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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 - 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="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> |