HCoop / clinton / guile-figl.git / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
history | raw | HEAD
rename upstream-man-pages to upstream-doc
[clinton/guile-figl.git] / upstream-doc / man4 / glTexParameter.xml
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>, <constant>GL_TEXTURE_1D_ARRAY</constant>,
47 <constant>GL_TEXTURE_2D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>,
48 or <constant>GL_TEXTURE_CUBE_MAP</constant>.
49 </para>
50 </listitem>
51 </varlistentry>
52 <varlistentry>
53 <term><parameter>pname</parameter></term>
54 <listitem>
55 <para>
56 Specifies the symbolic name of a single-valued texture parameter.
57 <parameter>pname</parameter> can be one of the following:
58 <constant>GL_DEPTH_STENCIL_TEXTURE_MODE</constant>,
59 <constant>GL_TEXTURE_BASE_LEVEL</constant>,
60 <constant>GL_TEXTURE_COMPARE_FUNC</constant>,
61 <constant>GL_TEXTURE_COMPARE_MODE</constant>,
62 <constant>GL_TEXTURE_LOD_BIAS</constant>,
63 <constant>GL_TEXTURE_MIN_FILTER</constant>,
64 <constant>GL_TEXTURE_MAG_FILTER</constant>,
65 <constant>GL_TEXTURE_MIN_LOD</constant>,
66 <constant>GL_TEXTURE_MAX_LOD</constant>,
67 <constant>GL_TEXTURE_MAX_LEVEL</constant>,
68 <constant>GL_TEXTURE_SWIZZLE_R</constant>,
69 <constant>GL_TEXTURE_SWIZZLE_G</constant>,
70 <constant>GL_TEXTURE_SWIZZLE_B</constant>,
71 <constant>GL_TEXTURE_SWIZZLE_A</constant>,
72 <constant>GL_TEXTURE_WRAP_S</constant>,
73 <constant>GL_TEXTURE_WRAP_T</constant>, or
74 <constant>GL_TEXTURE_WRAP_R</constant>.
75 </para>
76 </listitem>
77 </varlistentry>
78 <varlistentry>
79 <term><parameter>param</parameter></term>
80 <listitem>
81 <para>
82 Specifies the value of <parameter>pname</parameter>.
83 </para>
84 </listitem>
85 </varlistentry>
86 </variablelist>
87 </refsect1>
88 <refsynopsisdiv><title>C Specification</title>
89 <funcsynopsis>
90 <funcprototype>
91 <funcdef>void <function>glTexParameterfv</function></funcdef>
92 <paramdef>GLenum <parameter>target</parameter></paramdef>
93 <paramdef>GLenum <parameter>pname</parameter></paramdef>
94 <paramdef>const GLfloat * <parameter>params</parameter></paramdef>
95 </funcprototype>
96 </funcsynopsis>
97 <funcsynopsis>
98 <funcprototype>
99 <funcdef>void <function>glTexParameteriv</function></funcdef>
100 <paramdef>GLenum <parameter>target</parameter></paramdef>
101 <paramdef>GLenum <parameter>pname</parameter></paramdef>
102 <paramdef>const GLint * <parameter>params</parameter></paramdef>
103 </funcprototype>
104 </funcsynopsis>
105 <funcsynopsis>
106 <funcprototype>
107 <funcdef>void <function>glTexParameterIiv</function></funcdef>
108 <paramdef>GLenum <parameter>target</parameter></paramdef>
109 <paramdef>GLenum <parameter>pname</parameter></paramdef>
110 <paramdef>const GLint * <parameter>params</parameter></paramdef>
111 </funcprototype>
112 </funcsynopsis>
113 <funcsynopsis>
114 <funcprototype>
115 <funcdef>void <function>glTexParameterIuiv</function></funcdef>
116 <paramdef>GLenum <parameter>target</parameter></paramdef>
117 <paramdef>GLenum <parameter>pname</parameter></paramdef>
118 <paramdef>const GLuint * <parameter>params</parameter></paramdef>
119 </funcprototype>
120 </funcsynopsis>
121 </refsynopsisdiv>
122 <refsect1 id="parameters2"><title>Parameters</title>
123 <variablelist>
124 <varlistentry>
125 <term><parameter>target</parameter></term>
126 <listitem>
127 <para>
128 Specifies the target texture,
129 which must be either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>,
130 <constant>GL_TEXTURE_3D</constant>, <constant>GL_TEXTURE_1D_ARRAY</constant>,
131 <constant>GL_TEXTURE_2D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>,
132 or <constant>GL_TEXTURE_CUBE_MAP</constant>.
133 </para>
134 </listitem>
135 </varlistentry>
136 <varlistentry>
137 <term><parameter>pname</parameter></term>
138 <listitem>
139 <para>
140 Specifies the symbolic name of a texture parameter.
141 <parameter>pname</parameter> can be one of the following:
142 <constant>GL_DEPTH_STENCIL_TEXTURE_MODE</constant>,
143 <constant>GL_TEXTURE_BASE_LEVEL</constant>,
144 <constant>GL_TEXTURE_BORDER_COLOR</constant>,
145 <constant>GL_TEXTURE_COMPARE_FUNC</constant>,
146 <constant>GL_TEXTURE_COMPARE_MODE</constant>,
147 <constant>GL_TEXTURE_LOD_BIAS</constant>,
148 <constant>GL_TEXTURE_MIN_FILTER</constant>,
149 <constant>GL_TEXTURE_MAG_FILTER</constant>,
150 <constant>GL_TEXTURE_MIN_LOD</constant>,
151 <constant>GL_TEXTURE_MAX_LOD</constant>,
152 <constant>GL_TEXTURE_MAX_LEVEL</constant>,
153 <constant>GL_TEXTURE_SWIZZLE_R</constant>,
154 <constant>GL_TEXTURE_SWIZZLE_G</constant>,
155 <constant>GL_TEXTURE_SWIZZLE_B</constant>,
156 <constant>GL_TEXTURE_SWIZZLE_A</constant>,
157 <constant>GL_TEXTURE_SWIZZLE_RGBA</constant>,
158 <constant>GL_TEXTURE_WRAP_S</constant>,
159 <constant>GL_TEXTURE_WRAP_T</constant>, or
160 <constant>GL_TEXTURE_WRAP_R</constant>.
161 </para>
162 </listitem>
163 </varlistentry>
164 <varlistentry>
165 <term><parameter>params</parameter></term>
166 <listitem>
167 <para>
168 Specifies a pointer to an array where the value or values of <parameter>pname</parameter>
169 are stored.
170 </para>
171 </listitem>
172 </varlistentry>
173 </variablelist>
174 </refsect1>
175 <refsect1 id="description"><title>Description</title>
176 <para>
177 <function>glTexParameter</function> assigns the value or values in <parameter>params</parameter> to the texture parameter
178 specified as <parameter>pname</parameter>.
179 <parameter>target</parameter> defines the target texture,
180 either <constant>GL_TEXTURE_1D</constant>, <constant>GL_TEXTURE_2D</constant>, <constant>GL_TEXTURE_1D_ARRAY</constant>,
181 <constant>GL_TEXTURE_2D_ARRAY</constant>, <constant>GL_TEXTURE_RECTANGLE</constant>, or <constant>GL_TEXTURE_3D</constant>.
182 The following symbols are accepted in <parameter>pname</parameter>:
183 </para>
184 <variablelist>
185 <varlistentry>
186 <term><constant>GL_DEPTH_STENCIL_TEXTURE_MODE</constant></term>
187 <listitem>
188 <para>
189 Specifies the mode used to read from depth-stencil format textures. <parameter>params</parameter>
190 must be one of <constant>GL_DEPTH_COMPONENT</constant> or <constant>GL_STENCIL_COMPONENT</constant>.
191 If the depth stencil mode is <constant>GL_DEPTH_COMPONENT</constant>, then reads from depth-stencil
192 format textures will return the depth component of the texel in
193 <inlineequation><mml:math><mml:msub><mml:mi>R</mml:mi><mml:mi>t</mml:mi></mml:msub></mml:math></inlineequation> and the stencil component
194 will be discarded. If the depth stencil mode is <constant>GL_STENCIL_COMPONENT</constant> then
195 the stencil component is returned in <inlineequation><mml:math><mml:msub><mml:mi>R</mml:mi><mml:mi>t</mml:mi></mml:msub></mml:math></inlineequation>
196 and the depth component is discarded. The initial value is <constant>GL_DEPTH_COMPONENT</constant>.
197 </para>
198 </listitem>
199 </varlistentry>
200 </variablelist>
201 <variablelist>
202 <varlistentry>
203 <term><constant>GL_TEXTURE_BASE_LEVEL</constant></term>
204 <listitem>
205 <para>
206 Specifies the index of the lowest defined mipmap level. This is an
207 integer value. The initial value is 0.
208 </para>
209 </listitem>
210 </varlistentry>
211 </variablelist>
212 <para>
213 </para>
214 <variablelist>
215 <varlistentry>
216 <term><constant>GL_TEXTURE_BORDER_COLOR</constant></term>
217 <listitem>
218 <para>
219 The data in <parameter>params</parameter> specifies four values that define the border values that
220 should be used for border texels. If a texel is sampled from the border of the texture, the
221 values of <constant>GL_TEXTURE_BORDER_COLOR</constant> are interpreted as an RGBA color to match the
222 texture's internal format and substituted for the non-existent texel data. If the texture contains depth
223 components, the first component of <constant>GL_TEXTURE_BORDER_COLOR</constant> is interpreted as a depth value.
224 The initial value is
225 <inlineequation><mml:math>
226 <mml:mrow>
227 <mml:mfenced open="(" close=")">
228 <mml:mrow>
229 0.0, 0.0, 0.0, 0.0
230 </mml:mrow>
231 </mml:mfenced>
232 </mml:mrow>
233 </mml:math></inlineequation>.
234 </para>
235 <para>
236 If the values for <constant>GL_TEXTURE_BORDER_COLOR</constant> are specified with <function>glTexParameterIiv</function>
237 or <function>glTexParameterIuiv</function>, the values are stored unmodified with an internal data type of
238 integer. If specified with <function>glTexParameteriv</function>, they are converted to floating point with the following
239 equation:
240 <inlineequation><mml:math>
241 <mml:mrow>
242 <mml:mi mathvariant="italic">f</mml:mi>
243 <mml:mo>=</mml:mo>
244 <mml:mfrac>
245 <mml:mrow>
246 <mml:msub><mml:mn>2</mml:mn>
247 <mml:mi mathvariant="italic">c</mml:mi>
248 </mml:msub>
249 <mml:mo>+</mml:mo>
250 <mml:mn>1</mml:mn>
251 </mml:mrow>
252 <mml:mrow>
253 <mml:msup><mml:mn>2</mml:mn>
254 <mml:mi mathvariant="italic">b</mml:mi>
255 </mml:msup>
256 <mml:mo>-</mml:mo>
257 <mml:mn>1</mml:mn>
258 </mml:mrow>
259 </mml:mfrac>
260 </mml:mrow>
261 </mml:math></inlineequation>.
262 If specified with <function>glTexParameterfv</function>, they are stored unmodified as floating-point values.
263 </para>
264 </listitem>
265 </varlistentry>
266 <varlistentry>
267 <term><constant>GL_TEXTURE_COMPARE_FUNC</constant></term>
268 <listitem>
269 <para>
270 Specifies the comparison operator used when <constant>GL_TEXTURE_COMPARE_MODE</constant> is
271 set to <constant>GL_COMPARE_REF_TO_TEXTURE</constant>. Permissible values are:
272 <informaltable frame="topbot">
273 <tgroup cols="2" align="left">
274 <colspec/>
275 <colspec/>
276 <thead>
277 <row>
278 <entry rowsep="1" align="left"><emphasis role="bold">
279 Texture Comparison Function
280 </emphasis></entry>
281 <entry rowsep="1" align="left"><emphasis role="bold">
282 Computed result
283 </emphasis></entry>
284 </row>
285 </thead>
286 <tbody>
287 <row>
288 <entry align="left">
289 <constant>GL_LEQUAL</constant>
290 </entry>
291 <entry align="left">
292 <informalequation><mml:math>
293 <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
294 <mml:mrow>
295 <mml:mi mathvariant="italic">result</mml:mi>
296 <mml:mo>=</mml:mo>
297 <mml:mfenced open="{" close="">
298 <mml:mrow>
299 <mml:mtable>
300 <mml:mtr><mml:mtd>
301 <mml:mn>1.0</mml:mn>
302 </mml:mtd></mml:mtr>
303 <mml:mtr><mml:mtd>
304 <mml:mn>0.0</mml:mn>
305 </mml:mtd></mml:mtr>
306 </mml:mtable>
307 <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
308 <mml:mtable>
309 <mml:mtr><mml:mtd>
310 <mml:mrow>
311 <mml:mi mathvariant="italic">r</mml:mi>
312 <mml:mo>&lt;=</mml:mo>
313 <mml:mfenced open="" close="">
314 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
315 <mml:mi mathvariant="italic">t</mml:mi>
316 </mml:msub>
317 </mml:mfenced>
318 </mml:mrow>
319 </mml:mtd></mml:mtr>
320 <mml:mtr><mml:mtd>
321 <mml:mrow>
322 <mml:mi mathvariant="italic">r</mml:mi>
323 <mml:mo>&gt;</mml:mo>
324 <mml:mfenced open="" close="">
325 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
326 <mml:mi mathvariant="italic">t</mml:mi>
327 </mml:msub>
328 </mml:mfenced>
329 </mml:mrow>
330 </mml:mtd></mml:mtr>
331 </mml:mtable>
332 </mml:mrow>
333 </mml:mfenced>
334 </mml:mrow>
335 </mml:math></informalequation>
336 </entry>
337 </row>
338 <row>
339 <entry align="left">
340 <constant>GL_GEQUAL</constant>
341 </entry>
342 <entry align="left">
343 <informalequation><mml:math>
344 <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
345 <mml:mrow>
346 <mml:mi mathvariant="italic">result</mml:mi>
347 <mml:mo>=</mml:mo>
348 <mml:mfenced open="{" close="">
349 <mml:mrow>
350 <mml:mtable>
351 <mml:mtr><mml:mtd>
352 <mml:mn>1.0</mml:mn>
353 </mml:mtd></mml:mtr>
354 <mml:mtr><mml:mtd>
355 <mml:mn>0.0</mml:mn>
356 </mml:mtd></mml:mtr>
357 </mml:mtable>
358 <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
359 <mml:mtable>
360 <mml:mtr><mml:mtd>
361 <mml:mrow>
362 <mml:mi mathvariant="italic">r</mml:mi>
363 <mml:mo>&gt;=</mml:mo>
364 <mml:mfenced open="" close="">
365 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
366 <mml:mi mathvariant="italic">t</mml:mi>
367 </mml:msub>
368 </mml:mfenced>
369 </mml:mrow>
370 </mml:mtd></mml:mtr>
371 <mml:mtr><mml:mtd>
372 <mml:mrow>
373 <mml:mi mathvariant="italic">r</mml:mi>
374 <mml:mo>&lt;</mml:mo>
375 <mml:mfenced open="" close="">
376 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
377 <mml:mi mathvariant="italic">t</mml:mi>
378 </mml:msub>
379 </mml:mfenced>
380 </mml:mrow>
381 </mml:mtd></mml:mtr>
382 </mml:mtable>
383 </mml:mrow>
384 </mml:mfenced>
385 </mml:mrow>
386 </mml:math></informalequation>
387 </entry>
388 </row>
389 <row>
390 <entry align="left">
391 <constant>GL_LESS</constant>
392 </entry>
393 <entry align="left">
394 <informalequation><mml:math>
395 <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
396 <mml:mrow>
397 <mml:mi mathvariant="italic">result</mml:mi>
398 <mml:mo>=</mml:mo>
399 <mml:mfenced open="{" close="">
400 <mml:mrow>
401 <mml:mtable>
402 <mml:mtr><mml:mtd>
403 <mml:mn>1.0</mml:mn>
404 </mml:mtd></mml:mtr>
405 <mml:mtr><mml:mtd>
406 <mml:mn>0.0</mml:mn>
407 </mml:mtd></mml:mtr>
408 </mml:mtable>
409 <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
410 <mml:mtable>
411 <mml:mtr><mml:mtd>
412 <mml:mrow>
413 <mml:mi mathvariant="italic">r</mml:mi>
414 <mml:mo>&lt;</mml:mo>
415 <mml:mfenced open="" close="">
416 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
417 <mml:mi mathvariant="italic">t</mml:mi>
418 </mml:msub>
419 </mml:mfenced>
420 </mml:mrow>
421 </mml:mtd></mml:mtr>
422 <mml:mtr><mml:mtd>
423 <mml:mrow>
424 <mml:mi mathvariant="italic">r</mml:mi>
425 <mml:mo>&gt;=</mml:mo>
426 <mml:mfenced open="" close="">
427 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
428 <mml:mi mathvariant="italic">t</mml:mi>
429 </mml:msub>
430 </mml:mfenced>
431 </mml:mrow>
432 </mml:mtd></mml:mtr>
433 </mml:mtable>
434 </mml:mrow>
435 </mml:mfenced>
436 </mml:mrow>
437 </mml:math></informalequation>
438 </entry>
439 </row>
440 <row>
441 <entry align="left">
442 <constant>GL_GREATER</constant>
443 </entry>
444 <entry align="left">
445 <informalequation><mml:math>
446 <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
447 <mml:mrow>
448 <mml:mi mathvariant="italic">result</mml:mi>
449 <mml:mo>=</mml:mo>
450 <mml:mfenced open="{" close="">
451 <mml:mrow>
452 <mml:mtable>
453 <mml:mtr><mml:mtd>
454 <mml:mn>1.0</mml:mn>
455 </mml:mtd></mml:mtr>
456 <mml:mtr><mml:mtd>
457 <mml:mn>0.0</mml:mn>
458 </mml:mtd></mml:mtr>
459 </mml:mtable>
460 <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
461 <mml:mtable>
462 <mml:mtr><mml:mtd>
463 <mml:mrow>
464 <mml:mi mathvariant="italic">r</mml:mi>
465 <mml:mo>&gt;</mml:mo>
466 <mml:mfenced open="" close="">
467 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
468 <mml:mi mathvariant="italic">t</mml:mi>
469 </mml:msub>
470 </mml:mfenced>
471 </mml:mrow>
472 </mml:mtd></mml:mtr>
473 <mml:mtr><mml:mtd>
474 <mml:mrow>
475 <mml:mi mathvariant="italic">r</mml:mi>
476 <mml:mo>&lt;=</mml:mo>
477 <mml:mfenced open="" close="">
478 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
479 <mml:mi mathvariant="italic">t</mml:mi>
480 </mml:msub>
481 </mml:mfenced>
482 </mml:mrow>
483 </mml:mtd></mml:mtr>
484 </mml:mtable>
485 </mml:mrow>
486 </mml:mfenced>
487 </mml:mrow>
488 </mml:math></informalequation>
489 </entry>
490 </row>
491 <row>
492 <entry align="left">
493 <constant>GL_EQUAL</constant>
494 </entry>
495 <entry align="left">
496 <informalequation><mml:math>
497 <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
498 <mml:mrow>
499 <mml:mi mathvariant="italic">result</mml:mi>
500 <mml:mo>=</mml:mo>
501 <mml:mfenced open="{" close="">
502 <mml:mrow>
503 <mml:mtable>
504 <mml:mtr><mml:mtd>
505 <mml:mn>1.0</mml:mn>
506 </mml:mtd></mml:mtr>
507 <mml:mtr><mml:mtd>
508 <mml:mn>0.0</mml:mn>
509 </mml:mtd></mml:mtr>
510 </mml:mtable>
511 <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
512 <mml:mtable>
513 <mml:mtr><mml:mtd>
514 <mml:mrow>
515 <mml:mi mathvariant="italic">r</mml:mi>
516 <mml:mo>=</mml:mo>
517 <mml:mfenced open="" close="">
518 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
519 <mml:mi mathvariant="italic">t</mml:mi>
520 </mml:msub>
521 </mml:mfenced>
522 </mml:mrow>
523 </mml:mtd></mml:mtr>
524 <mml:mtr><mml:mtd>
525 <mml:mrow>
526 <mml:mi mathvariant="italic">r</mml:mi>
527 <mml:mo>&ne;</mml:mo>
528 <mml:mfenced open="" close="">
529 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
530 <mml:mi mathvariant="italic">t</mml:mi>
531 </mml:msub>
532 </mml:mfenced>
533 </mml:mrow>
534 </mml:mtd></mml:mtr>
535 </mml:mtable>
536 </mml:mrow>
537 </mml:mfenced>
538 </mml:mrow>
539 </mml:math></informalequation>
540 </entry>
541 </row>
542 <row>
543 <entry align="left">
544 <constant>GL_NOTEQUAL</constant>
545 </entry>
546 <entry align="left">
547 <informalequation><mml:math>
548 <!-- eqn: result = left { cpile {1.0 above 0.0} lpile {r <= {D sub t} above r > {D sub t}}: -->
549 <mml:mrow>
550 <mml:mi mathvariant="italic">result</mml:mi>
551 <mml:mo>=</mml:mo>
552 <mml:mfenced open="{" close="">
553 <mml:mrow>
554 <mml:mtable>
555 <mml:mtr><mml:mtd>
556 <mml:mn>1.0</mml:mn>
557 </mml:mtd></mml:mtr>
558 <mml:mtr><mml:mtd>
559 <mml:mn>0.0</mml:mn>
560 </mml:mtd></mml:mtr>
561 </mml:mtable>
562 <mml:mo>&it;&nbsp;&nbsp;</mml:mo>
563 <mml:mtable>
564 <mml:mtr><mml:mtd>
565 <mml:mrow>
566 <mml:mi mathvariant="italic">r</mml:mi>
567 <mml:mo>&ne;</mml:mo>
568 <mml:mfenced open="" close="">
569 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
570 <mml:mi mathvariant="italic">t</mml:mi>
571 </mml:msub>
572 </mml:mfenced>
573 </mml:mrow>
574 </mml:mtd></mml:mtr>
575 <mml:mtr><mml:mtd>
576 <mml:mrow>
577 <mml:mi mathvariant="italic">r</mml:mi>
578 <mml:mo>=</mml:mo>
579 <mml:mfenced open="" close="">
580 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
581 <mml:mi mathvariant="italic">t</mml:mi>
582 </mml:msub>
583 </mml:mfenced>
584 </mml:mrow>
585 </mml:mtd></mml:mtr>
586 </mml:mtable>
587 </mml:mrow>
588 </mml:mfenced>
589 </mml:mrow>
590 </mml:math></informalequation>
591 </entry>
592 </row>
593 <row>
594 <entry align="left">
595 <constant>GL_ALWAYS</constant>
596 </entry>
597 <entry align="left">
598 <informalequation>
599 <mml:math>
600 <mml:mrow>
601 <mml:mi mathvariant="italic">result</mml:mi>
602 <mml:mo>=</mml:mo>
603 <mml:mi>1.0</mml:mi>
604 </mml:mrow>
605 </mml:math>
606 </informalequation>
607 </entry>
608 </row>
609 <row>
610 <entry align="left">
611 <constant>GL_NEVER</constant>
612 </entry>
613 <entry align="left">
614 <informalequation>
615 <mml:math>
616 <mml:mrow>
617 <mml:mi mathvariant="italic">result</mml:mi>
618 <mml:mo>=</mml:mo>
619 <mml:mi>0.0</mml:mi>
620 </mml:mrow>
621 </mml:math>
622 </informalequation>
623 </entry>
624 </row>
625 </tbody>
626 </tgroup>
627 </informaltable>
628 where <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
629 is the current interpolated texture coordinate, and
630 <inlineequation><mml:math>
631 <!-- eqn: D sub t: -->
632 <mml:msub><mml:mi mathvariant="italic">D</mml:mi>
633 <mml:mi mathvariant="italic">t</mml:mi>
634 </mml:msub>
635 </mml:math></inlineequation>
636 is the depth texture value sampled from the currently bound depth texture.
637 <inlineequation><mml:math><mml:mi mathvariant="italic">result</mml:mi></mml:math></inlineequation>
638 is assigned to the the red channel.
639 </para>
640 </listitem>
641 </varlistentry>
642 <varlistentry>
643 <term><constant>GL_TEXTURE_COMPARE_MODE</constant></term>
644 <listitem>
645 <para>
646 Specifies the texture comparison mode for currently bound depth textures.
647 That is, a texture whose internal format is <constant>GL_DEPTH_COMPONENT_*</constant>; see
648 <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>)
649 Permissible values are:
650 <variablelist>
651 <varlistentry>
652 <term><constant>GL_COMPARE_REF_TO_TEXTURE</constant></term>
653 <listitem>
654 <para>
655 Specifies that the interpolated and clamped
656 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
657 texture coordinate should
658 be compared to the value in the currently bound depth texture. See the
659 discussion of <constant>GL_TEXTURE_COMPARE_FUNC</constant> for details of how the comparison
660 is evaluated. The result of the comparison is assigned to the red channel.
661 </para>
662 </listitem>
663 </varlistentry>
664 <varlistentry>
665 <term><constant>GL_NONE</constant></term>
666 <listitem>
667 <para>
668 Specifies that the red channel should be assigned the
669 appropriate value from the currently bound depth texture.
670 </para>
671 </listitem>
672 </varlistentry>
673 </variablelist>
674 </para>
675 </listitem>
676 </varlistentry>
677 <varlistentry>
678 <term><constant>GL_TEXTURE_LOD_BIAS</constant></term>
679 <listitem>
680 <para>
681 <parameter>params</parameter> specifies a fixed bias value that is to be added to the level-of-detail
682 parameter for the texture before texture sampling. The specified value is added to the shader-supplied
683 bias value (if any) and subsequently clamped into the implementation-defined range
684 <inlineequation><mml:math>
685 <mml:mfenced open="[" close="]">
686 <mml:mfenced open="" close="">
687 <mml:mrow>
688 -
689 <mml:msub><mml:mi mathvariant="italic">bias</mml:mi>
690 <mml:mi mathvariant="italic">max</mml:mi>
691 </mml:msub>
692 </mml:mrow>
693 </mml:mfenced>
694 <mml:mrow>
695 <mml:mfenced open="" close="">
696 <mml:mrow>
697 <mml:msub><mml:mi mathvariant="italic">bias</mml:mi>
698 <mml:mi mathvariant="italic">max</mml:mi>
699 </mml:msub>
700 </mml:mrow>
701 </mml:mfenced>
702 </mml:mrow>
703 </mml:mfenced>
704 </mml:math></inlineequation>,
705 where
706 <inlineequation><mml:math>
707 <mml:mrow>
708 <mml:msub><mml:mi mathvariant="italic">bias</mml:mi>
709 <mml:mi mathvariant="italic">max</mml:mi>
710 </mml:msub>
711 </mml:mrow>
712 </mml:math></inlineequation>
713 is the value of the implementation defined constant <constant>GL_MAX_TEXTURE_LOD_BIAS</constant>. The initial value is 0.0.
714 </para>
715 </listitem>
716 </varlistentry>
717 <varlistentry>
718 <term><constant>GL_TEXTURE_MIN_FILTER</constant></term>
719 <listitem>
720 <para>
721 The texture minifying function is used whenever the level-of-detail function
722 used when sampling from the texture determines that the texture should be minified.
723 There are six defined minifying functions.
724 Two of them use either the nearest texture elements or a weighted average of multiple texture elements
725 to compute the texture value.
726 The other four use mipmaps.
727 </para>
728 <para>
729 A mipmap is an ordered set of arrays representing the same image
730 at progressively lower resolutions.
731 If the texture has dimensions
732 <inlineequation><mml:math>
733 <!-- eqn: 2 sup n times 2 sup m: -->
734 <mml:mrow>
735 <mml:msup><mml:mn>2</mml:mn>
736 <mml:mi mathvariant="italic">n</mml:mi>
737 </mml:msup>
738 <mml:mo>&times;</mml:mo>
739 <mml:msup><mml:mn>2</mml:mn>
740 <mml:mi mathvariant="italic">m</mml:mi>
741 </mml:msup>
742 </mml:mrow>
743 </mml:math></inlineequation>,
744 there are
745 <inlineequation><mml:math>
746 <!-- eqn: max ( n, m ) + 1: -->
747 <mml:mrow>
748 <mml:mrow>
749 <mml:mi mathvariant="italic">max</mml:mi>
750 <mml:mo>&af;</mml:mo>
751 <mml:mfenced open="(" close=")">
752 <mml:mi mathvariant="italic">n</mml:mi>
753 <mml:mi mathvariant="italic">m</mml:mi>
754 </mml:mfenced>
755 </mml:mrow>
756 <mml:mo>+</mml:mo>
757 <mml:mn>1</mml:mn>
758 </mml:mrow>
759 </mml:math></inlineequation>
760 mipmaps.
761 The first mipmap is the original texture,
762 with dimensions
763 <inlineequation><mml:math>
764 <!-- eqn: 2 sup n times 2 sup m: -->
765 <mml:mrow>
766 <mml:msup><mml:mn>2</mml:mn>
767 <mml:mi mathvariant="italic">n</mml:mi>
768 </mml:msup>
769 <mml:mo>&times;</mml:mo>
770 <mml:msup><mml:mn>2</mml:mn>
771 <mml:mi mathvariant="italic">m</mml:mi>
772 </mml:msup>
773 </mml:mrow>
774 </mml:math></inlineequation>.
775 Each subsequent mipmap has dimensions
776 <inlineequation><mml:math>
777 <!-- eqn: 2 sup { k - 1 } times 2 sup { l - 1 }: -->
778 <mml:mrow>
779 <mml:msup><mml:mn>2</mml:mn>
780 <mml:mfenced open="" close="">
781 <mml:mrow>
782 <mml:mi mathvariant="italic">k</mml:mi>
783 <mml:mo>-</mml:mo>
784 <mml:mn>1</mml:mn>
785 </mml:mrow>
786 </mml:mfenced>
787 </mml:msup>
788 <mml:mo>&times;</mml:mo>
789 <mml:msup><mml:mn>2</mml:mn>
790 <mml:mfenced open="" close="">
791 <mml:mrow>
792 <mml:mi mathvariant="italic">l</mml:mi>
793 <mml:mo>-</mml:mo>
794 <mml:mn>1</mml:mn>
795 </mml:mrow>
796 </mml:mfenced>
797 </mml:msup>
798 </mml:mrow>
799 </mml:math></inlineequation>,
800 where
801 <inlineequation><mml:math>
802 <!-- eqn: 2 sup k times 2 sup l: -->
803 <mml:mrow>
804 <mml:msup><mml:mn>2</mml:mn>
805 <mml:mi mathvariant="italic">k</mml:mi>
806 </mml:msup>
807 <mml:mo>&times;</mml:mo>
808 <mml:msup><mml:mn>2</mml:mn>
809 <mml:mi mathvariant="italic">l</mml:mi>
810 </mml:msup>
811 </mml:mrow>
812 </mml:math></inlineequation>
813 are the dimensions of the previous mipmap,
814 until either
815 <inlineequation><mml:math>
816 <!-- eqn: k = 0: -->
817 <mml:mrow>
818 <mml:mi mathvariant="italic">k</mml:mi>
819 <mml:mo>=</mml:mo>
820 <mml:mn>0</mml:mn>
821 </mml:mrow>
822 </mml:math></inlineequation>
823 or
824 <inlineequation><mml:math>
825 <!-- eqn: l = 0: -->
826 <mml:mrow>
827 <mml:mi mathvariant="italic">l</mml:mi>
828 <mml:mo>=</mml:mo>
829 <mml:mn>0</mml:mn>
830 </mml:mrow>
831 </mml:math></inlineequation>.
832 At that point,
833 subsequent mipmaps have dimension
834 <inlineequation><mml:math>
835 <!-- eqn: 1 times 2 sup { l - 1 }: -->
836 <mml:mrow>
837 <mml:mn>1</mml:mn>
838 <mml:mo>&times;</mml:mo>
839 <mml:msup><mml:mn>2</mml:mn>
840 <mml:mfenced open="" close="">
841 <mml:mrow>
842 <mml:mi mathvariant="italic">l</mml:mi>
843 <mml:mo>-</mml:mo>
844 <mml:mn>1</mml:mn>
845 </mml:mrow>
846 </mml:mfenced>
847 </mml:msup>
848 </mml:mrow>
849 </mml:math></inlineequation>
850 or
851 <inlineequation><mml:math>
852 <!-- eqn: 2 sup { k - 1} times 1: -->
853 <mml:mrow>
854 <mml:msup><mml:mn>2</mml:mn>
855 <mml:mfenced open="" close="">
856 <mml:mrow>
857 <mml:mi mathvariant="italic">k</mml:mi>
858 <mml:mo>-</mml:mo>
859 <mml:mn>1</mml:mn>
860 </mml:mrow>
861 </mml:mfenced>
862 </mml:msup>
863 <mml:mo>&times;</mml:mo>
864 <mml:mn>1</mml:mn>
865 </mml:mrow>
866 </mml:math></inlineequation>
867 until the final mipmap,
868 which has dimension
869 <inlineequation><mml:math>
870 <!-- eqn: 1 times 1: -->
871 <mml:mrow>
872 <mml:mn>1</mml:mn>
873 <mml:mo>&times;</mml:mo>
874 <mml:mn>1</mml:mn>
875 </mml:mrow>
876 </mml:math></inlineequation>.
877 To define the mipmaps, call <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
878 <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
879 <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>
880 with the <emphasis>level</emphasis> argument indicating the order of the mipmaps.
881 Level 0 is the original texture;
882 level
883 <inlineequation><mml:math>
884 <!-- eqn: max ( n, m ): -->
885 <mml:mrow>
886 <mml:mi mathvariant="italic">max</mml:mi>
887 <mml:mo>&af;</mml:mo>
888 <mml:mfenced open="(" close=")">
889 <mml:mi mathvariant="italic">n</mml:mi>
890 <mml:mi mathvariant="italic">m</mml:mi>
891 </mml:mfenced>
892 </mml:mrow>
893 </mml:math></inlineequation>
894 is the final
895 <inlineequation><mml:math>
896 <!-- eqn: 1 times 1: -->
897 <mml:mrow>
898 <mml:mn>1</mml:mn>
899 <mml:mo>&times;</mml:mo>
900 <mml:mn>1</mml:mn>
901 </mml:mrow>
902 </mml:math></inlineequation>
903 mipmap.
904 </para>
905 <para>
906 <parameter>params</parameter> supplies a function for minifying the texture as one of the
907 following:
908 <variablelist>
909 <varlistentry>
910 <term><constant>GL_NEAREST</constant></term>
911 <listitem>
912 <para>
913 Returns the value of the texture element that is nearest
914 (in Manhattan distance)
915 to the specified texture coordinates.
916 </para>
917 </listitem>
918 </varlistentry>
919 <varlistentry>
920 <term><constant>GL_LINEAR</constant></term>
921 <listitem>
922 <para>
923 Returns the weighted average of the four texture elements
924 that are closest to the specified texture coordinates.
925 These can include items wrapped or repeated from other parts of a texture,
926 depending on the values of <constant>GL_TEXTURE_WRAP_S</constant> and <constant>GL_TEXTURE_WRAP_T</constant>,
927 and on the exact mapping.
928 </para>
929 </listitem>
930 </varlistentry>
931 <varlistentry>
932 <term><constant>GL_NEAREST_MIPMAP_NEAREST</constant></term>
933 <listitem>
934 <para>
935 Chooses the mipmap that most closely matches the size of the pixel
936 being textured and uses the <constant>GL_NEAREST</constant> criterion
937 (the texture element closest to the specified texture coordinates)
938 to produce a texture value.
939 </para>
940 </listitem>
941 </varlistentry>
942 <varlistentry>
943 <term><constant>GL_LINEAR_MIPMAP_NEAREST</constant></term>
944 <listitem>
945 <para>
946 Chooses the mipmap that most closely matches the size of the pixel
947 being textured and uses the <constant>GL_LINEAR</constant> criterion
948 (a weighted average of the four texture elements that are closest to the specified texture coordinates)
949 to produce a texture value.
950 </para>
951 </listitem>
952 </varlistentry>
953 <varlistentry>
954 <term><constant>GL_NEAREST_MIPMAP_LINEAR</constant></term>
955 <listitem>
956 <para>
957 Chooses the two mipmaps that most closely match the size of the pixel
958 being textured and uses the <constant>GL_NEAREST</constant> criterion
959 (the texture element closest to the specified texture coordinates )
960 to produce a texture value from each mipmap.
961 The final texture value is a weighted average of those two values.
962 </para>
963 </listitem>
964 </varlistentry>
965 <varlistentry>
966 <term><constant>GL_LINEAR_MIPMAP_LINEAR</constant></term>
967 <listitem>
968 <para>
969 Chooses the two mipmaps that most closely match the size of the pixel
970 being textured and uses the <constant>GL_LINEAR</constant> criterion
971 (a weighted average of the texture elements that are closest to the specified texture coordinates)
972 to produce a texture value from each mipmap.
973 The final texture value is a weighted average of those two values.
974 </para>
975 </listitem>
976 </varlistentry>
977 </variablelist>
978 </para>
979 <para>
980 As more texture elements are sampled in the minification process,
981 fewer aliasing artifacts will be apparent.
982 While the <constant>GL_NEAREST</constant> and <constant>GL_LINEAR</constant> minification functions can be
983 faster than the other four,
984 they sample only one or multiple texture elements to determine the texture value
985 of the pixel being rendered and can produce moire patterns
986 or ragged transitions.
987 The initial value of <constant>GL_TEXTURE_MIN_FILTER</constant> is
988 <constant>GL_NEAREST_MIPMAP_LINEAR</constant>.
989 </para>
990 </listitem>
991 </varlistentry>
992 </variablelist>
993 <para>
994 </para>
995 <variablelist>
996 <varlistentry>
997 <term><constant>GL_TEXTURE_MAG_FILTER</constant></term>
998 <listitem>
999 <para>
1000 The texture magnification function is used whenever the level-of-detail function
1001 used when sampling from the texture determines that the texture should be magified.
1002 It sets the texture magnification function to either <constant>GL_NEAREST</constant>
1003 or <constant>GL_LINEAR</constant> (see below). <constant>GL_NEAREST</constant> is generally faster
1004 than <constant>GL_LINEAR</constant>,
1005 but it can produce textured images with sharper edges
1006 because the transition between texture elements is not as smooth.
1007 The initial value of <constant>GL_TEXTURE_MAG_FILTER</constant> is <constant>GL_LINEAR</constant>.
1008 <variablelist>
1009 <varlistentry>
1010 <term><constant>GL_NEAREST</constant></term>
1011 <listitem>
1012 <para>
1013 Returns the value of the texture element that is nearest
1014 (in Manhattan distance)
1015 to the specified texture coordinates.
1016 </para>
1017 </listitem>
1018 </varlistentry>
1019 <varlistentry>
1020 <term><constant>GL_LINEAR</constant></term>
1021 <listitem>
1022 <para>
1023 Returns the weighted average of the texture elements
1024 that are closest to the specified texture coordinates.
1025 These can include items wrapped or repeated from other parts of a texture,
1026 depending on the values of <constant>GL_TEXTURE_WRAP_S</constant> and <constant>GL_TEXTURE_WRAP_T</constant>,
1027 and on the exact mapping.
1028 </para>
1029 </listitem>
1030 </varlistentry>
1031 </variablelist>
1032 <para>
1033 </para>
1034 </para>
1035 </listitem>
1036 </varlistentry>
1037 </variablelist>
1038 <para>
1039 </para>
1040 <variablelist>
1041 <varlistentry>
1042 <term><constant>GL_TEXTURE_MIN_LOD</constant></term>
1043 <listitem>
1044 <para>
1045 Sets the minimum level-of-detail parameter. This floating-point value
1046 limits the selection of highest resolution mipmap (lowest mipmap
1047 level). The initial value is -1000.
1048 </para>
1049 </listitem>
1050 </varlistentry>
1051 </variablelist>
1052 <para>
1053 </para>
1054 <variablelist>
1055 <varlistentry>
1056 <term><constant>GL_TEXTURE_MAX_LOD</constant></term>
1057 <listitem>
1058 <para>
1059 Sets the maximum level-of-detail parameter. This floating-point value
1060 limits the selection of the lowest resolution mipmap (highest mipmap
1061 level). The initial value is 1000.
1062 </para>
1063 </listitem>
1064 </varlistentry>
1065 </variablelist>
1066 <para>
1067 </para>
1068 <variablelist>
1069 <varlistentry>
1070 <term><constant>GL_TEXTURE_MAX_LEVEL</constant></term>
1071 <listitem>
1072 <para>
1073 Sets the index of the highest defined mipmap level. This is an integer
1074 value. The initial value is 1000.
1075 </para>
1076 </listitem>
1077 </varlistentry>
1078 </variablelist>
1079 <para>
1080 </para>
1081 <variablelist>
1082 <varlistentry>
1083 <term><constant>GL_TEXTURE_SWIZZLE_R</constant></term>
1084 <listitem>
1085 <para>
1086 Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
1087 component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> are <constant>GL_RED</constant>,
1088 <constant>GL_GREEN</constant>, <constant>GL_BLUE</constant>, <constant>GL_ALPHA</constant>, <constant>GL_ZERO</constant> and
1089 <constant>GL_ONE</constant>.
1090 If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_RED</constant>, the value for
1091 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the first
1092 channel of the fetched texel.
1093 If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_GREEN</constant>, the value for
1094 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the second
1095 channel of the fetched texel.
1096 If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_BLUE</constant>, the value for
1097 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the third
1098 channel of the fetched texel.
1099 If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_ALPHA</constant>, the value for
1100 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be taken from the fourth
1101 channel of the fetched texel.
1102 If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_ZERO</constant>, the value for
1103 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be subtituted with
1104 <inlineequation><mml:math><mml:mn>0.0</mml:mn></mml:math></inlineequation>.
1105 If <constant>GL_TEXTURE_SWIZZLE_R</constant> is <constant>GL_ONE</constant>, the value for
1106 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation> will be subtituted with
1107 <inlineequation><mml:math><mml:mn>1.0</mml:mn></mml:math></inlineequation>.
1108 The initial value is <constant>GL_RED</constant>.
1109 </para>
1110 </listitem>
1111 </varlistentry>
1112 </variablelist>
1113 <para>
1114 </para>
1115 <variablelist>
1116 <varlistentry>
1117 <term><constant>GL_TEXTURE_SWIZZLE_G</constant></term>
1118 <listitem>
1119 <para>
1120 Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">g</mml:mi></mml:math></inlineequation>
1121 component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> and their effects are similar to
1122 those of <constant>GL_TEXTURE_SWIZZLE_R</constant>.
1123 The initial value is <constant>GL_GREEN</constant>.
1124 </para>
1125 </listitem>
1126 </varlistentry>
1127 </variablelist>
1128 <para>
1129 </para>
1130 <variablelist>
1131 <varlistentry>
1132 <term><constant>GL_TEXTURE_SWIZZLE_B</constant></term>
1133 <listitem>
1134 <para>
1135 Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">b</mml:mi></mml:math></inlineequation>
1136 component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> and their effects are similar to
1137 those of <constant>GL_TEXTURE_SWIZZLE_R</constant>.
1138 The initial value is <constant>GL_BLUE</constant>.
1139 </para>
1140 </listitem>
1141 </varlistentry>
1142 </variablelist>
1143 <para>
1144 </para>
1145 <variablelist>
1146 <varlistentry>
1147 <term><constant>GL_TEXTURE_SWIZZLE_A</constant></term>
1148 <listitem>
1149 <para>
1150 Sets the swizzle that will be applied to the <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
1151 component of a texel before it is returned to the shader. Valid values for <parameter>param</parameter> and their effects are similar to
1152 those of <constant>GL_TEXTURE_SWIZZLE_R</constant>.
1153 The initial value is <constant>GL_ALPHA</constant>.
1154 </para>
1155 </listitem>
1156 </varlistentry>
1157 </variablelist>
1158 <para>
1159 </para>
1160 <variablelist>
1161 <varlistentry>
1162 <term><constant>GL_TEXTURE_SWIZZLE_RGBA</constant></term>
1163 <listitem>
1164 <para>
1165 Sets the swizzles that will be applied to the
1166 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>,
1167 <inlineequation><mml:math><mml:mi mathvariant="italic">g</mml:mi></mml:math></inlineequation>,
1168 <inlineequation><mml:math><mml:mi mathvariant="italic">b</mml:mi></mml:math></inlineequation>, and
1169 <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
1170 components of a texel before they are returned to the shader. Valid values for <parameter>params</parameter> and their effects are similar to
1171 those of <constant>GL_TEXTURE_SWIZZLE_R</constant>, except that all channels are specified simultaneously.
1172 Setting the value of <constant>GL_TEXTURE_SWIZZLE_RGBA</constant> is equivalent (assuming no errors are generated) to
1173 setting the parameters of each of <constant>GL_TEXTURE_SWIZZLE_R</constant>,
1174 <constant>GL_TEXTURE_SWIZZLE_G</constant>,
1175 <constant>GL_TEXTURE_SWIZZLE_B</constant>, and
1176 <constant>GL_TEXTURE_SWIZZLE_A</constant> successively.
1177 </para>
1178 </listitem>
1179 </varlistentry>
1180 </variablelist>
1181 <para>
1182 </para>
1183 <variablelist>
1184 <varlistentry>
1185 <term><constant>GL_TEXTURE_WRAP_S</constant></term>
1186 <listitem>
1187 <para>
1188 Sets the wrap parameter for texture coordinate
1189 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1190 to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_CLAMP_TO_BORDER</constant>,
1191 <constant>GL_MIRRORED_REPEAT</constant>, or
1192 <constant>GL_REPEAT</constant>. <constant>GL_CLAMP_TO_EDGE</constant> causes
1193 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1194 coordinates to be clamped to the
1195 range
1196 <inlineequation><mml:math>
1197 <!-- eqn: left [ {1 over 2N}, 1 - {1 over 2N} right ]: -->
1198 <mml:mfenced open="[" close="]">
1199 <mml:mfenced open="" close="">
1200 <mml:mrow>
1201 <mml:mfrac>
1202 <mml:mn>1</mml:mn>
1203 <mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn>
1204 </mml:mfrac>
1205 </mml:mrow>
1206 </mml:mfenced>
1207 <mml:mrow>
1208 <mml:mn>1</mml:mn>
1209 <mml:mo>-</mml:mo>
1210 <mml:mfenced open="" close="">
1211 <mml:mrow>
1212 <mml:mfrac>
1213 <mml:mn>1</mml:mn>
1214 <mml:mn>2<mml:mi mathvariant="italic">N</mml:mi></mml:mn>
1215 </mml:mfrac>
1216 </mml:mrow>
1217 </mml:mfenced>
1218 </mml:mrow>
1219 </mml:mfenced>
1220 </mml:math></inlineequation>,
1221 where
1222 <inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation>
1223 is the size
1224 of the texture in the direction of clamping.
1225 <constant>GL_CLAMP_TO_BORDER</constant> evaluates <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation> coordinates in a similar manner to <constant>GL_CLAMP_TO_EDGE</constant>.
1226 However, in cases where clamping would have occurred in <constant>GL_CLAMP_TO_EDGE</constant> mode, the fetched texel data
1227 is substituted with the values specified by <constant>GL_TEXTURE_BORDER_COLOR</constant>.
1228 <constant>GL_REPEAT</constant> causes the
1229 integer part of the
1230 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1231 coordinate to be ignored; the GL uses only the
1232 fractional part, thereby creating a repeating pattern.
1233 <constant>GL_MIRRORED_REPEAT</constant> causes the
1234 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1235 coordinate to be set to the
1236 fractional part of the texture coordinate if the integer part of
1237 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1238 is
1239 even; if the integer part of
1240 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1241 is odd, then the
1242 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
1243 texture coordinate is
1244 set to
1245 <inlineequation><mml:math>
1246 <!-- eqn: 1 - frac(s): -->
1247 <mml:mrow>
1248 <mml:mn>1</mml:mn>
1249 <mml:mo>-</mml:mo>
1250 <mml:mrow>
1251 <mml:mi mathvariant="italic">frac</mml:mi>
1252 <mml:mo>&af;</mml:mo>
1253 <mml:mfenced open="(" close=")">
1254 <mml:mi mathvariant="italic">s</mml:mi>
1255 </mml:mfenced>
1256 </mml:mrow>
1257 </mml:mrow>
1258 </mml:math></inlineequation>,
1259 where
1260 <inlineequation><mml:math>
1261 <!-- eqn: frac(s): -->
1262 <mml:mrow>
1263 <mml:mi mathvariant="italic">frac</mml:mi>
1264 <mml:mo>&af;</mml:mo>
1265 <mml:mfenced open="(" close=")">
1266 <mml:mi mathvariant="italic">s</mml:mi>
1267 </mml:mfenced>
1268 </mml:mrow>
1269 </mml:math></inlineequation>
1270 represents the fractional part of
1271 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>.
1272 Initially, <constant>GL_TEXTURE_WRAP_S</constant> is set to <constant>GL_REPEAT</constant>.
1273 </para>
1274 </listitem>
1275 </varlistentry>
1276 </variablelist>
1277 <para>
1278 </para>
1279 <variablelist>
1280 <varlistentry>
1281 <term><constant>GL_TEXTURE_WRAP_T</constant></term>
1282 <listitem>
1283 <para>
1284 Sets the wrap parameter for texture coordinate
1285 <inlineequation><mml:math><mml:mi mathvariant="italic">t</mml:mi></mml:math></inlineequation>
1286 to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_CLAMP_TO_BORDER</constant>,
1287 <constant>GL_MIRRORED_REPEAT</constant>, or
1288 <constant>GL_REPEAT</constant>. See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>.
1289 Initially, <constant>GL_TEXTURE_WRAP_T</constant> is set to <constant>GL_REPEAT</constant>.
1290 </para>
1291 </listitem>
1292 </varlistentry>
1293 </variablelist>
1294 <para>
1295 </para>
1296 <variablelist>
1297 <varlistentry>
1298 <term><constant>GL_TEXTURE_WRAP_R</constant></term>
1299 <listitem>
1300 <para>
1301 Sets the wrap parameter for texture coordinate
1302 <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
1303 to either <constant>GL_CLAMP_TO_EDGE</constant>, <constant>GL_CLAMP_TO_BORDER</constant>,
1304 <constant>GL_MIRRORED_REPEAT</constant>, or
1305 <constant>GL_REPEAT</constant>. See the discussion under <constant>GL_TEXTURE_WRAP_S</constant>.
1306 Initially, <constant>GL_TEXTURE_WRAP_R</constant> is set to <constant>GL_REPEAT</constant>.
1307 </para>
1308 </listitem>
1309 </varlistentry>
1310 </variablelist>
1311 </refsect1>
1312 <refsect1 id="notes"><title>Notes</title>
1313 <para>
1314 Suppose that a program attempts to sample from a texture and
1315 has set <constant>GL_TEXTURE_MIN_FILTER</constant> to one of the functions that requires a
1316 mipmap. If either the dimensions of the texture images currently defined
1317 (with previous calls to <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
1318 <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>, or <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>) do not
1319 follow the proper sequence for mipmaps (described above), or there are
1320 fewer texture images defined than are needed, or the set of texture images
1321 have differing numbers of texture components, then the texture is considered <emphasis>incomplete</emphasis>.
1322 </para>
1323 <para>
1324 Linear filtering accesses the four nearest texture elements only in 2D
1325 textures. In 1D textures, linear filtering accesses the two nearest
1326 texture elements. In 3D textures, linear filtering accesses the eight nearest
1327 texture elements.
1328 </para>
1329 <para>
1330 <function>glTexParameter</function> specifies the texture parameters for the active texture unit, specified
1331 by calling <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>.
1332 </para>
1333 <para>
1334 <constant>GL_DEPTH_STENCIL_TEXTURE_MODE</constant> is available only if the GL version is 4.3 or greater.
1335 </para>
1336 </refsect1>
1337 <refsect1 id="errors"><title>Errors</title>
1338 <para>
1339 <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> or <parameter>pname</parameter> is not
1340 one of the accepted defined values.
1341 </para>
1342 <para>
1343 <constant>GL_INVALID_ENUM</constant> is generated if <parameter>params</parameter> should have a defined
1344 constant value (based on the value of <parameter>pname</parameter>) and does not.
1345 </para>
1346 </refsect1>
1347 <refsect1 id="associatedgets"><title>Associated Gets</title>
1348 <para>
1349 <citerefentry><refentrytitle>glGetTexParameter</refentrytitle></citerefentry>
1350 </para>
1351 <para>
1352 <citerefentry><refentrytitle>glGetTexLevelParameter</refentrytitle></citerefentry>
1353 </para>
1354 </refsect1>
1355 <refsect1 id="seealso"><title>See Also</title>
1356 <para>
1357 <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
1358 <citerefentry><refentrytitle>glBindTexture</refentrytitle></citerefentry>,
1359 <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
1360 <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
1361 <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
1362 <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
1363 <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
1364 <citerefentry><refentrytitle>glPixelStore</refentrytitle></citerefentry>,
1365 <citerefentry><refentrytitle>glSamplerParameter</refentrytitle></citerefentry>,
1366 <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
1367 <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
1368 <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
1369 <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
1370 <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>,
1371 <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>
1372 </para>
1373 </refsect1>
1374 <refsect1 id="Copyright"><title>Copyright</title>
1375 <para>
1376 Copyright <trademark class="copyright"></trademark> 1991-2006
1377 Silicon Graphics, Inc. This document is licensed under the SGI
1378 Free Software B License. For details, see
1379 <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
1380 </para>
1381 </refsect1>
1382 </refentry>
Unnamed repository; edit this file 'description' to name the repository.