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1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> |
2 | <!-- saved from url=(0013)about:internet --> | |
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>glEvalMesh</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glEvalMesh"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glEvalMesh — compute a one- or two-dimensional grid of points or lines</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">glEvalMesh1</b>(</code></td><td>GLenum </td><td><var class="pdparam">mode</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">i1</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">i2</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>mode</code></em></span></dt><dd><p> | |
4 | In <code class="function">glEvalMesh1</code>, specifies whether to compute a one-dimensional mesh of points or lines. | |
5 | Symbolic constants | |
6 | <code class="constant">GL_POINT</code> and | |
7 | <code class="constant">GL_LINE</code> are accepted. | |
8 | </p></dd><dt><span class="term"><em class="parameter"><code>i1</code></em>, </span><span class="term"><em class="parameter"><code>i2</code></em></span></dt><dd><p> | |
9 | Specify the first and last integer values for grid domain variable | |
10 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>. | |
11 | </p></dd></dl></div></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">glEvalMesh2</b>(</code></td><td>GLenum </td><td><var class="pdparam">mode</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">i1</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">i2</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">j1</var>, </td></tr><tr><td> </td><td>GLint </td><td><var class="pdparam">j2</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters2"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>mode</code></em></span></dt><dd><p> | |
12 | In <code class="function">glEvalMesh2</code>, specifies whether to compute a two-dimensional mesh of points, lines, | |
13 | or polygons. | |
14 | Symbolic constants | |
15 | <code class="constant">GL_POINT</code>, | |
16 | <code class="constant">GL_LINE</code>, and | |
17 | <code class="constant">GL_FILL</code> are accepted. | |
18 | </p></dd><dt><span class="term"><em class="parameter"><code>i1</code></em>, </span><span class="term"><em class="parameter"><code>i2</code></em></span></dt><dd><p> | |
19 | Specify the first and last integer values for grid domain variable | |
20 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>. | |
21 | </p></dd><dt><span class="term"><em class="parameter"><code>j1</code></em>, </span><span class="term"><em class="parameter"><code>j2</code></em></span></dt><dd><p> | |
22 | Specify the first and last integer values for grid domain variable | |
23 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>. | |
24 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
25 | <a class="citerefentry" href="glMapGrid.xml"><span class="citerefentry"><span class="refentrytitle">glMapGrid</span></span></a> and <code class="function">glEvalMesh</code> are used in tandem to efficiently | |
26 | generate and evaluate a series of evenly-spaced map domain values. | |
27 | <code class="function">glEvalMesh</code> steps through the integer domain of a one- or two-dimensional grid, | |
28 | whose range is the domain of the evaluation maps specified by | |
29 | <a class="citerefentry" href="glMap1.xml"><span class="citerefentry"><span class="refentrytitle">glMap1</span></span></a> and <a class="citerefentry" href="glMap2.xml"><span class="citerefentry"><span class="refentrytitle">glMap2</span></span></a>. | |
30 | <em class="parameter"><code>mode</code></em> determines whether the resulting vertices are connected as | |
31 | points, | |
32 | lines, | |
33 | or filled polygons. | |
34 | </p><p> | |
35 | In the one-dimensional case, | |
36 | <code class="function">glEvalMesh1</code>, | |
37 | the mesh is generated as if the following code fragment were executed: | |
38 | </p><p> | |
39 | </p><pre class="programlisting"> | |
40 | glBegin( <em class="parameter"><code>type</code></em> ); | |
41 | for ( i = <em class="parameter"><code>i1</code></em>; i <= <em class="parameter"><code>i2</code></em>; i += 1 ) | |
42 | glEvalCoord1( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
43 | ||
44 | <mml:mrow> | |
45 | <mml:mrow> | |
46 | <mml:mn>i</mml:mn> | |
47 | <mml:mo>·</mml:mo> | |
48 | <mml:mo>Δ</mml:mo> | |
49 | <mml:mi mathvariant="italic">u</mml:mi> | |
50 | </mml:mrow> | |
51 | <mml:mo>+</mml:mo> | |
52 | <mml:msub> | |
53 | <mml:mi mathvariant="italic">u</mml:mi> | |
54 | <mml:mn>1</mml:mn> | |
55 | </mml:msub> | |
56 | </mml:mrow> | |
57 | </mml:math> ); | |
58 | glEnd(); | |
59 | </pre><p> | |
60 | where | |
61 | </p><p> | |
62 | </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
63 | ||
64 | <mml:mrow> | |
65 | <mml:mrow> | |
66 | <mml:mo>Δ</mml:mo> | |
67 | <mml:mi mathvariant="italic">u</mml:mi> | |
68 | </mml:mrow> | |
69 | <mml:mo>=</mml:mo> | |
70 | <mml:mfrac> | |
71 | <mml:mfenced open="(" close=")"> | |
72 | <mml:mrow> | |
73 | <mml:msub> | |
74 | <mml:mi mathvariant="italic">u</mml:mi> | |
75 | <mml:mn>2</mml:mn> | |
76 | </mml:msub> | |
77 | <mml:mo>-</mml:mo> | |
78 | <mml:msub> | |
79 | <mml:mi mathvariant="italic">u</mml:mi> | |
80 | <mml:mn>1</mml:mn> | |
81 | </mml:msub> | |
82 | </mml:mrow> | |
83 | </mml:mfenced> | |
84 | <mml:mi mathvariant="italic">n</mml:mi> | |
85 | </mml:mfrac> | |
86 | </mml:mrow> | |
87 | </mml:math></div><p> | |
88 | </p><p> | |
89 | and | |
90 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>, | |
91 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
92 | ||
93 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
94 | <mml:mn>1</mml:mn> | |
95 | </mml:msub> | |
96 | </mml:math>, | |
97 | and | |
98 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
99 | ||
100 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
101 | <mml:mn>2</mml:mn> | |
102 | </mml:msub> | |
103 | </mml:math> | |
104 | are the arguments to the most recent | |
105 | <a class="citerefentry" href="glMapGrid1.xml"><span class="citerefentry"><span class="refentrytitle">glMapGrid1</span></span></a> command. | |
106 | <span class="emphasis"><em>type</em></span> is <code class="constant">GL_POINTS</code> if <em class="parameter"><code>mode</code></em> is <code class="constant">GL_POINT</code>, | |
107 | or <code class="constant">GL_LINES</code> if <em class="parameter"><code>mode</code></em> is <code class="constant">GL_LINE</code>. | |
108 | </p><p> | |
109 | The one absolute numeric requirement is that if | |
110 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
111 | ||
112 | <mml:mrow> | |
113 | <mml:mi mathvariant="italic">i</mml:mi> | |
114 | <mml:mo>=</mml:mo> | |
115 | <mml:mi mathvariant="italic">n</mml:mi> | |
116 | </mml:mrow> | |
117 | </mml:math>, | |
118 | then the | |
119 | value computed from | |
120 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
121 | ||
122 | <mml:mrow> | |
123 | <mml:mrow> | |
124 | <mml:mi mathvariant="italic">i</mml:mi> | |
125 | <mml:mo>·</mml:mo> | |
126 | <mml:mrow> | |
127 | <mml:mo>Δ</mml:mo> | |
128 | <mml:mi mathvariant="italic">u</mml:mi> | |
129 | </mml:mrow> | |
130 | </mml:mrow> | |
131 | <mml:mo>+</mml:mo> | |
132 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
133 | <mml:mn>1</mml:mn> | |
134 | </mml:msub> | |
135 | </mml:mrow> | |
136 | </mml:math> | |
137 | is exactly | |
138 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
139 | ||
140 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
141 | <mml:mn>2</mml:mn> | |
142 | </mml:msub> | |
143 | </mml:math>. | |
144 | </p><p> | |
145 | In the two-dimensional case, <code class="function">glEvalMesh2</code>, let | |
146 | .cp | |
147 | </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
148 | ||
149 | <mml:mrow> | |
150 | <mml:mrow> | |
151 | <mml:mo>Δ</mml:mo> | |
152 | <mml:mi mathvariant="italic">u</mml:mi> | |
153 | </mml:mrow> | |
154 | <mml:mo>=</mml:mo> | |
155 | <mml:mfrac> | |
156 | <mml:mfenced open="(" close=")"> | |
157 | <mml:mrow> | |
158 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
159 | <mml:mn>2</mml:mn> | |
160 | </mml:msub> | |
161 | <mml:mo>-</mml:mo> | |
162 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
163 | <mml:mn>1</mml:mn> | |
164 | </mml:msub> | |
165 | </mml:mrow> | |
166 | </mml:mfenced> | |
167 | <mml:mi mathvariant="italic">n</mml:mi> | |
168 | </mml:mfrac> | |
169 | </mml:mrow> | |
170 | </mml:math></div><p> | |
171 | </p><p> | |
172 | </p><div class="informalequation"><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
173 | ||
174 | <mml:mrow> | |
175 | <mml:mrow> | |
176 | <mml:mo>Δ</mml:mo> | |
177 | <mml:mi mathvariant="italic">v</mml:mi> | |
178 | </mml:mrow> | |
179 | <mml:mo>=</mml:mo> | |
180 | <mml:mfrac> | |
181 | <mml:mfenced open="(" close=")"> | |
182 | <mml:mrow> | |
183 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
184 | <mml:mn>2</mml:mn> | |
185 | </mml:msub> | |
186 | <mml:mo>-</mml:mo> | |
187 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
188 | <mml:mn>1</mml:mn> | |
189 | </mml:msub> | |
190 | </mml:mrow> | |
191 | </mml:mfenced> | |
192 | <mml:mi mathvariant="italic">m</mml:mi> | |
193 | </mml:mfrac> | |
194 | </mml:mrow> | |
195 | </mml:math></div><p> | |
196 | </p><p> | |
197 | where | |
198 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>, | |
199 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
200 | ||
201 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
202 | <mml:mn>1</mml:mn> | |
203 | </mml:msub> | |
204 | </mml:math>, | |
205 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
206 | ||
207 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
208 | <mml:mn>2</mml:mn> | |
209 | </mml:msub> | |
210 | </mml:math>, | |
211 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">m</mml:mi></mml:math>, | |
212 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
213 | ||
214 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
215 | <mml:mn>1</mml:mn> | |
216 | </mml:msub> | |
217 | </mml:math>, | |
218 | and | |
219 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
220 | ||
221 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
222 | <mml:mn>2</mml:mn> | |
223 | </mml:msub> | |
224 | </mml:math> | |
225 | are the | |
226 | arguments to the most recent <a class="citerefentry" href="glMapGrid2.xml"><span class="citerefentry"><span class="refentrytitle">glMapGrid2</span></span></a> command. Then, if | |
227 | <em class="parameter"><code>mode</code></em> is <code class="constant">GL_FILL</code>, the <code class="function">glEvalMesh2</code> command is equivalent | |
228 | to: | |
229 | </p><p> | |
230 | </p><pre class="programlisting"> | |
231 | for ( j = <em class="parameter"><code>j1</code></em>; j < <em class="parameter"><code>j2</code></em>; j += 1 ) { | |
232 | glBegin( GL_QUAD_STRIP ); | |
233 | for ( i = <em class="parameter"><code>i1</code></em>; i <= <em class="parameter"><code>i2</code></em>; i += 1 ) { | |
234 | glEvalCoord2( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
235 | ||
236 | <mml:mrow> | |
237 | <mml:mrow> | |
238 | <mml:mn>i</mml:mn> | |
239 | <mml:mo>·</mml:mo> | |
240 | <mml:mo>Δ</mml:mo> | |
241 | <mml:mi mathvariant="italic">u</mml:mi> | |
242 | </mml:mrow> | |
243 | <mml:mo>+</mml:mo> | |
244 | <mml:msub> | |
245 | <mml:mi mathvariant="italic">u</mml:mi> | |
246 | <mml:mn>1</mml:mn> | |
247 | </mml:msub> | |
248 | <mml:mo>,</mml:mo> | |
249 | ||
250 | <mml:mrow> | |
251 | <mml:mn>j</mml:mn> | |
252 | <mml:mo>·</mml:mo> | |
253 | <mml:mo>Δ</mml:mo> | |
254 | <mml:mi mathvariant="italic">v</mml:mi> | |
255 | ||
256 | </mml:mrow> | |
257 | <mml:mo>+</mml:mo> | |
258 | <mml:msub> | |
259 | <mml:mi mathvariant="italic">v</mml:mi> | |
260 | <mml:mn>1</mml:mn> | |
261 | </mml:msub> | |
262 | </mml:mrow> | |
263 | </mml:math> ); | |
264 | glEvalCoord2( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
265 | ||
266 | <mml:mrow> | |
267 | <mml:mrow> | |
268 | <mml:mn>i</mml:mn> | |
269 | <mml:mo>·</mml:mo> | |
270 | <mml:mo>Δ</mml:mo> | |
271 | <mml:mi mathvariant="italic">u</mml:mi> | |
272 | </mml:mrow> | |
273 | <mml:mo>+</mml:mo> | |
274 | <mml:msub> | |
275 | <mml:mi mathvariant="italic">u</mml:mi> | |
276 | <mml:mn>1</mml:mn> | |
277 | </mml:msub> | |
278 | <mml:mo>,</mml:mo> | |
279 | ||
280 | <mml:mrow> | |
281 | <mml:mrow> | |
282 | <mml:mfenced open="(" close=")"> | |
283 | <mml:mrow> | |
284 | <mml:mn>j</mml:mn> | |
285 | <mml:mo>+</mml:mo> | |
286 | <mml:mn>1</mml:mn> | |
287 | </mml:mrow> | |
288 | </mml:mfenced> | |
289 | </mml:mrow> | |
290 | <mml:mo>·</mml:mo> | |
291 | <mml:mo>Δ</mml:mo> | |
292 | <mml:mi mathvariant="italic">v</mml:mi> | |
293 | </mml:mrow> | |
294 | <mml:mo>+</mml:mo> | |
295 | <mml:msub> | |
296 | <mml:mi mathvariant="italic">v</mml:mi> | |
297 | <mml:mn>1</mml:mn> | |
298 | </mml:msub> | |
299 | </mml:mrow> | |
300 | </mml:math> ); | |
301 | } | |
302 | glEnd(); | |
303 | } | |
304 | </pre><p> | |
305 | </p><p> | |
306 | If <em class="parameter"><code>mode</code></em> is <code class="constant">GL_LINE</code>, then a call to <code class="function">glEvalMesh2</code> is equivalent to: | |
307 | </p><p> | |
308 | </p><pre class="programlisting"> | |
309 | for ( j = <em class="parameter"><code>j1</code></em>; j <= <em class="parameter"><code>j2</code></em>; j += 1 ) { | |
310 | glBegin( GL_LINE_STRIP ); | |
311 | for ( i = <em class="parameter"><code>i1</code></em>; i <= <em class="parameter"><code>i2</code></em>; i += 1 ) | |
312 | glEvalCoord2( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
313 | ||
314 | <mml:mrow> | |
315 | <mml:mrow> | |
316 | <mml:mn>i</mml:mn> | |
317 | <mml:mo>·</mml:mo> | |
318 | <mml:mo>Δ</mml:mo> | |
319 | <mml:mi mathvariant="italic">u</mml:mi> | |
320 | </mml:mrow> | |
321 | <mml:mo>+</mml:mo> | |
322 | <mml:msub> | |
323 | <mml:mi mathvariant="italic">u</mml:mi> | |
324 | <mml:mn>1</mml:mn> | |
325 | </mml:msub> | |
326 | <mml:mo>,</mml:mo> | |
327 | ||
328 | <mml:mrow> | |
329 | <mml:mn>j</mml:mn> | |
330 | <mml:mo>·</mml:mo> | |
331 | <mml:mo>Δ</mml:mo> | |
332 | <mml:mi mathvariant="italic">v</mml:mi> | |
333 | </mml:mrow> | |
334 | <mml:mo>+</mml:mo> | |
335 | <mml:msub> | |
336 | <mml:mi mathvariant="italic">v</mml:mi> | |
337 | <mml:mn>1</mml:mn> | |
338 | </mml:msub> | |
339 | </mml:mrow> | |
340 | </mml:math> ); | |
341 | glEnd(); | |
342 | } | |
343 | ||
344 | for ( i = <em class="parameter"><code>i1</code></em>; i <= <em class="parameter"><code>i2</code></em>; i += 1 ) { | |
345 | glBegin( GL_LINE_STRIP ); | |
346 | for ( j = <em class="parameter"><code>j1</code></em>; j <= <em class="parameter"><code>j1</code></em>; j += 1 ) | |
347 | glEvalCoord2( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
348 | ||
349 | <mml:mrow> | |
350 | <mml:mrow> | |
351 | <mml:mn>i</mml:mn> | |
352 | <mml:mo>·</mml:mo> | |
353 | <mml:mo>Δ</mml:mo> | |
354 | <mml:mi mathvariant="italic">u</mml:mi> | |
355 | </mml:mrow> | |
356 | <mml:mo>+</mml:mo> | |
357 | <mml:msub> | |
358 | <mml:mi mathvariant="italic">u</mml:mi> | |
359 | <mml:mn>1</mml:mn> | |
360 | </mml:msub> | |
361 | <mml:mo>,</mml:mo> | |
362 | ||
363 | <mml:mrow> | |
364 | <mml:mn>j</mml:mn> | |
365 | <mml:mo>·</mml:mo> | |
366 | <mml:mo>Δ</mml:mo> | |
367 | <mml:mi mathvariant="italic">v</mml:mi> | |
368 | </mml:mrow> | |
369 | <mml:mo>+</mml:mo> | |
370 | <mml:msub> | |
371 | <mml:mi mathvariant="italic">v</mml:mi> | |
372 | <mml:mn>1</mml:mn> | |
373 | </mml:msub> | |
374 | </mml:mrow> | |
375 | </mml:math> ); | |
376 | glEnd(); | |
377 | } | |
378 | </pre><p> | |
379 | </p><p> | |
380 | And finally, if <em class="parameter"><code>mode</code></em> is <code class="constant">GL_POINT</code>, then a call to | |
381 | <code class="function">glEvalMesh2</code> is equivalent to: | |
382 | </p><p> | |
383 | </p><pre class="programlisting"> | |
384 | glBegin( GL_POINTS ); | |
385 | for ( j = <em class="parameter"><code>j1</code></em>; j <= <em class="parameter"><code>j2</code></em>; j += 1 ) | |
386 | for ( i = <em class="parameter"><code>i1</code></em>; i <= <em class="parameter"><code>i2</code></em>; i += 1 ) | |
387 | glEvalCoord2( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
388 | ||
389 | <mml:mrow> | |
390 | <mml:mrow> | |
391 | <mml:mn>i</mml:mn> | |
392 | <mml:mo>·</mml:mo> | |
393 | <mml:mo>Δ</mml:mo> | |
394 | <mml:mi mathvariant="italic">u</mml:mi> | |
395 | </mml:mrow> | |
396 | <mml:mo>+</mml:mo> | |
397 | <mml:msub> | |
398 | <mml:mi mathvariant="italic">u</mml:mi> | |
399 | <mml:mn>1</mml:mn> | |
400 | </mml:msub> | |
401 | <mml:mo>,</mml:mo> | |
402 | ||
403 | <mml:mrow> | |
404 | <mml:mn>j</mml:mn> | |
405 | <mml:mo>·</mml:mo> | |
406 | <mml:mo>Δ</mml:mo> | |
407 | <mml:mi mathvariant="italic">v</mml:mi> | |
408 | </mml:mrow> | |
409 | <mml:mo>+</mml:mo> | |
410 | <mml:msub> | |
411 | <mml:mi mathvariant="italic">v</mml:mi> | |
412 | <mml:mn>1</mml:mn> | |
413 | </mml:msub> | |
414 | </mml:mrow> | |
415 | </mml:math> ); | |
416 | glEnd(); | |
417 | </pre><p> | |
418 | </p><p> | |
419 | In all three cases, the only absolute numeric requirements are that if | |
420 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
421 | ||
422 | <mml:mrow> | |
423 | <mml:mi mathvariant="italic">i</mml:mi> | |
424 | <mml:mo>=</mml:mo> | |
425 | <mml:mi mathvariant="italic">n</mml:mi> | |
426 | </mml:mrow> | |
427 | </mml:math>, | |
428 | then the value computed from | |
429 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
430 | ||
431 | <mml:mrow> | |
432 | <mml:mrow> | |
433 | <mml:mi mathvariant="italic">i</mml:mi> | |
434 | <mml:mo>·</mml:mo> | |
435 | <mml:mrow> | |
436 | <mml:mo>Δ</mml:mo> | |
437 | <mml:mi mathvariant="italic">u</mml:mi> | |
438 | </mml:mrow> | |
439 | </mml:mrow> | |
440 | <mml:mo>+</mml:mo> | |
441 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
442 | <mml:mn>1</mml:mn> | |
443 | </mml:msub> | |
444 | </mml:mrow> | |
445 | </mml:math> | |
446 | is exactly | |
447 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
448 | ||
449 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
450 | <mml:mn>2</mml:mn> | |
451 | </mml:msub> | |
452 | </mml:math>, | |
453 | and if | |
454 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
455 | ||
456 | <mml:mrow> | |
457 | <mml:mi mathvariant="italic">j</mml:mi> | |
458 | <mml:mo>=</mml:mo> | |
459 | <mml:mi mathvariant="italic">m</mml:mi> | |
460 | </mml:mrow> | |
461 | </mml:math>, | |
462 | then the value computed from | |
463 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
464 | ||
465 | <mml:mrow> | |
466 | <mml:mrow> | |
467 | <mml:mi mathvariant="italic">j</mml:mi> | |
468 | <mml:mo>·</mml:mo> | |
469 | <mml:mrow> | |
470 | <mml:mo>Δ</mml:mo> | |
471 | <mml:mi mathvariant="italic">v</mml:mi> | |
472 | </mml:mrow> | |
473 | </mml:mrow> | |
474 | <mml:mo>+</mml:mo> | |
475 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
476 | <mml:mn>1</mml:mn> | |
477 | </mml:msub> | |
478 | </mml:mrow> | |
479 | </mml:math> | |
480 | is exactly | |
481 | <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> | |
482 | ||
483 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
484 | <mml:mn>2</mml:mn> | |
485 | </mml:msub> | |
486 | </mml:math>. | |
487 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
488 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>mode</code></em> is not an accepted value. | |
489 | </p><p> | |
490 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glEvalMesh</code> | |
491 | is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> | |
492 | and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>. | |
493 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
494 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAP1_GRID_DOMAIN</code> | |
495 | </p><p> | |
496 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAP2_GRID_DOMAIN</code> | |
497 | </p><p> | |
498 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAP1_GRID_SEGMENTS</code> | |
499 | </p><p> | |
500 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_MAP2_GRID_SEGMENTS</code> | |
501 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
502 | <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>, | |
503 | <a class="citerefentry" href="glEvalCoord.xml"><span class="citerefentry"><span class="refentrytitle">glEvalCoord</span></span></a>, | |
504 | <a class="citerefentry" href="glEvalPoint.xml"><span class="citerefentry"><span class="refentrytitle">glEvalPoint</span></span></a>, | |
505 | <a class="citerefentry" href="glMap1.xml"><span class="citerefentry"><span class="refentrytitle">glMap1</span></span></a>, | |
506 | <a class="citerefentry" href="glMap2.xml"><span class="citerefentry"><span class="refentrytitle">glMap2</span></span></a>, | |
507 | <a class="citerefentry" href="glMapGrid.xml"><span class="citerefentry"><span class="refentrytitle">glMapGrid</span></span></a> | |
508 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
509 | Copyright <span class="trademark"></span>© 1991-2006 | |
510 | Silicon Graphics, Inc. This document is licensed under the SGI | |
511 | Free Software B License. For details, see | |
512 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
513 | </p></div></div></body></html> |