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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="glMap1"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glMap1</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glMap1</refname> | |
17 | <refpurpose>define a one-dimensional evaluator</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glMap1f</function></funcdef> | |
23 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
24 | <paramdef>GLfloat <parameter>u1</parameter></paramdef> | |
25 | <paramdef>GLfloat <parameter>u2</parameter></paramdef> | |
26 | <paramdef>GLint <parameter>stride</parameter></paramdef> | |
27 | <paramdef>GLint <parameter>order</parameter></paramdef> | |
28 | <paramdef>const GLfloat * <parameter>points</parameter></paramdef> | |
29 | </funcprototype> | |
30 | </funcsynopsis> | |
31 | <funcsynopsis> | |
32 | <funcprototype> | |
33 | <funcdef>void <function>glMap1d</function></funcdef> | |
34 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
35 | <paramdef>GLdouble <parameter>u1</parameter></paramdef> | |
36 | <paramdef>GLdouble <parameter>u2</parameter></paramdef> | |
37 | <paramdef>GLint <parameter>stride</parameter></paramdef> | |
38 | <paramdef>GLint <parameter>order</parameter></paramdef> | |
39 | <paramdef>const GLdouble * <parameter>points</parameter></paramdef> | |
40 | </funcprototype> | |
41 | </funcsynopsis> | |
42 | </refsynopsisdiv> | |
43 | <!-- eqn: ignoring delim $$ --> | |
44 | <refsect1 id="parameters"><title>Parameters</title> | |
45 | <variablelist> | |
46 | <varlistentry> | |
47 | <term><parameter>target</parameter></term> | |
48 | <listitem> | |
49 | <para> | |
50 | Specifies the kind of values that are generated by the evaluator. | |
51 | Symbolic constants | |
52 | <constant>GL_MAP1_VERTEX_3</constant>, | |
53 | <constant>GL_MAP1_VERTEX_4</constant>, | |
54 | <constant>GL_MAP1_INDEX</constant>, | |
55 | <constant>GL_MAP1_COLOR_4</constant>, | |
56 | <constant>GL_MAP1_NORMAL</constant>, | |
57 | <constant>GL_MAP1_TEXTURE_COORD_1</constant>, | |
58 | <constant>GL_MAP1_TEXTURE_COORD_2</constant>, | |
59 | <constant>GL_MAP1_TEXTURE_COORD_3</constant>, and | |
60 | <constant>GL_MAP1_TEXTURE_COORD_4</constant> are accepted. | |
61 | </para> | |
62 | </listitem> | |
63 | </varlistentry> | |
64 | <varlistentry> | |
65 | <term><parameter>u1</parameter></term> | |
66 | <term><parameter>u2</parameter></term> | |
67 | <listitem> | |
68 | <para> | |
69 | Specify a linear mapping of | |
70 | <inlineequation><mml:math><mml:mi mathvariant="italic">u</mml:mi></mml:math></inlineequation>, | |
71 | as presented to <citerefentry><refentrytitle>glEvalCoord1</refentrytitle></citerefentry>, | |
72 | to | |
73 | <inlineequation><mml:math> | |
74 | <!-- eqn: u hat:--> | |
75 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
76 | </mml:math></inlineequation>, | |
77 | the variable that is evaluated by the equations specified by this command. | |
78 | </para> | |
79 | </listitem> | |
80 | </varlistentry> | |
81 | <varlistentry> | |
82 | <term><parameter>stride</parameter></term> | |
83 | <listitem> | |
84 | <para> | |
85 | Specifies the number of floats or doubles between | |
86 | the beginning of one control point and the beginning of the next one | |
87 | in the data structure referenced in <parameter>points</parameter>. | |
88 | This allows control points to be embedded in arbitrary data structures. | |
89 | The only constraint is that the values for a particular control point | |
90 | must occupy contiguous memory locations. | |
91 | </para> | |
92 | </listitem> | |
93 | </varlistentry> | |
94 | <varlistentry> | |
95 | <term><parameter>order</parameter></term> | |
96 | <listitem> | |
97 | <para> | |
98 | Specifies the number of control points. | |
99 | Must be positive. | |
100 | </para> | |
101 | </listitem> | |
102 | </varlistentry> | |
103 | <varlistentry> | |
104 | <term><parameter>points</parameter></term> | |
105 | <listitem> | |
106 | <para> | |
107 | Specifies a pointer to the array of control points. | |
108 | </para> | |
109 | </listitem> | |
110 | </varlistentry> | |
111 | </variablelist> | |
112 | </refsect1> | |
113 | <refsect1 id="description"><title>Description</title> | |
114 | <para> | |
115 | Evaluators provide a way to use polynomial or rational polynomial mapping | |
116 | to produce vertices, | |
117 | normals, | |
118 | texture coordinates, | |
119 | and colors. | |
120 | The values produced by an evaluator are sent to further stages | |
121 | of GL processing just as if they had been presented using | |
122 | <citerefentry><refentrytitle>glVertex</refentrytitle></citerefentry>, | |
123 | <citerefentry><refentrytitle>glNormal</refentrytitle></citerefentry>, | |
124 | <citerefentry><refentrytitle>glTexCoord</refentrytitle></citerefentry>, and | |
125 | <citerefentry><refentrytitle>glColor</refentrytitle></citerefentry> commands, | |
126 | except that the generated values do not update the current normal, | |
127 | texture coordinates, | |
128 | or color. | |
129 | </para> | |
130 | <para> | |
131 | All polynomial or rational polynomial splines of any degree | |
132 | (up to the maximum degree supported by the GL implementation) | |
133 | can be described using evaluators. | |
134 | These include almost all splines used in computer graphics: B-splines, | |
135 | Bezier curves, Hermite splines, and so on. | |
136 | </para> | |
137 | <para> | |
138 | Evaluators define curves based on Bernstein polynomials. | |
139 | Define | |
140 | <inlineequation><mml:math> | |
141 | <!-- eqn: p ( u hat):--> | |
142 | <mml:mrow> | |
143 | <mml:mi mathvariant="italic">p</mml:mi> | |
144 | <mml:mo>⁡</mml:mo> | |
145 | <mml:mfenced open="(" close=")"> | |
146 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
147 | </mml:mfenced> | |
148 | </mml:mrow> | |
149 | </mml:math></inlineequation> | |
150 | as | |
151 | </para> | |
152 | <para> | |
153 | <informalequation><mml:math> | |
154 | <!-- eqn: p ( u hat) = sum from {i = 0} to {n} { {B sub i} sup n ( u hat ) R sub i }:--> | |
155 | <mml:mrow> | |
156 | <mml:mrow> | |
157 | <mml:mi mathvariant="italic">p</mml:mi> | |
158 | <mml:mo>⁡</mml:mo> | |
159 | <mml:mfenced open="(" close=")"> | |
160 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
161 | </mml:mfenced> | |
162 | </mml:mrow> | |
163 | <mml:mo>=</mml:mo> | |
164 | <mml:mrow> | |
165 | <mml:munderover> | |
166 | <mml:mo>Σ</mml:mo> | |
167 | <mml:mrow> | |
168 | <mml:mi mathvariant="italic">i</mml:mi> | |
169 | <mml:mo>=</mml:mo> | |
170 | <mml:mn>0</mml:mn> | |
171 | </mml:mrow> | |
172 | <mml:mi mathvariant="italic">n</mml:mi> | |
173 | </mml:munderover> | |
174 | <mml:mrow> | |
175 | <mml:mrow> | |
176 | <mml:msup><mml:mfenced open="" close=""> | |
177 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
178 | <mml:mi mathvariant="italic">i</mml:mi> | |
179 | </mml:msub> | |
180 | </mml:mfenced> | |
181 | <mml:mi mathvariant="italic">n</mml:mi> | |
182 | </mml:msup> | |
183 | <mml:mo>⁡</mml:mo> | |
184 | <mml:mfenced open="(" close=")"> | |
185 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
186 | </mml:mfenced> | |
187 | </mml:mrow> | |
188 | <mml:mo>⁢</mml:mo> | |
189 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
190 | <mml:mi mathvariant="italic">i</mml:mi> | |
191 | </mml:msub> | |
192 | </mml:mrow> | |
193 | </mml:mrow> | |
194 | </mml:mrow> | |
195 | </mml:math></informalequation> | |
196 | </para> | |
197 | <para> | |
198 | </para> | |
199 | <para> | |
200 | where | |
201 | <inlineequation><mml:math> | |
202 | <!-- eqn: R sub i:--> | |
203 | <mml:msub><mml:mi mathvariant="italic">R</mml:mi> | |
204 | <mml:mi mathvariant="italic">i</mml:mi> | |
205 | </mml:msub> | |
206 | </mml:math></inlineequation> | |
207 | is a control point and | |
208 | <inlineequation><mml:math> | |
209 | <!-- eqn: {B sub i} sup n ( u hat):--> | |
210 | <mml:mrow> | |
211 | <mml:msup><mml:mfenced open="" close=""> | |
212 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
213 | <mml:mi mathvariant="italic">i</mml:mi> | |
214 | </mml:msub> | |
215 | </mml:mfenced> | |
216 | <mml:mi mathvariant="italic">n</mml:mi> | |
217 | </mml:msup> | |
218 | <mml:mo>⁡</mml:mo> | |
219 | <mml:mfenced open="(" close=")"> | |
220 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
221 | </mml:mfenced> | |
222 | </mml:mrow> | |
223 | </mml:math></inlineequation> | |
224 | is the | |
225 | <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>th | |
226 | Bernstein polynomial of degree | |
227 | <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation> | |
228 | (<parameter>order</parameter> = | |
229 | <inlineequation><mml:math> | |
230 | <!-- eqn: n + 1:--> | |
231 | <mml:mrow> | |
232 | <mml:mi mathvariant="italic">n</mml:mi> | |
233 | <mml:mo>+</mml:mo> | |
234 | <mml:mn>1</mml:mn> | |
235 | </mml:mrow> | |
236 | </mml:math></inlineequation>): | |
237 | </para> | |
238 | <para> | |
239 | <inlineequation><mml:math> | |
240 | <!-- eqn: {B sub i} sup n ( u hat) = left ( {cpile { n above i }} right ) {u hat} sup i { ( 1 - u hat) sup { n - i } }:--> | |
241 | <mml:mrow> | |
242 | <mml:mrow> | |
243 | <mml:msup><mml:mfenced open="" close=""> | |
244 | <mml:msub><mml:mi mathvariant="italic">B</mml:mi> | |
245 | <mml:mi mathvariant="italic">i</mml:mi> | |
246 | </mml:msub> | |
247 | </mml:mfenced> | |
248 | <mml:mi mathvariant="italic">n</mml:mi> | |
249 | </mml:msup> | |
250 | <mml:mo>⁡</mml:mo> | |
251 | <mml:mfenced open="(" close=")"> | |
252 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
253 | </mml:mfenced> | |
254 | </mml:mrow> | |
255 | <mml:mo>=</mml:mo> | |
256 | <mml:mrow> | |
257 | <mml:mfenced open="(" close=")"> | |
258 | <mml:mfenced open="" close=""> | |
259 | <mml:mtable> | |
260 | <mml:mtr><mml:mtd> | |
261 | <mml:mi mathvariant="italic">n</mml:mi> | |
262 | </mml:mtd></mml:mtr> | |
263 | <mml:mtr><mml:mtd> | |
264 | <mml:mi mathvariant="italic">i</mml:mi> | |
265 | </mml:mtd></mml:mtr> | |
266 | </mml:mtable> | |
267 | </mml:mfenced> | |
268 | </mml:mfenced> | |
269 | <mml:mo>⁢</mml:mo> | |
270 | <mml:msup><mml:mfenced open="" close=""> | |
271 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
272 | </mml:mfenced> | |
273 | <mml:mi mathvariant="italic">i</mml:mi> | |
274 | </mml:msup> | |
275 | <mml:mo>⁢</mml:mo> | |
276 | <mml:mfenced open="" close=""> | |
277 | <mml:msup><mml:mfenced open="(" close=")"> | |
278 | <mml:mrow> | |
279 | <mml:mn>1</mml:mn> | |
280 | <mml:mo>-</mml:mo> | |
281 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
282 | </mml:mrow> | |
283 | </mml:mfenced> | |
284 | <mml:mfenced open="" close=""> | |
285 | <mml:mrow> | |
286 | <mml:mi mathvariant="italic">n</mml:mi> | |
287 | <mml:mo>-</mml:mo> | |
288 | <mml:mi mathvariant="italic">i</mml:mi> | |
289 | </mml:mrow> | |
290 | </mml:mfenced> | |
291 | </mml:msup> | |
292 | </mml:mfenced> | |
293 | </mml:mrow> | |
294 | </mml:mrow> | |
295 | </mml:math></inlineequation> | |
296 | </para> | |
297 | <para> | |
298 | Recall that | |
299 | </para> | |
300 | <para> | |
301 | <inlineequation><mml:math> | |
302 | <!-- eqn: 0 sup 0 == 1:--> | |
303 | <mml:mrow> | |
304 | <mml:msup><mml:mn>0</mml:mn> | |
305 | <mml:mn>0</mml:mn> | |
306 | </mml:msup> | |
307 | <mml:mo>==</mml:mo> | |
308 | <mml:mn>1</mml:mn> | |
309 | </mml:mrow> | |
310 | </mml:math></inlineequation> | |
311 | and | |
312 | <inlineequation><mml:math> | |
313 | <!-- eqn: left ( {cpile { n above 0 }} right ) == 1:--> | |
314 | <mml:mrow> | |
315 | <mml:mfenced open="(" close=")"> | |
316 | <mml:mfenced open="" close=""> | |
317 | <mml:mtable> | |
318 | <mml:mtr><mml:mtd> | |
319 | <mml:mi mathvariant="italic">n</mml:mi> | |
320 | </mml:mtd></mml:mtr> | |
321 | <mml:mtr><mml:mtd> | |
322 | <mml:mn>0</mml:mn> | |
323 | </mml:mtd></mml:mtr> | |
324 | </mml:mtable> | |
325 | </mml:mfenced> | |
326 | </mml:mfenced> | |
327 | <mml:mo>==</mml:mo> | |
328 | <mml:mn>1</mml:mn> | |
329 | </mml:mrow> | |
330 | </mml:math></inlineequation> | |
331 | </para> | |
332 | <para> | |
333 | <function>glMap1</function> is used to define the basis and to specify what kind of values | |
334 | are produced. | |
335 | Once defined, | |
336 | a map can be enabled and disabled by calling <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glDisable</refentrytitle></citerefentry> | |
337 | with the map name, one of the nine predefined values for <parameter>target</parameter> | |
338 | described below. | |
339 | <citerefentry><refentrytitle>glEvalCoord1</refentrytitle></citerefentry> evaluates the one-dimensional maps that are enabled. | |
340 | When | |
341 | <citerefentry><refentrytitle>glEvalCoord1</refentrytitle></citerefentry> presents a value | |
342 | <inlineequation><mml:math><mml:mi mathvariant="italic">u</mml:mi></mml:math></inlineequation>, | |
343 | the Bernstein functions are evaluated using | |
344 | <inlineequation><mml:math> | |
345 | <!-- eqn: u hat:--> | |
346 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
347 | </mml:math></inlineequation>, | |
348 | where | |
349 | <inlineequation><mml:math> | |
350 | <!-- eqn: u hat = {u - u1} over {u2 - u1}:--> | |
351 | <mml:mrow> | |
352 | <mml:mover><mml:mi mathvariant="italic">u</mml:mi><mml:mo>^</mml:mo></mml:mover> | |
353 | <mml:mo>=</mml:mo> | |
354 | <mml:mfrac> | |
355 | <mml:mfenced open="" close=""> | |
356 | <mml:mrow> | |
357 | <mml:mi mathvariant="italic">u</mml:mi> | |
358 | <mml:mo>-</mml:mo> | |
359 | <mml:mi mathvariant="italic">u1</mml:mi> | |
360 | </mml:mrow> | |
361 | </mml:mfenced> | |
362 | <mml:mfenced open="" close=""> | |
363 | <mml:mrow> | |
364 | <mml:mi mathvariant="italic">u2</mml:mi> | |
365 | <mml:mo>-</mml:mo> | |
366 | <mml:mi mathvariant="italic">u1</mml:mi> | |
367 | </mml:mrow> | |
368 | </mml:mfenced> | |
369 | </mml:mfrac> | |
370 | </mml:mrow> | |
371 | </mml:math></inlineequation> | |
372 | </para> | |
373 | <para> | |
374 | <parameter>target</parameter> is a symbolic constant that indicates what kind of control points | |
375 | are provided in <parameter>points</parameter>, | |
376 | and what output is generated when the map is evaluated. | |
377 | It can assume one of nine predefined values: | |
378 | </para> | |
379 | <variablelist> | |
380 | <varlistentry> | |
381 | <term><constant>GL_MAP1_VERTEX_3</constant></term> | |
382 | <listitem> | |
383 | <para> | |
384 | Each control point is three floating-point values representing | |
385 | <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>, | |
386 | <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>, | |
387 | and | |
388 | <inlineequation><mml:math><mml:mi mathvariant="italic">z</mml:mi></mml:math></inlineequation>. | |
389 | Internal <citerefentry><refentrytitle>glVertex3</refentrytitle></citerefentry> commands are generated when the map is evaluated. | |
390 | </para> | |
391 | </listitem> | |
392 | </varlistentry> | |
393 | <varlistentry> | |
394 | <term><constant>GL_MAP1_VERTEX_4</constant></term> | |
395 | <listitem> | |
396 | <para> | |
397 | Each control point is four floating-point values representing | |
398 | <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>, | |
399 | <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>, | |
400 | <inlineequation><mml:math><mml:mi mathvariant="italic">z</mml:mi></mml:math></inlineequation>, | |
401 | and | |
402 | <inlineequation><mml:math><mml:mi mathvariant="italic">w</mml:mi></mml:math></inlineequation>. | |
403 | Internal <citerefentry><refentrytitle>glVertex4</refentrytitle></citerefentry> commands are generated when the map is evaluated. | |
404 | </para> | |
405 | </listitem> | |
406 | </varlistentry> | |
407 | <varlistentry> | |
408 | <term><constant>GL_MAP1_INDEX</constant></term> | |
409 | <listitem> | |
410 | <para> | |
411 | Each control point is a single floating-point value representing a color index. | |
412 | Internal <citerefentry><refentrytitle>glIndex</refentrytitle></citerefentry> commands are generated when the map is evaluated | |
413 | but the current index is not updated with the value of these <citerefentry><refentrytitle>glIndex</refentrytitle></citerefentry> | |
414 | commands. | |
415 | </para> | |
416 | </listitem> | |
417 | </varlistentry> | |
418 | <varlistentry> | |
419 | <term><constant>GL_MAP1_COLOR_4</constant></term> | |
420 | <listitem> | |
421 | <para> | |
422 | Each control point is four floating-point values representing | |
423 | red, green, blue, and alpha. | |
424 | Internal <citerefentry><refentrytitle>glColor4</refentrytitle></citerefentry> commands are generated when the map is | |
425 | evaluated but the current color is not updated with the value of these | |
426 | <citerefentry><refentrytitle>glColor4</refentrytitle></citerefentry> commands. | |
427 | </para> | |
428 | </listitem> | |
429 | </varlistentry> | |
430 | <varlistentry> | |
431 | <term><constant>GL_MAP1_NORMAL</constant></term> | |
432 | <listitem> | |
433 | <para> | |
434 | Each control point is three floating-point values representing | |
435 | the | |
436 | <inlineequation><mml:math><mml:mi mathvariant="italic">x</mml:mi></mml:math></inlineequation>, | |
437 | <inlineequation><mml:math><mml:mi mathvariant="italic">y</mml:mi></mml:math></inlineequation>, | |
438 | and | |
439 | <inlineequation><mml:math><mml:mi mathvariant="italic">z</mml:mi></mml:math></inlineequation> | |
440 | components of a normal vector. | |
441 | Internal <citerefentry><refentrytitle>glNormal</refentrytitle></citerefentry> commands are generated when the map is | |
442 | evaluated but the current normal is not updated with the value of | |
443 | these <citerefentry><refentrytitle>glNormal</refentrytitle></citerefentry> commands. | |
444 | </para> | |
445 | </listitem> | |
446 | </varlistentry> | |
447 | <varlistentry> | |
448 | <term><constant>GL_MAP1_TEXTURE_COORD_1</constant></term> | |
449 | <listitem> | |
450 | <para> | |
451 | Each control point is a single floating-point value representing | |
452 | the | |
453 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
454 | texture coordinate. | |
455 | Internal | |
456 | <citerefentry><refentrytitle>glTexCoord1</refentrytitle></citerefentry> commands are generated when the map is | |
457 | evaluated but the current texture coordinates are not updated with the value | |
458 | of these <citerefentry><refentrytitle>glTexCoord</refentrytitle></citerefentry> commands. | |
459 | </para> | |
460 | </listitem> | |
461 | </varlistentry> | |
462 | <varlistentry> | |
463 | <term><constant>GL_MAP1_TEXTURE_COORD_2</constant></term> | |
464 | <listitem> | |
465 | <para> | |
466 | Each control point is two floating-point values representing | |
467 | the | |
468 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
469 | and | |
470 | <inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation> | |
471 | texture coordinates. | |
472 | Internal | |
473 | <citerefentry><refentrytitle>glTexCoord2</refentrytitle></citerefentry> commands are generated when the map is | |
474 | evaluated but the current texture coordinates are not updated with the value | |
475 | of these <citerefentry><refentrytitle>glTexCoord</refentrytitle></citerefentry> commands. | |
476 | </para> | |
477 | </listitem> | |
478 | </varlistentry> | |
479 | <varlistentry> | |
480 | <term><constant>GL_MAP1_TEXTURE_COORD_3</constant></term> | |
481 | <listitem> | |
482 | <para> | |
483 | Each control point is three floating-point values representing | |
484 | the | |
485 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>, | |
486 | <inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>, | |
487 | and | |
488 | <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> | |
489 | texture coordinates. | |
490 | Internal <citerefentry><refentrytitle>glTexCoord3</refentrytitle></citerefentry> commands are generated when the map is | |
491 | evaluated but the current texture coordinates are not updated with the value | |
492 | of these <citerefentry><refentrytitle>glTexCoord</refentrytitle></citerefentry> commands. | |
493 | </para> | |
494 | </listitem> | |
495 | </varlistentry> | |
496 | <varlistentry> | |
497 | <term><constant>GL_MAP1_TEXTURE_COORD_4</constant></term> | |
498 | <listitem> | |
499 | <para> | |
500 | Each control point is four floating-point values representing | |
501 | the | |
502 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>, | |
503 | <inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>, | |
504 | <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>, | |
505 | and | |
506 | <inlineequation><mml:math><mml:mi mathvariant="italic">q</mml:mi></mml:math></inlineequation> | |
507 | texture coordinates. | |
508 | Internal | |
509 | <citerefentry><refentrytitle>glTexCoord4</refentrytitle></citerefentry> commands are generated when the map is evaluated but | |
510 | the current texture coordinates are not updated with the value | |
511 | of these <citerefentry><refentrytitle>glTexCoord</refentrytitle></citerefentry> commands. | |
512 | </para> | |
513 | </listitem> | |
514 | </varlistentry> | |
515 | </variablelist> | |
516 | <para> | |
517 | <parameter>stride</parameter>, | |
518 | <parameter>order</parameter>, and | |
519 | <parameter>points</parameter> define the array addressing for accessing the control points. | |
520 | <parameter>points</parameter> is the location of the first control point, | |
521 | which occupies one, two, three, or four contiguous memory locations, | |
522 | depending on which map is being defined. | |
523 | <parameter>order</parameter> is the number of control points in the array. | |
524 | <parameter>stride</parameter> specifies how many float or double locations to advance the internal | |
525 | memory pointer to reach the next control point. | |
526 | </para> | |
527 | </refsect1> | |
528 | <refsect1 id="notes"><title>Notes</title> | |
529 | <para> | |
530 | As is the case with all GL commands that accept pointers to data, | |
531 | it is as if the contents of <parameter>points</parameter> were copied by <function>glMap1</function> before <function>glMap1</function> | |
532 | returns. | |
533 | Changes to the contents of <parameter>points</parameter> have no effect after <function>glMap1</function> is called. | |
534 | </para> | |
535 | </refsect1> | |
536 | <refsect1 id="errors"><title>Errors</title> | |
537 | <para> | |
538 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not an accepted value. | |
539 | </para> | |
540 | <para> | |
541 | <constant>GL_INVALID_VALUE</constant> is generated if <parameter>u1</parameter> is equal to <parameter>u2</parameter>. | |
542 | </para> | |
543 | <para> | |
544 | <constant>GL_INVALID_VALUE</constant> is generated if <parameter>stride</parameter> is less than the number | |
545 | of values in a control point. | |
546 | </para> | |
547 | <para> | |
548 | <constant>GL_INVALID_VALUE</constant> is generated if <parameter>order</parameter> is less than 1 or | |
549 | greater than the return value of <constant>GL_MAX_EVAL_ORDER</constant>. | |
550 | </para> | |
551 | <para> | |
552 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glMap1</function> | |
553 | is executed between the execution of | |
554 | <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
555 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
556 | </para> | |
557 | <para> | |
558 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glMap1</function> is called and the value | |
559 | of <constant>GL_ACTIVE_TEXTURE</constant> is not <constant>GL_TEXTURE0</constant>. | |
560 | </para> | |
561 | </refsect1> | |
562 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
563 | <para> | |
564 | <citerefentry><refentrytitle>glGetMap</refentrytitle></citerefentry> | |
565 | </para> | |
566 | <para> | |
567 | <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_EVAL_ORDER</constant> | |
568 | </para> | |
569 | <para> | |
570 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_VERTEX_3</constant> | |
571 | </para> | |
572 | <para> | |
573 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_VERTEX_4</constant> | |
574 | </para> | |
575 | <para> | |
576 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_INDEX</constant> | |
577 | </para> | |
578 | <para> | |
579 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_COLOR_4</constant> | |
580 | </para> | |
581 | <para> | |
582 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_NORMAL</constant> | |
583 | </para> | |
584 | <para> | |
585 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_TEXTURE_COORD_1</constant> | |
586 | </para> | |
587 | <para> | |
588 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_TEXTURE_COORD_2</constant> | |
589 | </para> | |
590 | <para> | |
591 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_TEXTURE_COORD_3</constant> | |
592 | </para> | |
593 | <para> | |
594 | <citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_MAP1_TEXTURE_COORD_4</constant> | |
595 | </para> | |
596 | </refsect1> | |
597 | <refsect1 id="seealso"><title>See Also</title> | |
598 | <para> | |
599 | <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>, | |
600 | <citerefentry><refentrytitle>glColor</refentrytitle></citerefentry>, | |
601 | <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry>, | |
602 | <citerefentry><refentrytitle>glEvalCoord</refentrytitle></citerefentry>, | |
603 | <citerefentry><refentrytitle>glEvalMesh</refentrytitle></citerefentry>, | |
604 | <citerefentry><refentrytitle>glEvalPoint</refentrytitle></citerefentry>, | |
605 | <citerefentry><refentrytitle>glMap2</refentrytitle></citerefentry>, | |
606 | <citerefentry><refentrytitle>glMapGrid</refentrytitle></citerefentry>, | |
607 | <citerefentry><refentrytitle>glNormal</refentrytitle></citerefentry>, | |
608 | <citerefentry><refentrytitle>glTexCoord</refentrytitle></citerefentry>, | |
609 | <citerefentry><refentrytitle>glVertex</refentrytitle></citerefentry> | |
610 | </para> | |
611 | </refsect1> | |
612 | <refsect1 id="Copyright"><title>Copyright</title> | |
613 | <para> | |
614 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
615 | Silicon Graphics, Inc. This document is licensed under the SGI | |
616 | Free Software B License. For details, see | |
617 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
618 | </para> | |
619 | </refsect1> | |
620 | </refentry> |