
<refentry id="glGetTexGen">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetTexGen</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetTexGen</refname>
        <refpurpose>return texture coordinate generation parameters</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetTexGendv</function></funcdef>
                <paramdef>GLenum <parameter>coord</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLdouble * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetTexGenfv</function></funcdef>
                <paramdef>GLenum <parameter>coord</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLfloat * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetTexGeniv</function></funcdef>
                <paramdef>GLenum <parameter>coord</parameter></paramdef>
                <paramdef>GLenum <parameter>pname</parameter></paramdef>
                <paramdef>GLint * <parameter>params</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <!-- eqn: ignoring delim $$ -->
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>coord</parameter></term>
            <listitem>
                <para>
                    Specifies a texture coordinate.
                    Must be
                    <constant>GL_S</constant>,
                    <constant>GL_T</constant>,
                    <constant>GL_R</constant>, or
                    <constant>GL_Q</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>pname</parameter></term>
            <listitem>
                <para>
                    Specifies the symbolic name of the value(s) to be returned.
                    Must be either <constant>GL_TEXTURE_GEN_MODE</constant>
                    or the name of one of the texture generation plane equations:
                    <constant>GL_OBJECT_PLANE</constant> or <constant>GL_EYE_PLANE</constant>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>params</parameter></term>
            <listitem>
                <para>
                    Returns the requested data.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glGetTexGen</function> returns in <parameter>params</parameter> selected parameters of a texture coordinate
            generation function that was specified using <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry>.
            <parameter>coord</parameter> names one of the (<emphasis>s</emphasis>, <emphasis>t</emphasis>, <emphasis>r</emphasis>, <emphasis>q</emphasis>)
            texture coordinates,
            using the symbolic constant
            <constant>GL_S</constant>,
            <constant>GL_T</constant>,
            <constant>GL_R</constant>, or
            <constant>GL_Q</constant>.
        </para>
        <para>
            <parameter>pname</parameter> specifies one of three symbolic names:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_TEXTURE_GEN_MODE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the single-valued texture generation function,
                        a symbolic constant. The initial value is <constant>GL_EYE_LINEAR</constant>.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_OBJECT_PLANE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the four plane equation coefficients that specify
                        object linear-coordinate generation.
                        Integer values, when requested,
                        are mapped directly from the internal floating-point representation.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_EYE_PLANE</constant></term>
                <listitem>
                    <para>
                        <parameter>params</parameter> returns the four plane equation coefficients that specify
                        eye linear-coordinate generation.
                        Integer values,
                        when requested,
                        are mapped directly from the internal floating-point representation.
                        The returned values are those maintained in eye coordinates.
                        They are not equal to the values specified using <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry>,
                        unless the modelview matrix was identity when <citerefentry><refentrytitle>glTexGen</refentrytitle></citerefentry> was called.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            If an error is generated,
            no change is made to the contents of <parameter>params</parameter>.
        </para>
        <para>
            For OpenGL versions 1.3 and greater, or when the <code>ARB_multitexture</code> extension is supported, <function>glGetTexGen</function> returns
            the texture coordinate generation parameters for the active texture unit.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_ENUM</constant> is generated if <parameter>coord</parameter> or <parameter>pname</parameter> is not an
            accepted value.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetTexGen</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="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glActiveTexture</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTexGen</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>
