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include more low-level bindings
[clinton/guile-figl.git] / upstream-man-pages / man4 / glPixelStore.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="glPixelStore">
5 <refmeta>
6 <refmetainfo>
7 <copyright>
8 <year>1991-2006</year>
9 <holder>Silicon Graphics, Inc.</holder>
10 </copyright>
11 </refmetainfo>
12 <refentrytitle>glPixelStore</refentrytitle>
13 <manvolnum>3G</manvolnum>
14 </refmeta>
15 <refnamediv>
16 <refname>glPixelStore</refname>
17 <refpurpose>set pixel storage modes</refpurpose>
18 </refnamediv>
19 <refsynopsisdiv><title>C Specification</title>
20 <funcsynopsis>
21 <funcprototype>
22 <funcdef>void <function>glPixelStoref</function></funcdef>
23 <paramdef>GLenum <parameter>pname</parameter></paramdef>
24 <paramdef>GLfloat <parameter>param</parameter></paramdef>
25 </funcprototype>
26 </funcsynopsis>
27 <funcsynopsis>
28 <funcprototype>
29 <funcdef>void <function>glPixelStorei</function></funcdef>
30 <paramdef>GLenum <parameter>pname</parameter></paramdef>
31 <paramdef>GLint <parameter>param</parameter></paramdef>
32 </funcprototype>
33 </funcsynopsis>
34 </refsynopsisdiv>
35 <!-- eqn: ignoring delim $$ -->
36 <refsect1 id="parameters"><title>Parameters</title>
37 <variablelist>
38 <varlistentry>
39 <term><parameter>pname</parameter></term>
40 <listitem>
41 <para>
42 Specifies the symbolic name of the parameter to be set.
43 Six values affect the packing of pixel data into memory:
44 <constant>GL_PACK_SWAP_BYTES</constant>,
45 <constant>GL_PACK_LSB_FIRST</constant>,
46 <constant>GL_PACK_ROW_LENGTH</constant>,
47 <constant>GL_PACK_IMAGE_HEIGHT</constant>,
48 <constant>GL_PACK_SKIP_PIXELS</constant>,
49 <constant>GL_PACK_SKIP_ROWS</constant>,
50 <constant>GL_PACK_SKIP_IMAGES</constant>, and
51 <constant>GL_PACK_ALIGNMENT</constant>.
52 Six more affect the unpacking of pixel data <emphasis>from</emphasis> memory:
53 <constant>GL_UNPACK_SWAP_BYTES</constant>,
54 <constant>GL_UNPACK_LSB_FIRST</constant>,
55 <constant>GL_UNPACK_ROW_LENGTH</constant>,
56 <constant>GL_UNPACK_IMAGE_HEIGHT</constant>,
57 <constant>GL_UNPACK_SKIP_PIXELS</constant>,
58 <constant>GL_UNPACK_SKIP_ROWS</constant>,
59 <constant>GL_UNPACK_SKIP_IMAGES</constant>, and
60 <constant>GL_UNPACK_ALIGNMENT</constant>.
61 </para>
62 </listitem>
63 </varlistentry>
64 <varlistentry>
65 <term><parameter>param</parameter></term>
66 <listitem>
67 <para>
68 Specifies the value that <parameter>pname</parameter> is set to.
69 </para>
70 </listitem>
71 </varlistentry>
72 </variablelist>
73 </refsect1>
74 <refsect1 id="description"><title>Description</title>
75 <para>
76 <function>glPixelStore</function> sets pixel storage modes that affect the operation of subsequent
77 <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry> as well as the unpacking of
78 texture patterns (see <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
79 <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
80 <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>),
81 <citerefentry><refentrytitle>glCompressedTexImage1D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCompressedTexImage2D</refentrytitle></citerefentry>,
82 <citerefentry><refentrytitle>glCompressedTexImage3D</refentrytitle></citerefentry>, <citerefentry><refentrytitle>glCompressedTexSubImage1D</refentrytitle></citerefentry>,
83 <citerefentry><refentrytitle>glCompressedTexSubImage2D</refentrytitle></citerefentry> or <citerefentry><refentrytitle>glCompressedTexSubImage1D</refentrytitle></citerefentry>.
84 </para>
85 <para>
86 <parameter>pname</parameter> is a symbolic constant indicating the parameter to be set, and
87 <parameter>param</parameter> is the new value. Six of the twelve storage parameters affect
88 how pixel data is returned to client memory.
89 They are as follows:
90 </para>
91 <variablelist>
92 <varlistentry>
93 <term><constant>GL_PACK_SWAP_BYTES</constant></term>
94 <listitem>
95 <para>
96 If true,
97 byte ordering for multibyte color components,
98 depth components,
99 or stencil indices
100 is reversed.
101 That is,
102 if a four-byte component consists of bytes
103 <inlineequation><mml:math>
104 <!-- eqn: b sub 0: -->
105 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
106 <mml:mn>0</mml:mn>
107 </mml:msub>
108 </mml:math></inlineequation>,
109 <inlineequation><mml:math>
110 <!-- eqn: b sub 1: -->
111 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
112 <mml:mn>1</mml:mn>
113 </mml:msub>
114 </mml:math></inlineequation>,
115 <inlineequation><mml:math>
116 <!-- eqn: b sub 2: -->
117 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
118 <mml:mn>2</mml:mn>
119 </mml:msub>
120 </mml:math></inlineequation>,
121 <inlineequation><mml:math>
122 <!-- eqn: b sub 3: -->
123 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
124 <mml:mn>3</mml:mn>
125 </mml:msub>
126 </mml:math></inlineequation>,
127 it is stored in memory as
128 <inlineequation><mml:math>
129 <!-- eqn: b sub 3: -->
130 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
131 <mml:mn>3</mml:mn>
132 </mml:msub>
133 </mml:math></inlineequation>,
134 <inlineequation><mml:math>
135 <!-- eqn: b sub 2: -->
136 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
137 <mml:mn>2</mml:mn>
138 </mml:msub>
139 </mml:math></inlineequation>,
140 <inlineequation><mml:math>
141 <!-- eqn: b sub 1: -->
142 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
143 <mml:mn>1</mml:mn>
144 </mml:msub>
145 </mml:math></inlineequation>,
146 <inlineequation><mml:math>
147 <!-- eqn: b sub 0: -->
148 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
149 <mml:mn>0</mml:mn>
150 </mml:msub>
151 </mml:math></inlineequation>
152 if <constant>GL_PACK_SWAP_BYTES</constant> is true.
153 <constant>GL_PACK_SWAP_BYTES</constant> has no effect on the memory order of components
154 within a pixel,
155 only on the order of bytes within components or indices.
156 For example,
157 the three components of a <constant>GL_RGB</constant> format pixel are always stored with
158 red first,
159 green second,
160 and blue third,
161 regardless of the value of <constant>GL_PACK_SWAP_BYTES</constant>.
162 </para>
163 </listitem>
164 </varlistentry>
165 <varlistentry>
166 <term><constant>GL_PACK_LSB_FIRST</constant></term>
167 <listitem>
168 <para>
169 If true,
170 bits are ordered within a byte from least significant to most significant;
171 otherwise,
172 the first bit in each byte is the most significant one.
173 </para>
174 </listitem>
175 </varlistentry>
176 <varlistentry>
177 <term><constant>GL_PACK_ROW_LENGTH</constant></term>
178 <listitem>
179 <para>
180 If greater than 0,
181 <constant>GL_PACK_ROW_LENGTH</constant> defines the number of pixels in a row.
182 If the first pixel of a row is placed at location
183 <inlineequation><mml:math><mml:mi mathvariant="italic">p</mml:mi></mml:math></inlineequation>
184 in memory,
185 then the location of the first pixel of the next row is obtained by skipping
186 </para>
187 <para>
188 <informalequation><mml:math>
189 <!-- eqn: k = left { lpile { n l above {a over s} left ceiling { s n l } over a right ceiling} lpile {s >= a above s < a }: -->
190 <mml:mrow>
191 <mml:mi mathvariant="italic">k</mml:mi>
192 <mml:mo>=</mml:mo>
193 <mml:mfenced open="{" close="">
194 <mml:mrow>
195 <mml:mtable>
196 <mml:mtr><mml:mtd>
197 <mml:mrow>
198 <mml:mi mathvariant="italic">n</mml:mi>
199 <mml:mo>&it;</mml:mo>
200 <mml:mi mathvariant="italic">l</mml:mi>
201 </mml:mrow>
202 </mml:mtd></mml:mtr>
203 <mml:mtr><mml:mtd>
204 <mml:mrow>
205 <mml:mfenced open="" close="">
206 <mml:mfrac>
207 <mml:mi mathvariant="italic">a</mml:mi>
208 <mml:mi mathvariant="italic">s</mml:mi>
209 </mml:mfrac>
210 </mml:mfenced>
211 <mml:mo>&it;</mml:mo>
212 <mml:mfenced open="&LeftCeiling;" close="&RightCeiling;">
213 <mml:mfrac>
214 <mml:mfenced open="" close="">
215 <mml:mrow>
216 <mml:mi mathvariant="italic">s</mml:mi>
217 <mml:mo>&it;</mml:mo>
218 <mml:mi mathvariant="italic">n</mml:mi>
219 <mml:mo>&it;</mml:mo>
220 <mml:mi mathvariant="italic">l</mml:mi>
221 </mml:mrow>
222 </mml:mfenced>
223 <mml:mi mathvariant="italic">a</mml:mi>
224 </mml:mfrac>
225 </mml:mfenced>
226 </mml:mrow>
227 </mml:mtd></mml:mtr>
228 </mml:mtable>
229 <mml:mo>&it;</mml:mo>
230 <mml:mtable>
231 <mml:mtr><mml:mtd>
232 <mml:mrow>
233 <mml:mi mathvariant="italic">s</mml:mi>
234 <mml:mo>&gt;=</mml:mo>
235 <mml:mi mathvariant="italic">a</mml:mi>
236 </mml:mrow>
237 </mml:mtd></mml:mtr>
238 <mml:mtr><mml:mtd>
239 <mml:mrow>
240 <mml:mi mathvariant="italic">s</mml:mi>
241 <mml:mo>&lt;</mml:mo>
242 <mml:mi mathvariant="italic">a</mml:mi>
243 </mml:mrow>
244 </mml:mtd></mml:mtr>
245 </mml:mtable>
246 </mml:mrow>
247 </mml:mfenced>
248 </mml:mrow>
249 </mml:math></informalequation>
250 </para>
251 <para>
252 components or indices,
253 where
254 <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
255 is the number of components or indices in a pixel,
256 <inlineequation><mml:math><mml:mi mathvariant="italic">l</mml:mi></mml:math></inlineequation>
257 is the number of pixels in a row
258 (<constant>GL_PACK_ROW_LENGTH</constant> if it is greater than 0,
259 the
260 <inlineequation><mml:math><mml:mi mathvariant="italic">width</mml:mi></mml:math></inlineequation>
261 argument to the pixel routine otherwise),
262 <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
263 is the value of <constant>GL_PACK_ALIGNMENT</constant>, and
264 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
265 is the size, in bytes, of a single component
266 (if
267 <inlineequation><mml:math>
268 <!-- eqn: a < s: -->
269 <mml:mrow>
270 <mml:mi mathvariant="italic">a</mml:mi>
271 <mml:mo>&lt;</mml:mo>
272 <mml:mi mathvariant="italic">s</mml:mi>
273 </mml:mrow>
274 </mml:math></inlineequation>,
275 then it is as if
276 <inlineequation><mml:math>
277 <!-- eqn: a = s: -->
278 <mml:mrow>
279 <mml:mi mathvariant="italic">a</mml:mi>
280 <mml:mo>=</mml:mo>
281 <mml:mi mathvariant="italic">s</mml:mi>
282 </mml:mrow>
283 </mml:math></inlineequation>).
284 In the case of 1-bit values,
285 the location of the next row is obtained by skipping
286 </para>
287 <para>
288 <inlineequation><mml:math>
289 <!-- eqn: k = 8 a left ceiling { n l } over { 8 a } right ceiling: -->
290 <mml:mrow>
291 <mml:mi mathvariant="italic">k</mml:mi>
292 <mml:mo>=</mml:mo>
293 <mml:mrow>
294 <mml:mn>8</mml:mn>
295 <mml:mo>&it;</mml:mo>
296 <mml:mi mathvariant="italic">a</mml:mi>
297 <mml:mo>&it;</mml:mo>
298 <mml:mfenced open="&LeftCeiling;" close="&RightCeiling;">
299 <mml:mfrac>
300 <mml:mfenced open="" close="">
301 <mml:mrow>
302 <mml:mi mathvariant="italic">n</mml:mi>
303 <mml:mo>&it;</mml:mo>
304 <mml:mi mathvariant="italic">l</mml:mi>
305 </mml:mrow>
306 </mml:mfenced>
307 <mml:mfenced open="" close="">
308 <mml:mrow>
309 <mml:mn>8</mml:mn>
310 <mml:mo>&it;</mml:mo>
311 <mml:mi mathvariant="italic">a</mml:mi>
312 </mml:mrow>
313 </mml:mfenced>
314 </mml:mfrac>
315 </mml:mfenced>
316 </mml:mrow>
317 </mml:mrow>
318 </mml:math></inlineequation>
319 </para>
320 <para>
321 components or indices.
322 </para>
323 <para>
324 The word <emphasis>component</emphasis> in this description refers to the nonindex values
325 red,
326 green,
327 blue,
328 alpha,
329 and depth.
330 Storage format <constant>GL_RGB</constant>,
331 for example,
332 has three components per pixel:
333 first red,
334 then green,
335 and finally blue.
336 </para>
337 </listitem>
338 </varlistentry>
339 <varlistentry>
340 <term><constant>GL_PACK_IMAGE_HEIGHT</constant></term>
341 <listitem>
342 <para>
343 If greater than 0,
344 <constant>GL_PACK_IMAGE_HEIGHT</constant> defines the number of pixels in an image
345 three-dimensional texture volume, where ``image'' is defined by all pixels
346 sharing the same third dimension index.
347 If the first pixel of a row is placed at location
348 <inlineequation><mml:math><mml:mi mathvariant="italic">p</mml:mi></mml:math></inlineequation>
349 in memory,
350 then the location of the first pixel of the next row is obtained by skipping
351 </para>
352 <para>
353 <informalequation><mml:math>
354 <!-- eqn: k = left { lpile { n l h above {a over s} left ceiling { s n l h } over a right ceiling} lpile {s >= a above s < a }: -->
355 <mml:mrow>
356 <mml:mi mathvariant="italic">k</mml:mi>
357 <mml:mo>=</mml:mo>
358 <mml:mfenced open="{" close="">
359 <mml:mrow>
360 <mml:mtable>
361 <mml:mtr><mml:mtd>
362 <mml:mrow>
363 <mml:mi mathvariant="italic">n</mml:mi>
364 <mml:mo>&it;</mml:mo>
365 <mml:mi mathvariant="italic">l</mml:mi>
366 <mml:mo>&it;</mml:mo>
367 <mml:mi mathvariant="italic">h</mml:mi>
368 </mml:mrow>
369 </mml:mtd></mml:mtr>
370 <mml:mtr><mml:mtd>
371 <mml:mrow>
372 <mml:mfenced open="" close="">
373 <mml:mfrac>
374 <mml:mi mathvariant="italic">a</mml:mi>
375 <mml:mi mathvariant="italic">s</mml:mi>
376 </mml:mfrac>
377 </mml:mfenced>
378 <mml:mo>&it;</mml:mo>
379 <mml:mfenced open="&LeftCeiling;" close="&RightCeiling;">
380 <mml:mfrac>
381 <mml:mfenced open="" close="">
382 <mml:mrow>
383 <mml:mi mathvariant="italic">s</mml:mi>
384 <mml:mo>&it;</mml:mo>
385 <mml:mi mathvariant="italic">n</mml:mi>
386 <mml:mo>&it;</mml:mo>
387 <mml:mi mathvariant="italic">l</mml:mi>
388 <mml:mo>&it;</mml:mo>
389 <mml:mi mathvariant="italic">h</mml:mi>
390 </mml:mrow>
391 </mml:mfenced>
392 <mml:mi mathvariant="italic">a</mml:mi>
393 </mml:mfrac>
394 </mml:mfenced>
395 </mml:mrow>
396 </mml:mtd></mml:mtr>
397 </mml:mtable>
398 <mml:mo>&it;</mml:mo>
399 <mml:mtable>
400 <mml:mtr><mml:mtd>
401 <mml:mrow>
402 <mml:mi mathvariant="italic">s</mml:mi>
403 <mml:mo>&gt;=</mml:mo>
404 <mml:mi mathvariant="italic">a</mml:mi>
405 </mml:mrow>
406 </mml:mtd></mml:mtr>
407 <mml:mtr><mml:mtd>
408 <mml:mrow>
409 <mml:mi mathvariant="italic">s</mml:mi>
410 <mml:mo>&lt;</mml:mo>
411 <mml:mi mathvariant="italic">a</mml:mi>
412 </mml:mrow>
413 </mml:mtd></mml:mtr>
414 </mml:mtable>
415 </mml:mrow>
416 </mml:mfenced>
417 </mml:mrow>
418 </mml:math></informalequation>
419 </para>
420 <para>
421 components or indices, where
422 <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
423 is the number of components or indices
424 in a pixel,
425 <inlineequation><mml:math><mml:mi mathvariant="italic">l</mml:mi></mml:math></inlineequation>
426 is the number of pixels in a row
427 (<constant>GL_PACK_ROW_LENGTH</constant> if it is greater than 0, the
428 <inlineequation><mml:math><mml:mi mathvariant="italic">width</mml:mi></mml:math></inlineequation>
429 argument to <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry> otherwise),
430 <inlineequation><mml:math><mml:mi mathvariant="italic">h</mml:mi></mml:math></inlineequation>
431 is the number of
432 rows in a pixel image (<constant>GL_PACK_IMAGE_HEIGHT</constant> if it is greater than
433 0, the
434 <inlineequation><mml:math><mml:mi mathvariant="italic">height</mml:mi></mml:math></inlineequation>
435 argument to the <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry> routine otherwise),
436 <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
437 is the value of
438 <constant>GL_PACK_ALIGNMENT</constant>, and
439 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
440 is the size, in bytes, of a single
441 component (if
442 <inlineequation><mml:math>
443 <!-- eqn: a < s: -->
444 <mml:mrow>
445 <mml:mi mathvariant="italic">a</mml:mi>
446 <mml:mo>&lt;</mml:mo>
447 <mml:mi mathvariant="italic">s</mml:mi>
448 </mml:mrow>
449 </mml:math></inlineequation>,
450 then it is as if
451 <inlineequation><mml:math>
452 <!-- eqn: a = s: -->
453 <mml:mrow>
454 <mml:mi mathvariant="italic">a</mml:mi>
455 <mml:mo>=</mml:mo>
456 <mml:mi mathvariant="italic">s</mml:mi>
457 </mml:mrow>
458 </mml:math></inlineequation>).
459 </para>
460 <para>
461 The word <emphasis>component</emphasis> in this description refers to the nonindex values
462 red,
463 green,
464 blue,
465 alpha,
466 and depth.
467 Storage format <constant>GL_RGB</constant>,
468 for example,
469 has three components per pixel:
470 first red,
471 then green,
472 and finally blue.
473 </para>
474 </listitem>
475 </varlistentry>
476 <varlistentry>
477 <term><constant>GL_PACK_SKIP_PIXELS</constant>, <constant>GL_PACK_SKIP_ROWS</constant>, and <constant>GL_PACK_SKIP_IMAGES</constant></term>
478 <listitem>
479 <para>
480 These values are provided as a convenience to the programmer;
481 they provide no functionality that cannot be duplicated simply by
482 incrementing the pointer passed to <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>.
483 Setting <constant>GL_PACK_SKIP_PIXELS</constant> to
484 <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>
485 is equivalent to incrementing
486 the pointer by
487 <inlineequation><mml:math>
488 <!-- eqn: i n: -->
489 <mml:mrow>
490 <mml:mi mathvariant="italic">i</mml:mi>
491 <mml:mo>&it;</mml:mo>
492 <mml:mi mathvariant="italic">n</mml:mi>
493 </mml:mrow>
494 </mml:math></inlineequation>
495 components or indices,
496 where
497 <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
498 is the number of components or indices in each pixel.
499 Setting <constant>GL_PACK_SKIP_ROWS</constant> to
500 <inlineequation><mml:math><mml:mi mathvariant="italic">j</mml:mi></mml:math></inlineequation>
501 is equivalent to incrementing
502 the pointer by
503 <inlineequation><mml:math>
504 <!-- eqn: j m: -->
505 <mml:mrow>
506 <mml:mi mathvariant="italic">j</mml:mi>
507 <mml:mo>&it;</mml:mo>
508 <mml:mi mathvariant="italic">m</mml:mi>
509 </mml:mrow>
510 </mml:math></inlineequation>
511 components or indices,
512 where
513 <inlineequation><mml:math><mml:mi mathvariant="italic">m</mml:mi></mml:math></inlineequation>
514 is the number of components or indices per row,
515 as just computed in the <constant>GL_PACK_ROW_LENGTH</constant> section.
516 Setting <constant>GL_PACK_SKIP_IMAGES</constant> to
517 <inlineequation><mml:math><mml:mi mathvariant="italic">k</mml:mi></mml:math></inlineequation>
518 is equivalent to incrementing
519 the pointer by
520 <inlineequation><mml:math>
521 <!-- eqn: k p: -->
522 <mml:mrow>
523 <mml:mi mathvariant="italic">k</mml:mi>
524 <mml:mo>&it;</mml:mo>
525 <mml:mi mathvariant="italic">p</mml:mi>
526 </mml:mrow>
527 </mml:math></inlineequation>,
528 where
529 <inlineequation><mml:math><mml:mi mathvariant="italic">p</mml:mi></mml:math></inlineequation>
530 is the number of components or indices
531 per image, as computed in the <constant>GL_PACK_IMAGE_HEIGHT</constant> section.
532 </para>
533 </listitem>
534 </varlistentry>
535 <varlistentry>
536 <term><constant>GL_PACK_ALIGNMENT</constant></term>
537 <listitem>
538 <para>
539 Specifies the alignment requirements for the start of each pixel row in memory.
540 The allowable values are
541 1 (byte-alignment),
542 2 (rows aligned to even-numbered bytes),
543 4 (word-alignment), and
544 8 (rows start on double-word boundaries).
545 </para>
546 </listitem>
547 </varlistentry>
548 </variablelist>
549 <para>
550 The other six of the twelve storage parameters affect how pixel data is
551 read from client memory.
552 These values are significant for
553 <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
554 <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
555 <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
556 <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
557 <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>, and
558 <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>
559 </para>
560 <para>
561 They are as follows:
562 </para>
563 <variablelist>
564 <varlistentry>
565 <term><constant>GL_UNPACK_SWAP_BYTES</constant></term>
566 <listitem>
567 <para>
568 If true,
569 byte ordering for multibyte color components,
570 depth components,
571 or stencil indices
572 is reversed.
573 That is,
574 if a four-byte component consists of bytes
575 <inlineequation><mml:math>
576 <!-- eqn: b sub 0: -->
577 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
578 <mml:mn>0</mml:mn>
579 </mml:msub>
580 </mml:math></inlineequation>,
581 <inlineequation><mml:math>
582 <!-- eqn: b sub 1: -->
583 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
584 <mml:mn>1</mml:mn>
585 </mml:msub>
586 </mml:math></inlineequation>,
587 <inlineequation><mml:math>
588 <!-- eqn: b sub 2: -->
589 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
590 <mml:mn>2</mml:mn>
591 </mml:msub>
592 </mml:math></inlineequation>,
593 <inlineequation><mml:math>
594 <!-- eqn: b sub 3: -->
595 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
596 <mml:mn>3</mml:mn>
597 </mml:msub>
598 </mml:math></inlineequation>,
599 it is taken from memory as
600 <inlineequation><mml:math>
601 <!-- eqn: b sub 3: -->
602 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
603 <mml:mn>3</mml:mn>
604 </mml:msub>
605 </mml:math></inlineequation>,
606 <inlineequation><mml:math>
607 <!-- eqn: b sub 2: -->
608 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
609 <mml:mn>2</mml:mn>
610 </mml:msub>
611 </mml:math></inlineequation>,
612 <inlineequation><mml:math>
613 <!-- eqn: b sub 1: -->
614 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
615 <mml:mn>1</mml:mn>
616 </mml:msub>
617 </mml:math></inlineequation>,
618 <inlineequation><mml:math>
619 <!-- eqn: b sub 0: -->
620 <mml:msub><mml:mi mathvariant="italic">b</mml:mi>
621 <mml:mn>0</mml:mn>
622 </mml:msub>
623 </mml:math></inlineequation>
624 if <constant>GL_UNPACK_SWAP_BYTES</constant> is true.
625 <constant>GL_UNPACK_SWAP_BYTES</constant> has no effect on the memory order of components
626 within a pixel,
627 only on the order of bytes within components or indices.
628 For example,
629 the three components of a <constant>GL_RGB</constant> format pixel are always stored with
630 red first,
631 green second,
632 and blue third,
633 regardless of the value of <constant>GL_UNPACK_SWAP_BYTES</constant>.
634 </para>
635 </listitem>
636 </varlistentry>
637 <varlistentry>
638 <term><constant>GL_UNPACK_LSB_FIRST</constant></term>
639 <listitem>
640 <para>
641 If true,
642 bits are ordered within a byte from least significant to most significant;
643 otherwise,
644 the first bit in each byte is the most significant one.
645 </para>
646 </listitem>
647 </varlistentry>
648 <varlistentry>
649 <term><constant>GL_UNPACK_ROW_LENGTH</constant></term>
650 <listitem>
651 <para>
652 If greater than 0,
653 <constant>GL_UNPACK_ROW_LENGTH</constant> defines the number of pixels in a row.
654 If the first pixel of a row is placed at location
655 <inlineequation><mml:math><mml:mi mathvariant="italic">p</mml:mi></mml:math></inlineequation>
656 in memory,
657 then the location of the first pixel of the next row is obtained by skipping
658 </para>
659 <para>
660 <informalequation><mml:math>
661 <!-- eqn: k = left { lpile { n l above {a over s} left ceiling { s n l } over a right ceiling } lpile { s >= a above s < a }: -->
662 <mml:mrow>
663 <mml:mi mathvariant="italic">k</mml:mi>
664 <mml:mo>=</mml:mo>
665 <mml:mfenced open="{" close="">
666 <mml:mrow>
667 <mml:mtable>
668 <mml:mtr><mml:mtd>
669 <mml:mrow>
670 <mml:mi mathvariant="italic">n</mml:mi>
671 <mml:mo>&it;</mml:mo>
672 <mml:mi mathvariant="italic">l</mml:mi>
673 </mml:mrow>
674 </mml:mtd></mml:mtr>
675 <mml:mtr><mml:mtd>
676 <mml:mrow>
677 <mml:mfenced open="" close="">
678 <mml:mfrac>
679 <mml:mi mathvariant="italic">a</mml:mi>
680 <mml:mi mathvariant="italic">s</mml:mi>
681 </mml:mfrac>
682 </mml:mfenced>
683 <mml:mo>&it;</mml:mo>
684 <mml:mfenced open="&LeftCeiling;" close="&RightCeiling;">
685 <mml:mfrac>
686 <mml:mfenced open="" close="">
687 <mml:mrow>
688 <mml:mi mathvariant="italic">s</mml:mi>
689 <mml:mo>&it;</mml:mo>
690 <mml:mi mathvariant="italic">n</mml:mi>
691 <mml:mo>&it;</mml:mo>
692 <mml:mi mathvariant="italic">l</mml:mi>
693 </mml:mrow>
694 </mml:mfenced>
695 <mml:mi mathvariant="italic">a</mml:mi>
696 </mml:mfrac>
697 </mml:mfenced>
698 </mml:mrow>
699 </mml:mtd></mml:mtr>
700 </mml:mtable>
701 <mml:mo>&it;</mml:mo>
702 <mml:mtable>
703 <mml:mtr><mml:mtd>
704 <mml:mrow>
705 <mml:mi mathvariant="italic">s</mml:mi>
706 <mml:mo>&gt;=</mml:mo>
707 <mml:mi mathvariant="italic">a</mml:mi>
708 </mml:mrow>
709 </mml:mtd></mml:mtr>
710 <mml:mtr><mml:mtd>
711 <mml:mrow>
712 <mml:mi mathvariant="italic">s</mml:mi>
713 <mml:mo>&lt;</mml:mo>
714 <mml:mi mathvariant="italic">a</mml:mi>
715 </mml:mrow>
716 </mml:mtd></mml:mtr>
717 </mml:mtable>
718 </mml:mrow>
719 </mml:mfenced>
720 </mml:mrow>
721 </mml:math></informalequation>
722 </para>
723 <para>
724 components or indices,
725 where
726 <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
727 is the number of components or indices in a pixel,
728 <inlineequation><mml:math><mml:mi mathvariant="italic">l</mml:mi></mml:math></inlineequation>
729 is the number of pixels in a row
730 (<constant>GL_UNPACK_ROW_LENGTH</constant> if it is greater than 0,
731 the
732 <inlineequation><mml:math><mml:mi mathvariant="italic">width</mml:mi></mml:math></inlineequation>
733 argument to the pixel routine otherwise),
734 <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
735 is the value of <constant>GL_UNPACK_ALIGNMENT</constant>, and
736 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
737 is the size, in bytes, of a single component
738 (if
739 <inlineequation><mml:math>
740 <!-- eqn: a < s: -->
741 <mml:mrow>
742 <mml:mi mathvariant="italic">a</mml:mi>
743 <mml:mo>&lt;</mml:mo>
744 <mml:mi mathvariant="italic">s</mml:mi>
745 </mml:mrow>
746 </mml:math></inlineequation>,
747 then it is as if
748 <inlineequation><mml:math>
749 <!-- eqn: a = s: -->
750 <mml:mrow>
751 <mml:mi mathvariant="italic">a</mml:mi>
752 <mml:mo>=</mml:mo>
753 <mml:mi mathvariant="italic">s</mml:mi>
754 </mml:mrow>
755 </mml:math></inlineequation>).
756 In the case of 1-bit values,
757 the location of the next row is obtained by skipping
758 </para>
759 <para>
760 <inlineequation><mml:math>
761 <!-- eqn: k = 8 a left ceiling { n l } over { 8 a } right ceiling: -->
762 <mml:mrow>
763 <mml:mi mathvariant="italic">k</mml:mi>
764 <mml:mo>=</mml:mo>
765 <mml:mrow>
766 <mml:mn>8</mml:mn>
767 <mml:mo>&it;</mml:mo>
768 <mml:mi mathvariant="italic">a</mml:mi>
769 <mml:mo>&it;</mml:mo>
770 <mml:mfenced open="&LeftCeiling;" close="&RightCeiling;">
771 <mml:mfrac>
772 <mml:mfenced open="" close="">
773 <mml:mrow>
774 <mml:mi mathvariant="italic">n</mml:mi>
775 <mml:mo>&it;</mml:mo>
776 <mml:mi mathvariant="italic">l</mml:mi>
777 </mml:mrow>
778 </mml:mfenced>
779 <mml:mfenced open="" close="">
780 <mml:mrow>
781 <mml:mn>8</mml:mn>
782 <mml:mo>&it;</mml:mo>
783 <mml:mi mathvariant="italic">a</mml:mi>
784 </mml:mrow>
785 </mml:mfenced>
786 </mml:mfrac>
787 </mml:mfenced>
788 </mml:mrow>
789 </mml:mrow>
790 </mml:math></inlineequation>
791 </para>
792 <para>
793 components or indices.
794 </para>
795 <para>
796 The word <emphasis>component</emphasis> in this description refers to the nonindex values
797 red,
798 green,
799 blue,
800 alpha,
801 and depth.
802 Storage format <constant>GL_RGB</constant>,
803 for example,
804 has three components per pixel:
805 first red,
806 then green,
807 and finally blue.
808 </para>
809 </listitem>
810 </varlistentry>
811 <varlistentry>
812 <term><constant>GL_UNPACK_IMAGE_HEIGHT</constant></term>
813 <listitem>
814 <para>
815 If greater than 0,
816 <constant>GL_UNPACK_IMAGE_HEIGHT</constant> defines the number of pixels in an image of
817 a three-dimensional texture volume. Where ``image'' is defined by all
818 pixel sharing the same third dimension index.
819 If the first pixel of a row is placed at location
820 <inlineequation><mml:math><mml:mi mathvariant="italic">p</mml:mi></mml:math></inlineequation>
821 in memory,
822 then the location of the first pixel of the next row is obtained by skipping
823 </para>
824 <para>
825 <informalequation><mml:math>
826 <!-- eqn: k = left { lpile { n l h above {a over s} left ceiling { s n l h } over a right ceiling } lpile { s >= a above s < a }: -->
827 <mml:mrow>
828 <mml:mi mathvariant="italic">k</mml:mi>
829 <mml:mo>=</mml:mo>
830 <mml:mfenced open="{" close="">
831 <mml:mrow>
832 <mml:mtable>
833 <mml:mtr><mml:mtd>
834 <mml:mrow>
835 <mml:mi mathvariant="italic">n</mml:mi>
836 <mml:mo>&it;</mml:mo>
837 <mml:mi mathvariant="italic">l</mml:mi>
838 <mml:mo>&it;</mml:mo>
839 <mml:mi mathvariant="italic">h</mml:mi>
840 </mml:mrow>
841 </mml:mtd></mml:mtr>
842 <mml:mtr><mml:mtd>
843 <mml:mrow>
844 <mml:mfenced open="" close="">
845 <mml:mfrac>
846 <mml:mi mathvariant="italic">a</mml:mi>
847 <mml:mi mathvariant="italic">s</mml:mi>
848 </mml:mfrac>
849 </mml:mfenced>
850 <mml:mo>&it;</mml:mo>
851 <mml:mfenced open="&LeftCeiling;" close="&RightCeiling;">
852 <mml:mfrac>
853 <mml:mfenced open="" close="">
854 <mml:mrow>
855 <mml:mi mathvariant="italic">s</mml:mi>
856 <mml:mo>&it;</mml:mo>
857 <mml:mi mathvariant="italic">n</mml:mi>
858 <mml:mo>&it;</mml:mo>
859 <mml:mi mathvariant="italic">l</mml:mi>
860 <mml:mo>&it;</mml:mo>
861 <mml:mi mathvariant="italic">h</mml:mi>
862 </mml:mrow>
863 </mml:mfenced>
864 <mml:mi mathvariant="italic">a</mml:mi>
865 </mml:mfrac>
866 </mml:mfenced>
867 </mml:mrow>
868 </mml:mtd></mml:mtr>
869 </mml:mtable>
870 <mml:mo>&it;</mml:mo>
871 <mml:mtable>
872 <mml:mtr><mml:mtd>
873 <mml:mrow>
874 <mml:mi mathvariant="italic">s</mml:mi>
875 <mml:mo>&gt;=</mml:mo>
876 <mml:mi mathvariant="italic">a</mml:mi>
877 </mml:mrow>
878 </mml:mtd></mml:mtr>
879 <mml:mtr><mml:mtd>
880 <mml:mrow>
881 <mml:mi mathvariant="italic">s</mml:mi>
882 <mml:mo>&lt;</mml:mo>
883 <mml:mi mathvariant="italic">a</mml:mi>
884 </mml:mrow>
885 </mml:mtd></mml:mtr>
886 </mml:mtable>
887 </mml:mrow>
888 </mml:mfenced>
889 </mml:mrow>
890 </mml:math></informalequation>
891 </para>
892 <para>
893 components or indices,
894 where
895 <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
896 is the number of components or indices in a pixel,
897 <inlineequation><mml:math><mml:mi mathvariant="italic">l</mml:mi></mml:math></inlineequation>
898 is the number of pixels in a row
899 (<constant>GL_UNPACK_ROW_LENGTH</constant> if it is greater than 0,
900 the
901 <inlineequation><mml:math><mml:mi mathvariant="italic">width</mml:mi></mml:math></inlineequation>
902 argument to <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry> otherwise),
903 <inlineequation><mml:math><mml:mi mathvariant="italic">h</mml:mi></mml:math></inlineequation>
904 is the number of rows in an image (<constant>GL_UNPACK_IMAGE_HEIGHT</constant> if
905 it is greater than 0, the
906 <inlineequation><mml:math><mml:mi mathvariant="italic">height</mml:mi></mml:math></inlineequation>
907 argument to <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry> otherwise),
908 <inlineequation><mml:math><mml:mi mathvariant="italic">a</mml:mi></mml:math></inlineequation>
909 is the value of <constant>GL_UNPACK_ALIGNMENT</constant>, and
910 <inlineequation><mml:math><mml:mi mathvariant="italic">s</mml:mi></mml:math></inlineequation>
911 is the size, in bytes, of a single component
912 (if
913 <inlineequation><mml:math>
914 <!-- eqn: a < s: -->
915 <mml:mrow>
916 <mml:mi mathvariant="italic">a</mml:mi>
917 <mml:mo>&lt;</mml:mo>
918 <mml:mi mathvariant="italic">s</mml:mi>
919 </mml:mrow>
920 </mml:math></inlineequation>,
921 then it is as if
922 <inlineequation><mml:math>
923 <!-- eqn: a = s: -->
924 <mml:mrow>
925 <mml:mi mathvariant="italic">a</mml:mi>
926 <mml:mo>=</mml:mo>
927 <mml:mi mathvariant="italic">s</mml:mi>
928 </mml:mrow>
929 </mml:math></inlineequation>).
930 </para>
931 <para>
932 The word <emphasis>component</emphasis> in this description refers to the nonindex values
933 red,
934 green,
935 blue,
936 alpha,
937 and depth.
938 Storage format <constant>GL_RGB</constant>,
939 for example,
940 has three components per pixel:
941 first red,
942 then green,
943 and finally blue.
944 </para>
945 </listitem>
946 </varlistentry>
947 <varlistentry>
948 <term><constant>GL_UNPACK_SKIP_PIXELS</constant> and <constant>GL_UNPACK_SKIP_ROWS</constant></term>
949 <listitem>
950 <para>
951 These values are provided as a convenience to the programmer;
952 they provide no functionality that cannot be duplicated by
953 incrementing the pointer passed to
954 <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
955 <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
956 <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry> or
957 <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>.
958 Setting <constant>GL_UNPACK_SKIP_PIXELS</constant> to
959 <inlineequation><mml:math><mml:mi mathvariant="italic">i</mml:mi></mml:math></inlineequation>
960 is equivalent to incrementing
961 the pointer by
962 <inlineequation><mml:math>
963 <!-- eqn: i n: -->
964 <mml:mrow>
965 <mml:mi mathvariant="italic">i</mml:mi>
966 <mml:mo>&it;</mml:mo>
967 <mml:mi mathvariant="italic">n</mml:mi>
968 </mml:mrow>
969 </mml:math></inlineequation>
970 components or indices,
971 where
972 <inlineequation><mml:math><mml:mi mathvariant="italic">n</mml:mi></mml:math></inlineequation>
973 is the number of components or indices in each pixel.
974 Setting <constant>GL_UNPACK_SKIP_ROWS</constant> to
975 <inlineequation><mml:math><mml:mi mathvariant="italic">j</mml:mi></mml:math></inlineequation>
976 is equivalent to incrementing
977 the pointer by
978 <inlineequation><mml:math>
979 <!-- eqn: j k: -->
980 <mml:mrow>
981 <mml:mi mathvariant="italic">j</mml:mi>
982 <mml:mo>&it;</mml:mo>
983 <mml:mi mathvariant="italic">k</mml:mi>
984 </mml:mrow>
985 </mml:math></inlineequation>
986 components or indices,
987 where
988 <inlineequation><mml:math><mml:mi mathvariant="italic">k</mml:mi></mml:math></inlineequation>
989 is the number of components or indices per row,
990 as just computed in the <constant>GL_UNPACK_ROW_LENGTH</constant> section.
991 </para>
992 </listitem>
993 </varlistentry>
994 <varlistentry>
995 <term><constant>GL_UNPACK_ALIGNMENT</constant></term>
996 <listitem>
997 <para>
998 Specifies the alignment requirements for the start of each pixel row in memory.
999 The allowable values are
1000 1 (byte-alignment),
1001 2 (rows aligned to even-numbered bytes),
1002 4 (word-alignment), and
1003 8 (rows start on double-word boundaries).
1004 </para>
1005 </listitem>
1006 </varlistentry>
1007 </variablelist>
1008 <para>
1009 The following table gives the type,
1010 initial value,
1011 and range of valid values for each storage parameter
1012 that can be set with <function>glPixelStore</function>.
1013 </para>
1014 <para>
1015 </para>
1016 <informaltable frame="topbot">
1017 <tgroup cols="4" align="left">
1018 <colspec colwidth="2.5*" />
1019 <colspec colwidth="1*" align="center"/>
1020 <colspec colwidth="1*" align="center"/>
1021 <colspec colwidth="2*" align="center"/>
1022 <thead>
1023 <row>
1024 <entry rowsep="1" align="left"><emphasis role="bold">
1025 <parameter>pname</parameter>
1026 </emphasis></entry>
1027 <entry rowsep="1" align="center"><emphasis role="bold">
1028 Type
1029 </emphasis></entry>
1030 <entry rowsep="1" align="center"><emphasis role="bold">
1031 Initial Value
1032 </emphasis></entry>
1033 <entry rowsep="1" align="center"><emphasis role="bold">
1034 Valid Range
1035 </emphasis></entry>
1036 </row>
1037 </thead>
1038 <tbody>
1039 <row>
1040 <entry align="left">
1041 <constant>GL_PACK_SWAP_BYTES</constant>
1042 </entry>
1043 <entry align="center">
1044 boolean
1045 </entry>
1046 <entry align="center">
1047 false
1048 </entry>
1049 <entry align="center">
1050 true or false
1051 </entry>
1052 </row>
1053 <row>
1054 <entry align="left">
1055 <constant>GL_PACK_LSB_FIRST</constant>
1056 </entry>
1057 <entry align="center">
1058 boolean
1059 </entry>
1060 <entry align="center">
1061 false
1062 </entry>
1063 <entry align="center">
1064 true or false
1065 </entry>
1066 </row>
1067 <row>
1068 <entry align="left">
1069 <constant>GL_PACK_ROW_LENGTH</constant>
1070 </entry>
1071 <entry align="center">
1072 integer
1073 </entry>
1074 <entry align="center">
1075 0
1076 </entry>
1077 <entry align="center">
1078 <inlineequation><mml:math>
1079 <!-- eqn: left [ 0,\(if right ): -->
1080 <mml:mfenced open="[" close=")">
1081 <mml:mn>0</mml:mn>
1082 <mml:infinity/>
1083 </mml:mfenced>
1084 </mml:math></inlineequation>
1085 </entry>
1086 </row>
1087 <row>
1088 <entry align="left">
1089 <constant>GL_PACK_IMAGE_HEIGHT</constant>
1090 </entry>
1091 <entry align="center">
1092 integer
1093 </entry>
1094 <entry align="center">
1095 0
1096 </entry>
1097 <entry align="center">
1098 <inlineequation><mml:math>
1099 <!-- eqn: left [ 0, \(if right ): -->
1100 <mml:mfenced open="[" close=")">
1101 <mml:mn>0</mml:mn>
1102 <mml:infinity/>
1103 </mml:mfenced>
1104 </mml:math></inlineequation>
1105 </entry>
1106 </row>
1107 <row>
1108 <entry align="left">
1109 <constant>GL_PACK_SKIP_ROWS</constant>
1110 </entry>
1111 <entry align="center">
1112 integer
1113 </entry>
1114 <entry align="center">
1115 0
1116 </entry>
1117 <entry align="center">
1118 <inlineequation><mml:math>
1119 <!-- eqn: left [ 0,\(if right ): -->
1120 <mml:mfenced open="[" close=")">
1121 <mml:mn>0</mml:mn>
1122 <mml:infinity/>
1123 </mml:mfenced>
1124 </mml:math></inlineequation>
1125 </entry>
1126 </row>
1127 <row>
1128 <entry align="left">
1129 <constant>GL_PACK_SKIP_PIXELS</constant>
1130 </entry>
1131 <entry align="center">
1132 integer
1133 </entry>
1134 <entry align="center">
1135 0
1136 </entry>
1137 <entry align="center">
1138 <inlineequation><mml:math>
1139 <!-- eqn: left [ 0,\(if right ): -->
1140 <mml:mfenced open="[" close=")">
1141 <mml:mn>0</mml:mn>
1142 <mml:infinity/>
1143 </mml:mfenced>
1144 </mml:math></inlineequation>
1145 </entry>
1146 </row>
1147 <row>
1148 <entry align="left">
1149 <constant>GL_PACK_SKIP_IMAGES</constant>
1150 </entry>
1151 <entry align="center">
1152 integer
1153 </entry>
1154 <entry align="center">
1155 0
1156 </entry>
1157 <entry align="center">
1158 <inlineequation><mml:math>
1159 <!-- eqn: left [ 0,\(if right ): -->
1160 <mml:mfenced open="[" close=")">
1161 <mml:mn>0</mml:mn>
1162 <mml:infinity/>
1163 </mml:mfenced>
1164 </mml:math></inlineequation>
1165 </entry>
1166 </row>
1167 <row>
1168 <entry align="left">
1169 <constant>GL_PACK_ALIGNMENT</constant>
1170 </entry>
1171 <entry align="center">
1172 integer
1173 </entry>
1174 <entry align="center">
1175 4
1176 </entry>
1177 <entry align="center">
1178 1, 2, 4, or 8
1179 </entry>
1180 </row>
1181 <row>
1182 <entry align="left">
1183 <constant>GL_UNPACK_SWAP_BYTES</constant>
1184 </entry>
1185 <entry align="center">
1186 boolean
1187 </entry>
1188 <entry align="center">
1189 false
1190 </entry>
1191 <entry align="center">
1192 true or false
1193 </entry>
1194 </row>
1195 <row>
1196 <entry align="left">
1197 <constant>GL_UNPACK_LSB_FIRST</constant>
1198 </entry>
1199 <entry align="center">
1200 boolean
1201 </entry>
1202 <entry align="center">
1203 false
1204 </entry>
1205 <entry align="center">
1206 true or false
1207 </entry>
1208 </row>
1209 <row>
1210 <entry align="left">
1211 <constant>GL_UNPACK_ROW_LENGTH</constant>
1212 </entry>
1213 <entry align="center">
1214 integer
1215 </entry>
1216 <entry align="center">
1217 0
1218 </entry>
1219 <entry align="center">
1220 <inlineequation><mml:math>
1221 <!-- eqn: left [ 0,\(if right ): -->
1222 <mml:mfenced open="[" close=")">
1223 <mml:mn>0</mml:mn>
1224 <mml:infinity/>
1225 </mml:mfenced>
1226 </mml:math></inlineequation>
1227 </entry>
1228 </row>
1229 <row>
1230 <entry align="left">
1231 <constant>GL_UNPACK_IMAGE_HEIGHT</constant>
1232 </entry>
1233 <entry align="center">
1234 integer
1235 </entry>
1236 <entry align="center">
1237 0
1238 </entry>
1239 <entry align="center">
1240 <inlineequation><mml:math>
1241 <!-- eqn: left [ 0,\(if right ): -->
1242 <mml:mfenced open="[" close=")">
1243 <mml:mn>0</mml:mn>
1244 <mml:infinity/>
1245 </mml:mfenced>
1246 </mml:math></inlineequation>
1247 </entry>
1248 </row>
1249 <row>
1250 <entry align="left">
1251 <constant>GL_UNPACK_SKIP_ROWS</constant>
1252 </entry>
1253 <entry align="center">
1254 integer
1255 </entry>
1256 <entry align="center">
1257 0
1258 </entry>
1259 <entry align="center">
1260 <inlineequation><mml:math>
1261 <!-- eqn: left [ 0,\(if right ): -->
1262 <mml:mfenced open="[" close=")">
1263 <mml:mn>0</mml:mn>
1264 <mml:infinity/>
1265 </mml:mfenced>
1266 </mml:math></inlineequation>
1267 </entry>
1268 </row>
1269 <row>
1270 <entry align="left">
1271 <constant>GL_UNPACK_SKIP_PIXELS</constant>
1272 </entry>
1273 <entry align="center">
1274 integer
1275 </entry>
1276 <entry align="center">
1277 0
1278 </entry>
1279 <entry align="center">
1280 <inlineequation><mml:math>
1281 <!-- eqn: left [ 0,\(if right ): -->
1282 <mml:mfenced open="[" close=")">
1283 <mml:mn>0</mml:mn>
1284 <mml:infinity/>
1285 </mml:mfenced>
1286 </mml:math></inlineequation>
1287 </entry>
1288 </row>
1289 <row>
1290 <entry align="left">
1291 <constant>GL_UNPACK_SKIP_IMAGES</constant>
1292 </entry>
1293 <entry align="center">
1294 integer
1295 </entry>
1296 <entry align="center">
1297 0
1298 </entry>
1299 <entry align="center">
1300 <inlineequation><mml:math>
1301 <!-- eqn: left [ 0,\(if right ): -->
1302 <mml:mfenced open="[" close=")">
1303 <mml:mn>0</mml:mn>
1304 <mml:infinity/>
1305 </mml:mfenced>
1306 </mml:math></inlineequation>
1307 </entry>
1308 </row>
1309 <row>
1310 <entry align="left">
1311 <constant>GL_UNPACK_ALIGNMENT</constant>
1312 </entry>
1313 <entry align="center">
1314 integer
1315 </entry>
1316 <entry align="center">
1317 4
1318 </entry>
1319 <entry align="center">
1320 1, 2, 4, or 8
1321 </entry>
1322 </row>
1323 </tbody>
1324 </tgroup>
1325 </informaltable>
1326 <para>
1327 <function>glPixelStoref</function> can be used to set any pixel store parameter.
1328 If the parameter type is boolean,
1329 then if <parameter>param</parameter> is 0,
1330 the parameter is false;
1331 otherwise it is set to true.
1332 If <parameter>pname</parameter> is a integer type parameter,
1333 <parameter>param</parameter> is rounded to the nearest integer.
1334 </para>
1335 <para>
1336 Likewise, <function>glPixelStorei</function> can also be used to set any of the
1337 pixel store parameters.
1338 Boolean parameters are set to false if <parameter>param</parameter> is 0 and true otherwise.
1339 </para>
1340 </refsect1>
1341 <refsect1 id="errors"><title>Errors</title>
1342 <para>
1343 <constant>GL_INVALID_ENUM</constant> is generated if <parameter>pname</parameter> is not an accepted value.
1344 </para>
1345 <para>
1346 <constant>GL_INVALID_VALUE</constant> is generated if a negative row length,
1347 pixel skip,
1348 or row skip value is specified,
1349 or if alignment is specified as other than 1, 2, 4, or 8.
1350 </para>
1351 </refsect1>
1352 <refsect1 id="associatedgets"><title>Associated Gets</title>
1353 <para>
1354 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_SWAP_BYTES</constant>
1355 </para>
1356 <para>
1357 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_LSB_FIRST</constant>
1358 </para>
1359 <para>
1360 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_ROW_LENGTH</constant>
1361 </para>
1362 <para>
1363 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_IMAGE_HEIGHT</constant>
1364 </para>
1365 <para>
1366 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_SKIP_ROWS</constant>
1367 </para>
1368 <para>
1369 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_SKIP_PIXELS</constant>
1370 </para>
1371 <para>
1372 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_SKIP_IMAGES</constant>
1373 </para>
1374 <para>
1375 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PACK_ALIGNMENT</constant>
1376 </para>
1377 <para>
1378 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_SWAP_BYTES</constant>
1379 </para>
1380 <para>
1381 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_LSB_FIRST</constant>
1382 </para>
1383 <para>
1384 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_ROW_LENGTH</constant>
1385 </para>
1386 <para>
1387 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_IMAGE_HEIGHT</constant>
1388 </para>
1389 <para>
1390 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_SKIP_ROWS</constant>
1391 </para>
1392 <para>
1393 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_SKIP_PIXELS</constant>
1394 </para>
1395 <para>
1396 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_SKIP_IMAGES</constant>
1397 </para>
1398 <para>
1399 <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_UNPACK_ALIGNMENT</constant>
1400 </para>
1401 </refsect1>
1402 <refsect1 id="seealso"><title>See Also</title>
1403 <para>
1404 <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>,
1405 <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
1406 <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
1407 <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
1408 <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
1409 <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>,
1410 <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>,
1411 <citerefentry><refentrytitle>glCompressedTexImage1D</refentrytitle></citerefentry>,
1412 <citerefentry><refentrytitle>glCompressedTexImage2D</refentrytitle></citerefentry>,
1413 <citerefentry><refentrytitle>glCompressedTexImage3D</refentrytitle></citerefentry>,
1414 <citerefentry><refentrytitle>glCompressedTexSubImage1D</refentrytitle></citerefentry>,
1415 <citerefentry><refentrytitle>glCompressedTexSubImage2D</refentrytitle></citerefentry>,
1416 <citerefentry><refentrytitle>glCompressedTexSubImage1D</refentrytitle></citerefentry>.
1417 </para>
1418 </refsect1>
1419 <refsect1 id="Copyright"><title>Copyright</title>
1420 <para>
1421 Copyright <trademark class="copyright"></trademark> 1991-2006
1422 Silicon Graphics, Inc. <trademark class="copyright"></trademark> 2011
1423 Khronos Group. This document is licensed under the SGI
1424 Free Software B License. For details, see
1425 <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
1426 </para>
1427 </refsect1>
1428 </refentry>
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