><p>
 117         </p><p>
 118             where
 119             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 120
 121                 <mml:msub><mml:mi mathvariant="italic">R</mml:mi>
 122                 <mml:mi mathvariant="italic">i</mml:mi>
 123                 </mml:msub>
 124             </mml:math>
 125             is a control point and
 126             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 127
 128                 <mml:mrow>
 129                     <mml:msup><mml:mfenced open="" close="">
 130                         <mml:msub><mml:mi mathvariant="italic">B</mml:mi>
 131                         <mml:mi mathvariant="italic">i</mml:mi>
 132                         </mml:msub>
 133                     </mml:mfenced>
 134                     <mml:mi mathvariant="italic">n</mml:mi>
 135                     </mml:msup>
 136                     <mml:mo>⁡</mml:mo>
 137                     <mml:mfenced open="(" close=")">
 138                         <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 139                     </mml:mfenced>
 140                 </mml:mrow>
 141             </mml:math>
 142             is the
 143             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>th
 144             Bernstein polynomial of degree
 145             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
 146             (<em class="parameter"><code>order</code></em> =
 147             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 148
 149                 <mml:mrow>
 150                     <mml:mi mathvariant="italic">n</mml:mi>
 151                     <mml:mo>+</mml:mo>
 152                     <mml:mn>1</mml:mn>
 153                 </mml:mrow>
 154             </mml:math>):
 155         </p><p>
 156             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 157
 158                 <mml:mrow>
 159                     <mml:mrow>
 160                         <mml:msup><mml:mfenced open="" close="">
 161                             <mml:msub><mml:mi mathvariant="italic">B</mml:mi>
 162                             <mml:mi mathvariant="italic">i</mml:mi>
 163                             </mml:msub>
 164                         </mml:mfenced>
 165                         <mml:mi mathvariant="italic">n</mml:mi>
 166                         </mml:msup>
 167                         <mml:mo>⁡</mml:mo>
 168                         <mml:mfenced open="(" close=")">
 169                             <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 170                         </mml:mfenced>
 171                     </mml:mrow>
 172                     <mml:mo>=</mml:mo>
 173                     <mml:mrow>
 174                         <mml:mfenced open="(" close=")">
 175                             <mml:mfenced open="" close="">
 176                                 <mml:mtable>
 177                                     <mml:mtr><mml:mtd>
 178                                         <mml:mi mathvariant="italic">n</mml:mi>
 179                                     </mml:mtd></mml:mtr>
 180                                     <mml:mtr><mml:mtd>
 181                                         <mml:mi mathvariant="italic">i</mml:mi>
 182                                     </mml:mtd></mml:mtr>
 183                                 </mml:mtable>
 184                             </mml:mfenced>
 185                         </mml:mfenced>
 186                         <mml:mo>⁢</mml:mo>
 187                         <mml:msup><mml:mfenced open="" close="">
 188                             <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 189                         </mml:mfenced>
 190                         <mml:mi mathvariant="italic">i</mml:mi>
 191                         </mml:msup>
 192                         <mml:mo>⁢</mml:mo>
 193                         <mml:mfenced open="" close="">
 194                             <mml:msup><mml:mfenced open="(" close=")">
 195                                 <mml:mrow>
 196                                     <mml:mn>1</mml:mn>
 197                                     <mml:mo>-</mml:mo>
 198                                     <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 199                                 </mml:mrow>
 200                             </mml:mfenced>
 201                             <mml:mfenced open="" close="">
 202                                 <mml:mrow>
 203                                     <mml:mi mathvariant="italic">n</mml:mi>
 204                                     <mml:mo>-</mml:mo>
 205                                     <mml:mi mathvariant="italic">i</mml:mi>
 206                                 </mml:mrow>
 207                             </mml:mfenced>
 208                             </mml:msup>
 209                         </mml:mfenced>
 210                     </mml:mrow>
 211                 </mml:mrow>
 212             </mml:math>
 213         </p><p>
 214             Recall that
 215         </p><p>
 216             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 217
 218                 <mml:mrow>
 219                     <mml:msup><mml:mn>0</mml:mn>
 220                     <mml:mn>0</mml:mn>
 221                     </mml:msup>
 222                     <mml:mo>==</mml:mo>
 223                     <mml:mn>1</mml:mn>
 224                 </mml:mrow>
 225             </mml:math>
 226             and
 227             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 228
 229                 <mml:mrow>
 230                     <mml:mfenced open="(" close=")">
 231                         <mml:mfenced open="" close="">
 232                             <mml:mtable>
 233                                 <mml:mtr><mml:mtd>
 234                                     <mml:mi mathvariant="italic">n</mml:mi>
 235                                 </mml:mtd></mml:mtr>
 236                                 <mml:mtr><mml:mtd>
 237                                     <mml:mn>0</mml:mn>
 238                                 </mml:mtd></mml:mtr>
 239                             </mml:mtable>
 240                         </mml:mfenced>
 241                     </mml:mfenced>
 242                     <mml:mo>==</mml:mo>
 243                     <mml:mn>1</mml:mn>
 244                 </mml:mrow>
 245             </mml:math>
 246         </p><p>
 247             <code class="function">glMap1</code> is used to define the basis and to specify what kind of values
 248             are produced.
 249             Once defined,
 250             a map can be enabled and disabled by calling <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a>
 251             with the map name, one of the nine predefined values for <em class="parameter"><code>target</code></em>
 252             described below.
 253             <a class="citerefentry" href="glEvalCoord1.xml"><span class="citerefentry"><span class="refentrytitle">glEvalCoord1</span></span></a> evaluates the one-dimensional maps that are enabled.
 254             When
 255             <a class="citerefentry" href="glEvalCoord1.xml"><span class="citerefentry"><span class="refentrytitle">glEvalCoord1</span></span></a> presents a value
 256             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">u</mml:mi></mml:math>,
 257             the Bernstein functions are evaluated using
 258             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 259
 260                 <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 261             </mml:math>,
 262             where
 263             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 264
 265                 <mml:mrow>
 266                     <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>̂</mml:mo></mml:mover>
 267                     <mml:mo>=</mml:mo>
 268                     <mml:mfrac>
 269                         <mml:mfenced open="" close="">
 270                             <mml:mrow>
 271                                 <mml:mi mathvariant="italic">u</mml:mi>
 272                                 <mml:mo>-</mml:mo>
 273                                 <mml:mi mathvariant="italic">u1</mml:mi>
 274                             </mml:mrow>
 275                         </mml:mfenced>
 276                         <mml:mfenced open="" close="">
 277                             <mml:mrow>
 278                                 <mml:mi mathvariant="italic">u2</mml:mi>
 279                                 <mml:mo>-</mml:mo>
 280                                 <mml:mi mathvariant="italic">u1</mml:mi>
 281                             </mml:mrow>
 282                         </mml:mfenced>
 283                     </mml:mfrac>
 284                 </mml:mrow>
 285             </mml:math>
 286         </p><p>
 287             <em class="parameter"><code>target</code></em> is a symbolic constant that indicates what kind of control points
 288             are provided in <em class="parameter"><code>points</code></em>,
 289             and what output is generated when the map is evaluated.
 290             It can assume one of nine predefined values:
 291         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_MAP1_VERTEX_3</code></span></dt><dd><p>
 292                         Each control point is three floating-point values representing
 293                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>,
 294                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>,
 295                         and
 296                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">z</mml:mi></mml:math>.
 297                         Internal <a class="citerefentry" href="glVertex3.xml"><span class="citerefentry"><span class="refentrytitle">glVertex3</span></span></a> commands are generated when the map is evaluated.
 298                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_VERTEX_4</code></span></dt><dd><p>
 299                         Each control point is four floating-point values representing
 300                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>,
 301                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>,
 302                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">z</mml:mi></mml:math>,
 303                         and
 304                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">w</mml:mi></mml:math>.
 305                         Internal <a class="citerefentry" href="glVertex4.xml"><span class="citerefentry"><span class="refentrytitle">glVertex4</span></span></a> commands are generated when the map is evaluated.
 306                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_INDEX</code></span></dt><dd><p>
 307                         Each control point is a single floating-point value representing a color index.
 308                         Internal <a class="citerefentry" href="glIndex.xml"><span class="citerefentry"><span class="refentrytitle">glIndex</span></span></a> commands are generated when the map is evaluated
 309                         but the current index is not updated with the value of these <a class="citerefentry" href="glIndex.xml"><span class="citerefentry"><span class="refentrytitle">glIndex</span></span></a>
 310                         commands.
 311                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_COLOR_4</code></span></dt><dd><p>
 312                         Each control point is four floating-point values representing
 313                         red, green, blue, and alpha.
 314                         Internal <a class="citerefentry" href="glColor4.xml"><span class="citerefentry"><span class="refentrytitle">glColor4</span></span></a> commands are generated when the map is
 315                         evaluated but the current color is not updated with the value of these
 316                         <a class="citerefentry" href="glColor4.xml"><span class="citerefentry"><span class="refentrytitle">glColor4</span></span></a> commands.
 317                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_NORMAL</code></span></dt><dd><p>
 318                         Each control point is three floating-point values representing
 319                         the
 320                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">x</mml:mi></mml:math>,
 321                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">y</mml:mi></mml:math>,
 322                         and
 323                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">z</mml:mi></mml:math>
 324                         components of a normal vector.
 325                         Internal <a class="citerefentry" href="glNormal.xml"><span class="citerefentry"><span class="refentrytitle">glNormal</span></span></a> commands are generated when the map is
 326                         evaluated but the current normal is not updated with the value of
 327                         these <a class="citerefentry" href="glNormal.xml"><span class="citerefentry"><span class="refentrytitle">glNormal</span></span></a> commands.
 328                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_TEXTURE_COORD_1</code></span></dt><dd><p>
 329                         Each control point is a single floating-point value representing
 330                         the
 331                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 332                         texture coordinate.
 333                         Internal
 334                         <a class="citerefentry" href="glTexCoord1.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord1</span></span></a> commands are generated when the map is
 335                         evaluated but the current texture coordinates are not updated with the value
 336                         of these <a class="citerefentry" href="glTexCoord.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord</span></span></a> commands.
 337                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_TEXTURE_COORD_2</code></span></dt><dd><p>
 338                         Each control point is two floating-point values representing
 339                         the
 340                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>
 341                         and
 342                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math>
 343                         texture coordinates.
 344                         Internal
 345                         <a class="citerefentry" href="glTexCoord2.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord2</span></span></a> commands are generated when the map is
 346                         evaluated but the current texture coordinates are not updated with the value
 347                         of these <a class="citerefentry" href="glTexCoord.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord</span></span></a> commands.
 348                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_TEXTURE_COORD_3</code></span></dt><dd><p>
 349                         Each control point is three floating-point values representing
 350                         the
 351                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>,
 352                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math>,
 353                         and
 354                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">r</mml:mi></mml:math>
 355                         texture coordinates.
 356                         Internal <a class="citerefentry" href="glTexCoord3.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord3</span></span></a> commands are generated when the map is
 357                         evaluated but the current texture coordinates are not updated with the value
 358                         of these <a class="citerefentry" href="glTexCoord.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord</span></span></a> commands.
 359                     </p></dd><dt><span class="term"><code class="constant">GL_MAP1_TEXTURE_COORD_4</code></span></dt><dd><p>
 360                         Each control point is four floating-point values representing
 361                         the
 362                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">s</mml:mi></mml:math>,
 363                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">t</mml:mi></mml:math>,
 364                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">r</mml:mi></mml:math>,
 365                         and
 366                         <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">q</mml:mi></mml:math>
 367                         texture coordinates.
 368                         Internal
 369                         <a class="citerefentry" href="glTexCoord4.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord4</span></span></a> commands are generated when the map is evaluated but
 370                         the current texture coordinates are not updated with the value
 371                         of these <a class="citerefentry" href="glTexCoord.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord</span></span></a> commands.
 372                     </p></dd></dl></div><p>
 373             <em class="parameter"><code>stride</code></em>,
 374             <em class="parameter"><code>order</code></em>, and
 375             <em class="parameter"><code>points</code></em> define the array addressing for accessing the control points.
 376             <em class="parameter"><code>points</code></em> is the location of the first control point,
 377             which occupies one, two, three, or four contiguous memory locations,
 378             depending on which map is being defined.
 379             <em class="parameter"><code>order</code></em> is the number of control points in the array.
 380             <em class="parameter"><code>stride</code></em> specifies how many float or double locations to advance the internal
 381             memory pointer to reach the next control point.
 382         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 383             As is the case with all GL commands that accept pointers to data,
 384             it is as if the contents of <em class="parameter"><code>points</code></em> were copied by <code class="function">glMap1</code> before <code class="function">glMap1</code>
 385             returns.
 386             Changes to the contents of <em class="parameter"><code>points</code></em> have no effect after <code class="function">glMap1</code> is called.
 387         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 388             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not an accepted value.
 389         </p><p>
 390             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>u1</code></em> is equal to <em class="parameter"><code>u2</code></em>.
 391         </p><p>
 392             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>stride</code></em> is less than the number
 393             of values in a control point.
 394         </p><p>
 395             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>order</code></em> is less than 1 or
 396             greater than the return value of <code class="constant">GL_MAX_EVAL_ORDER</code>.
 397         </p><p>
 398             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glMap1</code>
 399             is executed between the execution of
 400             <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
 401             and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
 402         </p><p>
 403             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glMap1</code> is called and the value
 404             of <code class="constant">GL_ACTIVE_TEXTURE</code> is not <code class="constant">GL_TEXTURE0</code>.
 405         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 406             <a class="citerefentry" href="glGetMap.xml"><span class="citerefentry"><span class="refentrytitle">glGetMap</span></span></a>
 407         </p><p>
 408             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAX_EVAL_ORDER</code>
 409         </p><p>
 410             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_VERTEX_3</code>
 411         </p><p>
 412             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_VERTEX_4</code>
 413         </p><p>
 414             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_INDEX</code>
 415         </p><p>
 416             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_COLOR_4</code>
 417         </p><p>
 418             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_NORMAL</code>
 419         </p><p>
 420             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_TEXTURE_COORD_1</code>
 421         </p><p>
 422             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_TEXTURE_COORD_2</code>
 423         </p><p>
 424             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_TEXTURE_COORD_3</code>
 425         </p><p>
 426             <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_MAP1_TEXTURE_COORD_4</code>
 427         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 428             <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>,
 429             <a class="citerefentry" href="glColor.xml"><span class="citerefentry"><span class="refentrytitle">glColor</span></span></a>,
 430             <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
 431             <a class="citerefentry" href="glEvalCoord.xml"><span class="citerefentry"><span class="refentrytitle">glEvalCoord</span></span></a>,
 432             <a class="citerefentry" href="glEvalMesh.xml"><span class="citerefentry"><span class="refentrytitle">glEvalMesh</span></span></a>,
 433             <a class="citerefentry" href="glEvalPoint.xml"><span class="citerefentry"><span class="refentrytitle">glEvalPoint</span></span></a>,
 434             <a class="citerefentry" href="glMap2.xml"><span class="citerefentry"><span class="refentrytitle">glMap2</span></span></a>,
 435             <a class="citerefentry" href="glMapGrid.xml"><span class="citerefentry"><span class="refentrytitle">glMapGrid</span></span></a>,
 436             <a class="citerefentry" href="glNormal.xml"><span class="citerefentry"><span class="refentrytitle">glNormal</span></span></a>,
 437             <a class="citerefentry" href="glTexCoord.xml"><span class="citerefentry"><span class="refentrytitle">glTexCoord</span></span></a>,
 438             <a class="citerefentry" href="glVertex.xml"><span class="citerefentry"><span class="refentrytitle">glVertex</span></span></a>
 439         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 440             Copyright <span class="trademark"></span>© 1991-2006
 441             Silicon Graphics, Inc. This document is licensed under the SGI
 442             Free Software B License. For details, see
 443             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 444         </p></div></div></body></html>