upstream-man-pages/man4/xhtml/glGetTexLevelParameter.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>glGetTexLevelParameter - 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="glGetTexLevelParameter"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetTexLevelParameter — return texture parameter values for a specific level of detail</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">glGetTexLevelParameterfv</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">pname</var>, </td></tr><tr><td> </td><td>GLfloat *  </td><td><var class="pdparam">params</var><code>)</code>;</td></tr></table></div><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glGetTexLevelParameteriv</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">pname</var>, </td></tr><tr><td> </td><td>GLint *  </td><td><var class="pdparam">params</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 the symbolic name of the target texture,
   6                     one of
   7                     <code class="constant">GL_TEXTURE_1D</code>,
   8                     <code class="constant">GL_TEXTURE_2D</code>,
   9                     <code class="constant">GL_TEXTURE_3D</code>,
  10                     <code class="constant">GL_TEXTURE_1D_ARRAY</code>,
  11                     <code class="constant">GL_TEXTURE_2D_ARRAY</code>,
  12                     <code class="constant">GL_TEXTURE_RECTANGLE</code>,
  13                     <code class="constant">GL_TEXTURE_2D_MULTISAMPLE</code>,
  14                     <code class="constant">GL_TEXTURE_2D_MULTISAMPLE_ARRAY</code>,
  15                     <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_X</code>,
  16                     <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_X</code>,
  17                     <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Y</code>,
  18                     <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</code>,
  19                     <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Z</code>,
  20                     <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code>,
  21                     <code class="constant">GL_PROXY_TEXTURE_1D</code>,
  22                     <code class="constant">GL_PROXY_TEXTURE_2D</code>,
  23                     <code class="constant">GL_PROXY_TEXTURE_3D</code>,
  24                     <code class="constant">GL_PROXY_TEXTURE_1D_ARRAY</code>,
  25                     <code class="constant">GL_PROXY_TEXTURE_2D_ARRAY</code>,
  26                     <code class="constant">GL_PROXY_TEXTURE_RECTANGLE</code>,
  27                     <code class="constant">GL_PROXY_TEXTURE_2D_MULTISAMPLE</code>,
  28                     <code class="constant">GL_PROXY_TEXTURE_2D_MULTISAMPLE_ARRAY</code>,
  29                     <code class="constant">GL_PROXY_TEXTURE_CUBE_MAP</code>, or
  30                     <code class="constant">GL_TEXTURE_BUFFER</code>.
  31                 </p></dd><dt><span class="term"><em class="parameter"><code>level</code></em></span></dt><dd><p>
  32                     Specifies the level-of-detail number of the desired image.
  33                     Level 0 is the base image level.
  34                     Level
  35                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>
  36                     is the
  37                     <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">n</mml:mi></mml:math>th
  38                     mipmap reduction image.
  39                 </p></dd><dt><span class="term"><em class="parameter"><code>pname</code></em></span></dt><dd><p>
  40                     Specifies the symbolic name of a texture parameter.
  41                     <code class="constant">GL_TEXTURE_WIDTH</code>,
  42                     <code class="constant">GL_TEXTURE_HEIGHT</code>,
  43                     <code class="constant">GL_TEXTURE_DEPTH</code>,
  44                     <code class="constant">GL_TEXTURE_INTERNAL_FORMAT</code>,
  45                     <code class="constant">GL_TEXTURE_BORDER</code>,
  46                     <code class="constant">GL_TEXTURE_RED_SIZE</code>,
  47                     <code class="constant">GL_TEXTURE_GREEN_SIZE</code>,
  48                     <code class="constant">GL_TEXTURE_BLUE_SIZE</code>,
  49                     <code class="constant">GL_TEXTURE_ALPHA_SIZE</code>,
  50                     <code class="constant">GL_TEXTURE_DEPTH_SIZE</code>,
  51                     <code class="constant">GL_TEXTURE_COMPRESSED</code>,
  52                     <code class="constant">GL_TEXTURE_COMPRESSED_IMAGE_SIZE</code>, and
  53                     <code class="constant">GL_TEXTURE_BUFFER_OFFSET</code>
  54                      are accepted.
  55                 </p></dd><dt><span class="term"><em class="parameter"><code>params</code></em></span></dt><dd><p>
  56                     Returns the requested data.
  57                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
  58             <code class="function">glGetTexLevelParameter</code> returns in <em class="parameter"><code>params</code></em> texture parameter values for a specific
  59             level-of-detail value,
  60             specified as <em class="parameter"><code>level</code></em>.
  61             <em class="parameter"><code>target</code></em> defines the target texture,
  62             either <code class="constant">GL_TEXTURE_1D</code>, <code class="constant">GL_TEXTURE_2D</code>, <code class="constant">GL_TEXTURE_3D</code>,
  63             <code class="constant">GL_PROXY_TEXTURE_1D</code>,
  64             <code class="constant">GL_PROXY_TEXTURE_2D</code>,
  65             <code class="constant">GL_PROXY_TEXTURE_3D</code>,
  66             <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_X</code>,
  67             <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_X</code>,
  68             <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Y</code>,
  69             <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Y</code>,
  70             <code class="constant">GL_TEXTURE_CUBE_MAP_POSITIVE_Z</code>,
  71             <code class="constant">GL_TEXTURE_CUBE_MAP_NEGATIVE_Z</code>, or
  72             <code class="constant">GL_PROXY_TEXTURE_CUBE_MAP</code>.
  73         </p><p>
  74             <code class="constant">GL_MAX_TEXTURE_SIZE</code>, and <code class="constant">GL_MAX_3D_TEXTURE_SIZE</code> are not really
  75             descriptive enough.
  76             It has to report the largest square texture image that can be
  77             accommodated with mipmaps and borders,
  78             but a long skinny texture, or a texture without mipmaps and borders, may
  79             easily fit in texture memory.
  80             The proxy targets allow the user to more accurately query
  81             whether the GL can accommodate a texture of a given configuration.
  82             If the texture cannot be accommodated, the texture state variables, which
  83             may be queried with <code class="function">glGetTexLevelParameter</code>, are set to 0.  If the texture can be accommodated,
  84             the texture state values will be set as they would be set for a
  85             non-proxy target.
  86         </p><p>
  87             <em class="parameter"><code>pname</code></em> specifies the texture parameter whose value or values
  88             will be returned.
  89         </p><p>
  90             The accepted parameter names are as follows:
  91         </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_TEXTURE_WIDTH</code></span></dt><dd><p>
  92                     </p><p>
  93                         <em class="parameter"><code>params</code></em> returns a single value,
  94                         the width of the texture image.
  95                         This value includes the border of the texture image. The initial value is
  96                         0.
  97                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_HEIGHT</code></span></dt><dd><p>
  98                     </p><p>
  99                         <em class="parameter"><code>params</code></em> returns a single value,
 100                         the height of the texture image.
 101                         This value includes the border of the texture image. The initial value is
 102                         0.
 103                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_DEPTH</code></span></dt><dd><p>
 104                     </p><p>
 105                         <em class="parameter"><code>params</code></em> returns a single value,
 106                         the depth of the texture image.
 107                         This value includes the border of the texture image. The initial value is
 108                         0.
 109                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_INTERNAL_FORMAT</code></span></dt><dd><p>
 110                     </p><p>
 111                         <em class="parameter"><code>params</code></em> returns a single value,
 112                         the internal format of the texture image.
 113                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_RED_TYPE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_GREEN_TYPE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_BLUE_TYPE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_ALPHA_TYPE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_DEPTH_TYPE</code></span></dt><dd><p>
 114                     </p><p>
 115                         The data type used to store the component.
 116                         The types <code class="constant">GL_NONE</code>, <code class="constant">GL_SIGNED_NORMALIZED</code>,
 117                         <code class="constant">GL_UNSIGNED_NORMALIZED</code>, <code class="constant">GL_FLOAT</code>,
 118                         <code class="constant">GL_INT</code>, and <code class="constant">GL_UNSIGNED_INT</code> may be returned
 119                         to indicate signed normalized fixed-point, unsigned normalized fixed-point, floating-point, integer unnormalized, and
 120                         unsigned integer unnormalized components, respectively.
 121                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_RED_SIZE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_GREEN_SIZE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_BLUE_SIZE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_ALPHA_SIZE</code>,</span></dt><dd></dd><dt><span class="term"><code class="constant">GL_TEXTURE_DEPTH_SIZE</code></span></dt><dd><p>
 122                     </p><p>
 123                         The internal storage resolution of an individual component.
 124                         The resolution chosen by the GL will be a close match for the resolution
 125                         requested by the user with the component argument of <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 126                         <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>, <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>, <a href="glCopyTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage1D</span></span></a>, and
 127                         <a href="glCopyTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>. The initial value is 0.
 128                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_COMPRESSED</code></span></dt><dd><p>
 129                     </p><p>
 130                         <em class="parameter"><code>params</code></em> returns a single boolean value indicating if the texture image is
 131                         stored in a compressed internal format.  The initiali value is <code class="constant">GL_FALSE</code>.
 132                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_COMPRESSED_IMAGE_SIZE</code></span></dt><dd><p>
 133                     </p><p>
 134                         <em class="parameter"><code>params</code></em> returns a single integer value, the number of unsigned bytes of the
 135                         compressed texture image that would be returned from
 136                         <a href="glGetCompressedTexImage.xml"><span class="citerefentry"><span class="refentrytitle">glGetCompressedTexImage</span></span></a>.
 137                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_BUFFER_OFFSET</code></span></dt><dd><p>
 138                     </p><p>
 139                         <em class="parameter"><code>params</code></em> returns a single integer value, the offset into the
 140                         data store of the buffer bound to a buffer texture.
 141                         <a href="glTexBufferRange.xml"><span class="citerefentry"><span class="refentrytitle">glTexBufferRange</span></span></a>.
 142                     </p></dd><dt><span class="term"><code class="constant">GL_TEXTURE_BUFFER_SIZE</code></span></dt><dd><p>
 143                     </p><p>
 144                         <em class="parameter"><code>params</code></em> returns a single integer value, the size of the range of a
 145                         data store of the buffer bound to a buffer texture.
 146                         <a href="glTexBufferRange.xml"><span class="citerefentry"><span class="refentrytitle">glTexBufferRange</span></span></a>.
 147                     </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
 148             If an error is generated,
 149             no change is made to the contents of <em class="parameter"><code>params</code></em>.
 150         </p><p>
 151             <code class="function">glGetTexLevelParameter</code> returns the texture level parameters for the active texture unit.
 152         </p><p>
 153             <code class="constant">GL_TEXTURE_BUFFER_OFFSET</code> and <code class="constant">GL_TEXTURE_BUFFER_SIZE</code> are available only
 154             if the GL version is 4.3 or greater.
 155         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
 156             <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> or <em class="parameter"><code>pname</code></em> is not an
 157             accepted value.
 158         </p><p>
 159             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>level</code></em> is less than 0.
 160         </p><p>
 161             <code class="constant">GL_INVALID_VALUE</code> may be generated if <em class="parameter"><code>level</code></em> is greater
 162             than
 163             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
 164
 165                 <mml:msub><mml:mi mathvariant="italic">log</mml:mi>
 166                 <mml:mn>2</mml:mn>
 167                 </mml:msub>
 168             </mml:math>
 169             <span class="emphasis"><em>max</em></span>,
 170             where <span class="emphasis"><em>max</em></span> is the returned value of <code class="constant">GL_MAX_TEXTURE_SIZE</code>.
 171         </p><p>
 172             <code class="constant">GL_INVALID_VALUE</code> is generated if <em class="parameter"><code>target</code></em> is <code class="constant">GL_TEXTURE_BUFFER</code>
 173             and <em class="parameter"><code>level</code></em> is not zero.
 174         </p><p>
 175             <code class="constant">GL_INVALID_OPERATION</code> is generated if
 176             <code class="constant">GL_TEXTURE_COMPRESSED_IMAGE_SIZE</code> is queried on texture images with an
 177             uncompressed internal format or on proxy targets.
 178         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
 179             <a href="glActiveTexture.xml"><span class="citerefentry"><span class="refentrytitle">glActiveTexture</span></span></a>,
 180             <a href="glGetTexParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetTexParameter</span></span></a>,
 181             <a href="glCopyTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage1D</span></span></a>,
 182             <a href="glCopyTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexImage2D</span></span></a>,
 183             <a href="glCopyTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage1D</span></span></a>,
 184             <a href="glCopyTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage2D</span></span></a>,
 185             <a href="glCopyTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glCopyTexSubImage3D</span></span></a>,
 186             <a href="glTexImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage1D</span></span></a>,
 187             <a href="glTexImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
 188             <a href="glTexImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexImage3D</span></span></a>,
 189             <a href="glTexSubImage1D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage1D</span></span></a>,
 190             <a href="glTexSubImage2D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>,
 191             <a href="glTexSubImage3D.xml"><span class="citerefentry"><span class="refentrytitle">glTexSubImage3D</span></span></a>,
 192             <a href="glTexParameter.xml"><span class="citerefentry"><span class="refentrytitle">glTexParameter</span></span></a>
 193         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
 194             Copyright <span class="trademark"></span>© 1991-2006
 195             Silicon Graphics, Inc. Copyright <span class="trademark"></span>© 2010-2012
 196             Khronos Group. This document is licensed under the SGI
 197             Free Software B License. For details, see
 198             <a href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
 199         </p></div></div></body></html>