upstream-doc/man2/glPolygonMode.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="glPolygonMode">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glPolygonMode</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glPolygonMode</refname>
  17         <refpurpose>select a polygon rasterization mode</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glPolygonMode</function></funcdef>
  23                 <paramdef>GLenum <parameter>face</parameter></paramdef>
  24                 <paramdef>GLenum <parameter>mode</parameter></paramdef>
  25             </funcprototype>
  26         </funcsynopsis>
  27     </refsynopsisdiv>
  28     <refsect1 id="parameters"><title>Parameters</title>
  29         <variablelist>
  30         <varlistentry>
  31             <term><parameter>face</parameter></term>
  32             <listitem>
  33                 <para>
  34                     Specifies the polygons that <parameter>mode</parameter> applies to.
  35                     Must be
  36                     <constant>GL_FRONT</constant> for front-facing polygons,
  37                     <constant>GL_BACK</constant> for back-facing polygons,
  38                     or <constant>GL_FRONT_AND_BACK</constant> for front- and back-facing polygons.
  39                 </para>
  40             </listitem>
  41         </varlistentry>
  42         <varlistentry>
  43             <term><parameter>mode</parameter></term>
  44             <listitem>
  45                 <para>
  46                     Specifies how polygons will be rasterized.
  47                     Accepted values are
  48                     <constant>GL_POINT</constant>,
  49                     <constant>GL_LINE</constant>, and
  50                     <constant>GL_FILL</constant>.
  51                     The initial value is <constant>GL_FILL</constant> for both front- and back-facing polygons.
  52                 </para>
  53             </listitem>
  54         </varlistentry>
  55         </variablelist>
  56     </refsect1>
  57     <refsect1 id="description"><title>Description</title>
  58         <para>
  59             <function>glPolygonMode</function> controls the interpretation of polygons for rasterization.
  60             <parameter>face</parameter> describes which polygons <parameter>mode</parameter> applies to:
  61             front-facing polygons (<constant>GL_FRONT</constant>),
  62             back-facing polygons (<constant>GL_BACK</constant>),
  63             or both (<constant>GL_FRONT_AND_BACK</constant>).
  64             The polygon mode affects only the final rasterization of polygons.
  65             In particular,
  66             a polygon's vertices are lit and
  67             the polygon is clipped and possibly culled before these modes are applied.
  68         </para>
  69         <para>
  70             Three modes are defined and can be specified in <parameter>mode</parameter>:
  71         </para>
  72         <variablelist>
  73             <varlistentry>
  74                 <term><constant>GL_POINT</constant></term>
  75                 <listitem>
  76                     <para>
  77                         Polygon vertices that are marked as the start of a boundary edge
  78                         are drawn as points.
  79                         Point attributes such as
  80                         <constant>GL_POINT_SIZE</constant> and
  81                         <constant>GL_POINT_SMOOTH</constant> control
  82                         the rasterization of the points.
  83                         Polygon rasterization attributes other than <constant>GL_POLYGON_MODE</constant> have no effect.
  84                     </para>
  85                 </listitem>
  86             </varlistentry>
  87             <varlistentry>
  88                 <term><constant>GL_LINE</constant></term>
  89                 <listitem>
  90                     <para>
  91                         Boundary edges of the polygon are drawn as line segments.
  92                         They are treated as connected line segments for line stippling;
  93                         the line stipple counter and pattern are not reset between segments
  94                         (see <citerefentry><refentrytitle>glLineStipple</refentrytitle></citerefentry>).
  95                         Line attributes such as
  96                         <constant>GL_LINE_WIDTH</constant> and
  97                         <constant>GL_LINE_SMOOTH</constant> control
  98                         the rasterization of the lines.
  99                         Polygon rasterization attributes other than <constant>GL_POLYGON_MODE</constant> have no effect.
 100                     </para>
 101                 </listitem>
 102             </varlistentry>
 103             <varlistentry>
 104                 <term><constant>GL_FILL</constant></term>
 105                 <listitem>
 106                     <para>
 107                         The interior of the polygon is filled.
 108                         Polygon attributes such as
 109                         <constant>GL_POLYGON_STIPPLE</constant> and
 110                         <constant>GL_POLYGON_SMOOTH</constant> control the rasterization of the polygon.
 111                     </para>
 112                 </listitem>
 113             </varlistentry>
 114         </variablelist>
 115     </refsect1>
 116     <refsect1 id="examples"><title>Examples</title>
 117         <para>
 118             To draw a surface with filled back-facing polygons
 119             and outlined front-facing polygons,
 120             call
 121             <programlisting>
 122 glPolygonMode(<constant>GL_FRONT</constant>, <constant>GL_LINE</constant>);
 123             </programlisting>
 124         </para>
 125     </refsect1>
 126     <refsect1 id="notes"><title>Notes</title>
 127         <para>
 128             Vertices are marked as boundary or nonboundary with an edge flag.
 129             Edge flags are generated internally by the GL when it decomposes
 130             polygons; they can be set explicitly using <citerefentry><refentrytitle>glEdgeFlag</refentrytitle></citerefentry>.
 131         </para>
 132     </refsect1>
 133     <refsect1 id="errors"><title>Errors</title>
 134         <para>
 135             <constant>GL_INVALID_ENUM</constant> is generated if either <parameter>face</parameter> or <parameter>mode</parameter> is not
 136             an accepted value.
 137         </para>
 138         <para>
 139             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glPolygonMode</function>
 140             is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
 141             and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 142         </para>
 143     </refsect1>
 144     <refsect1 id="associatedgets"><title>Associated Gets</title>
 145         <para>
 146             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_POLYGON_MODE</constant>
 147         </para>
 148     </refsect1>
 149     <refsect1 id="seealso"><title>See Also</title>
 150         <para>
 151             <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>,
 152             <citerefentry><refentrytitle>glEdgeFlag</refentrytitle></citerefentry>,
 153             <citerefentry><refentrytitle>glLineStipple</refentrytitle></citerefentry>,
 154             <citerefentry><refentrytitle>glLineWidth</refentrytitle></citerefentry>,
 155             <citerefentry><refentrytitle>glPointSize</refentrytitle></citerefentry>,
 156             <citerefentry><refentrytitle>glPolygonStipple</refentrytitle></citerefentry>
 157         </para>
 158     </refsect1>
 159     <refsect1 id="Copyright"><title>Copyright</title>
 160         <para>
 161             Copyright <trademark class="copyright"></trademark> 1991-2006
 162             Silicon Graphics, Inc. This document is licensed under the SGI
 163             Free Software B License. For details, see
 164             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 165         </para>
 166     </refsect1>
 167 </refentry>