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OpenGL ES 1.0 and EGL 1.0 reference manual and man pages (written by
Claude Knaus, based on OpenGL SI man pages).

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.2//EN" "DTD/docbook/docbookx.dtd">

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  Original Code. The Original Code is: OpenGL ES Reference Manual,
  Version 1.0, released September 2003, developed by Silicon Graphics,
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<refentry id="glIntro">

  <refmeta>
    <refentrytitle>glIntro</refentrytitle>
    <manvolnum>3G</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>glIntro</refname>
    <refpurpose>
      introduction to <acronym>OpenGL ES</acronym>
    </refpurpose>
  </refnamediv>

  <refsect1>
    <title>Overview</title>

    <para>
      OpenGL ES (GL) is a 3D-oriented renderer for embedded systems.
    </para>

    <para>
      See <citerefentry><refentrytitle>eglIntro</refentrytitle></citerefentry>
      for a short example program.
    </para>
  </refsect1>
 
  <refsect1>
    <title>OpenGL Extensions</title>

    <para>
      The following extensions currently exist. Note that the set
      of supported extensions depends on the implementation.
    </para>

    <variablelist>
      <varlistentry>
        <term><constant>OES_query_matrix</constant></term>
        <listitem><para>
          provides a way to query the values of the current matrix.
          Each matrix value is returned as a mantissa/exponent pair.
          If the implementation supports tracking of invalid values, 
          they are indicated in the returned status value.
        </para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Using OpenGL ES Extensions</title>

    <para>
      Function names and tokens for OpenGL ES extensions are suffixed with OES
      or with a vendor-specfic acronym. OES is used for extensions that have
      been reviewed by the Khronos Group and might be supported by more than
      one OpenGL ES vendor.
    </para>

    <para>
      All supported extensions have an associated macro definition in
      <filename>gl.h</filename> and
      a corresponding token in the extensions string returned by
      <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>.
      For example, if the <constant>OES_query_matrix</constant> extension
      is supported, then the token
      <constant>GL_OES_query_matrix</constant> will be defined in
      <filename>gl.h</filename> and
      <constant>GL_OES_query_matrix</constant> will appear in the
      extensions string returned by
      <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>.
    </para>

    <para>
      The definitions in <filename>gl.h</filename>
      can be used at compile time to determine if an
      extension's tokens and procedures exist in the OpenGL ES library. However,
      the tokens returned by
      <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
      must be consulted at runtime to determine whether the extension is
      supported on the particular context in use at that moment.
    </para>
  </refsect1>

  <refsect1>
    <title>Files</title>

    <variablelist>
      <varlistentry>
	<term><filename>GLES/gl.h</filename></term>
	<listitem><para>
          OpenGL ES header file
        </para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>See Also</title>

    <para>
      <citerefentry><refentrytitle>eglIntro</refentrytitle></citerefentry>,
      <citerefentry><refentrytitle>glGetString</refentrytitle></citerefentry>
    </para>
  </refsect1>

</refentry>