192 lines
8.8 KiB
XML
192 lines
8.8 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="glScale">
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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>glScale</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glScale</refname>
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<refpurpose>multiply the current matrix by a general scaling matrix</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>void <function>glScaled</function></funcdef>
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<paramdef>GLdouble <parameter>x</parameter></paramdef>
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<paramdef>GLdouble <parameter>y</parameter></paramdef>
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<paramdef>GLdouble <parameter>z</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glScalef</function></funcdef>
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<paramdef>GLfloat <parameter>x</parameter></paramdef>
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<paramdef>GLfloat <parameter>y</parameter></paramdef>
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<paramdef>GLfloat <parameter>z</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>x</parameter></term>
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<term><parameter>y</parameter></term>
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<term><parameter>z</parameter></term>
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<listitem>
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<para>
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Specify scale factors along the <emphasis>x</emphasis>, <emphasis>y</emphasis>, and <emphasis>z</emphasis> axes, respectively.
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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>glScale</function> produces a nonuniform scaling along the <emphasis>x</emphasis>, <emphasis>y</emphasis>, and
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<emphasis>z</emphasis> axes.
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The three parameters indicate the desired scale factor along
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each of the three axes.
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</para>
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<para>
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The current matrix
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(see <citerefentry><refentrytitle>glMatrixMode</refentrytitle></citerefentry>)
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is multiplied by this scale matrix,
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and the product replaces the current matrix
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as if <citerefentry><refentrytitle>glMultMatrix</refentrytitle></citerefentry> were called with the following matrix
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as its argument:
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</para>
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<para>
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<informalequation><mml:math>
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<!-- eqn: left ( matrix { ccol { x above 0 above 0 above 0 } ccol { 0 above y above 0 above 0 } ccol { 0 above 0 above z above 0 } ccol { 0 above 0 above 0 above 1} } right ):-->
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<mml:mfenced open="(" close=")">
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<mml:mtable>
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<mml:mtr>
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<mml:mtd>
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<mml:mi mathvariant="italic">x</mml:mi>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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</mml:mtr>
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<mml:mtr>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mi mathvariant="italic">y</mml:mi>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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</mml:mtr>
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<mml:mtr>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mi mathvariant="italic">z</mml:mi>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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</mml:mtr>
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<mml:mtr>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>0</mml:mn>
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</mml:mtd>
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<mml:mtd>
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<mml:mn>1</mml:mn>
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</mml:mtd>
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</mml:mtr>
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</mml:mtable>
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</mml:mfenced>
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</mml:math></informalequation>
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</para>
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<para>
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If the matrix mode is either <constant>GL_MODELVIEW</constant> or <constant>GL_PROJECTION</constant>,
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all objects drawn after <function>glScale</function> is called are scaled.
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</para>
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<para>
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Use <citerefentry><refentrytitle>glPushMatrix</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glPopMatrix</refentrytitle></citerefentry> to save and restore
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the unscaled coordinate
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system.
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</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para>
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If scale factors other than 1 are applied to the modelview matrix
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and lighting is enabled, lighting often appears wrong.
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In that case, enable automatic normalization of normals by
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calling <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> with the argument <constant>GL_NORMALIZE</constant>.
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</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glScale</function>
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is executed between the execution of
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<citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
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and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
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</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MATRIX_MODE</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_COLOR_MATRIX</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MODELVIEW_MATRIX</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PROJECTION_MATRIX</constant>
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</para>
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<para>
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<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_MATRIX</constant>
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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>glMatrixMode</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glMultMatrix</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glPushMatrix</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glRotate</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glTranslate</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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