upstream-man-pages/man3/xhtml/glGetTexImage.xml

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   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>glGetTexImage</title><meta name="generator" content="DocBook XSL Stylesheets V1.69.1" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetTexImage"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetTexImage — return a texture image</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">glGetTexImage</b>(</code></td><td>GLenum  </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLint  </td><td><var class="pdparam">level</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">img</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>target</code></em></span></dt><dd><p>
   5                     Specifies which texture is to be obtained.
   6                     <code class="constant">GL_TEXTURE_1D</code>,
   7                     <code class="constant">GL_TEXTURE_2D</code>,
   8                     <code class="constant">GL_TEXTURE_3D</code>,
   9                     <code class="constant">GL_TEXTURE_1D_ARRAY</code>,
  10                     <code class="constant">GL_TEXTURE_2D_ARRAY</code>,
  11                     <code class="constant">GL_TEXTURE_RECTANGLE</code>,
  12                     <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_X</code>,
  13                     <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_X</code>,
  14                     <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Y</code>,
  15                     <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</code>,
  16                     <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Z</code>, and
  17                     <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code>
  18                     are accepted.
  19                 </p></dd><dt><span class="term"><em class="parameter"><code>level</code></em></span></dt><dd><p>
  20                     Specifies the level-of-detail number of the desired image.
  21                     Level 0 is the base image level.
  22                     Level
  23                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
  24                     is the
  25                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>th
  26                     mipmap reduction image.
  27                 </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p>
  28                     Specifies a pixel format for the returned data.
  29                     The supported formats are
  30                     <code class="constant">GL_STENCIL_INDEX</code>,
  31                     <code class="constant">GL_DEPTH_COMPONENT</code>,
  32                     <code class="constant">GL_DEPTH_STENCIL</code>,
  33                     <code class="constant">GL_RED</code>,
  34                     <code class="constant">GL_GREEN</code>,
  35                     <code class="constant">GL_BLUE</code>,
  36                     <code class="constant">GL_RG</code>,
  37                     <code class="constant">GL_RGB</code>,
  38                     <code class="constant">GL_RGBA</code>,
  39                     <code class="constant">GL_BGR</code>,
  40                     <code class="constant">GL_BGRA</code>,
  41                     <code class="constant">GL_RED_INTEGER</code>,
  42                     <code class="constant">GL_GREEN_INTEGER</code>,
  43                     <code class="constant">GL_BLUE_INTEGER</code>,
  44                     <code class="constant">GL_RG_INTEGER</code>,
  45                     <code class="constant">GL_RGB_INTEGER</code>,
  46                     <code class="constant">GL_RGBA_INTEGER</code>,
  47                     <code class="constant">GL_BGR_INTEGER</code>,
  48                     <code class="constant">GL_BGRA_INTEGER</code>.
  49                 </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p>
  50                     Specifies a pixel type for the returned data.
  51                     The supported types are
  52                     <code class="constant">GL_UNSIGNED_BYTE</code>,
  53                     <code class="constant">GL_BYTE</code>,
  54                     <code class="constant">GL_UNSIGNED_SHORT</code>,
  55                     <code class="constant">GL_SHORT</code>,
  56                     <code class="constant">GL_UNSIGNED_INT</code>,
  57                     <code class="constant">GL_INT</code>,
  58                     <code class="constant">GL_HALF_FLOAT</code>,
  59                     <code class="constant">GL_FLOAT</code>,
  60                     <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
  61                     <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
  62                     <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
  63                     <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>,
  64                     <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
  65                     <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
  66                     <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
  67                     <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
  68                     <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
  69                     <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
  70                     <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>,
  71                     <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>,
  72                     <code class="constant">GL_UNSIGNED_INT_24_8</code>,
  73                     <code class="constant">GL_UNSIGNED_INT_10F_11F_11F_REV</code>,
  74                     <code class="constant">GL_UNSIGNED_INT_5_9_9_9_REV</code>, and
  75                     <code class="constant">GL_FLOAT_32_UNSIGNED_INT_24_8_REV</code>.
  76                 </p></dd><dt><span class="term"><em class="parameter"><code>img</code></em></span></dt><dd><p>
  77                     Returns the texture image.
  78                     Should be a pointer to an array of the type specified by <em class="parameter"><code>type</code></em>.
  79                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  80             <code class="function">glGetTexImage</code> returns a texture image into <em class="parameter"><code>img</code></em>.
  81             <em class="parameter"><code>target</code></em> specifies whether the desired texture image is one specified by
  82             <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a> (<code class="constant">GL_TEXTURE_1D</code>),
  83             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a> (<code class="constant">GL_TEXTURE_1D_ARRAY</code>, <code class="constant">GL_TEXTURE_RECTANGLE</code>,
  84             <code class="constant">GL_TEXTURE_2D</code> or any of
  85             <code class="constant">GL_TEXTURE_CUBE_MAP_*</code>),
  86             or
  87             <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a> (<code class="constant">GL_TEXTURE_2D_ARRAY</code>,
  88             <code class="constant">GL_TEXTURE_3D</code>).
  89             <em class="parameter"><code>level</code></em> specifies the level-of-detail number of the desired image.
  90             <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em> specify the format and type of the desired image array.
  91             See the reference page for <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>
  92             for a description of the acceptable values for the <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>
  93             parameters, respectively.
  94         </p><p>
  95             If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target
  96             (see <a href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a texture image is
  97             requested, <em class="parameter"><code>img</code></em> is treated as a byte offset into the buffer object's data store.
  98         </p><p>
  99             To understand the operation of <code class="function">glGetTexImage</code>, consider the selected internal
 100             four-component texture image to be an RGBA color buffer the size of the image.
 101             The semantics of <code class="function">glGetTexImage</code> are then identical to those of <a href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
 102             with the exception that no pixel transfer operations are performed,
 103             when called with the same <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>,
 104             with <span class="emphasis"><em>x</em></span> and <span class="emphasis"><em>y</em></span> set to 0,
 105             <span class="emphasis"><em>width</em></span> set to the width of the texture image
 106             and <span class="emphasis"><em>height</em></span> set to 1 for 1D images,
 107             or to the height of the texture image
 108             for 2D images.
 109         </p><p>
 110             If the selected texture image does not contain four components,
 111             the following mappings are applied.
 112             Single-component textures are treated as RGBA buffers with red set
 113             to the single-component value,
 114             green set to 0, blue set to 0, and alpha set to 1.
 115             Two-component textures are treated as RGBA buffers with red set to
 116             the value of component zero,
 117             alpha set to the value of component one,
 118             and green and blue set to 0.
 119             Finally,
 120             three-component textures are treated as RGBA buffers with red set to
 121             component zero,
 122             green set to component one,
 123             blue set to component two,
 124             and alpha set to 1.
 125         </p><p>
 126             To determine the required size of <em class="parameter"><code>img</code></em>,
 127             use <a href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> to determine the dimensions of the
 128             internal texture image,
 129             then scale the required number of pixels by the storage required for
 130             each pixel,
 131             based on <em class="parameter"><code>format</code></em> and <em class="parameter"><code>type</code></em>.
 132             Be sure to take the pixel storage parameters into account,
 133             especially <code class="constant">GL_PACK_ALIGNMENT</code>.
 134         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 135             If an error is generated,
 136             no change is made to the contents of <em class="parameter"><code>img</code></em>.
 137         </p><p>
 138             <code class="function">glGetTexImage</code> returns the texture image for the active texture unit.
 139         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 140             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em>, <em class="parameter"><code>format</code></em>, or <em class="parameter"><code>type</code></em> is not
 141             an accepted value.
 142         </p><p>
 143             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>level</code></em> is less than 0.
 144         </p><p>
 145             <code class="constant">GL_INVALID_VALUE</code> may be generated if <em class="parameter"><code>level</code></em> is greater
 146             than
 147             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 148
 149                 <mml:mrow>
 150                     <mml:msub><mml:mi mathvariant="italic">log</mml:mi>
 151                     <mml:mn>2</mml:mn>
 152                     </mml:msub>
 153                     <mml:mo>⁡</mml:mo>
 154                     <mml:mfenced open="(" close=")">
 155                         <mml:mi mathvariant="italic">max</mml:mi>
 156                     </mml:mfenced>
 157                 </mml:mrow>
 158             </mml:math>,
 159             where
 160             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">max</mml:mi></mml:math>
 161             is the returned value of <code class="constant">GL_MAX_TEXTURE_SIZE</code>.
 162         </p><p>
 163             <code class="constant">GL_INVALID_OPERATION</code> is returned if <em class="parameter"><code>type</code></em> is one of
 164             <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>,
 165             <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>,
 166             <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>,
 167             <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>, or
 168             <code class="constant">GL_UNSIGNED_INT_10F_11F_11F_REV</code> and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>.
 169         </p><p>
 170             <code class="constant">GL_INVALID_OPERATION</code> is returned if <em class="parameter"><code>type</code></em> is one of
 171             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>,
 172             <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>,
 173             <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>,
 174             <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>,
 175             <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>,
 176             <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>,
 177             <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>,
 178             <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code>, or
 179             <code class="constant">GL_UNSIGNED_INT_5_9_9_9_REV</code> and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code>
 180             or <code class="constant">GL_BGRA</code>.
 181         </p><p>
 182             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 183             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped.
 184         </p><p>
 185             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 186             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer
 187             object such that the memory writes required would exceed the data store size.
 188         </p><p>
 189             <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the
 190             <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>img</code></em> is not evenly divisible
 191             into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>.
 192         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
 193             <a href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_WIDTH</code>
 194         </p><p>
 195             <a href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_HEIGHT</code>
 196         </p><p>
 197             <a href="glGetTexLevelParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexLevelParameter</span></span></a> with argument <code class="constant">GL_TEXTURE_INTERNAL_FORMAT</code>
 198         </p><p>
 199             <a href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with arguments <code class="constant">GL_PACK_ALIGNMENT</code> and others
 200         </p><p>
 201             <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>
 202         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 203             <a href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>,
 204             <a href="glReadPixels.xml"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
 205             <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 206             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 207             <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
 208             <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
 209             <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,
 210             <a href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>,
 211             <a href="glTexParameter.xml"><span class="citerefentry"><span class="refentrytitle">glTexParameter</span></span></a>
 212         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 213             Copyright <span class="trademark"></span>© 1991-2006
 214             Silicon Graphics, Inc. Copyright <span class="trademark"></span>© 2010
 215             Khronos Group. This document is licensed under the SGI
 216             Free Software B License. For details, see
 217             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 218         </p></div></div></body></html>