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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
<refentry id="gluUnProject4">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>gluUnProject4</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>gluUnProject4</refname>
<refpurpose>map window and clip coordinates to object coordinates</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>GLint <function>gluUnProject4</function></funcdef>
<paramdef>GLdouble <parameter>winX</parameter></paramdef>
<paramdef>GLdouble <parameter>winY</parameter></paramdef>
<paramdef>GLdouble <parameter>winZ</parameter></paramdef>
<paramdef>GLdouble <parameter>clipW</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>nearVal</parameter></paramdef>
<paramdef>GLdouble <parameter>farVal</parameter></paramdef>
<paramdef>GLdouble* <parameter>objX</parameter></paramdef>
<paramdef>GLdouble* <parameter>objY</parameter></paramdef>
<paramdef>GLdouble* <parameter>objZ</parameter></paramdef>
<paramdef>GLdouble* <parameter>objW</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>winX</parameter></term>
<term><parameter>winY</parameter></term>
<term><parameter>winZ</parameter></term>
<listitem>
<para>
Specify the window coordinates to be mapped.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>clipW</parameter></term>
<listitem>
<para>
Specify the clip w coordinate to be mapped.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>model</parameter></term>
<listitem>
<para>
Specifies the modelview matrix (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>proj</parameter></term>
<listitem>
<para>
Specifies the projection matrix (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>view</parameter></term>
<listitem>
<para>
Specifies the viewport (as from a <citerefentry><refentrytitle>glGetIntegerv</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>nearVal</parameter></term>
<term><parameter>farVal</parameter></term>
<listitem>
<para>
Specifies the near and far planes (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>objX</parameter></term>
<term><parameter>objY</parameter></term>
<term><parameter>objZ</parameter></term>
<term><parameter>objW</parameter></term>
<listitem>
<para>
Returns the computed object coordinates.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>gluUnProject4</function> maps the specified window coordinatesi: <parameter>winX</parameter>, <parameter>winY</parameter>, and <parameter>winZ</parameter>
and its clip w coordinate <parameter>clipW</parameter>
into object
coordinates
<inlineequation><mml:math>
<!-- eqn: (objX, objY, objZ, objW):-->
<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:mi mathvariant="italic">objW</mml:mi>
</mml:mfenced>
</mml:math></inlineequation>
using <parameter>model</parameter>, <parameter>proj</parameter>, and <parameter>view</parameter>. <parameter>clipW</parameter> can be other than
1 as for vertices in <citerefentry><refentrytitle>glFeedbackBuffer</refentrytitle></citerefentry> when data type
<constant>GLU_4D_COLOR_TEXTURE</constant> is returned.
This also handles the case
where the <parameter>nearVal</parameter> and <parameter>farVal</parameter> planes are different from the default,
0 and 1, respectively.
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
<inlineequation><mml:math>
<!-- eqn: (objX, objY, objZ, objW):-->
<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:mi mathvariant="italic">objW</mml:mi>
</mml:mfenced>
</mml:math></inlineequation>,
<function>gluUnProject4</function> multiplies the normalized device coordinates by the inverse of
<parameter>model</parameter> * <parameter>proj</parameter> as follows:
</para>
<para>
<informalequation><mml:math>
<!-- eqn: left ( cpile { objX above objY above objZ above objW} right ) = INV(P M) left ( cpile { {2(winX - view[0])} over {view[2]} - 1 above {2(winY - view[1])} over {view[3]} - 1 above {2(winZ - nearVal)} over {(farVal - nearVal)} - 1 above clipW} right ):-->
<mml:mrow>
<mml:mfenced open="(" close=")">
<mml:mtable>
<mml:mtr><mml:mtd>
<mml:mi mathvariant="italic">objX</mml:mi>
</mml:mtd></mml:mtr>
<mml:mtr><mml:mtd>
<mml:mi mathvariant="italic">objY</mml:mi>
</mml:mtd></mml:mtr>
<mml:mtr><mml:mtd>
<mml:mi mathvariant="italic">objZ</mml:mi>
</mml:mtd></mml:mtr>
<mml:mtr><mml:mtd>
<mml:mi mathvariant="italic">objW</mml:mi>
</mml:mtd></mml:mtr>
</mml:mtable>
</mml:mfenced>
<mml:mo>=</mml:mo>
<mml:mrow>
<mml:mrow>
<mml:mi mathvariant="italic">INV</mml:mi>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:mi mathvariant="italic">P</mml:mi>
<mml:mo>⁢</mml:mo>
<mml:mi mathvariant="italic">M</mml:mi>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
<mml:mo>⁢</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mtable>
<mml:mtr><mml:mtd>
<mml:mrow>
<mml:mfrac>
<mml:mfenced open="" close="">
<mml:mrow>
<mml:mn>2</mml:mn>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:mi mathvariant="italic">winX</mml:mi>
<mml:mo>-</mml:mo>
<mml:mrow>
<mml:mi mathvariant="italic">view</mml:mi>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="[" close="]">
<mml:mn>0</mml:mn>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mfenced>
<mml:mfenced open="" close="">
<mml:mrow>
<mml:mi mathvariant="italic">view</mml:mi>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="[" close="]">
<mml:mn>2</mml:mn>
</mml:mfenced>
</mml:mrow>
</mml:mfenced>
</mml:mfrac>
<mml:mo>-</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:mtd></mml:mtr>
<mml:mtr><mml:mtd>
<mml:mrow>
<mml:mfrac>
<mml:mfenced open="" close="">
<mml:mrow>
<mml:mn>2</mml:mn>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:mi mathvariant="italic">winY</mml:mi>
<mml:mo>-</mml:mo>
<mml:mrow>
<mml:mi mathvariant="italic">view</mml:mi>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="[" close="]">
<mml:mn>1</mml:mn>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mfenced>
<mml:mfenced open="" close="">
<mml:mrow>
<mml:mi mathvariant="italic">view</mml:mi>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="[" close="]">
<mml:mn>3</mml:mn>
</mml:mfenced>
</mml:mrow>
</mml:mfenced>
</mml:mfrac>
<mml:mo>-</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:mtd></mml:mtr>
<mml:mtr><mml:mtd>
<mml:mrow>
<mml:mfrac>
<mml:mfenced open="" close="">
<mml:mrow>
<mml:mn>2</mml:mn>
<mml:mo>⁡</mml:mo>
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:mi mathvariant="italic">winZ</mml:mi>
<mml:mo>-</mml:mo>
<mml:mi mathvariant="italic">nearVal</mml:mi>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mfenced>
<mml:mfenced open="" close="">
<mml:mfenced open="(" close=")">
<mml:mrow>
<mml:mi mathvariant="italic">farVal</mml:mi>
<mml:mo>-</mml:mo>
<mml:mi mathvariant="italic">nearVal</mml:mi>
</mml:mrow>
</mml:mfenced>
</mml:mfenced>
</mml:mfrac>
<mml:mo>-</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:mtd></mml:mtr>
<mml:mtr><mml:mtd>
<mml:mi mathvariant="italic">clipW</mml:mi>
</mml:mtd></mml:mtr>
</mml:mtable>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math></informalequation>
</para>
<para>
<inlineequation><mml:math><mml:mi mathvariant="italic">INV</mml:mi></mml:math></inlineequation>
denotes matrix inversion.
</para>
<para>
<function>gluUnProject4</function> is equivalent to <citerefentry><refentrytitle>gluUnProject</refentrytitle></citerefentry> when <parameter>clipW</parameter> is 1, <parameter>nearVal</parameter> is 0, and
<parameter>farVal</parameter> is 1.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
<function>gluUnProject4</function> is available only if the GLU version is 1.3 or greater.
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>gluProject</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>gluUnProject</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glFeedbackBuffer</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>