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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="glScale">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glScale</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glScale</refname>
<refpurpose>multiply the current matrix by a general scaling matrix</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glScaled</function></funcdef>
<paramdef>GLdouble <parameter>x</parameter></paramdef>
<paramdef>GLdouble <parameter>y</parameter></paramdef>
<paramdef>GLdouble <parameter>z</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glScalef</function></funcdef>
<paramdef>GLfloat <parameter>x</parameter></paramdef>
<paramdef>GLfloat <parameter>y</parameter></paramdef>
<paramdef>GLfloat <parameter>z</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>x</parameter></term>
<term><parameter>y</parameter></term>
<term><parameter>z</parameter></term>
<listitem>
<para>
Specify scale factors along the <emphasis>x</emphasis>, <emphasis>y</emphasis>, and <emphasis>z</emphasis> axes, respectively.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>glScale</function> produces a nonuniform scaling along the <emphasis>x</emphasis>, <emphasis>y</emphasis>, and
<emphasis>z</emphasis> axes.
The three parameters indicate the desired scale factor along
each of the three axes.
</para>
<para>
The current matrix
(see <citerefentry><refentrytitle>glMatrixMode</refentrytitle></citerefentry>)
is multiplied by this scale matrix,
and the product replaces the current matrix
as if <citerefentry><refentrytitle>glMultMatrix</refentrytitle></citerefentry> were called with the following matrix
as its argument:
</para>
<para>
<informalequation><mml:math>
<!-- 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 ):-->
<mml:mfenced open="(" close=")">
<mml:mtable>
<mml:mtr>
<mml:mtd>
<mml:mi mathvariant="italic">x</mml:mi>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
</mml:mtr>
<mml:mtr>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mi mathvariant="italic">y</mml:mi>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
</mml:mtr>
<mml:mtr>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mi mathvariant="italic">z</mml:mi>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
</mml:mtr>
<mml:mtr>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>0</mml:mn>
</mml:mtd>
<mml:mtd>
<mml:mn>1</mml:mn>
</mml:mtd>
</mml:mtr>
</mml:mtable>
</mml:mfenced>
</mml:math></informalequation>
</para>
<para>
If the matrix mode is either <constant>GL_MODELVIEW</constant> or <constant>GL_PROJECTION</constant>,
all objects drawn after <function>glScale</function> is called are scaled.
</para>
<para>
Use <citerefentry><refentrytitle>glPushMatrix</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glPopMatrix</refentrytitle></citerefentry> to save and restore
the unscaled coordinate
system.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
If scale factors other than 1 are applied to the modelview matrix
and lighting is enabled, lighting often appears wrong.
In that case, enable automatic normalization of normals by
calling <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry> with the argument <constant>GL_NORMALIZE</constant>.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if <function>glScale</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="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MATRIX_MODE</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_COLOR_MATRIX</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MODELVIEW_MATRIX</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_PROJECTION_MATRIX</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_TEXTURE_MATRIX</constant>
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glMatrixMode</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glMultMatrix</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glPushMatrix</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glRotate</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glTranslate</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>