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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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<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>
