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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="glEdgeFlag">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glEdgeFlag</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glEdgeFlag</refname>
<refpurpose>flag edges as either boundary or nonboundary</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glEdgeFlag</function></funcdef>
<paramdef>GLboolean <parameter>flag</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>flag</parameter></term>
<listitem>
<para>
Specifies the current edge flag value,
either <constant>GL_TRUE</constant> or <constant>GL_FALSE</constant>. The initial value is <constant>GL_TRUE</constant>.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glEdgeFlagv</function></funcdef>
<paramdef>const GLboolean * <parameter>flag</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters2"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>flag</parameter></term>
<listitem>
<para>
Specifies a pointer to an array that contains a single boolean element,
which replaces the current edge flag value.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
Each vertex of a polygon,
separate triangle,
or separate quadrilateral specified between a <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>/<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry> pair
is marked as the start of either a boundary or nonboundary edge.
If the current edge flag is true when the vertex is specified,
the vertex is marked as the start of a boundary edge.
Otherwise, the vertex is marked as the start of a nonboundary edge.
<function>glEdgeFlag</function> sets the edge flag bit to <constant>GL_TRUE</constant> if <parameter>flag</parameter> is <constant>GL_TRUE</constant>
and to <constant>GL_FALSE</constant> otherwise.
</para>
<para>
The vertices of connected triangles and connected quadrilaterals are always
marked as boundary,
regardless of the value of the edge flag.
</para>
<para>
Boundary and nonboundary edge flags on vertices are significant only if
<constant>GL_POLYGON_MODE</constant> is set to <constant>GL_POINT</constant> or <constant>GL_LINE</constant>.
See <citerefentry><refentrytitle>glPolygonMode</refentrytitle></citerefentry>.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
The current edge flag can be updated at any time.
In particular,
<function>glEdgeFlag</function> can be called between a call to <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding
call to <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
</para>
</refsect1>
<refsect1 id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_EDGE_FLAG</constant>
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>,
<function>glEdgeFlagPointer</function>,
<citerefentry><refentrytitle>glPolygonMode</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>