
<refentry id="gluProject">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>gluProject</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>gluProject</refname>
        <refpurpose>map object coordinates to window coordinates</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>GLint <function>gluProject</function></funcdef>
                <paramdef>GLdouble <parameter>objX</parameter></paramdef>
                <paramdef>GLdouble <parameter>objY</parameter></paramdef>
                <paramdef>GLdouble <parameter>objZ</parameter></paramdef>
                <paramdef>const GLdouble * <parameter>model</parameter></paramdef>
                <paramdef>const GLdouble * <parameter>proj</parameter></paramdef>
                <paramdef>const GLint * <parameter>view</parameter></paramdef>
                <paramdef>GLdouble* <parameter>winX</parameter></paramdef>
                <paramdef>GLdouble* <parameter>winY</parameter></paramdef>
                <paramdef>GLdouble* <parameter>winZ</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <!-- eqn: ignoring delim $$ -->
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>objX</parameter></term>
            <term><parameter>objY</parameter></term>
            <term><parameter>objZ</parameter></term>
            <listitem>
                <para>
                    Specify the object coordinates.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>model</parameter></term>
            <listitem>
                <para>
                    Specifies the current modelview matrix (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>proj</parameter></term>
            <listitem>
                <para>
                    Specifies the current projection matrix (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>view</parameter></term>
            <listitem>
                <para>
                    Specifies the current viewport (as from a <citerefentry><refentrytitle>glGetIntegerv</refentrytitle></citerefentry> call).
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>winX</parameter></term>
            <term><parameter>winY</parameter></term>
            <term><parameter>winZ</parameter></term>
            <listitem>
                <para>
                    Return the computed window coordinates.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>gluProject</function> transforms the specified object coordinates into window coordinates
            using <parameter>model</parameter>, <parameter>proj</parameter>, and <parameter>view</parameter>. The result is stored 
            in <parameter>winX</parameter>, <parameter>winY</parameter>, and <parameter>winZ</parameter>. A return value of 
            <constant>GLU_TRUE</constant> indicates success, a return value of <constant>GLU_FALSE</constant>
            indicates failure.
        </para>
        <para>
            To compute the coordinates,
            let 
            <inlineequation><mml:math>
                <!-- eqn: v  =  (objX, objY, objZ, 1.0):-->
                <mml:mrow>
                    <mml:mi mathvariant="italic">v</mml:mi>
                    <mml:mo>=</mml:mo>
                    <mml:mfenced open="(" close=")">
                        <mml:mi mathvariant="italic">objX</mml:mi>
                        <mml:mi mathvariant="italic">objY</mml:mi>
                        <mml:mi mathvariant="italic">objZ</mml:mi>
                        <mml:mn>1.0</mml:mn>
                    </mml:mfenced>
                </mml:mrow>
            </mml:math></inlineequation>
            represented as a matrix with 4 rows and 1 column.
            Then <function>gluProject</function> computes 
            <inlineequation><mml:math>
                <!-- eqn: v sup prime:-->
                <mml:msup><mml:mi mathvariant="italic">v</mml:mi>
                <mml:mo>&Prime;</mml:mo>
                </mml:msup>
            </mml:math></inlineequation>
            as follows: 
        </para>
        <para>
            <informalequation><mml:math>
                <!-- eqn: v sup prime  =  P  times  M  times  v:-->
                <mml:mrow>
                    <mml:msup><mml:mi mathvariant="italic">v</mml:mi>
                    <mml:mo>&Prime;</mml:mo>
                    </mml:msup>
                    <mml:mo>=</mml:mo>
                    <mml:mrow>
                        <mml:mi mathvariant="italic">P</mml:mi>
                        <mml:mo>&times;</mml:mo>
                        <mml:mi mathvariant="italic">M</mml:mi>
                        <mml:mo>&times;</mml:mo>
                        <mml:mi mathvariant="italic">v</mml:mi>
                    </mml:mrow>
                </mml:mrow>
            </mml:math></informalequation>
        </para>
        <para>
            where 
            <inlineequation><mml:math><mml:mi mathvariant="italic">P</mml:mi></mml:math></inlineequation>
            is the current projection matrix <parameter>proj</parameter> and 
            <inlineequation><mml:math><mml:mi mathvariant="italic">M</mml:mi></mml:math></inlineequation>
            is the current
            modelview matrix <parameter>model</parameter> (both represented as
            <inlineequation><mml:math>
                <!-- eqn: 4 times 4:-->
                <mml:mrow>
                    <mml:mn>4</mml:mn>
                    <mml:mo>&times;</mml:mo>
                    <mml:mn>4</mml:mn>
                </mml:mrow>
            </mml:math></inlineequation>
            matrices in column-major order).
        </para>
        <para>
            The window coordinates are then computed as follows: 
        </para>
        <para>
            <informalequation><mml:math>
                <!-- eqn: winX  =  view (0)  +  view (2)  *    (v sup prime (0)  +  1) / 2:-->
                <mml:mrow>
                    <mml:mi mathvariant="italic">winX</mml:mi>
                    <mml:mo>=</mml:mo>
                    <mml:mrow>
                        <mml:mrow>
                            <mml:mi mathvariant="italic">view</mml:mi>
                            <mml:mo>&af;</mml:mo>
                            <mml:mfenced open="(" close=")">
                                <mml:mn>0</mml:mn>
                            </mml:mfenced>
                        </mml:mrow>
                        <mml:mo>+</mml:mo>
                        <mml:mfrac>
                            <mml:mrow>
                                <mml:mrow>
                                    <mml:mi mathvariant="italic">view</mml:mi>
                                    <mml:mo>&af;</mml:mo>
                                    <mml:mfenced open="(" close=")">
                                        <mml:mn>2</mml:mn>
                                    </mml:mfenced>
                                </mml:mrow>
                                <mml:mo>&times;</mml:mo>
                                <mml:mfenced open="(" close=")">
                                    <mml:mrow>
                                        <mml:mrow>
                                            <mml:msup><mml:mi mathvariant="italic">v</mml:mi>
                                            <mml:mo>&Prime;</mml:mo>
                                            </mml:msup>
                                            <mml:mo>&af;</mml:mo>
                                            <mml:mfenced open="(" close=")">
                                                <mml:mn>0</mml:mn>
                                            </mml:mfenced>
                                        </mml:mrow>
                                        <mml:mo>+</mml:mo>
                                        <mml:mn>1</mml:mn>
                                    </mml:mrow>
                                </mml:mfenced>
                            </mml:mrow>
                            <mml:mn>2</mml:mn>
                        </mml:mfrac>
                    </mml:mrow>
                </mml:mrow>
            </mml:math></informalequation>
            <para>
                <informalequation><mml:math>
                    <!-- eqn: winY  =  view (1)  +  view (3)  *    (v sup prime (1)  +  1) / 2:-->
                    <mml:mrow>
                        <mml:mi mathvariant="italic">winY</mml:mi>
                        <mml:mo>=</mml:mo>
                        <mml:mrow>
                            <mml:mrow>
                                <mml:mi mathvariant="italic">view</mml:mi>
                                <mml:mo>&af;</mml:mo>
                                <mml:mfenced open="(" close=")">
                                    <mml:mn>1</mml:mn>
                                </mml:mfenced>
                            </mml:mrow>
                            <mml:mo>+</mml:mo>
                            <mml:mfrac>
                                <mml:mrow>
                                    <mml:mrow>
                                        <mml:mi mathvariant="italic">view</mml:mi>
                                        <mml:mo>&af;</mml:mo>
                                        <mml:mfenced open="(" close=")">
                                            <mml:mn>3</mml:mn>
                                        </mml:mfenced>
                                    </mml:mrow>
                                    <mml:mo>&times;</mml:mo>
                                    <mml:mfenced open="(" close=")">
                                        <mml:mrow>
                                            <mml:mrow>
                                                <mml:msup><mml:mi mathvariant="italic">v</mml:mi>
                                                <mml:mo>&Prime;</mml:mo>
                                                </mml:msup>
                                                <mml:mo>&af;</mml:mo>
                                                <mml:mfenced open="(" close=")">
                                                    <mml:mn>1</mml:mn>
                                                </mml:mfenced>
                                            </mml:mrow>
                                            <mml:mo>+</mml:mo>
                                            <mml:mn>1</mml:mn>
                                        </mml:mrow>
                                    </mml:mfenced>
                                </mml:mrow>
                                <mml:mn>2</mml:mn>
                            </mml:mfrac>
                        </mml:mrow>
                    </mml:mrow>
                </mml:math></informalequation>
            </para>
            <para>
                <informalequation><mml:math>
                    <!-- eqn: winZ  =  (v sup prime (2)   +  1) /  2:-->
                    <mml:mrow>
                        <mml:mi mathvariant="italic">winZ</mml:mi>
                        <mml:mo>=</mml:mo>
                        <mml:mfrac>
                            <mml:mfenced open="(" close=")">
                                <mml:mrow>
                                    <mml:mrow>
                                        <mml:msup><mml:mi mathvariant="italic">v</mml:mi>
                                        <mml:mo>&Prime;</mml:mo>
                                        </mml:msup>
                                        <mml:mo>&af;</mml:mo>
                                        <mml:mfenced open="(" close=")">
                                            <mml:mn>2</mml:mn>
                                        </mml:mfenced>
                                    </mml:mrow>
                                    <mml:mo>+</mml:mo>
                                    <mml:mn>1</mml:mn>
                                </mml:mrow>
                            </mml:mfenced>
                            <mml:mn>2</mml:mn>
                        </mml:mfrac>
                    </mml:mrow>
                </mml:math></informalequation>
            </para>
        </para>
        <para>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>gluUnProject</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGet</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>
