--- /dev/null
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd">
+<!-- saved from url=(0013)about:internet -->
+<?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 4 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>
+ Specify the window coordinates of the first pixel
+ that is read from the frame buffer.
+ This location is the lower left corner of a rectangular block of pixels.
+ </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>
+ Specify the dimensions of the pixel rectangle.
+ <em class="parameter"><code>width</code></em> and <em class="parameter"><code>height</code></em> of one correspond to a single pixel.
+ </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
+ Specifies the format of the pixel data.
+ The following symbolic values are accepted:
+ <code class="constant">GL_STENCIL_INDEX</code>,
+ <code class="constant">GL_DEPTH_COMPONENT</code>,
+ <code class="constant">GL_DEPTH_STENCIL</code>,
+ <code class="constant">GL_RED</code>,
+ <code class="constant">GL_GREEN</code>,
+ <code class="constant">GL_BLUE</code>,
+ <code class="constant">GL_RGB</code>,
+ <code class="constant">GL_BGR</code>,
+ <code class="constant">GL_RGBA</code>, and
+ <code class="constant">GL_BGRA</code>.
+ </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
+ Specifies the data type of the pixel data.
+ Must be one of
+ <code class="constant">GL_UNSIGNED_BYTE</code>,
+ <code class="constant">GL_BYTE</code>,
+ <code class="constant">GL_UNSIGNED_SHORT</code>,
+ <code class="constant">GL_SHORT</code>,
+ <code class="constant">GL_UNSIGNED_INT</code>,
+ <code class="constant">GL_INT</code>,
+ <code class="constant">GL_HALF_FLOAT</code>,
+ <code class="constant">GL_FLOAT</code>,
+ <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
+ <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
+ <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
+ <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
+ <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>,
+ <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>,
+ <code class="constant">GL_UNSIGNED_INT_24_8</code>,
+ <code class="constant">GL_UNSIGNED_INT_10F_11F_11F_REV</code>,
+ <code class="constant">GL_UNSIGNED_INT_5_9_9_9_REV</code>, or
+ <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>.
+ </p></dd><dt><span class="term"><em class="parameter"><code>data</code></em></span></dt><dd><p>
+ Returns the pixel data.
+ </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
+ <code class="function">glReadPixels</code> returns pixel data from the frame buffer,
+ starting with the pixel whose lower left corner
+ is at location (<em class="parameter"><code>x</code></em>, <em class="parameter"><code>y</code></em>),
+ into client memory starting at location <em class="parameter"><code>data</code></em>.
+ Several parameters control the processing of the pixel data before
+ it is placed into client memory.
+ These parameters are set with <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>.
+ This reference page describes the effects on <code class="function">glReadPixels</code> of most,
+ but not all of the parameters specified by these three commands.
+ </p><p>
+ If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target
+ (see <a href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a block of pixels is
+ requested, <em class="parameter"><code>data</code></em> is treated as a byte offset into the buffer object's data store
+ rather than a pointer to client memory.
+ </p><p>
+ <code class="function">glReadPixels</code> returns values from each pixel with lower left corner at
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:mi mathvariant="italic">x</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ </mml:mrow>
+ <mml:mrow>
+ <mml:mi mathvariant="italic">y</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mi mathvariant="italic">j</mml:mi>
+ </mml:mrow>
+ </mml:mfenced>
+ </mml:math>
+ for
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mn>0</mml:mn>
+ <mml:mo><=</mml:mo>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ <mml:mo><</mml:mo>
+ <mml:mi mathvariant="italic">width</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ and
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mn>0</mml:mn>
+ <mml:mo><=</mml:mo>
+ <mml:mi mathvariant="italic">j</mml:mi>
+ <mml:mo><</mml:mo>
+ <mml:mi mathvariant="italic">height</mml:mi>
+ </mml:mrow>
+ </mml:math>.
+ This pixel is said to be the
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>th
+ pixel in the
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>th
+ row.
+ Pixels are returned in row order from the lowest to the highest row,
+ left to right in each row.
+ </p><p>
+ <em class="parameter"><code>format</code></em> specifies the format for the returned pixel values;
+ accepted values are:
+ </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_STENCIL_INDEX</code></span></dt><dd><p>
+ Stencil values are read from the stencil buffer.
+ Each index is converted to fixed point,
+ shifted left or right depending on the value and sign of <code class="constant">GL_INDEX_SHIFT</code>,
+ and added to <code class="constant">GL_INDEX_OFFSET</code>.
+ If <code class="constant">GL_MAP_STENCIL</code> is <code class="constant">GL_TRUE</code>,
+ indices are replaced by their mappings in the table <code class="constant">GL_PIXEL_MAP_S_TO_S</code>.
+ </p></dd><dt><span class="term"><code class="constant">GL_DEPTH_COMPONENT</code></span></dt><dd><p>
+ Depth values are read from the depth buffer.
+ Each component is converted to floating point such that the minimum depth
+ value maps to 0 and the maximum value maps to 1.
+ Each component is then multiplied by <code class="constant">GL_DEPTH_SCALE</code>,
+ added to <code class="constant">GL_DEPTH_BIAS</code>,
+ and finally clamped to the range
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mfenced open="[" close="]">
+ <mml:mn>0</mml:mn>
+ <mml:mn>1</mml:mn>
+ </mml:mfenced>
+ </mml:math>.
+ </p></dd><dt><span class="term"><code class="constant">GL_DEPTH_STENCIL</code></span></dt><dd><p>
+ Values are taken from both the depth and stencil buffers. The <em class="parameter"><code>type</code></em> parameter
+ must be <code class="constant">GL_UNSIGNED_INT_24_8</code> or <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>.
+ </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>
+ Finally, the indices or components
+ are converted to the proper format,
+ as specified by <em class="parameter"><code>type</code></em>.
+ If <em class="parameter"><code>format</code></em> is <code class="constant">GL_STENCIL_INDEX</code>
+ and <em class="parameter"><code>type</code></em> is not <code class="constant">GL_FLOAT</code>,
+ each index is masked with the mask value given in the following table.
+ If <em class="parameter"><code>type</code></em> is <code class="constant">GL_FLOAT</code>, then each integer index is converted to
+ single-precision floating-point format.
+ </p><p>
+ If <em class="parameter"><code>format</code></em> is
+ <code class="constant">GL_RED</code>,
+ <code class="constant">GL_GREEN</code>,
+ <code class="constant">GL_BLUE</code>,
+ <code class="constant">GL_RGB</code>,
+ <code class="constant">GL_BGR</code>,
+ <code class="constant">GL_RGBA</code>, or
+ <code class="constant">GL_BGRA</code> and <em class="parameter"><code>type</code></em> is not <code class="constant">GL_FLOAT</code>,
+ each component is multiplied by the multiplier shown in the following table.
+ If type is <code class="constant">GL_FLOAT</code>, then each component is passed as is
+ (or converted to the client's single-precision floating-point format if
+ it is different from the one used by the GL).
+ </p><p>
+ </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="center" /><col align="center" /></colgroup><thead><tr><th align="left">
+ <em class="parameter"><code>type</code></em>
+ </th><th align="center"><span class="bold"><strong>
+ Index Mask
+ </strong></span></th><th align="center"><span class="bold"><strong>
+ Component Conversion
+ </strong></span></th></tr></thead><tbody><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_BYTE</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>8</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>8</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_BYTE</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>7</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mfrac>
+ <mml:mfenced open="" close="">
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>8</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mn>2</mml:mn>
+ </mml:mfrac>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>16</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>16</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_SHORT</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>15</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mfrac>
+ <mml:mfenced open="" close="">
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>16</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mn>2</mml:mn>
+ </mml:mfrac>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>32</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>32</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_INT</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>31</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mfrac>
+ <mml:mfenced open="" close="">
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>32</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mn>2</mml:mn>
+ </mml:mfrac>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_HALF_FLOAT</code>
+ </td><td align="center">
+ none
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">c</mml:mi></mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_FLOAT</code>
+ </td><td align="center">
+ none
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">c</mml:mi></mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_24_8</code>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:math>
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mrow>
+ <mml:msup><mml:mn>2</mml:mn>
+ <mml:mn>N</mml:mn>
+ </mml:msup>
+ <mml:mo>-</mml:mo>
+ <mml:mn>1</mml:mn>
+ </mml:mrow>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">c</mml:mi>
+ </mml:mrow>
+ </mml:math>
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_10F_11F_11F_REV</code>
+ </td><td align="center">
+ --
+ </td><td align="left">
+ Special
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_UNSIGNED_INT_5_9_9_9_REV</code>
+ </td><td align="center">
+ --
+ </td><td align="left">
+ Special
+ </td></tr><tr><td align="left">
+ <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>
+ </td><td align="center">
+ none
+ </td><td align="center">
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">c</mml:mi></mml:math> (Depth Only)
+ </td></tr></tbody></table></div><p>
+ Return values are placed in memory as follows.
+ If <em class="parameter"><code>format</code></em> is
+ <code class="constant">GL_STENCIL_INDEX</code>,
+ <code class="constant">GL_DEPTH_COMPONENT</code>,
+ <code class="constant">GL_RED</code>,
+ <code class="constant">GL_GREEN</code>, or
+ <code class="constant">GL_BLUE</code>,
+ a single value is returned and the data for the
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">i</mml:mi></mml:math>th
+ pixel in the
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">j</mml:mi></mml:math>th
+ row
+ is placed in location
+ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
+
+ <mml:mrow>
+ <mml:mfenced open="(" close=")">
+ <mml:mi mathvariant="italic">j</mml:mi>
+ </mml:mfenced>
+ <mml:mo></mml:mo>
+ <mml:mi mathvariant="italic">width</mml:mi>
+ <mml:mo>+</mml:mo>
+ <mml:mi mathvariant="italic">i</mml:mi>
+ </mml:mrow>
+ </mml:math>.
+ <code class="constant">GL_RGB</code> and <code class="constant">GL_BGR</code> return three values,
+ <code class="constant">GL_RGBA</code> and <code class="constant">GL_BGRA</code> return four values for each pixel,
+ with all values corresponding to a single pixel occupying contiguous space
+ in <em class="parameter"><code>data</code></em>.
+ Storage parameters set by <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>,
+ such as <code class="constant">GL_PACK_LSB_FIRST</code> and <code class="constant">GL_PACK_SWAP_BYTES</code>,
+ affect the way that data is written into memory.
+ See <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a> for a description.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
+ Values for pixels that lie outside the window
+ connected to the current GL context are undefined.
+ </p><p>
+ If an error is generated,
+ no change is made to the contents of <em class="parameter"><code>data</code></em>.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
+ <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
+ accepted value.
+ </p><p>
+ <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.
+ </p><p>
+ <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>
+ and there is no stencil buffer.
+ </p><p>
+ <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>
+ and there is no depth buffer.
+ </p><p>
+ <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>
+ and there is no depth buffer or if there is no stencil buffer.
+ </p><p>
+ <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>
+ 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>.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
+ <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
+ <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or
+ <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>
+ and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of
+ <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
+ <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
+ <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
+ <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
+ <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or
+ <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>
+ and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code> nor <code class="constant">GL_BGRA</code>.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
+ <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
+ <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer
+ object such that the memory writes required would exceed the data store size.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
+ <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>data</code></em> is not evenly divisible
+ into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
+ </p><p>
+ <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="constant">GL_READ_FRAMEBUFFER_BINDING</code>
+ is non-zero, the read framebuffer is complete, and the value of <code class="constant">GL_SAMPLE_BUFFERS</code>
+ for the read framebuffer is greater than zero.
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
+ <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_INDEX_MODE</code>
+ </p><p>
+ <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>
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
+ <a href="glPixelStore.xml"><span class="citerefentry"><span class="refentrytitle">glPixelStore</span></span></a>,
+ <a href="glReadBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glReadBuffer</span></span></a>
+ </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
+ Copyright <span class="trademark"></span>© 1991-2006
+ Silicon Graphics, Inc. This document is licensed under the SGI
+ Free Software B License. For details, see
+ <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
+ </p></div></div></body></html>
HCoop / clinton / guile-figl.git / blobdiff