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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="glPolygonOffset">
+    <refmeta>
+        <refmetainfo>
+            <copyright>
+                <year>1991-2006</year>
+                <holder>Silicon Graphics, Inc.</holder>
+            </copyright>
+        </refmetainfo>
+        <refentrytitle>glPolygonOffset</refentrytitle>
+        <manvolnum>3G</manvolnum>
+    </refmeta>
+    <refnamediv>
+        <refname>glPolygonOffset</refname>
+        <refpurpose>set the scale and units used to calculate depth values</refpurpose>
+    </refnamediv>
+    <refsynopsisdiv><title>C Specification</title>
+        <funcsynopsis>
+            <funcprototype>
+                <funcdef>void <function>glPolygonOffset</function></funcdef>
+                <paramdef>GLfloat <parameter>factor</parameter></paramdef>
+                <paramdef>GLfloat <parameter>units</parameter></paramdef>
+            </funcprototype>
+        </funcsynopsis>
+    </refsynopsisdiv>
+    <!-- eqn: ignoring delim $$ -->
+    <refsect1 id="parameters"><title>Parameters</title>
+        <variablelist>
+        <varlistentry>
+            <term><parameter>factor</parameter></term>
+            <listitem>
+                <para>
+                    Specifies a scale factor that is used to create a variable
+                    depth offset for each polygon. The initial value is 0.
+                </para>
+            </listitem>
+        </varlistentry>
+        <varlistentry>
+            <term><parameter>units</parameter></term>
+            <listitem>
+                <para>
+                    Is multiplied by an implementation-specific value to
+                    create a constant depth offset. The initial value is 0.
+                </para>
+            </listitem>
+        </varlistentry>
+        </variablelist>
+    </refsect1>
+    <refsect1 id="description"><title>Description</title>
+        <para>
+            When <constant>GL_POLYGON_OFFSET_FILL</constant>, <constant>GL_POLYGON_OFFSET_LINE</constant>, or
+            <constant>GL_POLYGON_OFFSET_POINT</constant> is enabled, each
+            fragment's <emphasis>depth</emphasis> value will be offset after it is interpolated
+            from the <emphasis>depth</emphasis> values of the appropriate vertices.
+            The value of the offset is 
+            <inlineequation><mml:math>
+                <!-- eqn: factor  *  DZ   +   r  *  units:-->
+                <mml:mrow>
+                    <mml:mrow>
+                        <mml:mi mathvariant="italic">factor</mml:mi>
+                        <mml:mo>&times;</mml:mo>
+                        <mml:mi mathvariant="italic">DZ</mml:mi>
+                    </mml:mrow>
+                    <mml:mo>+</mml:mo>
+                    <mml:mrow>
+                        <mml:mi mathvariant="italic">r</mml:mi>
+                        <mml:mo>&times;</mml:mo>
+                        <mml:mi mathvariant="italic">units</mml:mi>
+                    </mml:mrow>
+                </mml:mrow>
+            </mml:math></inlineequation>,
+            where 
+            <inlineequation><mml:math>
+                <!-- eqn: DZ:-->
+                <mml:mi mathvariant="italic">DZ</mml:mi>
+            </mml:math></inlineequation>
+            is a measurement of the change in depth relative to the screen
+            area of the polygon, and 
+            <inlineequation><mml:math><mml:mi mathvariant="italic">r</mml:mi></mml:math></inlineequation>
+            is the smallest value that is guaranteed to
+            produce a resolvable offset for a given implementation.
+            The offset is added before the depth test is performed and before
+            the value is written into the depth buffer.
+        </para>
+        <para>
+            <function>glPolygonOffset</function> is useful for rendering hidden-line images, for applying decals
+            to surfaces, and for rendering solids with highlighted edges.
+        </para>
+    </refsect1>
+    <refsect1 id="notes"><title>Notes</title>
+        <para>
+            <function>glPolygonOffset</function> is available only if the GL version is 1.1 or greater.
+        </para>
+        <para>
+            <function>glPolygonOffset</function> has no effect on depth coordinates placed in the
+            feedback buffer.
+        </para>
+        <para>
+            <function>glPolygonOffset</function> has no effect on selection.
+        </para>
+    </refsect1>
+    <refsect1 id="errors"><title>Errors</title>
+        <para>
+            <constant>GL_INVALID_OPERATION</constant> is generated if <function>glPolygonOffset</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>glIsEnabled</refentrytitle></citerefentry> with argument
+            <constant>GL_POLYGON_OFFSET_FILL</constant>,
+            <constant>GL_POLYGON_OFFSET_LINE</constant>,
+            or <constant>GL_POLYGON_OFFSET_POINT</constant>.
+        </para>
+        <para>
+            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_POLYGON_OFFSET_FACTOR</constant> or
+            <constant>GL_POLYGON_OFFSET_UNITS</constant>.
+        </para>
+    </refsect1>
+    <refsect1 id="seealso"><title>See Also</title>
+        <para>
+            <citerefentry><refentrytitle>glDepthFunc</refentrytitle></citerefentry>,
+            <citerefentry><refentrytitle>glEnable</refentrytitle></citerefentry>,
+            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>,
+            <citerefentry><refentrytitle>glIsEnabled</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>