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1 | <?xml version="1.0" encoding="UTF-8"?> |
2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN" | |
3 | "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd"> | |
4 | <refentry id="glEvalMesh"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glEvalMesh</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glEvalMesh</refname> | |
17 | <refpurpose>compute a one- or two-dimensional grid of points or lines</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glEvalMesh1</function></funcdef> | |
23 | <paramdef>GLenum <parameter>mode</parameter></paramdef> | |
24 | <paramdef>GLint <parameter>i1</parameter></paramdef> | |
25 | <paramdef>GLint <parameter>i2</parameter></paramdef> | |
26 | </funcprototype> | |
27 | </funcsynopsis> | |
28 | </refsynopsisdiv> | |
29 | <!-- eqn: ignoring delim $$ --> | |
30 | <refsect1 id="parameters"><title>Parameters</title> | |
31 | <variablelist> | |
32 | <varlistentry> | |
33 | <term><parameter>mode</parameter></term> | |
34 | <listitem> | |
35 | <para> | |
36 | In <function>glEvalMesh1</function>, specifies whether to compute a one-dimensional mesh of points or lines. | |
37 | Symbolic constants | |
38 | <constant>GL_POINT</constant> and | |
39 | <constant>GL_LINE</constant> are accepted. | |
40 | </para> | |
41 | </listitem> | |
42 | </varlistentry> | |
43 | <varlistentry> | |
44 | <term><parameter>i1</parameter></term> | |
45 | <term><parameter>i2</parameter></term> | |
46 | <listitem> | |
47 | <para> | |
48 | Specify the first and last integer values for grid domain variable | |
49 | <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>. | |
50 | </para> | |
51 | </listitem> | |
52 | </varlistentry> | |
53 | </variablelist> | |
54 | </refsect1> | |
55 | <refsynopsisdiv><title>C Specification</title> | |
56 | <funcsynopsis> | |
57 | <funcprototype> | |
58 | <funcdef>void <function>glEvalMesh2</function></funcdef> | |
59 | <paramdef>GLenum <parameter>mode</parameter></paramdef> | |
60 | <paramdef>GLint <parameter>i1</parameter></paramdef> | |
61 | <paramdef>GLint <parameter>i2</parameter></paramdef> | |
62 | <paramdef>GLint <parameter>j1</parameter></paramdef> | |
63 | <paramdef>GLint <parameter>j2</parameter></paramdef> | |
64 | </funcprototype> | |
65 | </funcsynopsis> | |
66 | </refsynopsisdiv> | |
67 | <refsect1 id="parameters2"><title>Parameters</title> | |
68 | <variablelist> | |
69 | <varlistentry> | |
70 | <term><parameter>mode</parameter></term> | |
71 | <listitem> | |
72 | <para> | |
73 | In <function>glEvalMesh2</function>, specifies whether to compute a two-dimensional mesh of points, lines, | |
74 | or polygons. | |
75 | Symbolic constants | |
76 | <constant>GL_POINT</constant>, | |
77 | <constant>GL_LINE</constant>, and | |
78 | <constant>GL_FILL</constant> are accepted. | |
79 | </para> | |
80 | </listitem> | |
81 | </varlistentry> | |
82 | <varlistentry> | |
83 | <term><parameter>i1</parameter></term> | |
84 | <term><parameter>i2</parameter></term> | |
85 | <listitem> | |
86 | <para> | |
87 | Specify the first and last integer values for grid domain variable | |
88 | <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>. | |
89 | </para> | |
90 | </listitem> | |
91 | </varlistentry> | |
92 | <varlistentry> | |
93 | <term><parameter>j1</parameter></term> | |
94 | <term><parameter>j2</parameter></term> | |
95 | <listitem> | |
96 | <para> | |
97 | Specify the first and last integer values for grid domain variable | |
98 | <inlineequation><mml:math><mml:mi mathvariant="italic">j</mml:mi></mml:math></inlineequation>. | |
99 | </para> | |
100 | </listitem> | |
101 | </varlistentry> | |
102 | </variablelist> | |
103 | </refsect1> | |
104 | <refsect1 id="description"><title>Description</title> | |
105 | <para> | |
106 | <citerefentry><refentrytitle>glMapGrid</refentrytitle></citerefentry> and <function>glEvalMesh</function> are used in tandem to efficiently | |
107 | generate and evaluate a series of evenly-spaced map domain values. | |
108 | <function>glEvalMesh</function> steps through the integer domain of a one- or two-dimensional grid, | |
109 | whose range is the domain of the evaluation maps specified by | |
110 | <citerefentry><refentrytitle>glMap1</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glMap2</refentrytitle></citerefentry>. | |
111 | <parameter>mode</parameter> determines whether the resulting vertices are connected as | |
112 | points, | |
113 | lines, | |
114 | or filled polygons. | |
115 | </para> | |
116 | <para> | |
117 | In the one-dimensional case, | |
118 | <function>glEvalMesh1</function>, | |
119 | the mesh is generated as if the following code fragment were executed: | |
120 | </para> | |
121 | <para> | |
122 | <programlisting> | |
123 | glBegin( <parameter>type</parameter> ); | |
124 | for ( i = <parameter>i1</parameter>; i <= <parameter>i2</parameter>; i += 1 ) | |
125 | glEvalCoord1( <mml:math> | |
126 | <!-- eqn: i \cdot DELTA u + u sub 1 :--> | |
127 | <mml:mrow> | |
128 | <mml:mrow> | |
129 | <mml:mn>i</mml:mn> | |
130 | <mml:mo>·</mml:mo> | |
131 | <mml:mo>Δ</mml:mo> | |
132 | <mml:mi mathvariant="italic">u</mml:mi> | |
133 | </mml:mrow> | |
134 | <mml:mo>+</mml:mo> | |
135 | <mml:msub> | |
136 | <mml:mi mathvariant="italic">u</mml:mi> | |
137 | <mml:mn>1</mml:mn> | |
138 | </mml:msub> | |
139 | </mml:mrow> | |
140 | </mml:math> ); | |
141 | glEnd(); | |
142 | </programlisting> | |
143 | where | |
144 | </para> | |
145 | <para> | |
146 | <informalequation><mml:math> | |
147 | <!-- eqn: DELTA u = (u sub 2 - u sub 1 ) / n:--> | |
148 | <mml:mrow> | |
149 | <mml:mrow> | |
150 | <mml:mo>Δ</mml:mo> | |
151 | <mml:mi mathvariant="italic">u</mml:mi> | |
152 | </mml:mrow> | |
153 | <mml:mo>=</mml:mo> | |
154 | <mml:mfrac> | |
155 | <mml:mfenced open="(" close=")"> | |
156 | <mml:mrow> | |
157 | <mml:msub> | |
158 | <mml:mi mathvariant="italic">u</mml:mi> | |
159 | <mml:mn>2</mml:mn> | |
160 | </mml:msub> | |
161 | <mml:mo>-</mml:mo> | |
162 | <mml:msub> | |
163 | <mml:mi mathvariant="italic">u</mml:mi> | |
164 | <mml:mn>1</mml:mn> | |
165 | </mml:msub> | |
166 | </mml:mrow> | |
167 | </mml:mfenced> | |
168 | <mml:mi mathvariant="italic">n</mml:mi> | |
169 | </mml:mfrac> | |
170 | </mml:mrow> | |
171 | </mml:math></informalequation> | |
172 | </para> | |
173 | <para> | |
174 | and | |
175 | <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>, | |
176 | <inlineequation><mml:math> | |
177 | <!-- eqn: u sub 1:--> | |
178 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
179 | <mml:mn>1</mml:mn> | |
180 | </mml:msub> | |
181 | </mml:math></inlineequation>, | |
182 | and | |
183 | <inlineequation><mml:math> | |
184 | <!-- eqn: u sub 2:--> | |
185 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
186 | <mml:mn>2</mml:mn> | |
187 | </mml:msub> | |
188 | </mml:math></inlineequation> | |
189 | are the arguments to the most recent | |
190 | <citerefentry><refentrytitle>glMapGrid1</refentrytitle></citerefentry> command. | |
191 | <emphasis>type</emphasis> is <constant>GL_POINTS</constant> if <parameter>mode</parameter> is <constant>GL_POINT</constant>, | |
192 | or <constant>GL_LINES</constant> if <parameter>mode</parameter> is <constant>GL_LINE</constant>. | |
193 | </para> | |
194 | <para> | |
195 | The one absolute numeric requirement is that if | |
196 | <inlineequation><mml:math> | |
197 | <!-- eqn: i = n:--> | |
198 | <mml:mrow> | |
199 | <mml:mi mathvariant="italic">i</mml:mi> | |
200 | <mml:mo>=</mml:mo> | |
201 | <mml:mi mathvariant="italic">n</mml:mi> | |
202 | </mml:mrow> | |
203 | </mml:math></inlineequation>, | |
204 | then the | |
205 | value computed from | |
206 | <inlineequation><mml:math> | |
207 | <!-- eqn: i cdot DELTA u + u sub 1:--> | |
208 | <mml:mrow> | |
209 | <mml:mrow> | |
210 | <mml:mi mathvariant="italic">i</mml:mi> | |
211 | <mml:mo>·</mml:mo> | |
212 | <mml:mrow> | |
213 | <mml:mo>Δ</mml:mo> | |
214 | <mml:mi mathvariant="italic">u</mml:mi> | |
215 | </mml:mrow> | |
216 | </mml:mrow> | |
217 | <mml:mo>+</mml:mo> | |
218 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
219 | <mml:mn>1</mml:mn> | |
220 | </mml:msub> | |
221 | </mml:mrow> | |
222 | </mml:math></inlineequation> | |
223 | is exactly | |
224 | <inlineequation><mml:math> | |
225 | <!-- eqn: u sub 2:--> | |
226 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
227 | <mml:mn>2</mml:mn> | |
228 | </mml:msub> | |
229 | </mml:math></inlineequation>. | |
230 | </para> | |
231 | <para> | |
232 | In the two-dimensional case, <function>glEvalMesh2</function>, let | |
233 | .cp | |
234 | <informalequation><mml:math> | |
235 | <!-- eqn: DELTA u = ( u sub 2 - u sub 1 ) / n:--> | |
236 | <mml:mrow> | |
237 | <mml:mrow> | |
238 | <mml:mo>Δ</mml:mo> | |
239 | <mml:mi mathvariant="italic">u</mml:mi> | |
240 | </mml:mrow> | |
241 | <mml:mo>=</mml:mo> | |
242 | <mml:mfrac> | |
243 | <mml:mfenced open="(" close=")"> | |
244 | <mml:mrow> | |
245 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
246 | <mml:mn>2</mml:mn> | |
247 | </mml:msub> | |
248 | <mml:mo>-</mml:mo> | |
249 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
250 | <mml:mn>1</mml:mn> | |
251 | </mml:msub> | |
252 | </mml:mrow> | |
253 | </mml:mfenced> | |
254 | <mml:mi mathvariant="italic">n</mml:mi> | |
255 | </mml:mfrac> | |
256 | </mml:mrow> | |
257 | </mml:math></informalequation> | |
258 | </para> | |
259 | <para> | |
260 | <informalequation><mml:math> | |
261 | <!-- eqn: DELTA v = ( v sub 2 - v sub 1 ) / m:--> | |
262 | <mml:mrow> | |
263 | <mml:mrow> | |
264 | <mml:mo>Δ</mml:mo> | |
265 | <mml:mi mathvariant="italic">v</mml:mi> | |
266 | </mml:mrow> | |
267 | <mml:mo>=</mml:mo> | |
268 | <mml:mfrac> | |
269 | <mml:mfenced open="(" close=")"> | |
270 | <mml:mrow> | |
271 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
272 | <mml:mn>2</mml:mn> | |
273 | </mml:msub> | |
274 | <mml:mo>-</mml:mo> | |
275 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
276 | <mml:mn>1</mml:mn> | |
277 | </mml:msub> | |
278 | </mml:mrow> | |
279 | </mml:mfenced> | |
280 | <mml:mi mathvariant="italic">m</mml:mi> | |
281 | </mml:mfrac> | |
282 | </mml:mrow> | |
283 | </mml:math></informalequation> | |
284 | </para> | |
285 | <para> | |
286 | where | |
287 | <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>, | |
288 | <inlineequation><mml:math> | |
289 | <!-- eqn: u sub 1:--> | |
290 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
291 | <mml:mn>1</mml:mn> | |
292 | </mml:msub> | |
293 | </mml:math></inlineequation>, | |
294 | <inlineequation><mml:math> | |
295 | <!-- eqn: u sub 2:--> | |
296 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
297 | <mml:mn>2</mml:mn> | |
298 | </mml:msub> | |
299 | </mml:math></inlineequation>, | |
300 | <inlineequation><mml:math><mml:mi mathvariant="italic">m</mml:mi></mml:math></inlineequation>, | |
301 | <inlineequation><mml:math> | |
302 | <!-- eqn: v sub 1:--> | |
303 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
304 | <mml:mn>1</mml:mn> | |
305 | </mml:msub> | |
306 | </mml:math></inlineequation>, | |
307 | and | |
308 | <inlineequation><mml:math> | |
309 | <!-- eqn: v sub 2:--> | |
310 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
311 | <mml:mn>2</mml:mn> | |
312 | </mml:msub> | |
313 | </mml:math></inlineequation> | |
314 | are the | |
315 | arguments to the most recent <citerefentry><refentrytitle>glMapGrid2</refentrytitle></citerefentry> command. Then, if | |
316 | <parameter>mode</parameter> is <constant>GL_FILL</constant>, the <function>glEvalMesh2</function> command is equivalent | |
317 | to: | |
318 | </para> | |
319 | <para> | |
320 | <programlisting> | |
321 | for ( j = <parameter>j1</parameter>; j < <parameter>j2</parameter>; j += 1 ) { | |
322 | glBegin( GL_QUAD_STRIP ); | |
323 | for ( i = <parameter>i1</parameter>; i <= <parameter>i2</parameter>; i += 1 ) { | |
324 | glEvalCoord2( <mml:math> | |
325 | <!-- i \cdot DELTA u + u sub 1 :--> | |
326 | <mml:mrow> | |
327 | <mml:mrow> | |
328 | <mml:mn>i</mml:mn> | |
329 | <mml:mo>·</mml:mo> | |
330 | <mml:mo>Δ</mml:mo> | |
331 | <mml:mi mathvariant="italic">u</mml:mi> | |
332 | </mml:mrow> | |
333 | <mml:mo>+</mml:mo> | |
334 | <mml:msub> | |
335 | <mml:mi mathvariant="italic">u</mml:mi> | |
336 | <mml:mn>1</mml:mn> | |
337 | </mml:msub> | |
338 | <mml:mo>,</mml:mo> | |
339 | <!-- j \cdot DELTA v + v sub 1 :--> | |
340 | <mml:mrow> | |
341 | <mml:mn>j</mml:mn> | |
342 | <mml:mo>·</mml:mo> | |
343 | <mml:mo>Δ</mml:mo> | |
344 | <mml:mi mathvariant="italic">v</mml:mi> | |
345 | ||
346 | </mml:mrow> | |
347 | <mml:mo>+</mml:mo> | |
348 | <mml:msub> | |
349 | <mml:mi mathvariant="italic">v</mml:mi> | |
350 | <mml:mn>1</mml:mn> | |
351 | </mml:msub> | |
352 | </mml:mrow> | |
353 | </mml:math> ); | |
354 | glEvalCoord2( <mml:math> | |
355 | <!-- i \cdot DELTA u + u sub 1, :--> | |
356 | <mml:mrow> | |
357 | <mml:mrow> | |
358 | <mml:mn>i</mml:mn> | |
359 | <mml:mo>·</mml:mo> | |
360 | <mml:mo>Δ</mml:mo> | |
361 | <mml:mi mathvariant="italic">u</mml:mi> | |
362 | </mml:mrow> | |
363 | <mml:mo>+</mml:mo> | |
364 | <mml:msub> | |
365 | <mml:mi mathvariant="italic">u</mml:mi> | |
366 | <mml:mn>1</mml:mn> | |
367 | </mml:msub> | |
368 | <mml:mo>,</mml:mo> | |
369 | <!-- (j + 1) \cdot DELTA v + v sub 1 :--> | |
370 | <mml:mrow> | |
371 | <mml:mrow> | |
372 | <mml:mfenced open="(" close=")"> | |
373 | <mml:mrow> | |
374 | <mml:mn>j</mml:mn> | |
375 | <mml:mo>+</mml:mo> | |
376 | <mml:mn>1</mml:mn> | |
377 | </mml:mrow> | |
378 | </mml:mfenced> | |
379 | </mml:mrow> | |
380 | <mml:mo>·</mml:mo> | |
381 | <mml:mo>Δ</mml:mo> | |
382 | <mml:mi mathvariant="italic">v</mml:mi> | |
383 | </mml:mrow> | |
384 | <mml:mo>+</mml:mo> | |
385 | <mml:msub> | |
386 | <mml:mi mathvariant="italic">v</mml:mi> | |
387 | <mml:mn>1</mml:mn> | |
388 | </mml:msub> | |
389 | </mml:mrow> | |
390 | </mml:math> ); | |
391 | } | |
392 | glEnd(); | |
393 | } | |
394 | </programlisting> | |
395 | </para> | |
396 | <para> | |
397 | If <parameter>mode</parameter> is <constant>GL_LINE</constant>, then a call to <function>glEvalMesh2</function> is equivalent to: | |
398 | </para> | |
399 | <para> | |
400 | <programlisting> | |
401 | for ( j = <parameter>j1</parameter>; j <= <parameter>j2</parameter>; j += 1 ) { | |
402 | glBegin( GL_LINE_STRIP ); | |
403 | for ( i = <parameter>i1</parameter>; i <= <parameter>i2</parameter>; i += 1 ) | |
404 | glEvalCoord2( <mml:math> | |
405 | <!-- i \cdot DELTA u + u sub 1 :--> | |
406 | <mml:mrow> | |
407 | <mml:mrow> | |
408 | <mml:mn>i</mml:mn> | |
409 | <mml:mo>·</mml:mo> | |
410 | <mml:mo>Δ</mml:mo> | |
411 | <mml:mi mathvariant="italic">u</mml:mi> | |
412 | </mml:mrow> | |
413 | <mml:mo>+</mml:mo> | |
414 | <mml:msub> | |
415 | <mml:mi mathvariant="italic">u</mml:mi> | |
416 | <mml:mn>1</mml:mn> | |
417 | </mml:msub> | |
418 | <mml:mo>,</mml:mo> | |
419 | <!-- i \cdot DELTA v + v sub 1 :--> | |
420 | <mml:mrow> | |
421 | <mml:mn>j</mml:mn> | |
422 | <mml:mo>·</mml:mo> | |
423 | <mml:mo>Δ</mml:mo> | |
424 | <mml:mi mathvariant="italic">v</mml:mi> | |
425 | </mml:mrow> | |
426 | <mml:mo>+</mml:mo> | |
427 | <mml:msub> | |
428 | <mml:mi mathvariant="italic">v</mml:mi> | |
429 | <mml:mn>1</mml:mn> | |
430 | </mml:msub> | |
431 | </mml:mrow> | |
432 | </mml:math> ); | |
433 | glEnd(); | |
434 | } | |
435 | ||
436 | for ( i = <parameter>i1</parameter>; i <= <parameter>i2</parameter>; i += 1 ) { | |
437 | glBegin( GL_LINE_STRIP ); | |
438 | for ( j = <parameter>j1</parameter>; j <= <parameter>j1</parameter>; j += 1 ) | |
439 | glEvalCoord2( <mml:math> | |
440 | <!-- i \cdot DELTA u + u sub 1 :--> | |
441 | <mml:mrow> | |
442 | <mml:mrow> | |
443 | <mml:mn>i</mml:mn> | |
444 | <mml:mo>·</mml:mo> | |
445 | <mml:mo>Δ</mml:mo> | |
446 | <mml:mi mathvariant="italic">u</mml:mi> | |
447 | </mml:mrow> | |
448 | <mml:mo>+</mml:mo> | |
449 | <mml:msub> | |
450 | <mml:mi mathvariant="italic">u</mml:mi> | |
451 | <mml:mn>1</mml:mn> | |
452 | </mml:msub> | |
453 | <mml:mo>,</mml:mo> | |
454 | <!-- i \cdot DELTA v + v sub 1 :--> | |
455 | <mml:mrow> | |
456 | <mml:mn>j</mml:mn> | |
457 | <mml:mo>·</mml:mo> | |
458 | <mml:mo>Δ</mml:mo> | |
459 | <mml:mi mathvariant="italic">v</mml:mi> | |
460 | </mml:mrow> | |
461 | <mml:mo>+</mml:mo> | |
462 | <mml:msub> | |
463 | <mml:mi mathvariant="italic">v</mml:mi> | |
464 | <mml:mn>1</mml:mn> | |
465 | </mml:msub> | |
466 | </mml:mrow> | |
467 | </mml:math> ); | |
468 | glEnd(); | |
469 | } | |
470 | </programlisting> | |
471 | </para> | |
472 | <para> | |
473 | And finally, if <parameter>mode</parameter> is <constant>GL_POINT</constant>, then a call to | |
474 | <function>glEvalMesh2</function> is equivalent to: | |
475 | </para> | |
476 | <para> | |
477 | <programlisting> | |
478 | glBegin( GL_POINTS ); | |
479 | for ( j = <parameter>j1</parameter>; j <= <parameter>j2</parameter>; j += 1 ) | |
480 | for ( i = <parameter>i1</parameter>; i <= <parameter>i2</parameter>; i += 1 ) | |
481 | glEvalCoord2( <mml:math> | |
482 | <!-- i \cdot DELTA u + u sub 1 :--> | |
483 | <mml:mrow> | |
484 | <mml:mrow> | |
485 | <mml:mn>i</mml:mn> | |
486 | <mml:mo>·</mml:mo> | |
487 | <mml:mo>Δ</mml:mo> | |
488 | <mml:mi mathvariant="italic">u</mml:mi> | |
489 | </mml:mrow> | |
490 | <mml:mo>+</mml:mo> | |
491 | <mml:msub> | |
492 | <mml:mi mathvariant="italic">u</mml:mi> | |
493 | <mml:mn>1</mml:mn> | |
494 | </mml:msub> | |
495 | <mml:mo>,</mml:mo> | |
496 | <!-- i \cdot DELTA v + v sub 1 :--> | |
497 | <mml:mrow> | |
498 | <mml:mn>j</mml:mn> | |
499 | <mml:mo>·</mml:mo> | |
500 | <mml:mo>Δ</mml:mo> | |
501 | <mml:mi mathvariant="italic">v</mml:mi> | |
502 | </mml:mrow> | |
503 | <mml:mo>+</mml:mo> | |
504 | <mml:msub> | |
505 | <mml:mi mathvariant="italic">v</mml:mi> | |
506 | <mml:mn>1</mml:mn> | |
507 | </mml:msub> | |
508 | </mml:mrow> | |
509 | </mml:math> ); | |
510 | glEnd(); | |
511 | </programlisting> | |
512 | </para> | |
513 | <para> | |
514 | In all three cases, the only absolute numeric requirements are that if | |
515 | <inlineequation><mml:math> | |
516 | <!-- eqn: i = n:--> | |
517 | <mml:mrow> | |
518 | <mml:mi mathvariant="italic">i</mml:mi> | |
519 | <mml:mo>=</mml:mo> | |
520 | <mml:mi mathvariant="italic">n</mml:mi> | |
521 | </mml:mrow> | |
522 | </mml:math></inlineequation>, | |
523 | then the value computed from | |
524 | <inlineequation><mml:math> | |
525 | <!-- eqn: i cdot DELTA u + u sub 1:--> | |
526 | <mml:mrow> | |
527 | <mml:mrow> | |
528 | <mml:mi mathvariant="italic">i</mml:mi> | |
529 | <mml:mo>·</mml:mo> | |
530 | <mml:mrow> | |
531 | <mml:mo>Δ</mml:mo> | |
532 | <mml:mi mathvariant="italic">u</mml:mi> | |
533 | </mml:mrow> | |
534 | </mml:mrow> | |
535 | <mml:mo>+</mml:mo> | |
536 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
537 | <mml:mn>1</mml:mn> | |
538 | </mml:msub> | |
539 | </mml:mrow> | |
540 | </mml:math></inlineequation> | |
541 | is exactly | |
542 | <inlineequation><mml:math> | |
543 | <!-- eqn: u sub 2:--> | |
544 | <mml:msub><mml:mi mathvariant="italic">u</mml:mi> | |
545 | <mml:mn>2</mml:mn> | |
546 | </mml:msub> | |
547 | </mml:math></inlineequation>, | |
548 | and if | |
549 | <inlineequation><mml:math> | |
550 | <!-- eqn: j = m:--> | |
551 | <mml:mrow> | |
552 | <mml:mi mathvariant="italic">j</mml:mi> | |
553 | <mml:mo>=</mml:mo> | |
554 | <mml:mi mathvariant="italic">m</mml:mi> | |
555 | </mml:mrow> | |
556 | </mml:math></inlineequation>, | |
557 | then the value computed from | |
558 | <inlineequation><mml:math> | |
559 | <!-- eqn: j cdot DELTA v + v sub 1:--> | |
560 | <mml:mrow> | |
561 | <mml:mrow> | |
562 | <mml:mi mathvariant="italic">j</mml:mi> | |
563 | <mml:mo>·</mml:mo> | |
564 | <mml:mrow> | |
565 | <mml:mo>Δ</mml:mo> | |
566 | <mml:mi mathvariant="italic">v</mml:mi> | |
567 | </mml:mrow> | |
568 | </mml:mrow> | |
569 | <mml:mo>+</mml:mo> | |
570 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
571 | <mml:mn>1</mml:mn> | |
572 | </mml:msub> | |
573 | </mml:mrow> | |
574 | </mml:math></inlineequation> | |
575 | is exactly | |
576 | <inlineequation><mml:math> | |
577 | <!-- eqn: v sub 2:--> | |
578 | <mml:msub><mml:mi mathvariant="italic">v</mml:mi> | |
579 | <mml:mn>2</mml:mn> | |
580 | </mml:msub> | |
581 | </mml:math></inlineequation>. | |
582 | </para> | |
583 | </refsect1> | |
584 | <refsect1 id="errors"><title>Errors</title> | |
585 | <para> | |
586 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not an accepted value. | |
587 | </para> | |
588 | <para> | |
589 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glEvalMesh</function> | |
590 | is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
591 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
592 | </para> | |
593 | </refsect1> | |
594 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
595 | <para> | |
596 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAP1_GRID_DOMAIN</constant> | |
597 | </para> | |
598 | <para> | |
599 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAP2_GRID_DOMAIN</constant> | |
600 | </para> | |
601 | <para> | |
602 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAP1_GRID_SEGMENTS</constant> | |
603 | </para> | |
604 | <para> | |
605 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAP2_GRID_SEGMENTS</constant> | |
606 | </para> | |
607 | </refsect1> | |
608 | <refsect1 id="seealso"><title>See Also</title> | |
609 | <para> | |
610 | <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>, | |
611 | <citerefentry><refentrytitle>glEvalCoord</refentrytitle></citerefentry>, | |
612 | <citerefentry><refentrytitle>glEvalPoint</refentrytitle></citerefentry>, | |
613 | <citerefentry><refentrytitle>glMap1</refentrytitle></citerefentry>, | |
614 | <citerefentry><refentrytitle>glMap2</refentrytitle></citerefentry>, | |
615 | <citerefentry><refentrytitle>glMapGrid</refentrytitle></citerefentry> | |
616 | </para> | |
617 | </refsect1> | |
618 | <refsect1 id="Copyright"><title>Copyright</title> | |
619 | <para> | |
620 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
621 | Silicon Graphics, Inc. This document is licensed under the SGI | |
622 | Free Software B License. For details, see | |
623 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
624 | </para> | |
625 | </refsect1> | |
626 | </refentry> |