upstream-man-pages/man2/xhtml/glClearIndex.xml

   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>glClearIndex</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glClearIndex"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glClearIndex — specify the clear value for the color index buffers</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">glClearIndex</b>(</code></td><td>GLfloat  </td><td><var class="pdparam">c</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>c</code></em></span></dt><dd><p>
   4                     Specifies the index used when the color index buffers are cleared.
   5                     The initial value is 0.
   6                 </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
   7             <code class="function">glClearIndex</code> specifies the index used by <a class="citerefentry" href="glClear.xml"><span class="citerefentry"><span class="refentrytitle">glClear</span></span></a>
   8             to clear the color index buffers.
   9             <em class="parameter"><code>c</code></em> is not clamped.
  10             Rather,
  11             <em class="parameter"><code>c</code></em> is converted to a fixed-point value with unspecified precision
  12             to the right of the binary point.
  13             The integer part of this value is then masked with
  14             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
  15
  16                 <mml:mrow>
  17                     <mml:msup><mml:mn>2</mml:mn>
  18                     <mml:mi mathvariant="italic">m</mml:mi>
  19                     </mml:msup>
  20                     <mml:mo>-</mml:mo>
  21                     <mml:mn>1</mml:mn>
  22                 </mml:mrow>
  23             </mml:math>,
  24             where
  25             <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:mi mathvariant="italic">m</mml:mi></mml:math>
  26             is the number of bits in a color index stored in the frame buffer.
  27         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
  28             <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glClearIndex</code>
  29             is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
  30             and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
  31         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
  32             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_INDEX_CLEAR_VALUE</code>
  33         </p><p>
  34             <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_INDEX_BITS</code>
  35         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
  36             <a class="citerefentry" href="glClear.xml"><span class="citerefentry"><span class="refentrytitle">glClear</span></span></a>
  37         </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p>
  38             Copyright <span class="trademark"></span>© 1991-2006
  39             Silicon Graphics, Inc. This document is licensed under the SGI
  40             Free Software B License. For details, see
  41             <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
  42         </p></div></div></body></html>