
<refentry id="glGetPixelMap">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetPixelMap</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetPixelMap</refname>
        <refpurpose>return the specified pixel map</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetPixelMapfv</function></funcdef>
                <paramdef>GLenum <parameter>map</parameter></paramdef>
                <paramdef>GLfloat * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetPixelMapuiv</function></funcdef>
                <paramdef>GLenum <parameter>map</parameter></paramdef>
                <paramdef>GLuint * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetPixelMapusv</function></funcdef>
                <paramdef>GLenum <parameter>map</parameter></paramdef>
                <paramdef>GLushort * <parameter>data</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>map</parameter></term>
            <listitem>
                <para>
                    Specifies the name of the pixel map to return.
                    Accepted values are
                    <constant>GL_PIXEL_MAP_I_TO_I</constant>,
                    <constant>GL_PIXEL_MAP_S_TO_S</constant>,
                    <constant>GL_PIXEL_MAP_I_TO_R</constant>,
                    <constant>GL_PIXEL_MAP_I_TO_G</constant>,
                    <constant>GL_PIXEL_MAP_I_TO_B</constant>,
                    <constant>GL_PIXEL_MAP_I_TO_A</constant>,
                    <constant>GL_PIXEL_MAP_R_TO_R</constant>,
                    <constant>GL_PIXEL_MAP_G_TO_G</constant>,
                    <constant>GL_PIXEL_MAP_B_TO_B</constant>, and
                    <constant>GL_PIXEL_MAP_A_TO_A</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>data</parameter></term>
            <listitem>
                <para>
                    Returns the pixel map contents.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            See the <citerefentry><refentrytitle>glPixelMap</refentrytitle></citerefentry> reference page for a description of the acceptable
            values for the <parameter>map</parameter> parameter.
            <function>glGetPixelMap</function> returns in <parameter>data</parameter> the contents of the pixel map
            specified in <parameter>map</parameter>.
            Pixel maps are used during the execution of
            <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>, and
            <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>.
            to map color indices,
            stencil indices,
            color components,
            and depth components to other values.
        </para>
        <para>
            If a non-zero named buffer object is bound to the <constant>GL_PIXEL_PACK_BUFFER</constant> target 
            (see <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>) while a pixel map is
            requested, <parameter>data</parameter> is treated as a byte offset into the buffer object's data store.
        </para>
        <para>
            Unsigned integer values,
            if requested,
            are linearly mapped from the internal fixed or floating-point representation
            such that 1.0 maps to the largest representable integer value,
            and 0.0 maps to 0.
            Return unsigned integer values are undefined if the map value was
            not in the range [0,1].
        </para>
        <para>
            To determine the required size of <parameter>map</parameter>,
            call <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with the appropriate symbolic
            constant.
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            If an error is generated,
            no change is made to the contents of <parameter>data</parameter>.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>map</parameter> is not an accepted value.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
            <constant>GL_PIXEL_PACK_BUFFER</constant> target and the buffer object's data store is currently mapped.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to the
            <constant>GL_PIXEL_PACK_BUFFER</constant> target and the data would be packed to the buffer 
            object such that the memory writes required would exceed the data store size.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by <function>glGetPixelMapfv</function> if a non-zero buffer object name is bound to the
            <constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>data</parameter> is not evenly divisible 
            into the number of bytes needed to store in memory a GLfloat datum.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by <function>glGetPixelMapuiv</function> if a non-zero buffer object name is bound to the
            <constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>data</parameter> is not evenly divisible 
            into the number of bytes needed to store in memory a GLuint datum.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated by <function>glGetPixelMapusv</function> if a non-zero buffer object name is bound to the
            <constant>GL_PIXEL_PACK_BUFFER</constant> target and <parameter>data</parameter> is not evenly divisible 
            into the number of bytes needed to store in memory a GLushort datum.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetPixelMap</function>
            is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
            and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
        </para>
    </refsect1>
    <refsect1 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_I_TO_I_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_S_TO_S_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_I_TO_R_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_I_TO_G_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_I_TO_B_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_I_TO_A_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_R_TO_R_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_G_TO_G_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_B_TO_B_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_MAP_A_TO_A_SIZE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_PIXEL_MAP_TABLE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PIXEL_PACK_BUFFER_BINDING</constant>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glColorSubTable</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glColorTable</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glConvolutionFilter1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glConvolutionFilter2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyColorSubTable</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyColorTable</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyPixels</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glCopyTexSubImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawPixels</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetHistogram</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetMinmax</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetTexImage</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glPixelMap</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glPixelTransfer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glReadPixels</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glSeparableFilter2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>
            <citerefentry><refentrytitle>glTexImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexImage3D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexSubImage1D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexSubImage2D</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexSubImage3D</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
        </para>
    </refsect1>
</refentry>
