upstream-man-pages/man2/glClearIndex.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="glClearIndex">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glClearIndex</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glClearIndex</refname>
  17         <refpurpose>specify the clear value for the color index buffers</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glClearIndex</function></funcdef>
  23                 <paramdef>GLfloat <parameter>c</parameter></paramdef>
  24             </funcprototype>
  25         </funcsynopsis>
  26     </refsynopsisdiv>
  27     <!-- eqn: ignoring delim $$ -->
  28     <refsect1 id="parameters"><title>Parameters</title>
  29         <variablelist>
  30         <varlistentry>
  31             <term><parameter>c</parameter></term>
  32             <listitem>
  33                 <para>
  34                     Specifies the index used when the color index buffers are cleared.
  35                     The initial value is 0.
  36                 </para>
  37             </listitem>
  38         </varlistentry>
  39         </variablelist>
  40     </refsect1>
  41     <refsect1 id="description"><title>Description</title>
  42         <para>
  43             <function>glClearIndex</function> specifies the index used by <citerefentry><refentrytitle>glClear</refentrytitle></citerefentry>
  44             to clear the color index buffers.
  45             <parameter>c</parameter> is not clamped.
  46             Rather,
  47             <parameter>c</parameter> is converted to a fixed-point value with unspecified precision
  48             to the right of the binary point.
  49             The integer part of this value is then masked with
  50             <inlineequation><mml:math>
  51                 <!-- eqn: 2 sup m - 1:-->
  52                 <mml:mrow>
  53                     <mml:msup><mml:mn>2</mml:mn>
  54                     <mml:mi mathvariant="italic">m</mml:mi>
  55                     </mml:msup>
  56                     <mml:mo>-</mml:mo>
  57                     <mml:mn>1</mml:mn>
  58                 </mml:mrow>
  59             </mml:math></inlineequation>,
  60             where
  61             <inlineequation><mml:math><mml:mi mathvariant="italic">m</mml:mi></mml:math></inlineequation>
  62             is the number of bits in a color index stored in the frame buffer.
  63         </para>
  64     </refsect1>
  65     <refsect1 id="errors"><title>Errors</title>
  66         <para>
  67             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glClearIndex</function>
  68             is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
  69             and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
  70         </para>
  71     </refsect1>
  72     <refsect1 id="associatedgets"><title>Associated Gets</title>
  73         <para>
  74             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_INDEX_CLEAR_VALUE</constant>
  75         </para>
  76         <para>
  77             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_INDEX_BITS</constant>
  78         </para>
  79     </refsect1>
  80     <refsect1 id="seealso"><title>See Also</title>
  81         <para>
  82             <citerefentry><refentrytitle>glClear</refentrytitle></citerefentry>
  83         </para>
  84     </refsect1>
  85     <refsect1 id="Copyright"><title>Copyright</title>
  86         <para>
  87             Copyright <trademark class="copyright"></trademark> 1991-2006
  88             Silicon Graphics, Inc. This document is licensed under the SGI
  89             Free Software B License. For details, see
  90             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
  91         </para>
  92     </refsect1>
  93 </refentry>