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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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<refentry id="glClear">
  <refmeta>
    <refentrytitle>glClear</refentrytitle>
    <manvolnum>3G</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>glClear</refname>
    <refpurpose>clear buffers to preset values</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <title>C Specification</title>

    <funcsynopsis>
      <funcprototype>
        <funcdef>void <function>glClear</function></funcdef>
        <paramdef>GLbitfield <parameter>mask</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Parameters</title>

    <variablelist>
      <varlistentry>
        <term>
          <parameter>mask</parameter>
        </term>

        <listitem>
          <para>Bitwise OR of masks that indicate the buffers to be
          cleared. Valid masks are 
          <constant>GL_COLOR_BUFFER_BIT</constant>, 
          <constant>GL_DEPTH_BUFFER_BIT</constant>, and 
          <constant>GL_STENCIL_BUFFER_BIT</constant>.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

    <para>
    <function>glClear</function>
    sets the bitplane area of the window to values previously selected by 
    <citerefentry><refentrytitle>glClearColor</refentrytitle></citerefentry>, 
    <citerefentry><refentrytitle>glClearDepth</refentrytitle></citerefentry>,
    and 
    <citerefentry><refentrytitle>glClearStencil</refentrytitle></citerefentry>.
    </para>

    <para>The pixel ownership test, the scissor test, dithering,
    and the color buffer masks affect the operation of 
    <function>glClear</function>.
    The scissor box bounds the cleared region. Alpha function,
    blend function, logical operation, stenciling, texture mapping,
    and depth-buffering are ignored by <function>glClear</function>.</para>

    <para>
    <function>glClear</function>
    takes a single argument that is the bitwise OR of several
    values indicating which buffer is to be cleared.</para>

    <para>The values are as follows:</para>

    <variablelist>
      <varlistentry>
        <term>
          <constant>GL_COLOR_BUFFER_BIT</constant>
        </term>

        <listitem>
          <para>Indicates the color buffer.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_DEPTH_BUFFER_BIT</constant>
        </term>

        <listitem>
          <para>Indicates the depth buffer.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>
          <constant>GL_STENCIL_BUFFER_BIT</constant>
        </term>

        <listitem>
          <para>Indicates the stencil buffer.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>The value to which each buffer is cleared depends on the
    setting of the clear value for that buffer.</para>
  </refsect1>

  <refsect1>
    <title>Notes</title>

    <para>If a buffer is not present, then a <function>glClear</function>
    directed at that buffer has no effect.</para>
  </refsect1>

  <refsect1>
    <title>Errors</title>

    <para><constant>GL_INVALID_VALUE</constant>
    is generated if any bit other than the defined bits is set in 
    <parameter>mask</parameter>.</para>
  </refsect1>

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

    <para>
    <citerefentry><refentrytitle>glClearColor</refentrytitle></citerefentry>, 
    <citerefentry><refentrytitle>glClearDepth</refentrytitle></citerefentry>, 
    <citerefentry><refentrytitle>glClearStencil</refentrytitle></citerefentry>, 
    <citerefentry><refentrytitle>glColorMask</refentrytitle></citerefentry>, 
    <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry>, 
    <citerefentry><refentrytitle>glScissor</refentrytitle></citerefentry>,
    </para>
  </refsect1>
</refentry>