| 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> |
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| 3 | <?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" /><title>glGetHistogram</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glGetHistogram"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glGetHistogram — get histogram table</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">glGetHistogram</b>(</code></td><td>GLenum </td><td><var class="pdparam">target</var>, </td></tr><tr><td> </td><td>GLboolean </td><td><var class="pdparam">reset</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">values</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> |
| 4 | Must be |
| 5 | <code class="constant">GL_HISTOGRAM</code>. |
| 6 | </p></dd><dt><span class="term"><em class="parameter"><code>reset</code></em></span></dt><dd><p> |
| 7 | If <code class="constant">GL_TRUE</code>, each component counter that is actually returned |
| 8 | is reset to zero. (Other counters are unaffected.) |
| 9 | If <code class="constant">GL_FALSE</code>, none of the counters in the histogram table is modified. |
| 10 | </p></dd><dt><span class="term"><em class="parameter"><code>format</code></em></span></dt><dd><p> |
| 11 | The format of values to be returned in <em class="parameter"><code>values</code></em>. |
| 12 | Must be one of |
| 13 | <code class="constant">GL_RED</code>, |
| 14 | <code class="constant">GL_GREEN</code>, |
| 15 | <code class="constant">GL_BLUE</code>, |
| 16 | <code class="constant">GL_ALPHA</code>, |
| 17 | <code class="constant">GL_RGB</code>, |
| 18 | <code class="constant">GL_BGR</code>, |
| 19 | <code class="constant">GL_RGBA</code>, |
| 20 | <code class="constant">GL_BGRA</code>, |
| 21 | <code class="constant">GL_LUMINANCE</code>, or |
| 22 | <code class="constant">GL_LUMINANCE_ALPHA</code>. |
| 23 | </p></dd><dt><span class="term"><em class="parameter"><code>type</code></em></span></dt><dd><p> |
| 24 | The type of values to be returned in <em class="parameter"><code>values</code></em>. |
| 25 | Symbolic constants |
| 26 | <code class="constant">GL_UNSIGNED_BYTE</code>, |
| 27 | <code class="constant">GL_BYTE</code>, |
| 28 | <code class="constant">GL_BITMAP</code>, |
| 29 | <code class="constant">GL_UNSIGNED_SHORT</code>, |
| 30 | <code class="constant">GL_SHORT</code>, |
| 31 | <code class="constant">GL_UNSIGNED_INT</code>, |
| 32 | <code class="constant">GL_INT</code>, |
| 33 | <code class="constant">GL_FLOAT</code>, |
| 34 | <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>, |
| 35 | <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>, |
| 36 | <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, |
| 37 | <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code>, |
| 38 | <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>, |
| 39 | <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>, |
| 40 | <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>, |
| 41 | <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>, |
| 42 | <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>, |
| 43 | <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>, |
| 44 | <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, and |
| 45 | <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code> |
| 46 | are accepted. |
| 47 | </p></dd><dt><span class="term"><em class="parameter"><code>values</code></em></span></dt><dd><p> |
| 48 | A pointer to storage for the returned histogram table. |
| 49 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> |
| 50 | <code class="function">glGetHistogram</code> returns the current histogram table as a one-dimensional image |
| 51 | with the same width as the histogram. |
| 52 | No pixel transfer operations are performed on this image, but pixel storage |
| 53 | modes that are applicable to 1D images are honored. |
| 54 | </p><p> |
| 55 | If a non-zero named buffer object is bound to the <code class="constant">GL_PIXEL_PACK_BUFFER</code> target |
| 56 | (see <a class="citerefentry" href="glBindBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glBindBuffer</span></span></a>) while a histogram table is |
| 57 | requested, <em class="parameter"><code>values</code></em> is treated as a byte offset into the buffer object's data store. |
| 58 | </p><p> |
| 59 | Color components that are requested in the specified <em class="parameter"><code>format</code></em>, but which |
| 60 | are not included in the internal format of the histogram, are returned as |
| 61 | zero. |
| 62 | The assignments of internal color components to the components |
| 63 | requested by <em class="parameter"><code>format</code></em> are: |
| 64 | </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> |
| 65 | Internal Component |
| 66 | </strong></span></th><th align="left"><span class="bold"><strong> |
| 67 | Resulting Component |
| 68 | </strong></span></th></tr></thead><tbody><tr><td align="left"> |
| 69 | Red |
| 70 | </td><td align="left"> |
| 71 | Red |
| 72 | </td></tr><tr><td align="left"> |
| 73 | Green |
| 74 | </td><td align="left"> |
| 75 | Green |
| 76 | </td></tr><tr><td align="left"> |
| 77 | Blue |
| 78 | </td><td align="left"> |
| 79 | Blue |
| 80 | </td></tr><tr><td align="left"> |
| 81 | Alpha |
| 82 | </td><td align="left"> |
| 83 | Alpha |
| 84 | </td></tr><tr><td align="left"> |
| 85 | Luminance |
| 86 | </td><td align="left"> |
| 87 | Red |
| 88 | </td></tr></tbody></table></div><p> |
| 89 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> |
| 90 | <code class="function">glGetHistogram</code> is present only if <code class="code">ARB_imaging</code> is returned when <a class="citerefentry" href="glGetString.xml"><span class="citerefentry"><span class="refentrytitle">glGetString</span></span></a> |
| 91 | is called with an argument of <code class="constant">GL_EXTENSIONS</code>. |
| 92 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> |
| 93 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>target</code></em> is not <code class="constant">GL_HISTOGRAM</code>. |
| 94 | </p><p> |
| 95 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>format</code></em> is not one of the allowable |
| 96 | values. |
| 97 | </p><p> |
| 98 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>type</code></em> is not one of the allowable |
| 99 | values. |
| 100 | </p><p> |
| 101 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of |
| 102 | <code class="constant">GL_UNSIGNED_BYTE_3_3_2</code>, |
| 103 | <code class="constant">GL_UNSIGNED_BYTE_2_3_3_REV</code>, |
| 104 | <code class="constant">GL_UNSIGNED_SHORT_5_6_5</code>, or |
| 105 | <code class="constant">GL_UNSIGNED_SHORT_5_6_5_REV</code> |
| 106 | and <em class="parameter"><code>format</code></em> is not <code class="constant">GL_RGB</code>. |
| 107 | </p><p> |
| 108 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <em class="parameter"><code>type</code></em> is one of |
| 109 | <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4</code>, |
| 110 | <code class="constant">GL_UNSIGNED_SHORT_4_4_4_4_REV</code>, |
| 111 | <code class="constant">GL_UNSIGNED_SHORT_5_5_5_1</code>, |
| 112 | <code class="constant">GL_UNSIGNED_SHORT_1_5_5_5_REV</code>, |
| 113 | <code class="constant">GL_UNSIGNED_INT_8_8_8_8</code>, |
| 114 | <code class="constant">GL_UNSIGNED_INT_8_8_8_8_REV</code>, |
| 115 | <code class="constant">GL_UNSIGNED_INT_10_10_10_2</code>, or |
| 116 | <code class="constant">GL_UNSIGNED_INT_2_10_10_10_REV</code> |
| 117 | and <em class="parameter"><code>format</code></em> is neither <code class="constant">GL_RGBA</code> nor <code class="constant">GL_BGRA</code>. |
| 118 | </p><p> |
| 119 | <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the |
| 120 | <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the buffer object's data store is currently mapped. |
| 121 | </p><p> |
| 122 | <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the |
| 123 | <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and the data would be packed to the buffer |
| 124 | object such that the memory writes required would exceed the data store size. |
| 125 | </p><p> |
| 126 | <code class="constant">GL_INVALID_OPERATION</code> is generated if a non-zero buffer object name is bound to the |
| 127 | <code class="constant">GL_PIXEL_PACK_BUFFER</code> target and <em class="parameter"><code>values</code></em> is not evenly divisible |
| 128 | into the number of bytes needed to store in memory a datum indicated by <em class="parameter"><code>type</code></em>. |
| 129 | </p><p> |
| 130 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glGetHistogram</code> is executed |
| 131 | between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> and the corresponding |
| 132 | execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>. |
| 133 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> |
| 134 | <a class="citerefentry" href="glGetHistogramParameter.xml"><span class="citerefentry"><span class="refentrytitle">glGetHistogramParameter</span></span></a> |
| 135 | </p><p> |
| 136 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_PIXEL_PACK_BUFFER_BINDING</code> |
| 137 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> |
| 138 | <a class="citerefentry" href="glHistogram.xml"><span class="citerefentry"><span class="refentrytitle">glHistogram</span></span></a>, |
| 139 | <a class="citerefentry" href="glResetHistogram.xml"><span class="citerefentry"><span class="refentrytitle">glResetHistogram</span></span></a>, |
| 140 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> |
| 141 | Copyright <span class="trademark"></span>© 1991-2006 |
| 142 | Silicon Graphics, Inc. This document is licensed under the SGI |
| 143 | Free Software B License. For details, see |
| 144 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. |
| 145 | </p></div></div></body></html> |