294 lines
14 KiB
XML
294 lines
14 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="gluProject">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>gluProject</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>gluProject</refname>
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<refpurpose>map object coordinates to window coordinates</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>GLint <function>gluProject</function></funcdef>
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<paramdef>GLdouble <parameter>objX</parameter></paramdef>
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<paramdef>GLdouble <parameter>objY</parameter></paramdef>
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<paramdef>GLdouble <parameter>objZ</parameter></paramdef>
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<paramdef>const GLdouble * <parameter>model</parameter></paramdef>
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<paramdef>const GLdouble * <parameter>proj</parameter></paramdef>
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<paramdef>const GLint * <parameter>view</parameter></paramdef>
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<paramdef>GLdouble* <parameter>winX</parameter></paramdef>
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<paramdef>GLdouble* <parameter>winY</parameter></paramdef>
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<paramdef>GLdouble* <parameter>winZ</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<!-- eqn: ignoring delim $$ -->
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>objX</parameter></term>
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<term><parameter>objY</parameter></term>
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<term><parameter>objZ</parameter></term>
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<listitem>
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<para>
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Specify the object coordinates.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>model</parameter></term>
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<listitem>
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<para>
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Specifies the current modelview matrix (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>proj</parameter></term>
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<listitem>
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<para>
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Specifies the current projection matrix (as from a <citerefentry><refentrytitle>glGetDoublev</refentrytitle></citerefentry> call).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>view</parameter></term>
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<listitem>
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<para>
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Specifies the current viewport (as from a <citerefentry><refentrytitle>glGetIntegerv</refentrytitle></citerefentry> call).
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>winX</parameter></term>
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<term><parameter>winY</parameter></term>
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<term><parameter>winZ</parameter></term>
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<listitem>
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<para>
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Return the computed window coordinates.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para>
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<function>gluProject</function> transforms the specified object coordinates into window coordinates
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using <parameter>model</parameter>, <parameter>proj</parameter>, and <parameter>view</parameter>. The result is stored
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in <parameter>winX</parameter>, <parameter>winY</parameter>, and <parameter>winZ</parameter>. A return value of
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<constant>GLU_TRUE</constant> indicates success, a return value of <constant>GLU_FALSE</constant>
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indicates failure.
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</para>
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<para>
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To compute the coordinates,
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let
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<inlineequation><mml:math>
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<!-- eqn: v = (objX, objY, objZ, 1.0):-->
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<mml:mrow>
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<mml:mi mathvariant="italic">v</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mi mathvariant="italic">objX</mml:mi>
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<mml:mi mathvariant="italic">objY</mml:mi>
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<mml:mi mathvariant="italic">objZ</mml:mi>
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<mml:mn>1.0</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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</mml:math></inlineequation>
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represented as a matrix with 4 rows and 1 column.
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Then <function>gluProject</function> computes
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<inlineequation><mml:math>
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<!-- eqn: v sup prime:-->
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<mml:msup><mml:mi mathvariant="italic">v</mml:mi>
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<mml:mo>″</mml:mo>
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</mml:msup>
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</mml:math></inlineequation>
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as follows:
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</para>
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<para>
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<informalequation><mml:math>
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<!-- eqn: v sup prime = P times M times v:-->
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<mml:mrow>
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<mml:msup><mml:mi mathvariant="italic">v</mml:mi>
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<mml:mo>″</mml:mo>
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</mml:msup>
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<mml:mo>=</mml:mo>
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<mml:mrow>
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<mml:mi mathvariant="italic">P</mml:mi>
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<mml:mo>×</mml:mo>
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<mml:mi mathvariant="italic">M</mml:mi>
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<mml:mo>×</mml:mo>
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<mml:mi mathvariant="italic">v</mml:mi>
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</mml:mrow>
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</mml:mrow>
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</mml:math></informalequation>
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</para>
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<para>
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where
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<inlineequation><mml:math><mml:mi mathvariant="italic">P</mml:mi></mml:math></inlineequation>
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is the current projection matrix <parameter>proj</parameter> and
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<inlineequation><mml:math><mml:mi mathvariant="italic">M</mml:mi></mml:math></inlineequation>
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is the current
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modelview matrix <parameter>model</parameter> (both represented as
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<inlineequation><mml:math>
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<!-- eqn: 4 times 4:-->
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<mml:mrow>
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<mml:mn>4</mml:mn>
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<mml:mo>×</mml:mo>
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<mml:mn>4</mml:mn>
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</mml:mrow>
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</mml:math></inlineequation>
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matrices in column-major order).
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</para>
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<para>
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The window coordinates are then computed as follows:
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</para>
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<para>
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<informalequation><mml:math>
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<!-- eqn: winX = view (0) + view (2) * (v sup prime (0) + 1) / 2:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">winX</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mrow>
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<mml:mrow>
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<mml:mi mathvariant="italic">view</mml:mi>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>0</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>+</mml:mo>
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<mml:mfrac>
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<mml:mrow>
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<mml:mrow>
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<mml:mi mathvariant="italic">view</mml:mi>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>2</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>×</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mrow>
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<mml:mrow>
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<mml:msup><mml:mi mathvariant="italic">v</mml:mi>
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<mml:mo>″</mml:mo>
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</mml:msup>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>0</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>+</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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<mml:mn>2</mml:mn>
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</mml:mfrac>
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</mml:mrow>
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</mml:mrow>
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</mml:math></informalequation>
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<para>
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<informalequation><mml:math>
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<!-- eqn: winY = view (1) + view (3) * (v sup prime (1) + 1) / 2:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">winY</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mrow>
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<mml:mrow>
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<mml:mi mathvariant="italic">view</mml:mi>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>1</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>+</mml:mo>
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<mml:mfrac>
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<mml:mrow>
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<mml:mrow>
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<mml:mi mathvariant="italic">view</mml:mi>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>3</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>×</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mrow>
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<mml:mrow>
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<mml:msup><mml:mi mathvariant="italic">v</mml:mi>
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<mml:mo>″</mml:mo>
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</mml:msup>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>1</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>+</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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</mml:mfenced>
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</mml:mrow>
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<mml:mn>2</mml:mn>
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</mml:mfrac>
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</mml:mrow>
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</mml:mrow>
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</mml:math></informalequation>
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</para>
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<para>
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<informalequation><mml:math>
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<!-- eqn: winZ = (v sup prime (2) + 1) / 2:-->
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<mml:mrow>
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<mml:mi mathvariant="italic">winZ</mml:mi>
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<mml:mo>=</mml:mo>
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<mml:mfrac>
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<mml:mfenced open="(" close=")">
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<mml:mrow>
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<mml:mrow>
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<mml:msup><mml:mi mathvariant="italic">v</mml:mi>
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<mml:mo>″</mml:mo>
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</mml:msup>
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<mml:mo>⁡</mml:mo>
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<mml:mfenced open="(" close=")">
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<mml:mn>2</mml:mn>
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</mml:mfenced>
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</mml:mrow>
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<mml:mo>+</mml:mo>
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<mml:mn>1</mml:mn>
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</mml:mrow>
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</mml:mfenced>
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<mml:mn>2</mml:mn>
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</mml:mfrac>
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</mml:mrow>
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</mml:math></informalequation>
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</para>
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</para>
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<para>
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>gluUnProject</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
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</para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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