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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="glTexParameter"> | |
5 | <refmeta> | |
6 | <refmetainfo> | |
7 | <copyright> | |
8 | <year>1991-2006</year> | |
9 | <holder>Silicon Graphics, Inc.</holder> | |
10 | </copyright> | |
11 | </refmetainfo> | |
12 | <refentrytitle>glTexParameter</refentrytitle> | |
13 | <manvolnum>3G</manvolnum> | |
14 | </refmeta> | |
15 | <refnamediv> | |
16 | <refname>glTexParameter</refname> | |
17 | <refpurpose>set texture parameters</refpurpose> | |
18 | </refnamediv> | |
19 | <refsynopsisdiv><title>C Specification</title> | |
20 | <funcsynopsis> | |
21 | <funcprototype> | |
22 | <funcdef>void <function>glTexParameterf</function></funcdef> | |
23 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
24 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
25 | <paramdef>GLfloat <parameter>param</parameter></paramdef> | |
26 | </funcprototype> | |
27 | </funcsynopsis> | |
28 | <funcsynopsis> | |
29 | <funcprototype> | |
30 | <funcdef>void <function>glTexParameteri</function></funcdef> | |
31 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
32 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
33 | <paramdef>GLint <parameter>param</parameter></paramdef> | |
34 | </funcprototype> | |
35 | </funcsynopsis> | |
36 | </refsynopsisdiv> | |
37 | <!-- eqn: ignoring delim $$ --> | |
38 | <refsect1 id="parameters"><title>Parameters</title> | |
39 | <variablelist> | |
40 | <varlistentry> | |
41 | <term><parameter>target</parameter></term> | |
42 | <listitem> | |
43 | <para> | |
44 | Specifies the target texture, | |
45 | which must be either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>, | |
46 | <constant>GL_TEXTURE_3D</constant>, or <constant>GL_TEXTURE_CUBE_MAP</constant>. | |
47 | </para> | |
48 | </listitem> | |
49 | </varlistentry> | |
50 | <varlistentry> | |
51 | <term><parameter>pname</parameter></term> | |
52 | <listitem> | |
53 | <para> | |
54 | Specifies the symbolic name of a single-valued texture parameter. | |
55 | <parameter>pname</parameter> can be one of the following: | |
56 | <constant>GL_TEXTURE_MIN_FILTER</constant>, | |
57 | <constant>GL_TEXTURE_MAG_FILTER</constant>, | |
58 | <constant>GL_TEXTURE_MIN_LOD</constant>, | |
59 | <constant>GL_TEXTURE_MAX_LOD</constant>, | |
60 | <constant>GL_TEXTURE_BASE_LEVEL</constant>, | |
61 | <constant>GL_TEXTURE_MAX_LEVEL</constant>, | |
62 | <constant>GL_TEXTURE_WRAP_S</constant>, | |
63 | <constant>GL_TEXTURE_WRAP_T</constant>, | |
64 | <constant>GL_TEXTURE_WRAP_R</constant>, | |
65 | <constant>GL_TEXTURE_PRIORITY</constant>, | |
66 | <constant>GL_TEXTURE_COMPARE_MODE</constant>, | |
67 | <constant>GL_TEXTURE_COMPARE_FUNC</constant>, | |
68 | <constant>GL_DEPTH_TEXTURE_MODE</constant>, or | |
69 | <constant>GL_GENERATE_MIPMAP</constant>. | |
70 | </para> | |
71 | </listitem> | |
72 | </varlistentry> | |
73 | <varlistentry> | |
74 | <term><parameter>param</parameter></term> | |
75 | <listitem> | |
76 | <para> | |
77 | Specifies the value of <parameter>pname</parameter>. | |
78 | </para> | |
79 | </listitem> | |
80 | </varlistentry> | |
81 | </variablelist> | |
82 | </refsect1> | |
83 | <refsynopsisdiv><title>C Specification</title> | |
84 | <funcsynopsis> | |
85 | <funcprototype> | |
86 | <funcdef>void <function>glTexParameterfv</function></funcdef> | |
87 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
88 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
89 | <paramdef>const GLfloat * <parameter>params</parameter></paramdef> | |
90 | </funcprototype> | |
91 | </funcsynopsis> | |
92 | <funcsynopsis> | |
93 | <funcprototype> | |
94 | <funcdef>void <function>glTexParameteriv</function></funcdef> | |
95 | <paramdef>GLenum <parameter>target</parameter></paramdef> | |
96 | <paramdef>GLenum <parameter>pname</parameter></paramdef> | |
97 | <paramdef>const GLint * <parameter>params</parameter></paramdef> | |
98 | </funcprototype> | |
99 | </funcsynopsis> | |
100 | </refsynopsisdiv> | |
101 | <refsect1 id="parameters2"><title>Parameters</title> | |
102 | <variablelist> | |
103 | <varlistentry> | |
104 | <term><parameter>target</parameter></term> | |
105 | <listitem> | |
106 | <para> | |
107 | Specifies the target texture, | |
108 | which must be either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant> or | |
109 | <constant>GL_TEXTURE_3D</constant>. | |
110 | </para> | |
111 | </listitem> | |
112 | </varlistentry> | |
113 | <varlistentry> | |
114 | <term><parameter>pname</parameter></term> | |
115 | <listitem> | |
116 | <para> | |
117 | Specifies the symbolic name of a texture parameter. | |
118 | <parameter>pname</parameter> can be one of the following: | |
119 | <constant>GL_TEXTURE_MIN_FILTER</constant>, | |
120 | <constant>GL_TEXTURE_MAG_FILTER</constant>, | |
121 | <constant>GL_TEXTURE_MIN_LOD</constant>, | |
122 | <constant>GL_TEXTURE_MAX_LOD</constant>, | |
123 | <constant>GL_TEXTURE_BASE_LEVEL</constant>, | |
124 | <constant>GL_TEXTURE_MAX_LEVEL</constant>, | |
125 | <constant>GL_TEXTURE_WRAP_S</constant>, | |
126 | <constant>GL_TEXTURE_WRAP_T</constant>, | |
127 | <constant>GL_TEXTURE_WRAP_R</constant>, | |
128 | <constant>GL_TEXTURE_BORDER_COLOR</constant>, | |
129 | <constant>GL_TEXTURE_PRIORITY</constant>, | |
130 | <constant>GL_TEXTURE_COMPARE_MODE</constant>, | |
131 | <constant>GL_TEXTURE_COMPARE_FUNC</constant>, | |
132 | <constant>GL_DEPTH_TEXTURE_MODE</constant>, or | |
133 | <constant>GL_GENERATE_MIPMAP</constant>. | |
134 | </para> | |
135 | </listitem> | |
136 | </varlistentry> | |
137 | <varlistentry> | |
138 | <term><parameter>params</parameter></term> | |
139 | <listitem> | |
140 | <para> | |
141 | Specifies a pointer to an array where the value or values of <parameter>pname</parameter> | |
142 | are stored. | |
143 | </para> | |
144 | </listitem> | |
145 | </varlistentry> | |
146 | </variablelist> | |
147 | </refsect1> | |
148 | <refsect1 id="description"><title>Description</title> | |
149 | <para> | |
150 | Texture mapping is a technique that applies an image onto an object's surface | |
151 | as if the image were a decal or cellophane shrink-wrap. | |
152 | The image is created in texture space, | |
153 | with an | |
154 | (<inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>, | |
155 | <inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>) | |
156 | coordinate system. | |
157 | A texture is a one- or two-dimensional image and a set of parameters | |
158 | that determine how samples are derived from the image. | |
159 | </para> | |
160 | <para> | |
161 | <function>glTexParameter</function> assigns the value or values in <parameter>params</parameter> to the texture parameter | |
162 | specified as <parameter>pname</parameter>. | |
163 | <parameter>target</parameter> defines the target texture, | |
164 | either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>, or <constant>GL_TEXTURE_3D</constant>. | |
165 | The following symbols are accepted in <parameter>pname</parameter>: | |
166 | </para> | |
167 | <variablelist> | |
168 | <varlistentry> | |
169 | <term><constant>GL_TEXTURE_MIN_FILTER</constant></term> | |
170 | <listitem> | |
171 | <para> | |
172 | The texture minifying function is used whenever the pixel being textured | |
173 | maps to an area greater than one texture element. | |
174 | There are six defined minifying functions. | |
175 | Two of them use the nearest one or nearest four texture elements | |
176 | to compute the texture value. | |
177 | The other four use mipmaps. | |
178 | </para> | |
179 | <para> | |
180 | A mipmap is an ordered set of arrays representing the same image | |
181 | at progressively lower resolutions. | |
182 | If the texture has dimensions | |
183 | <inlineequation><mml:math> | |
184 | <!-- eqn: 2 sup n times 2 sup m:--> | |
185 | <mml:mrow> | |
186 | <mml:msup><mml:mn>2</mml:mn> | |
187 | <mml:mi mathvariant="italic">n</mml:mi> | |
188 | </mml:msup> | |
189 | <mml:mo>×</mml:mo> | |
190 | <mml:msup><mml:mn>2</mml:mn> | |
191 | <mml:mi mathvariant="italic">m</mml:mi> | |
192 | </mml:msup> | |
193 | </mml:mrow> | |
194 | </mml:math></inlineequation>, | |
195 | there are | |
196 | <inlineequation><mml:math> | |
197 | <!-- eqn: max ( n, m ) + 1:--> | |
198 | <mml:mrow> | |
199 | <mml:mrow> | |
200 | <mml:mi mathvariant="italic">max</mml:mi> | |
201 | <mml:mo>⁡</mml:mo> | |
202 | <mml:mfenced open="(" close=")"> | |
203 | <mml:mi mathvariant="italic">n</mml:mi> | |
204 | <mml:mi mathvariant="italic">m</mml:mi> | |
205 | </mml:mfenced> | |
206 | </mml:mrow> | |
207 | <mml:mo>+</mml:mo> | |
208 | <mml:mn>1</mml:mn> | |
209 | </mml:mrow> | |
210 | </mml:math></inlineequation> | |
211 | mipmaps. | |
212 | The first mipmap is the original texture, | |
213 | with dimensions | |
214 | <inlineequation><mml:math> | |
215 | <!-- eqn: 2 sup n times 2 sup m:--> | |
216 | <mml:mrow> | |
217 | <mml:msup><mml:mn>2</mml:mn> | |
218 | <mml:mi mathvariant="italic">n</mml:mi> | |
219 | </mml:msup> | |
220 | <mml:mo>×</mml:mo> | |
221 | <mml:msup><mml:mn>2</mml:mn> | |
222 | <mml:mi mathvariant="italic">m</mml:mi> | |
223 | </mml:msup> | |
224 | </mml:mrow> | |
225 | </mml:math></inlineequation>. | |
226 | Each subsequent mipmap has dimensions | |
227 | <inlineequation><mml:math> | |
228 | <!-- eqn: 2 sup { k - 1 } times 2 sup { l - 1 }:--> | |
229 | <mml:mrow> | |
230 | <mml:msup><mml:mn>2</mml:mn> | |
231 | <mml:mfenced open="" close=""> | |
232 | <mml:mrow> | |
233 | <mml:mi mathvariant="italic">k</mml:mi> | |
234 | <mml:mo>-</mml:mo> | |
235 | <mml:mn>1</mml:mn> | |
236 | </mml:mrow> | |
237 | </mml:mfenced> | |
238 | </mml:msup> | |
239 | <mml:mo>×</mml:mo> | |
240 | <mml:msup><mml:mn>2</mml:mn> | |
241 | <mml:mfenced open="" close=""> | |
242 | <mml:mrow> | |
243 | <mml:mi mathvariant="italic">l</mml:mi> | |
244 | <mml:mo>-</mml:mo> | |
245 | <mml:mn>1</mml:mn> | |
246 | </mml:mrow> | |
247 | </mml:mfenced> | |
248 | </mml:msup> | |
249 | </mml:mrow> | |
250 | </mml:math></inlineequation>, | |
251 | where | |
252 | <inlineequation><mml:math> | |
253 | <!-- eqn: 2 sup k times 2 sup l:--> | |
254 | <mml:mrow> | |
255 | <mml:msup><mml:mn>2</mml:mn> | |
256 | <mml:mi mathvariant="italic">k</mml:mi> | |
257 | </mml:msup> | |
258 | <mml:mo>×</mml:mo> | |
259 | <mml:msup><mml:mn>2</mml:mn> | |
260 | <mml:mi mathvariant="italic">l</mml:mi> | |
261 | </mml:msup> | |
262 | </mml:mrow> | |
263 | </mml:math></inlineequation> | |
264 | are the dimensions of the previous mipmap, | |
265 | until either | |
266 | <inlineequation><mml:math> | |
267 | <!-- eqn: k = 0:--> | |
268 | <mml:mrow> | |
269 | <mml:mi mathvariant="italic">k</mml:mi> | |
270 | <mml:mo>=</mml:mo> | |
271 | <mml:mn>0</mml:mn> | |
272 | </mml:mrow> | |
273 | </mml:math></inlineequation> | |
274 | or | |
275 | <inlineequation><mml:math> | |
276 | <!-- eqn: l = 0:--> | |
277 | <mml:mrow> | |
278 | <mml:mi mathvariant="italic">l</mml:mi> | |
279 | <mml:mo>=</mml:mo> | |
280 | <mml:mn>0</mml:mn> | |
281 | </mml:mrow> | |
282 | </mml:math></inlineequation>. | |
283 | At that point, | |
284 | subsequent mipmaps have dimension | |
285 | <inlineequation><mml:math> | |
286 | <!-- eqn: 1 times 2 sup { l - 1 }:--> | |
287 | <mml:mrow> | |
288 | <mml:mn>1</mml:mn> | |
289 | <mml:mo>×</mml:mo> | |
290 | <mml:msup><mml:mn>2</mml:mn> | |
291 | <mml:mfenced open="" close=""> | |
292 | <mml:mrow> | |
293 | <mml:mi mathvariant="italic">l</mml:mi> | |
294 | <mml:mo>-</mml:mo> | |
295 | <mml:mn>1</mml:mn> | |
296 | </mml:mrow> | |
297 | </mml:mfenced> | |
298 | </mml:msup> | |
299 | </mml:mrow> | |
300 | </mml:math></inlineequation> | |
301 | or | |
302 | <inlineequation><mml:math> | |
303 | <!-- eqn: 2 sup { k - 1} times 1:--> | |
304 | <mml:mrow> | |
305 | <mml:msup><mml:mn>2</mml:mn> | |
306 | <mml:mfenced open="" close=""> | |
307 | <mml:mrow> | |
308 | <mml:mi mathvariant="italic">k</mml:mi> | |
309 | <mml:mo>-</mml:mo> | |
310 | <mml:mn>1</mml:mn> | |
311 | </mml:mrow> | |
312 | </mml:mfenced> | |
313 | </mml:msup> | |
314 | <mml:mo>×</mml:mo> | |
315 | <mml:mn>1</mml:mn> | |
316 | </mml:mrow> | |
317 | </mml:math></inlineequation> | |
318 | until the final mipmap, | |
319 | which has dimension | |
320 | <inlineequation><mml:math> | |
321 | <!-- eqn: 1 times 1:--> | |
322 | <mml:mrow> | |
323 | <mml:mn>1</mml:mn> | |
324 | <mml:mo>×</mml:mo> | |
325 | <mml:mn>1</mml:mn> | |
326 | </mml:mrow> | |
327 | </mml:math></inlineequation>. | |
328 | To define the mipmaps, call <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>, | |
329 | <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>, | |
330 | <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry> | |
331 | with the <emphasis>level</emphasis> argument indicating the order of the mipmaps. | |
332 | Level 0 is the original texture; | |
333 | level | |
334 | <inlineequation><mml:math> | |
335 | <!-- eqn: max ( n, m ):--> | |
336 | <mml:mrow> | |
337 | <mml:mi mathvariant="italic">max</mml:mi> | |
338 | <mml:mo>⁡</mml:mo> | |
339 | <mml:mfenced open="(" close=")"> | |
340 | <mml:mi mathvariant="italic">n</mml:mi> | |
341 | <mml:mi mathvariant="italic">m</mml:mi> | |
342 | </mml:mfenced> | |
343 | </mml:mrow> | |
344 | </mml:math></inlineequation> | |
345 | is the final | |
346 | <inlineequation><mml:math> | |
347 | <!-- eqn: 1 times 1:--> | |
348 | <mml:mrow> | |
349 | <mml:mn>1</mml:mn> | |
350 | <mml:mo>×</mml:mo> | |
351 | <mml:mn>1</mml:mn> | |
352 | </mml:mrow> | |
353 | </mml:math></inlineequation> | |
354 | mipmap. | |
355 | </para> | |
356 | <para> | |
357 | <parameter>params</parameter> supplies a function for minifying the texture as one of the | |
358 | following: | |
359 | <variablelist> | |
360 | <varlistentry> | |
361 | <term><constant>GL_NEAREST</constant></term> | |
362 | <listitem> | |
363 | <para> | |
364 | Returns the value of the texture element that is nearest | |
365 | (in Manhattan distance) | |
366 | to the center of the pixel being textured. | |
367 | </para> | |
368 | </listitem> | |
369 | </varlistentry> | |
370 | <varlistentry> | |
371 | <term><constant>GL_LINEAR</constant></term> | |
372 | <listitem> | |
373 | <para> | |
374 | Returns the weighted average of the four texture elements | |
375 | that are closest to the center of the pixel being textured. | |
376 | These can include border texture elements, | |
377 | depending on the values of <constant>GL_TEXTURE_WRAP_S</constant> and <constant>GL_TEXTURE_WRAP_T</constant>, | |
378 | and on the exact mapping. | |
379 | </para> | |
380 | </listitem> | |
381 | </varlistentry> | |
382 | <varlistentry> | |
383 | <term><constant>GL_NEAREST_MIPMAP_NEAREST</constant></term> | |
384 | <listitem> | |
385 | <para> | |
386 | Chooses the mipmap that most closely matches the size of the pixel | |
387 | being textured and uses the <constant>GL_NEAREST</constant> criterion | |
388 | (the texture element nearest to the center of the pixel) | |
389 | to produce a texture value. | |
390 | </para> | |
391 | </listitem> | |
392 | </varlistentry> | |
393 | <varlistentry> | |
394 | <term><constant>GL_LINEAR_MIPMAP_NEAREST</constant></term> | |
395 | <listitem> | |
396 | <para> | |
397 | Chooses the mipmap that most closely matches the size of the pixel | |
398 | being textured and uses the <constant>GL_LINEAR</constant> criterion | |
399 | (a weighted average of the four texture elements that are closest | |
400 | to the center of the pixel) | |
401 | to produce a texture value. | |
402 | </para> | |
403 | </listitem> | |
404 | </varlistentry> | |
405 | <varlistentry> | |
406 | <term><constant>GL_NEAREST_MIPMAP_LINEAR</constant></term> | |
407 | <listitem> | |
408 | <para> | |
409 | Chooses the two mipmaps that most closely match the size of the pixel | |
410 | being textured and uses the <constant>GL_NEAREST</constant> criterion | |
411 | (the texture element nearest to the center of the pixel) | |
412 | to produce a texture value from each mipmap. | |
413 | The final texture value is a weighted average of those two values. | |
414 | </para> | |
415 | </listitem> | |
416 | </varlistentry> | |
417 | <varlistentry> | |
418 | <term><constant>GL_LINEAR_MIPMAP_LINEAR</constant></term> | |
419 | <listitem> | |
420 | <para> | |
421 | Chooses the two mipmaps that most closely match the size of the pixel | |
422 | being textured and uses the <constant>GL_LINEAR</constant> criterion | |
423 | (a weighted average of the four texture elements that are closest | |
424 | to the center of the pixel) | |
425 | to produce a texture value from each mipmap. | |
426 | The final texture value is a weighted average of those two values. | |
427 | </para> | |
428 | </listitem> | |
429 | </varlistentry> | |
430 | </variablelist> | |
431 | </para> | |
432 | <para> | |
433 | As more texture elements are sampled in the minification process, | |
434 | fewer aliasing artifacts will be apparent. | |
435 | While the <constant>GL_NEAREST</constant> and <constant>GL_LINEAR</constant> minification functions can be | |
436 | faster than the other four, | |
437 | they sample only one or four texture elements to determine the texture value | |
438 | of the pixel being rendered and can produce moire patterns | |
439 | or ragged transitions. | |
440 | The initial value of <constant>GL_TEXTURE_MIN_FILTER</constant> is | |
441 | <constant>GL_NEAREST_MIPMAP_LINEAR</constant>. | |
442 | </para> | |
443 | </listitem> | |
444 | </varlistentry> | |
445 | <varlistentry> | |
446 | <term><constant>GL_TEXTURE_MAG_FILTER</constant></term> | |
447 | <listitem> | |
448 | <para> | |
449 | The texture magnification function is used when the pixel being textured | |
450 | maps to an area less than or equal to one texture element. | |
451 | It sets the texture magnification function to either <constant>GL_NEAREST</constant> | |
452 | or <constant>GL_LINEAR</constant> (see below). <constant>GL_NEAREST</constant> is generally faster | |
453 | than <constant>GL_LINEAR</constant>, | |
454 | but it can produce textured images with sharper edges | |
455 | because the transition between texture elements is not as smooth. | |
456 | The initial value of <constant>GL_TEXTURE_MAG_FILTER</constant> is <constant>GL_LINEAR</constant>. | |
457 | <variablelist> | |
458 | <varlistentry> | |
459 | <term><constant>GL_NEAREST</constant></term> | |
460 | <listitem> | |
461 | <para> | |
462 | Returns the value of the texture element that is nearest | |
463 | (in Manhattan distance) | |
464 | to the center of the pixel being textured. | |
465 | </para> | |
466 | </listitem> | |
467 | </varlistentry> | |
468 | <varlistentry> | |
469 | <term><constant>GL_LINEAR</constant></term> | |
470 | <listitem> | |
471 | <para> | |
472 | Returns the weighted average of the four texture elements | |
473 | that are closest to the center of the pixel being textured. | |
474 | These can include border texture elements, | |
475 | depending on the values of <constant>GL_TEXTURE_WRAP_S</constant> and <constant>GL_TEXTURE_WRAP_T</constant>, | |
476 | and on the exact mapping. | |
477 | </para> | |
478 | </listitem> | |
479 | </varlistentry> | |
480 | </variablelist> | |
481 | <para> | |
482 | </para> | |
483 | </para> | |
484 | </listitem> | |
485 | </varlistentry> | |
486 | </variablelist> | |
487 | <para> | |
488 | </para> | |
489 | <variablelist> | |
490 | <varlistentry> | |
491 | <term><constant>GL_TEXTURE_MIN_LOD</constant></term> | |
492 | <listitem> | |
493 | <para> | |
494 | Sets the minimum level-of-detail parameter. This floating-point value | |
495 | limits the selection of highest resolution mipmap (lowest mipmap | |
496 | level). The initial value is -1000. | |
497 | </para> | |
498 | </listitem> | |
499 | </varlistentry> | |
500 | </variablelist> | |
501 | <para> | |
502 | </para> | |
503 | <variablelist> | |
504 | <varlistentry> | |
505 | <term><constant>GL_TEXTURE_MAX_LOD</constant></term> | |
506 | <listitem> | |
507 | <para> | |
508 | Sets the maximum level-of-detail parameter. This floating-point value | |
509 | limits the selection of the lowest resolution mipmap (highest mipmap | |
510 | level). The initial value is 1000. | |
511 | </para> | |
512 | </listitem> | |
513 | </varlistentry> | |
514 | </variablelist> | |
515 | <para> | |
516 | </para> | |
517 | <variablelist> | |
518 | <varlistentry> | |
519 | <term><constant>GL_TEXTURE_BASE_LEVEL</constant></term> | |
520 | <listitem> | |
521 | <para> | |
522 | Specifies the index of the lowest defined mipmap level. This is an | |
523 | integer value. The initial value is 0. | |
524 | </para> | |
525 | </listitem> | |
526 | </varlistentry> | |
527 | </variablelist> | |
528 | <para> | |
529 | </para> | |
530 | <variablelist> | |
531 | <varlistentry> | |
532 | <term><constant>GL_TEXTURE_MAX_LEVEL</constant></term> | |
533 | <listitem> | |
534 | <para> | |
535 | Sets the index of the highest defined mipmap level. This is an integer | |
536 | value. The initial value is 1000. | |
537 | </para> | |
538 | </listitem> | |
539 | </varlistentry> | |
540 | </variablelist> | |
541 | <para> | |
542 | </para> | |
543 | <variablelist> | |
544 | <varlistentry> | |
545 | <term><constant>GL_TEXTURE_WRAP_S</constant></term> | |
546 | <listitem> | |
547 | <para> | |
548 | Sets the wrap parameter for texture coordinate | |
549 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
550 | to either <constant>GL_CLAMP</constant>, | |
551 | <constant>GL_CLAMP_TO_BORDER</constant>, <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_MIRRORED_REPEAT</constant>, or | |
552 | <constant>GL_REPEAT</constant>. <constant>GL_CLAMP</constant> causes | |
553 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
554 | coordinates to be clamped to the | |
555 | range [0,1] and is useful for preventing wrapping artifacts when mapping a | |
556 | single image onto an object. <constant>GL_CLAMP_TO_BORDER</constant> causes the | |
557 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
558 | coordinate to be clamped to the range | |
559 | <inlineequation><mml:math> | |
560 | <!-- eqn: left [ {-1 over 2N}, 1 + {1 over 2N} right ]:--> | |
561 | <mml:mfenced open="[" close="]"> | |
562 | <mml:mfenced open="" close=""> | |
563 | <mml:mrow> | |
564 | <mml:mfrac> | |
565 | <mml:mn>-1</mml:mn> | |
566 | <mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn> | |
567 | </mml:mfrac> | |
568 | </mml:mrow> | |
569 | </mml:mfenced> | |
570 | <mml:mrow> | |
571 | <mml:mn>1</mml:mn> | |
572 | <mml:mo>+</mml:mo> | |
573 | <mml:mfenced open="" close=""> | |
574 | <mml:mrow> | |
575 | <mml:mfrac> | |
576 | <mml:mn>1</mml:mn> | |
577 | <mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn> | |
578 | </mml:mfrac> | |
579 | </mml:mrow> | |
580 | </mml:mfenced> | |
581 | </mml:mrow> | |
582 | </mml:mfenced> | |
583 | </mml:math></inlineequation>, | |
584 | where | |
585 | <inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation> | |
586 | is the size of the texture in the direction of | |
587 | clamping.<constant>GL_CLAMP_TO_EDGE</constant> causes | |
588 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
589 | coordinates to be clamped to the | |
590 | range | |
591 | <inlineequation><mml:math> | |
592 | <!-- eqn: left [ {1 over 2N}, 1 - {1 over 2N} right ]:--> | |
593 | <mml:mfenced open="[" close="]"> | |
594 | <mml:mfenced open="" close=""> | |
595 | <mml:mrow> | |
596 | <mml:mfrac> | |
597 | <mml:mn>1</mml:mn> | |
598 | <mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn> | |
599 | </mml:mfrac> | |
600 | </mml:mrow> | |
601 | </mml:mfenced> | |
602 | <mml:mrow> | |
603 | <mml:mn>1</mml:mn> | |
604 | <mml:mo>-</mml:mo> | |
605 | <mml:mfenced open="" close=""> | |
606 | <mml:mrow> | |
607 | <mml:mfrac> | |
608 | <mml:mn>1</mml:mn> | |
609 | <mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn> | |
610 | </mml:mfrac> | |
611 | </mml:mrow> | |
612 | </mml:mfenced> | |
613 | </mml:mrow> | |
614 | </mml:mfenced> | |
615 | </mml:math></inlineequation>, | |
616 | where | |
617 | <inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation> | |
618 | is the size | |
619 | of the texture in the direction of clamping. <constant>GL_REPEAT</constant> causes the | |
620 | integer part of the | |
621 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
622 | coordinate to be ignored; the GL uses only the | |
623 | fractional part, thereby creating a repeating pattern. | |
624 | <constant>GL_MIRRORED_REPEAT</constant> causes the | |
625 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
626 | coordinate to be set to the | |
627 | fractional part of the texture coordinate if the integer part of | |
628 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
629 | is | |
630 | even; if the integer part of | |
631 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
632 | is odd, then the | |
633 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> | |
634 | texture coordinate is | |
635 | set to | |
636 | <inlineequation><mml:math> | |
637 | <!-- eqn: 1 - frac(s):--> | |
638 | <mml:mrow> | |
639 | <mml:mn>1</mml:mn> | |
640 | <mml:mo>-</mml:mo> | |
641 | <mml:mrow> | |
642 | <mml:mi mathvariant="italic">frac</mml:mi> | |
643 | <mml:mo>⁡</mml:mo> | |
644 | <mml:mfenced open="(" close=")"> | |
645 | <mml:mi mathvariant="italic">s</mml:mi> | |
646 | </mml:mfenced> | |
647 | </mml:mrow> | |
648 | </mml:mrow> | |
649 | </mml:math></inlineequation>, | |
650 | where | |
651 | <inlineequation><mml:math> | |
652 | <!-- eqn: frac(s):--> | |
653 | <mml:mrow> | |
654 | <mml:mi mathvariant="italic">frac</mml:mi> | |
655 | <mml:mo>⁡</mml:mo> | |
656 | <mml:mfenced open="(" close=")"> | |
657 | <mml:mi mathvariant="italic">s</mml:mi> | |
658 | </mml:mfenced> | |
659 | </mml:mrow> | |
660 | </mml:math></inlineequation> | |
661 | represents the fractional part of | |
662 | <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>. | |
663 | Border texture | |
664 | elements are accessed only if wrapping is set to <constant>GL_CLAMP</constant> or <constant>GL_CLAMP_TO_BORDER</constant>. Initially, | |
665 | <constant>GL_TEXTURE_WRAP_S</constant> is set to <constant>GL_REPEAT</constant>. | |
666 | </para> | |
667 | </listitem> | |
668 | </varlistentry> | |
669 | </variablelist> | |
670 | <para> | |
671 | </para> | |
672 | <variablelist> | |
673 | <varlistentry> | |
674 | <term><constant>GL_TEXTURE_WRAP_T</constant></term> | |
675 | <listitem> | |
676 | <para> | |
677 | Sets the wrap parameter for texture coordinate | |
678 | <inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation> | |
679 | to either <constant>GL_CLAMP</constant>, | |
680 | <constant>GL_CLAMP_TO_BORDER</constant>, <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_MIRRORED_REPEAT</constant>, or | |
681 | <constant>GL_REPEAT</constant>. See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>. | |
682 | Initially, <constant>GL_TEXTURE_WRAP_T</constant> is set to <constant>GL_REPEAT</constant>. | |
683 | </para> | |
684 | </listitem> | |
685 | </varlistentry> | |
686 | <varlistentry> | |
687 | <term><constant>GL_TEXTURE_WRAP_R</constant></term> | |
688 | <listitem> | |
689 | <para> | |
690 | Sets the wrap parameter for texture coordinate | |
691 | <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> | |
692 | to either <constant>GL_CLAMP</constant>, | |
693 | <constant>GL_CLAMP_TO_BORDER</constant>, <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_MIRRORED_REPEAT</constant>, or | |
694 | <constant>GL_REPEAT</constant>. See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>. | |
695 | Initially, <constant>GL_TEXTURE_WRAP_R</constant> is set to <constant>GL_REPEAT</constant>. | |
696 | </para> | |
697 | </listitem> | |
698 | </varlistentry> | |
699 | <varlistentry> | |
700 | <term><constant>GL_TEXTURE_BORDER_COLOR</constant></term> | |
701 | <listitem> | |
702 | <para> | |
703 | Sets a border color. <parameter>params</parameter> contains four values that comprise the RGBA | |
704 | color of the texture border. Integer color components are interpreted | |
705 | linearly such that the most positive integer maps to 1.0, and the most | |
706 | negative integer maps to -1.0. The values are clamped to the range [0,1] | |
707 | when they are specified. Initially, the border color is (0, 0, 0, 0). | |
708 | </para> | |
709 | </listitem> | |
710 | </varlistentry> | |
711 | <varlistentry> | |
712 | <term><constant>GL_TEXTURE_PRIORITY</constant></term> | |
713 | <listitem> | |
714 | <para> | |
715 | Specifies the texture residence priority of the currently bound texture. | |
716 | Permissible values are in the range | |
717 | <inlineequation><mml:math> | |
718 | <!-- eqn: [0,1]:--> | |
719 | <mml:mfenced open="[" close="]"> | |
720 | <mml:mn>0</mml:mn> | |
721 | <mml:mn>1</mml:mn> | |
722 | </mml:mfenced> | |
723 | </mml:math></inlineequation>. | |
724 | See <citerefentry><refentrytitle>glPrioritizeTextures</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glBindTexture</refentrytitle></citerefentry> for more information. | |
725 | </para> | |
726 | </listitem> | |
727 | </varlistentry> | |
728 | <varlistentry> | |
729 | <term><constant>GL_TEXTURE_COMPARE_MODE</constant></term> | |
730 | <listitem> | |
731 | <para> | |
732 | Specifies the texture comparison mode for currently bound depth textures. | |
733 | That is, a texture whose internal format is <constant>GL_DEPTH_COMPONENT_*</constant>; see | |
734 | <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>) | |
735 | Permissible values are: | |
736 | <variablelist> | |
737 | <varlistentry> | |
738 | <term><constant>GL_COMPARE_R_TO_TEXTURE</constant></term> | |
739 | <listitem> | |
740 | <para> | |
741 | Specifies that the interpolated and clamped | |
742 | <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> | |
743 | texture coordinate should | |
744 | be compared to the value in the currently bound depth texture. See the | |
745 | discussion of <constant>GL_TEXTURE_COMPARE_FUNC</constant> for details of how the comparison | |
746 | is evaluated. The result of the comparison is assigned to luminance, | |
747 | intensity, or alpha (as specified by <constant>GL_DEPTH_TEXTURE_MODE</constant>). | |
748 | </para> | |
749 | </listitem> | |
750 | </varlistentry> | |
751 | <varlistentry> | |
752 | <term><constant>GL_NONE</constant></term> | |
753 | <listitem> | |
754 | <para> | |
755 | Specifies that the luminance, intensity, or alpha (as specified by | |
756 | <constant>GL_DEPTH_TEXTURE_MODE</constant>) should be assigned the | |
757 | appropriate value from the currently bound depth texture. | |
758 | </para> | |
759 | </listitem> | |
760 | </varlistentry> | |
761 | </variablelist> | |
762 | </para> | |
763 | </listitem> | |
764 | </varlistentry> | |
765 | <varlistentry> | |
766 | <term><constant>GL_TEXTURE_COMPARE_FUNC</constant></term> | |
767 | <listitem> | |
768 | <para> | |
769 | Specifies the comparison operator used when <constant>GL_TEXTURE_COMPARE_MODE</constant> is | |
770 | set to <constant>GL_COMPARE_R_TO_TEXTURE</constant>. Permissible values are: | |
771 | <informaltable frame="topbot"> | |
772 | <tgroup cols="2" align="left"> | |
773 | <colspec/> | |
774 | <colspec/> | |
775 | <thead> | |
776 | <row> | |
777 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
778 | Texture Comparison Function | |
779 | </emphasis></entry> | |
780 | <entry rowsep="1" align="left"><emphasis role="bold"> | |
781 | Computed result | |
782 | </emphasis></entry> | |
783 | </row> | |
784 | </thead> | |
785 | <tbody> | |
786 | <row> | |
787 | <entry align="left"> | |
788 | <constant>GL_LEQUAL</constant> | |
789 | </entry> | |
790 | <entry align="left"> | |
791 | <informalequation><mml:math> | |
792 | <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}:--> | |
793 | <mml:mrow> | |
794 | <mml:mi mathvariant="italic">result</mml:mi> | |
795 | <mml:mo>=</mml:mo> | |
796 | <mml:mfenced open="{" close=""> | |
797 | <mml:mrow> | |
798 | <mml:mtable> | |
799 | <mml:mtr><mml:mtd> | |
800 | <mml:mn>1.0</mml:mn> | |
801 | </mml:mtd></mml:mtr> | |
802 | <mml:mtr><mml:mtd> | |
803 | <mml:mn>0.0</mml:mn> | |
804 | </mml:mtd></mml:mtr> | |
805 | </mml:mtable> | |
806 | <mml:mo>⁢ </mml:mo> | |
807 | <mml:mtable> | |
808 | <mml:mtr><mml:mtd> | |
809 | <mml:mrow> | |
810 | <mml:mi mathvariant="italic">r</mml:mi> | |
811 | <mml:mo><=</mml:mo> | |
812 | <mml:mfenced open="" close=""> | |
813 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
814 | <mml:mi mathvariant="italic">t</mml:mi> | |
815 | </mml:msub> | |
816 | </mml:mfenced> | |
817 | </mml:mrow> | |
818 | </mml:mtd></mml:mtr> | |
819 | <mml:mtr><mml:mtd> | |
820 | <mml:mrow> | |
821 | <mml:mi mathvariant="italic">r</mml:mi> | |
822 | <mml:mo>></mml:mo> | |
823 | <mml:mfenced open="" close=""> | |
824 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
825 | <mml:mi mathvariant="italic">t</mml:mi> | |
826 | </mml:msub> | |
827 | </mml:mfenced> | |
828 | </mml:mrow> | |
829 | </mml:mtd></mml:mtr> | |
830 | </mml:mtable> | |
831 | </mml:mrow> | |
832 | </mml:mfenced> | |
833 | </mml:mrow> | |
834 | </mml:math></informalequation> | |
835 | </entry> | |
836 | </row> | |
837 | <row> | |
838 | <entry align="left"> | |
839 | <constant>GL_GEQUAL</constant> | |
840 | </entry> | |
841 | <entry align="left"> | |
842 | <informalequation><mml:math> | |
843 | <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}:--> | |
844 | <mml:mrow> | |
845 | <mml:mi mathvariant="italic">result</mml:mi> | |
846 | <mml:mo>=</mml:mo> | |
847 | <mml:mfenced open="{" close=""> | |
848 | <mml:mrow> | |
849 | <mml:mtable> | |
850 | <mml:mtr><mml:mtd> | |
851 | <mml:mn>1.0</mml:mn> | |
852 | </mml:mtd></mml:mtr> | |
853 | <mml:mtr><mml:mtd> | |
854 | <mml:mn>0.0</mml:mn> | |
855 | </mml:mtd></mml:mtr> | |
856 | </mml:mtable> | |
857 | <mml:mo>⁢ </mml:mo> | |
858 | <mml:mtable> | |
859 | <mml:mtr><mml:mtd> | |
860 | <mml:mrow> | |
861 | <mml:mi mathvariant="italic">r</mml:mi> | |
862 | <mml:mo>>=</mml:mo> | |
863 | <mml:mfenced open="" close=""> | |
864 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
865 | <mml:mi mathvariant="italic">t</mml:mi> | |
866 | </mml:msub> | |
867 | </mml:mfenced> | |
868 | </mml:mrow> | |
869 | </mml:mtd></mml:mtr> | |
870 | <mml:mtr><mml:mtd> | |
871 | <mml:mrow> | |
872 | <mml:mi mathvariant="italic">r</mml:mi> | |
873 | <mml:mo><</mml:mo> | |
874 | <mml:mfenced open="" close=""> | |
875 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
876 | <mml:mi mathvariant="italic">t</mml:mi> | |
877 | </mml:msub> | |
878 | </mml:mfenced> | |
879 | </mml:mrow> | |
880 | </mml:mtd></mml:mtr> | |
881 | </mml:mtable> | |
882 | </mml:mrow> | |
883 | </mml:mfenced> | |
884 | </mml:mrow> | |
885 | </mml:math></informalequation> | |
886 | </entry> | |
887 | </row> | |
888 | <row> | |
889 | <entry align="left"> | |
890 | <constant>GL_LESS</constant> | |
891 | </entry> | |
892 | <entry align="left"> | |
893 | <informalequation><mml:math> | |
894 | <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}:--> | |
895 | <mml:mrow> | |
896 | <mml:mi mathvariant="italic">result</mml:mi> | |
897 | <mml:mo>=</mml:mo> | |
898 | <mml:mfenced open="{" close=""> | |
899 | <mml:mrow> | |
900 | <mml:mtable> | |
901 | <mml:mtr><mml:mtd> | |
902 | <mml:mn>1.0</mml:mn> | |
903 | </mml:mtd></mml:mtr> | |
904 | <mml:mtr><mml:mtd> | |
905 | <mml:mn>0.0</mml:mn> | |
906 | </mml:mtd></mml:mtr> | |
907 | </mml:mtable> | |
908 | <mml:mo>⁢ </mml:mo> | |
909 | <mml:mtable> | |
910 | <mml:mtr><mml:mtd> | |
911 | <mml:mrow> | |
912 | <mml:mi mathvariant="italic">r</mml:mi> | |
913 | <mml:mo><</mml:mo> | |
914 | <mml:mfenced open="" close=""> | |
915 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
916 | <mml:mi mathvariant="italic">t</mml:mi> | |
917 | </mml:msub> | |
918 | </mml:mfenced> | |
919 | </mml:mrow> | |
920 | </mml:mtd></mml:mtr> | |
921 | <mml:mtr><mml:mtd> | |
922 | <mml:mrow> | |
923 | <mml:mi mathvariant="italic">r</mml:mi> | |
924 | <mml:mo>>=</mml:mo> | |
925 | <mml:mfenced open="" close=""> | |
926 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
927 | <mml:mi mathvariant="italic">t</mml:mi> | |
928 | </mml:msub> | |
929 | </mml:mfenced> | |
930 | </mml:mrow> | |
931 | </mml:mtd></mml:mtr> | |
932 | </mml:mtable> | |
933 | </mml:mrow> | |
934 | </mml:mfenced> | |
935 | </mml:mrow> | |
936 | </mml:math></informalequation> | |
937 | </entry> | |
938 | </row> | |
939 | <row> | |
940 | <entry align="left"> | |
941 | <constant>GL_GREATER</constant> | |
942 | </entry> | |
943 | <entry align="left"> | |
944 | <informalequation><mml:math> | |
945 | <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}:--> | |
946 | <mml:mrow> | |
947 | <mml:mi mathvariant="italic">result</mml:mi> | |
948 | <mml:mo>=</mml:mo> | |
949 | <mml:mfenced open="{" close=""> | |
950 | <mml:mrow> | |
951 | <mml:mtable> | |
952 | <mml:mtr><mml:mtd> | |
953 | <mml:mn>1.0</mml:mn> | |
954 | </mml:mtd></mml:mtr> | |
955 | <mml:mtr><mml:mtd> | |
956 | <mml:mn>0.0</mml:mn> | |
957 | </mml:mtd></mml:mtr> | |
958 | </mml:mtable> | |
959 | <mml:mo>⁢ </mml:mo> | |
960 | <mml:mtable> | |
961 | <mml:mtr><mml:mtd> | |
962 | <mml:mrow> | |
963 | <mml:mi mathvariant="italic">r</mml:mi> | |
964 | <mml:mo>></mml:mo> | |
965 | <mml:mfenced open="" close=""> | |
966 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
967 | <mml:mi mathvariant="italic">t</mml:mi> | |
968 | </mml:msub> | |
969 | </mml:mfenced> | |
970 | </mml:mrow> | |
971 | </mml:mtd></mml:mtr> | |
972 | <mml:mtr><mml:mtd> | |
973 | <mml:mrow> | |
974 | <mml:mi mathvariant="italic">r</mml:mi> | |
975 | <mml:mo><=</mml:mo> | |
976 | <mml:mfenced open="" close=""> | |
977 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
978 | <mml:mi mathvariant="italic">t</mml:mi> | |
979 | </mml:msub> | |
980 | </mml:mfenced> | |
981 | </mml:mrow> | |
982 | </mml:mtd></mml:mtr> | |
983 | </mml:mtable> | |
984 | </mml:mrow> | |
985 | </mml:mfenced> | |
986 | </mml:mrow> | |
987 | </mml:math></informalequation> | |
988 | </entry> | |
989 | </row> | |
990 | <row> | |
991 | <entry align="left"> | |
992 | <constant>GL_EQUAL</constant> | |
993 | </entry> | |
994 | <entry align="left"> | |
995 | <informalequation><mml:math> | |
996 | <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}:--> | |
997 | <mml:mrow> | |
998 | <mml:mi mathvariant="italic">result</mml:mi> | |
999 | <mml:mo>=</mml:mo> | |
1000 | <mml:mfenced open="{" close=""> | |
1001 | <mml:mrow> | |
1002 | <mml:mtable> | |
1003 | <mml:mtr><mml:mtd> | |
1004 | <mml:mn>1.0</mml:mn> | |
1005 | </mml:mtd></mml:mtr> | |
1006 | <mml:mtr><mml:mtd> | |
1007 | <mml:mn>0.0</mml:mn> | |
1008 | </mml:mtd></mml:mtr> | |
1009 | </mml:mtable> | |
1010 | <mml:mo>⁢ </mml:mo> | |
1011 | <mml:mtable> | |
1012 | <mml:mtr><mml:mtd> | |
1013 | <mml:mrow> | |
1014 | <mml:mi mathvariant="italic">r</mml:mi> | |
1015 | <mml:mo>=</mml:mo> | |
1016 | <mml:mfenced open="" close=""> | |
1017 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
1018 | <mml:mi mathvariant="italic">t</mml:mi> | |
1019 | </mml:msub> | |
1020 | </mml:mfenced> | |
1021 | </mml:mrow> | |
1022 | </mml:mtd></mml:mtr> | |
1023 | <mml:mtr><mml:mtd> | |
1024 | <mml:mrow> | |
1025 | <mml:mi mathvariant="italic">r</mml:mi> | |
1026 | <mml:mo>≠</mml:mo> | |
1027 | <mml:mfenced open="" close=""> | |
1028 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
1029 | <mml:mi mathvariant="italic">t</mml:mi> | |
1030 | </mml:msub> | |
1031 | </mml:mfenced> | |
1032 | </mml:mrow> | |
1033 | </mml:mtd></mml:mtr> | |
1034 | </mml:mtable> | |
1035 | </mml:mrow> | |
1036 | </mml:mfenced> | |
1037 | </mml:mrow> | |
1038 | </mml:math></informalequation> | |
1039 | </entry> | |
1040 | </row> | |
1041 | <row> | |
1042 | <entry align="left"> | |
1043 | <constant>GL_NOTEQUAL</constant> | |
1044 | </entry> | |
1045 | <entry align="left"> | |
1046 | <informalequation><mml:math> | |
1047 | <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}:--> | |
1048 | <mml:mrow> | |
1049 | <mml:mi mathvariant="italic">result</mml:mi> | |
1050 | <mml:mo>=</mml:mo> | |
1051 | <mml:mfenced open="{" close=""> | |
1052 | <mml:mrow> | |
1053 | <mml:mtable> | |
1054 | <mml:mtr><mml:mtd> | |
1055 | <mml:mn>1.0</mml:mn> | |
1056 | </mml:mtd></mml:mtr> | |
1057 | <mml:mtr><mml:mtd> | |
1058 | <mml:mn>0.0</mml:mn> | |
1059 | </mml:mtd></mml:mtr> | |
1060 | </mml:mtable> | |
1061 | <mml:mo>⁢ </mml:mo> | |
1062 | <mml:mtable> | |
1063 | <mml:mtr><mml:mtd> | |
1064 | <mml:mrow> | |
1065 | <mml:mi mathvariant="italic">r</mml:mi> | |
1066 | <mml:mo>≠</mml:mo> | |
1067 | <mml:mfenced open="" close=""> | |
1068 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
1069 | <mml:mi mathvariant="italic">t</mml:mi> | |
1070 | </mml:msub> | |
1071 | </mml:mfenced> | |
1072 | </mml:mrow> | |
1073 | </mml:mtd></mml:mtr> | |
1074 | <mml:mtr><mml:mtd> | |
1075 | <mml:mrow> | |
1076 | <mml:mi mathvariant="italic">r</mml:mi> | |
1077 | <mml:mo>=</mml:mo> | |
1078 | <mml:mfenced open="" close=""> | |
1079 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
1080 | <mml:mi mathvariant="italic">t</mml:mi> | |
1081 | </mml:msub> | |
1082 | </mml:mfenced> | |
1083 | </mml:mrow> | |
1084 | </mml:mtd></mml:mtr> | |
1085 | </mml:mtable> | |
1086 | </mml:mrow> | |
1087 | </mml:mfenced> | |
1088 | </mml:mrow> | |
1089 | </mml:math></informalequation> | |
1090 | </entry> | |
1091 | </row> | |
1092 | <row> | |
1093 | <entry align="left"> | |
1094 | <constant>GL_ALWAYS</constant> | |
1095 | </entry> | |
1096 | <entry align="left"> | |
1097 | <informalequation> | |
1098 | <mml:math> | |
1099 | <mml:mrow> | |
1100 | <mml:mi mathvariant="italic">result</mml:mi> | |
1101 | <mml:mo>=</mml:mo> | |
1102 | <mml:mi>1.0</mml:mi> | |
1103 | </mml:mrow> | |
1104 | </mml:math> | |
1105 | </informalequation> | |
1106 | </entry> | |
1107 | </row> | |
1108 | <row> | |
1109 | <entry align="left"> | |
1110 | <constant>GL_NEVER</constant> | |
1111 | </entry> | |
1112 | <entry align="left"> | |
1113 | <informalequation> | |
1114 | <mml:math> | |
1115 | <mml:mrow> | |
1116 | <mml:mi mathvariant="italic">result</mml:mi> | |
1117 | <mml:mo>=</mml:mo> | |
1118 | <mml:mi>0.0</mml:mi> | |
1119 | </mml:mrow> | |
1120 | </mml:math> | |
1121 | </informalequation> | |
1122 | </entry> | |
1123 | </row> | |
1124 | </tbody> | |
1125 | </tgroup> | |
1126 | </informaltable> | |
1127 | where <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> | |
1128 | is the current interpolated texture coordinate, and | |
1129 | <inlineequation><mml:math> | |
1130 | <!-- eqn: D sub t:--> | |
1131 | <mml:msub><mml:mi mathvariant="italic">D</mml:mi> | |
1132 | <mml:mi mathvariant="italic">t</mml:mi> | |
1133 | </mml:msub> | |
1134 | </mml:math></inlineequation> | |
1135 | is the depth texture value sampled from the currently bound depth texture. | |
1136 | <inlineequation><mml:math><mml:mi mathvariant="italic">result</mml:mi></mml:math></inlineequation> | |
1137 | is assigned to the either the luminance, intensity, or alpha (as | |
1138 | specified by <constant>GL_DEPTH_TEXTURE_MODE</constant>.) | |
1139 | </para> | |
1140 | </listitem> | |
1141 | </varlistentry> | |
1142 | <varlistentry> | |
1143 | <term><constant>GL_DEPTH_TEXTURE_MODE</constant></term> | |
1144 | <listitem> | |
1145 | <para> | |
1146 | Specifies a single symbolic constant indicating how depth values should be | |
1147 | treated during filtering and texture application. Accepted values are | |
1148 | <constant>GL_LUMINANCE</constant>, <constant>GL_INTENSITY</constant>, and <constant>GL_ALPHA</constant>. The initial value | |
1149 | is <constant>GL_LUMINANCE</constant>. | |
1150 | </para> | |
1151 | </listitem> | |
1152 | </varlistentry> | |
1153 | <varlistentry> | |
1154 | <term><constant>GL_GENERATE_MIPMAP</constant></term> | |
1155 | <listitem> | |
1156 | <para> | |
1157 | Specifies a boolean value that indicates if all levels of a mipmap array | |
1158 | should be automatically updated when any modification to the base level | |
1159 | mipmap is done. The initial value is <constant>GL_FALSE</constant>. | |
1160 | </para> | |
1161 | </listitem> | |
1162 | </varlistentry> | |
1163 | </variablelist> | |
1164 | </refsect1> | |
1165 | <refsect1 id="notes"><title>Notes</title> | |
1166 | <para> | |
1167 | <constant>GL_TEXTURE_3D</constant>, <constant>GL_TEXTURE_MIN_LOD</constant>, <constant>GL_TEXTURE_MAX_LOD</constant>, | |
1168 | <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_TEXTURE_BASE_LEVEL</constant>, and <constant>GL_TEXTURE_MAX_LEVEL</constant> are | |
1169 | available only if the GL version is 1.2 or greater. | |
1170 | </para> | |
1171 | <para> | |
1172 | <constant>GL_CLAMP_TO_BORDER</constant> is available only if the GL version is 1.3 or greater. | |
1173 | </para> | |
1174 | <para> | |
1175 | <constant>GL_MIRRORED_REPEAT</constant>, <constant>GL_TEXTURE_COMPARE_MODE</constant>, | |
1176 | <constant>GL_TEXTURE_COMPARE_FUNC</constant>, <constant>GL_DEPTH_TEXTURE_MODE</constant>, and | |
1177 | <constant>GL_GENERATE_MIPMAP</constant> are available only if the GL version is 1.4 or | |
1178 | greater. | |
1179 | </para> | |
1180 | <para> | |
1181 | <constant>GL_TEXTURE_COMPARE_FUNC</constant> allows the following additional comparison modes only | |
1182 | if the GL version is 1.5 or greater: | |
1183 | <constant>GL_LESS</constant>, <constant>GL_GREATER</constant>, | |
1184 | <constant>GL_EQUAL</constant>, <constant>GL_NOTEQUAL</constant>, | |
1185 | <constant>GL_ALWAYS</constant>, and <constant>GL_NEVER</constant>. | |
1186 | </para> | |
1187 | <para> | |
1188 | Suppose that a program has enabled texturing (by calling <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> with | |
1189 | argument <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>, or <constant>GL_TEXTURE_3D</constant>) and | |
1190 | has set <constant>GL_TEXTURE_MIN_FILTER</constant> to one of the functions that requires a | |
1191 | mipmap. If either the dimensions of the texture images currently defined | |
1192 | (with previous calls to <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>, | |
1193 | <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>) do not | |
1194 | follow the proper sequence for mipmaps (described above), or there are | |
1195 | fewer texture images defined than are needed, or the set of texture images | |
1196 | have differing numbers of texture components, then it is as if texture | |
1197 | mapping were disabled. | |
1198 | </para> | |
1199 | <para> | |
1200 | Linear filtering accesses the four nearest texture elements only in 2D | |
1201 | textures. In 1D textures, linear filtering accesses the two nearest | |
1202 | texture elements. | |
1203 | </para> | |
1204 | <para> | |
1205 | For OpenGL versions 1.3 and greater, or when the <code>ARB_multitexture</code> extension is supported, <function>glTexParameter</function> | |
1206 | specifies the texture parameters for the active texture unit, specified | |
1207 | by calling <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>. | |
1208 | </para> | |
1209 | </refsect1> | |
1210 | <refsect1 id="errors"><title>Errors</title> | |
1211 | <para> | |
1212 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> or <parameter>pname</parameter> is not | |
1213 | one of the accepted defined values. | |
1214 | </para> | |
1215 | <para> | |
1216 | <constant>GL_INVALID_ENUM</constant> is generated if <parameter>params</parameter> should have a defined | |
1217 | constant value (based on the value of <parameter>pname</parameter>) and does not. | |
1218 | </para> | |
1219 | <para> | |
1220 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glTexParameter</function> is executed between the | |
1221 | execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
1222 | </para> | |
1223 | </refsect1> | |
1224 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
1225 | <para> | |
1226 | <citerefentry><refentrytitle>glGetTexParameter</refentrytitle></citerefentry> | |
1227 | </para> | |
1228 | <para> | |
1229 | <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry> | |
1230 | </para> | |
1231 | </refsect1> | |
1232 | <refsect1 id="seealso"><title>See Also</title> | |
1233 | <para> | |
1234 | <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>, | |
1235 | <citerefentry><refentrytitle>glBindTexture</refentrytitle></citerefentry>, | |
1236 | <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>, | |
1237 | <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, | |
1238 | <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>, | |
1239 | <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>, | |
1240 | <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>, | |
1241 | <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>, | |
1242 | <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>, | |
1243 | <citerefentry><refentrytitle>glPixelStore</refentrytitle></citerefentry>, | |
1244 | <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>, | |
1245 | <citerefentry><refentrytitle>glPrioritizeTextures</refentrytitle></citerefentry>, | |
1246 | <citerefentry><refentrytitle>glTexEnv</refentrytitle></citerefentry>, | |
1247 | <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry>, | |
1248 | <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, | |
1249 | <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>, | |
1250 | <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>, | |
1251 | <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>, | |
1252 | <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>, | |
1253 | <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry> | |
1254 | </para> | |
1255 | </refsect1> | |
1256 | <refsect1 id="Copyright"><title>Copyright</title> | |
1257 | <para> | |
1258 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
1259 | Silicon Graphics, Inc. This document is licensed under the SGI | |
1260 | Free Software B License. For details, see | |
1261 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
1262 | </para> | |
1263 | </refsect1> | |
1264 | </refentry> |