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AW		 1<?xml version="1.0" encoding="UTF-8"?>
2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
3<!-- saved from url=(0013)about:internet -->
c7b31271 4<?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="stylesheet" type="text/css" href="opengl-man.css" /><title>glReadPixels - OpenGL 3.3 Reference Pages</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glReadPixels"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glReadPixels — read a block of pixels from the frame buffer</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glReadPixels</b>(</code></td><td>GLint  </td><td><var class="pdparam">x</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">y</var>, </td></tr><tr><td> </td><td>GLsizei  </td><td><var class="pdparam">width</var>, </td></tr><tr><td> </td><td>GLsizei  </td><td><var class="pdparam">height</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">format</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">type</var>, </td></tr><tr><td> </td><td>GLvoid *  </td><td><var class="pdparam">data</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>x</code></em>, </span><span class="term"><em class="parameter"><code>y</code></em></span></dt><dd><p>
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AW		 5 Specify the window coordinates of the first pixel
6 that is read from the frame buffer.
7 This location is the lower left corner of a rectangular block of pixels.
8 </p></dd><dt><span class="term"><em class="parameter"><code>width</code></em>, </span><span class="term"><em class="parameter"><code>height</code></em></span></dt><dd><p>
9 Specify the dimensions of the pixel rectangle.
10 <em class="parameter"><code>width</code></em> and <em class="parameter"><code>height</code></em> of one correspond to a single pixel.
11 </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
12 Specifies the format of the pixel data.
13 The following symbolic values are accepted:
14 <code class="constant">GL_STENCIL_INDEX</code>,
15 <code class="constant">GL_DEPTH_COMPONENT</code>,
16 <code class="constant">GL_DEPTH_STENCIL</code>,
17 <code class="constant">GL_RED</code>,
18 <code class="constant">GL_GREEN</code>,
19 <code class="constant">GL_BLUE</code>,
20 <code class="constant">GL_RGB</code>,
21 <code class="constant">GL_BGR</code>,
22 <code class="constant">GL_RGBA</code>, and
23 <code class="constant">GL_BGRA</code>.
24 </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
25 Specifies the data type of the pixel data.
26 Must be one of
27 <code class="constant">GL_UNSIGNED_BYTE</code>,
28 <code class="constant">GL_BYTE</code>,
29 <code class="constant">GL_UNSIGNED_SHORT</code>,
30 <code class="constant">GL_SHORT</code>,
31 <code class="constant">GL_UNSIGNED_INT</code>,
32 <code class="constant">GL_INT</code>,
33 <code class="constant">GL_HALF_FLOAT</code>,
34 <code class="constant">GL_FLOAT</code>,
35 <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
36 <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
37 <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
38 <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
39 <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
40 <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
41 <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
42 <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
43 <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
44 <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
45 <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>,
46 <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>,
47 <code class="constant">GL_UNSIGNED_INT_24_8</code>,
48 <code class="constant">GL_UNSIGNED_INT_10F_11F_11F_REV</code>,
49 <code class="constant">GL_UNSIGNED_INT_5_9_9_9_REV</code>, or
50 <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>.
51 </p></dd><dt><span class="term"><em class="parameter"><code>data</code></em></span></dt><dd><p>
52 Returns the pixel data.
c7b31271 53 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
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AW		 54 <code class="function">glReadPixels</code> returns pixel data from the frame buffer,
55 starting with the pixel whose lower left corner
56 is at location (<em class="parameter"><code>x</code></em>, <em class="parameter"><code>y</code></em>),
57 into client memory starting at location <em class="parameter"><code>data</code></em>.
58 Several parameters control the processing of the pixel data before
59 it is placed into client memory.
c7b31271 60 These parameters are set with <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>.
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AW		 61 This reference page describes the effects on <code class="function">glReadPixels</code> of most,
62 but not all of the parameters specified by these three commands.
63 </p><p>
64 If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target
c7b31271 65 (see <a href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a block of pixels is
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AW		 66 requested, <em class="parameter"><code>data</code></em> is treated as a byte offset into the buffer object's data store
67 rather than a pointer to client memory.
68 </p><p>
69 <code class="function">glReadPixels</code> returns values from each pixel with lower left corner at
70 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
71
72 <mml:mfenced open="(" close=")">
73 <mml:mrow>
74 <mml:mi mathvariant="italic">x</mml:mi>
75 <mml:mo>+</mml:mo>
76 <mml:mi mathvariant="italic">i</mml:mi>
77 </mml:mrow>
78 <mml:mrow>
79 <mml:mi mathvariant="italic">y</mml:mi>
80 <mml:mo>+</mml:mo>
81 <mml:mi mathvariant="italic">j</mml:mi>
82 </mml:mrow>
83 </mml:mfenced>
84 </mml:math>
85 for
86 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
87
88 <mml:mrow>
89 <mml:mn>0</mml:mn>
90 <mml:mo>&lt;=</mml:mo>
91 <mml:mi mathvariant="italic">i</mml:mi>
92 <mml:mo>&lt;</mml:mo>
93 <mml:mi mathvariant="italic">width</mml:mi>
94 </mml:mrow>
95 </mml:math>
96 and
97 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
98
99 <mml:mrow>
100 <mml:mn>0</mml:mn>
101 <mml:mo>&lt;=</mml:mo>
102 <mml:mi mathvariant="italic">j</mml:mi>
103 <mml:mo>&lt;</mml:mo>
104 <mml:mi mathvariant="italic">height</mml:mi>
105 </mml:mrow>
106 </mml:math>.
107 This pixel is said to be the
108 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>th
109 pixel in the
110 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>th
111 row.
112 Pixels are returned in row order from the lowest to the highest row,
113 left to right in each row.
114 </p><p>
115 <em class="parameter"><code>format</code></em> specifies the format for the returned pixel values;
116 accepted values are:
117 </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_STENCIL_INDEX</code></span></dt><dd><p>
118 Stencil values are read from the stencil buffer.
c7b31271 119 Each index is converted to fixed point.
7faf1d71
AW		 120 </p></dd><dt><span class="term"><code class="constant">GL_DEPTH_COMPONENT</code></span></dt><dd><p>
121 Depth values are read from the depth buffer.
122 Each component is converted to floating point such that the minimum depth
123 value maps to 0 and the maximum value maps to 1.
c7b31271 124 Each component is clamped to the range
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AW		 125 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
126
127 <mml:mfenced open="[" close="]">
128 <mml:mn>0</mml:mn>
129 <mml:mn>1</mml:mn>
130 </mml:mfenced>
131 </mml:math>.
132 </p></dd><dt><span class="term"><code class="constant">GL_DEPTH_STENCIL</code></span></dt><dd><p>
133 Values are taken from both the depth and stencil buffers. The <em class="parameter"><code>type</code></em> parameter
134 must be <code class="constant">GL_UNSIGNED_INT_24_8</code> or <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>.
135 </p></dd><dt><span class="term"><code class="constant">GL_RED</code></span></dt><dd></dd><dt><span class="term"><code class="constant">GL_GREEN</code></span></dt><dd></dd><dt><span class="term"><code class="constant">GL_BLUE</code></span></dt><dd></dd><dt><span class="term"><code class="constant">GL_RGB</code></span></dt><dd></dd><dt><span class="term"><code class="constant">GL_BGR</code></span></dt><dd></dd><dt><span class="term"><code class="constant">GL_RGBA</code></span></dt><dd></dd><dt><span class="term"><code class="constant">GL_BGRA</code></span></dt><dd></dd></dl></div><p>
136 Finally, the indices or components
137 are converted to the proper format,
138 as specified by <em class="parameter"><code>type</code></em>.
139 If <em class="parameter"><code>format</code></em> is <code class="constant">GL_STENCIL_INDEX</code>
140 and <em class="parameter"><code>type</code></em> is not <code class="constant">GL_FLOAT</code>,
141 each index is masked with the mask value given in the following table.
142 If <em class="parameter"><code>type</code></em> is <code class="constant">GL_FLOAT</code>, then each integer index is converted to
143 single-precision floating-point format.
144 </p><p>
145 If <em class="parameter"><code>format</code></em> is
146 <code class="constant">GL_RED</code>,
147 <code class="constant">GL_GREEN</code>,
148 <code class="constant">GL_BLUE</code>,
149 <code class="constant">GL_RGB</code>,
150 <code class="constant">GL_BGR</code>,
151 <code class="constant">GL_RGBA</code>, or
152 <code class="constant">GL_BGRA</code> and <em class="parameter"><code>type</code></em> is not <code class="constant">GL_FLOAT</code>,
153 each component is multiplied by the multiplier shown in the following table.
154 If type is <code class="constant">GL_FLOAT</code>, then each component is passed as is
155 (or converted to the client's single-precision floating-point format if
156 it is different from the one used by the GL).
157 </p><p>
158 </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left">
159 <em class="parameter"><code>type</code></em>
160 </th><th align="center"><span class="bold"><strong>
161 Index Mask
162 </strong></span></th><th align="center"><span class="bold"><strong>
163 Component Conversion
164 </strong></span></th></tr></thead><tbody><tr><td align="left">
165 <code class="constant">GL_UNSIGNED_BYTE</code>
166 </td><td align="center">
167 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
168
169 <mml:mrow>
170 <mml:msup><mml:mn>2</mml:mn>
171 <mml:mn>8</mml:mn>
172 </mml:msup>
173 <mml:mo>-</mml:mo>
174 <mml:mn>1</mml:mn>
175 </mml:mrow>
176 </mml:math>
177 </td><td align="center">
178 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
179
180 <mml:mrow>
181 <mml:mfenced open="(" close=")">
182 <mml:mrow>
183 <mml:msup><mml:mn>2</mml:mn>
184 <mml:mn>8</mml:mn>
185 </mml:msup>
186 <mml:mo>-</mml:mo>
187 <mml:mn>1</mml:mn>
188 </mml:mrow>
189 </mml:mfenced>
190 <mml:mo>⁢</mml:mo>
191 <mml:mi mathvariant="italic">c</mml:mi>
192 </mml:mrow>
193 </mml:math>
194 </td></tr><tr><td align="left">
195 <code class="constant">GL_BYTE</code>
196 </td><td align="center">
197 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
198
199 <mml:mrow>
200 <mml:msup><mml:mn>2</mml:mn>
201 <mml:mn>7</mml:mn>
202 </mml:msup>
203 <mml:mo>-</mml:mo>
204 <mml:mn>1</mml:mn>
205 </mml:mrow>
206 </mml:math>
207 </td><td align="center">
208 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
209
210 <mml:mfrac>
211 <mml:mfenced open="" close="">
212 <mml:mrow>
213 <mml:mfenced open="(" close=")">
214 <mml:mrow>
215 <mml:msup><mml:mn>2</mml:mn>
216 <mml:mn>8</mml:mn>
217 </mml:msup>
218 <mml:mo>-</mml:mo>
219 <mml:mn>1</mml:mn>
220 </mml:mrow>
221 </mml:mfenced>
222 <mml:mo>⁢</mml:mo>
223 <mml:mi mathvariant="italic">c</mml:mi>
224 <mml:mo>-</mml:mo>
225 <mml:mn>1</mml:mn>
226 </mml:mrow>
227 </mml:mfenced>
228 <mml:mn>2</mml:mn>
229 </mml:mfrac>
230 </mml:math>
231 </td></tr><tr><td align="left">
232 <code class="constant">GL_UNSIGNED_SHORT</code>
233 </td><td align="center">
234 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
235
236 <mml:mrow>
237 <mml:msup><mml:mn>2</mml:mn>
238 <mml:mn>16</mml:mn>
239 </mml:msup>
240 <mml:mo>-</mml:mo>
241 <mml:mn>1</mml:mn>
242 </mml:mrow>
243 </mml:math>
244 </td><td align="center">
245 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
246
247 <mml:mrow>
248 <mml:mfenced open="(" close=")">
249 <mml:mrow>
250 <mml:msup><mml:mn>2</mml:mn>
251 <mml:mn>16</mml:mn>
252 </mml:msup>
253 <mml:mo>-</mml:mo>
254 <mml:mn>1</mml:mn>
255 </mml:mrow>
256 </mml:mfenced>
257 <mml:mo>⁢</mml:mo>
258 <mml:mi mathvariant="italic">c</mml:mi>
259 </mml:mrow>
260 </mml:math>
261 </td></tr><tr><td align="left">
262 <code class="constant">GL_SHORT</code>
263 </td><td align="center">
264 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
265
266 <mml:mrow>
267 <mml:msup><mml:mn>2</mml:mn>
268 <mml:mn>15</mml:mn>
269 </mml:msup>
270 <mml:mo>-</mml:mo>
271 <mml:mn>1</mml:mn>
272 </mml:mrow>
273 </mml:math>
274 </td><td align="center">
275 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
276
277 <mml:mfrac>
278 <mml:mfenced open="" close="">
279 <mml:mrow>
280 <mml:mfenced open="(" close=")">
281 <mml:mrow>
282 <mml:msup><mml:mn>2</mml:mn>
283 <mml:mn>16</mml:mn>
284 </mml:msup>
285 <mml:mo>-</mml:mo>
286 <mml:mn>1</mml:mn>
287 </mml:mrow>
288 </mml:mfenced>
289 <mml:mo>⁢</mml:mo>
290 <mml:mi mathvariant="italic">c</mml:mi>
291 <mml:mo>-</mml:mo>
292 <mml:mn>1</mml:mn>
293 </mml:mrow>
294 </mml:mfenced>
295 <mml:mn>2</mml:mn>
296 </mml:mfrac>
297 </mml:math>
298 </td></tr><tr><td align="left">
299 <code class="constant">GL_UNSIGNED_INT</code>
300 </td><td align="center">
301 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
302
303 <mml:mrow>
304 <mml:msup><mml:mn>2</mml:mn>
305 <mml:mn>32</mml:mn>
306 </mml:msup>
307 <mml:mo>-</mml:mo>
308 <mml:mn>1</mml:mn>
309 </mml:mrow>
310 </mml:math>
311 </td><td align="center">
312 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
313
314 <mml:mrow>
315 <mml:mfenced open="(" close=")">
316 <mml:mrow>
317 <mml:msup><mml:mn>2</mml:mn>
318 <mml:mn>32</mml:mn>
319 </mml:msup>
320 <mml:mo>-</mml:mo>
321 <mml:mn>1</mml:mn>
322 </mml:mrow>
323 </mml:mfenced>
324 <mml:mo>⁢</mml:mo>
325 <mml:mi mathvariant="italic">c</mml:mi>
326 </mml:mrow>
327 </mml:math>
328 </td></tr><tr><td align="left">
329 <code class="constant">GL_INT</code>
330 </td><td align="center">
331 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
332
333 <mml:mrow>
334 <mml:msup><mml:mn>2</mml:mn>
335 <mml:mn>31</mml:mn>
336 </mml:msup>
337 <mml:mo>-</mml:mo>
338 <mml:mn>1</mml:mn>
339 </mml:mrow>
340 </mml:math>
341 </td><td align="center">
342 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
343
344 <mml:mfrac>
345 <mml:mfenced open="" close="">
346 <mml:mrow>
347 <mml:mfenced open="(" close=")">
348 <mml:mrow>
349 <mml:msup><mml:mn>2</mml:mn>
350 <mml:mn>32</mml:mn>
351 </mml:msup>
352 <mml:mo>-</mml:mo>
353 <mml:mn>1</mml:mn>
354 </mml:mrow>
355 </mml:mfenced>
356 <mml:mo>⁢</mml:mo>
357 <mml:mi mathvariant="italic">c</mml:mi>
358 <mml:mo>-</mml:mo>
359 <mml:mn>1</mml:mn>
360 </mml:mrow>
361 </mml:mfenced>
362 <mml:mn>2</mml:mn>
363 </mml:mfrac>
364 </mml:math>
365 </td></tr><tr><td align="left">
366 <code class="constant">GL_HALF_FLOAT</code>
367 </td><td align="center">
368 none
369 </td><td align="center">
370 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">c</mml:mi></mml:math>
371 </td></tr><tr><td align="left">
372 <code class="constant">GL_FLOAT</code>
373 </td><td align="center">
374 none
375 </td><td align="center">
376 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">c</mml:mi></mml:math>
377 </td></tr><tr><td align="left">
378 <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>
379 </td><td align="center">
380 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
381
382 <mml:mrow>
383 <mml:msup><mml:mn>2</mml:mn>
384 <mml:mn>N</mml:mn>
385 </mml:msup>
386 <mml:mo>-</mml:mo>
387 <mml:mn>1</mml:mn>
388 </mml:mrow>
389 </mml:math>
390 </td><td align="center">
391 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
392
393 <mml:mrow>
394 <mml:mfenced open="(" close=")">
395 <mml:mrow>
396 <mml:msup><mml:mn>2</mml:mn>
397 <mml:mn>N</mml:mn>
398 </mml:msup>
399 <mml:mo>-</mml:mo>
400 <mml:mn>1</mml:mn>
401 </mml:mrow>
402 </mml:mfenced>
403 <mml:mo>⁢</mml:mo>
404 <mml:mi mathvariant="italic">c</mml:mi>
405 </mml:mrow>
406 </mml:math>
407 </td></tr><tr><td align="left">
408 <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>
409 </td><td align="center">
410 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
411
412 <mml:mrow>
413 <mml:msup><mml:mn>2</mml:mn>
414 <mml:mn>N</mml:mn>
415 </mml:msup>
416 <mml:mo>-</mml:mo>
417 <mml:mn>1</mml:mn>
418 </mml:mrow>
419 </mml:math>
420 </td><td align="center">
421 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
422
423 <mml:mrow>
424 <mml:mfenced open="(" close=")">
425 <mml:mrow>
426 <mml:msup><mml:mn>2</mml:mn>
427 <mml:mn>N</mml:mn>
428 </mml:msup>
429 <mml:mo>-</mml:mo>
430 <mml:mn>1</mml:mn>
431 </mml:mrow>
432 </mml:mfenced>
433 <mml:mo>⁢</mml:mo>
434 <mml:mi mathvariant="italic">c</mml:mi>
435 </mml:mrow>
436 </mml:math>
437 </td></tr><tr><td align="left">
438 <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>
439 </td><td align="center">
440 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
441
442 <mml:mrow>
443 <mml:msup><mml:mn>2</mml:mn>
444 <mml:mn>N</mml:mn>
445 </mml:msup>
446 <mml:mo>-</mml:mo>
447 <mml:mn>1</mml:mn>
448 </mml:mrow>
449 </mml:math>
450 </td><td align="center">
451 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
452
453 <mml:mrow>
454 <mml:mfenced open="(" close=")">
455 <mml:mrow>
456 <mml:msup><mml:mn>2</mml:mn>
457 <mml:mn>N</mml:mn>
458 </mml:msup>
459 <mml:mo>-</mml:mo>
460 <mml:mn>1</mml:mn>
461 </mml:mrow>
462 </mml:mfenced>
463 <mml:mo>⁢</mml:mo>
464 <mml:mi mathvariant="italic">c</mml:mi>
465 </mml:mrow>
466 </mml:math>
467 </td></tr><tr><td align="left">
468 <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
469 </td><td align="center">
470 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
471
472 <mml:mrow>
473 <mml:msup><mml:mn>2</mml:mn>
474 <mml:mn>N</mml:mn>
475 </mml:msup>
476 <mml:mo>-</mml:mo>
477 <mml:mn>1</mml:mn>
478 </mml:mrow>
479 </mml:math>
480 </td><td align="center">
481 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
482
483 <mml:mrow>
484 <mml:mfenced open="(" close=")">
485 <mml:mrow>
486 <mml:msup><mml:mn>2</mml:mn>
487 <mml:mn>N</mml:mn>
488 </mml:msup>
489 <mml:mo>-</mml:mo>
490 <mml:mn>1</mml:mn>
491 </mml:mrow>
492 </mml:mfenced>
493 <mml:mo>⁢</mml:mo>
494 <mml:mi mathvariant="italic">c</mml:mi>
495 </mml:mrow>
496 </mml:math>
497 </td></tr><tr><td align="left">
498 <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>
499 </td><td align="center">
500 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
501
502 <mml:mrow>
503 <mml:msup><mml:mn>2</mml:mn>
504 <mml:mn>N</mml:mn>
505 </mml:msup>
506 <mml:mo>-</mml:mo>
507 <mml:mn>1</mml:mn>
508 </mml:mrow>
509 </mml:math>
510 </td><td align="center">
511 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
512
513 <mml:mrow>
514 <mml:mfenced open="(" close=")">
515 <mml:mrow>
516 <mml:msup><mml:mn>2</mml:mn>
517 <mml:mn>N</mml:mn>
518 </mml:msup>
519 <mml:mo>-</mml:mo>
520 <mml:mn>1</mml:mn>
521 </mml:mrow>
522 </mml:mfenced>
523 <mml:mo>⁢</mml:mo>
524 <mml:mi mathvariant="italic">c</mml:mi>
525 </mml:mrow>
526 </mml:math>
527 </td></tr><tr><td align="left">
528 <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>
529 </td><td align="center">
530 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
531
532 <mml:mrow>
533 <mml:msup><mml:mn>2</mml:mn>
534 <mml:mn>N</mml:mn>
535 </mml:msup>
536 <mml:mo>-</mml:mo>
537 <mml:mn>1</mml:mn>
538 </mml:mrow>
539 </mml:math>
540 </td><td align="center">
541 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
542
543 <mml:mrow>
544 <mml:mfenced open="(" close=")">
545 <mml:mrow>
546 <mml:msup><mml:mn>2</mml:mn>
547 <mml:mn>N</mml:mn>
548 </mml:msup>
549 <mml:mo>-</mml:mo>
550 <mml:mn>1</mml:mn>
551 </mml:mrow>
552 </mml:mfenced>
553 <mml:mo>⁢</mml:mo>
554 <mml:mi mathvariant="italic">c</mml:mi>
555 </mml:mrow>
556 </mml:math>
557 </td></tr><tr><td align="left">
558 <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>
559 </td><td align="center">
560 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
561
562 <mml:mrow>
563 <mml:msup><mml:mn>2</mml:mn>
564 <mml:mn>N</mml:mn>
565 </mml:msup>
566 <mml:mo>-</mml:mo>
567 <mml:mn>1</mml:mn>
568 </mml:mrow>
569 </mml:math>
570 </td><td align="center">
571 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
572
573 <mml:mrow>
574 <mml:mfenced open="(" close=")">
575 <mml:mrow>
576 <mml:msup><mml:mn>2</mml:mn>
577 <mml:mn>N</mml:mn>
578 </mml:msup>
579 <mml:mo>-</mml:mo>
580 <mml:mn>1</mml:mn>
581 </mml:mrow>
582 </mml:mfenced>
583 <mml:mo>⁢</mml:mo>
584 <mml:mi mathvariant="italic">c</mml:mi>
585 </mml:mrow>
586 </mml:math>
587 </td></tr><tr><td align="left">
588 <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>
589 </td><td align="center">
590 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
591
592 <mml:mrow>
593 <mml:msup><mml:mn>2</mml:mn>
594 <mml:mn>N</mml:mn>
595 </mml:msup>
596 <mml:mo>-</mml:mo>
597 <mml:mn>1</mml:mn>
598 </mml:mrow>
599 </mml:math>
600 </td><td align="center">
601 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
602
603 <mml:mrow>
604 <mml:mfenced open="(" close=")">
605 <mml:mrow>
606 <mml:msup><mml:mn>2</mml:mn>
607 <mml:mn>N</mml:mn>
608 </mml:msup>
609 <mml:mo>-</mml:mo>
610 <mml:mn>1</mml:mn>
611 </mml:mrow>
612 </mml:mfenced>
613 <mml:mo>⁢</mml:mo>
614 <mml:mi mathvariant="italic">c</mml:mi>
615 </mml:mrow>
616 </mml:math>
617 </td></tr><tr><td align="left">
618 <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>
619 </td><td align="center">
620 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
621
622 <mml:mrow>
623 <mml:msup><mml:mn>2</mml:mn>
624 <mml:mn>N</mml:mn>
625 </mml:msup>
626 <mml:mo>-</mml:mo>
627 <mml:mn>1</mml:mn>
628 </mml:mrow>
629 </mml:math>
630 </td><td align="center">
631 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
632
633 <mml:mrow>
634 <mml:mfenced open="(" close=")">
635 <mml:mrow>
636 <mml:msup><mml:mn>2</mml:mn>
637 <mml:mn>N</mml:mn>
638 </mml:msup>
639 <mml:mo>-</mml:mo>
640 <mml:mn>1</mml:mn>
641 </mml:mrow>
642 </mml:mfenced>
643 <mml:mo>⁢</mml:mo>
644 <mml:mi mathvariant="italic">c</mml:mi>
645 </mml:mrow>
646 </mml:math>
647 </td></tr><tr><td align="left">
648 <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>
649 </td><td align="center">
650 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
651
652 <mml:mrow>
653 <mml:msup><mml:mn>2</mml:mn>
654 <mml:mn>N</mml:mn>
655 </mml:msup>
656 <mml:mo>-</mml:mo>
657 <mml:mn>1</mml:mn>
658 </mml:mrow>
659 </mml:math>
660 </td><td align="center">
661 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
662
663 <mml:mrow>
664 <mml:mfenced open="(" close=")">
665 <mml:mrow>
666 <mml:msup><mml:mn>2</mml:mn>
667 <mml:mn>N</mml:mn>
668 </mml:msup>
669 <mml:mo>-</mml:mo>
670 <mml:mn>1</mml:mn>
671 </mml:mrow>
672 </mml:mfenced>
673 <mml:mo>⁢</mml:mo>
674 <mml:mi mathvariant="italic">c</mml:mi>
675 </mml:mrow>
676 </mml:math>
677 </td></tr><tr><td align="left">
678 <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>
679 </td><td align="center">
680 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
681
682 <mml:mrow>
683 <mml:msup><mml:mn>2</mml:mn>
684 <mml:mn>N</mml:mn>
685 </mml:msup>
686 <mml:mo>-</mml:mo>
687 <mml:mn>1</mml:mn>
688 </mml:mrow>
689 </mml:math>
690 </td><td align="center">
691 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
692
693 <mml:mrow>
694 <mml:mfenced open="(" close=")">
695 <mml:mrow>
696 <mml:msup><mml:mn>2</mml:mn>
697 <mml:mn>N</mml:mn>
698 </mml:msup>
699 <mml:mo>-</mml:mo>
700 <mml:mn>1</mml:mn>
701 </mml:mrow>
702 </mml:mfenced>
703 <mml:mo>⁢</mml:mo>
704 <mml:mi mathvariant="italic">c</mml:mi>
705 </mml:mrow>
706 </mml:math>
707 </td></tr><tr><td align="left">
708 <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
709 </td><td align="center">
710 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
711
712 <mml:mrow>
713 <mml:msup><mml:mn>2</mml:mn>
714 <mml:mn>N</mml:mn>
715 </mml:msup>
716 <mml:mo>-</mml:mo>
717 <mml:mn>1</mml:mn>
718 </mml:mrow>
719 </mml:math>
720 </td><td align="center">
721 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
722
723 <mml:mrow>
724 <mml:mfenced open="(" close=")">
725 <mml:mrow>
726 <mml:msup><mml:mn>2</mml:mn>
727 <mml:mn>N</mml:mn>
728 </mml:msup>
729 <mml:mo>-</mml:mo>
730 <mml:mn>1</mml:mn>
731 </mml:mrow>
732 </mml:mfenced>
733 <mml:mo>⁢</mml:mo>
734 <mml:mi mathvariant="italic">c</mml:mi>
735 </mml:mrow>
736 </mml:math>
737 </td></tr><tr><td align="left">
738 <code class="constant">GL_UNSIGNED_INT_24_8</code>
739 </td><td align="center">
740 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
741
742 <mml:mrow>
743 <mml:msup><mml:mn>2</mml:mn>
744 <mml:mn>N</mml:mn>
745 </mml:msup>
746 <mml:mo>-</mml:mo>
747 <mml:mn>1</mml:mn>
748 </mml:mrow>
749 </mml:math>
750 </td><td align="center">
751 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
752
753 <mml:mrow>
754 <mml:mfenced open="(" close=")">
755 <mml:mrow>
756 <mml:msup><mml:mn>2</mml:mn>
757 <mml:mn>N</mml:mn>
758 </mml:msup>
759 <mml:mo>-</mml:mo>
760 <mml:mn>1</mml:mn>
761 </mml:mrow>
762 </mml:mfenced>
763 <mml:mo>⁢</mml:mo>
764 <mml:mi mathvariant="italic">c</mml:mi>
765 </mml:mrow>
766 </mml:math>
767 </td></tr><tr><td align="left">
768 <code class="constant">GL_UNSIGNED_INT_10F_11F_11F_REV</code>
769 </td><td align="center">
770 --
771 </td><td align="left">
772 Special
773 </td></tr><tr><td align="left">
774 <code class="constant">GL_UNSIGNED_INT_5_9_9_9_REV</code>
775 </td><td align="center">
776 --
777 </td><td align="left">
778 Special
779 </td></tr><tr><td align="left">
780 <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>
781 </td><td align="center">
782 none
783 </td><td align="center">
784 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">c</mml:mi></mml:math> (Depth Only)
785 </td></tr></tbody></table></div><p>
786 Return values are placed in memory as follows.
787 If <em class="parameter"><code>format</code></em> is
788 <code class="constant">GL_STENCIL_INDEX</code>,
789 <code class="constant">GL_DEPTH_COMPONENT</code>,
790 <code class="constant">GL_RED</code>,
791 <code class="constant">GL_GREEN</code>, or
792 <code class="constant">GL_BLUE</code>,
793 a single value is returned and the data for the
794 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>th
795 pixel in the
796 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>th
797 row
798 is placed in location
799 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
800
801 <mml:mrow>
802 <mml:mfenced open="(" close=")">
803 <mml:mi mathvariant="italic">j</mml:mi>
804 </mml:mfenced>
805 <mml:mo>⁢</mml:mo>
806 <mml:mi mathvariant="italic">width</mml:mi>
807 <mml:mo>+</mml:mo>
808 <mml:mi mathvariant="italic">i</mml:mi>
809 </mml:mrow>
810 </mml:math>.
811 <code class="constant">GL_RGB</code> and <code class="constant">GL_BGR</code> return three values,
812 <code class="constant">GL_RGBA</code> and <code class="constant">GL_BGRA</code> return four values for each pixel,
813 with all values corresponding to a single pixel occupying contiguous space
814 in <em class="parameter"><code>data</code></em>.
c7b31271 815 Storage parameters set by <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>,
7faf1d71
AW		 816 such as <code class="constant">GL_PACK_LSB_FIRST</code> and <code class="constant">GL_PACK_SWAP_BYTES</code>,
817 affect the way that data is written into memory.
c7b31271
DH		 818 See <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a> for a description.
819 </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
7faf1d71
AW		 820 Values for pixels that lie outside the window
821 connected to the current GL context are undefined.
822 </p><p>
823 If an error is generated,
824 no change is made to the contents of <em class="parameter"><code>data</code></em>.
c7b31271 825 </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
7faf1d71
AW		 826 <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> or <em class="parameter"><code>type</code></em> is not an
827 accepted value.
828 </p><p>
829 <code class="constant">GL_INVALID_VALUE</code> is generated if either <em class="parameter"><code>width</code></em> or <em class="parameter"><code>height</code></em> is negative.
830 </p><p>
831 <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>format</code></em> is <code class="constant">GL_STENCIL_INDEX</code>
832 and there is no stencil buffer.
833 </p><p>
834 <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>format</code></em> is <code class="constant">GL_DEPTH_COMPONENT</code>
835 and there is no depth buffer.
836 </p><p>
837 <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>format</code></em> is <code class="constant">GL_DEPTH_STENCIL</code>
838 and there is no depth buffer or if there is no stencil buffer.
839 </p><p>
840 <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> is <code class="constant">GL_DEPTH_STENCIL</code>
841 and <em class="parameter"><code>type</code></em> is not <code class="constant">GL_UNSIGNED_INT_24_8</code> or <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>.
842 </p><p>
843 <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
844 <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
845 <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
846 <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or
847 <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
848 and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
849 </p><p>
850 <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
851 <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
852 <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
853 <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
854 <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
855 <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
856 <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
857 <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or
858 <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
859 and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code> nor <code class="constant">GL_BGRA</code>.
860 </p><p>
861 <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
862 <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped.
863 </p><p>
864 <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
865 <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer
866 object such that the memory writes required would exceed the data store size.
867 </p><p>
868 <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
869 <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>data</code></em> is not evenly divisible
870 into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
871 </p><p>
872 <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="constant">GL_READ_FRAMEBUFFER_BINDING</code>
873 is non-zero, the read framebuffer is complete, and the value of <code class="constant">GL_SAMPLE_BUFFERS</code>
874 for the read framebuffer is greater than zero.
c7b31271
DH		 875 </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
876 <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PIXEL_PACK_BUFFER_BINDING</code>
877 </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
878 <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>,
879 <a href="glReadBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glReadBuffer</span></span></a>
880 </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
7faf1d71
AW		 881 Copyright <span class="trademark"></span>© 1991-2006
882 Silicon Graphics, Inc. This document is licensed under the SGI
883 Free Software B License. For details, see
c7b31271 884 <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
7faf1d71 885 </p></div></div></body></html>
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