upstream-man-pages/man2/glRenderMode.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="glRenderMode">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glRenderMode</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glRenderMode</refname>
  17         <refpurpose>set rasterization mode</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>GLint <function>glRenderMode</function></funcdef>
  23                 <paramdef>GLenum <parameter>mode</parameter></paramdef>
  24             </funcprototype>
  25         </funcsynopsis>
  26     </refsynopsisdiv>
  27     <refsect1 id="parameters"><title>Parameters</title>
  28         <variablelist>
  29         <varlistentry>
  30             <term><parameter>mode</parameter></term>
  31             <listitem>
  32                 <para>
  33                     Specifies the rasterization mode.
  34                     Three values are accepted:
  35                     <constant>GL_RENDER</constant>,
  36                     <constant>GL_SELECT</constant>, and
  37                     <constant>GL_FEEDBACK</constant>.
  38                     The initial value is <constant>GL_RENDER</constant>.
  39                 </para>
  40             </listitem>
  41         </varlistentry>
  42         </variablelist>
  43     </refsect1>
  44     <refsect1 id="description"><title>Description</title>
  45         <para>
  46             <function>glRenderMode</function> sets the rasterization mode.
  47             It takes one argument,
  48             <parameter>mode</parameter>,
  49             which can assume one of three predefined values:
  50         </para>
  51         <variablelist>
  52             <varlistentry>
  53                 <term><constant>GL_RENDER</constant></term>
  54                 <listitem>
  55                     <para>
  56                         Render mode. Primitives are rasterized,
  57                         producing pixel fragments,
  58                         which are written into the frame buffer.
  59                         This is the normal mode
  60                         and also the default mode.
  61                     </para>
  62                 </listitem>
  63             </varlistentry>
  64             <varlistentry>
  65                 <term><constant>GL_SELECT</constant></term>
  66                 <listitem>
  67                     <para>
  68                         Selection mode.
  69                         No pixel fragments are produced,
  70                         and no change to the frame buffer contents is made.
  71                         Instead,
  72                         a record of the names of primitives that would have been drawn
  73                         if the render mode had been <constant>GL_RENDER</constant> is returned in a select buffer,
  74                         which must be created (see <citerefentry><refentrytitle>glSelectBuffer</refentrytitle></citerefentry>) before selection mode
  75                         is entered.
  76                     </para>
  77                 </listitem>
  78             </varlistentry>
  79             <varlistentry>
  80                 <term><constant>GL_FEEDBACK</constant></term>
  81                 <listitem>
  82                     <para>
  83                         Feedback mode.
  84                         No pixel fragments are produced,
  85                         and no change to the frame buffer contents is made.
  86                         Instead,
  87                         the coordinates and attributes of vertices that would have been drawn
  88                         if the render mode had been <constant>GL_RENDER</constant> is returned in a feedback buffer,
  89                         which must be created (see <citerefentry><refentrytitle>glFeedbackBuffer</refentrytitle></citerefentry>) before feedback mode
  90                         is entered.
  91                     </para>
  92                 </listitem>
  93             </varlistentry>
  94         </variablelist>
  95         <para>
  96             The return value of <function>glRenderMode</function> is determined by the render mode at the time
  97             <function>glRenderMode</function> is called,
  98             rather than by <parameter>mode</parameter>.
  99             The values returned for the three render modes are as follows:
 100         </para>
 101         <variablelist>
 102             <varlistentry>
 103                 <term><constant>GL_RENDER</constant></term>
 104                 <listitem>
 105                     <para>
 106                         0.
 107                     </para>
 108                 </listitem>
 109             </varlistentry>
 110             <varlistentry>
 111                 <term><constant>GL_SELECT</constant></term>
 112                 <listitem>
 113                     <para>
 114                         The number of hit records transferred to the select buffer.
 115                     </para>
 116                 </listitem>
 117             </varlistentry>
 118             <varlistentry>
 119                 <term><constant>GL_FEEDBACK</constant></term>
 120                 <listitem>
 121                     <para>
 122                         The number of values (not vertices) transferred to the feedback buffer.
 123                     </para>
 124                 </listitem>
 125             </varlistentry>
 126         </variablelist>
 127         <para>
 128             See the <citerefentry><refentrytitle>glSelectBuffer</refentrytitle></citerefentry> and <citerefentry><refentrytitle>glFeedbackBuffer</refentrytitle></citerefentry> reference pages for
 129             more details concerning selection and feedback operation.
 130         </para>
 131     </refsect1>
 132     <refsect1 id="notes"><title>Notes</title>
 133         <para>
 134             If an error is generated,
 135             <function>glRenderMode</function> returns 0 regardless of the current render mode.
 136         </para>
 137     </refsect1>
 138     <refsect1 id="errors"><title>Errors</title>
 139         <para>
 140             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of the three
 141             accepted values.
 142         </para>
 143         <para>
 144             <constant>GL_INVALID_OPERATION</constant> is generated if <citerefentry><refentrytitle>glSelectBuffer</refentrytitle></citerefentry> is called
 145             while the render mode is <constant>GL_SELECT</constant>,
 146             or if <function>glRenderMode</function> is called with argument <constant>GL_SELECT</constant> before
 147             <citerefentry><refentrytitle>glSelectBuffer</refentrytitle></citerefentry> is called at least once.
 148         </para>
 149         <para>
 150             <constant>GL_INVALID_OPERATION</constant> is generated if <citerefentry><refentrytitle>glFeedbackBuffer</refentrytitle></citerefentry> is called
 151             while the render mode is <constant>GL_FEEDBACK</constant>,
 152             or if <function>glRenderMode</function> is called with argument <constant>GL_FEEDBACK</constant> before
 153             <citerefentry><refentrytitle>glFeedbackBuffer</refentrytitle></citerefentry> is called at least once.
 154         </para>
 155         <para>
 156             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glRenderMode</function>
 157             is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
 158             and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 159         </para>
 160     </refsect1>
 161     <refsect1 id="associatedgets"><title>Associated Gets</title>
 162         <para>
 163             <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_RENDER_MODE</constant>
 164         </para>
 165     </refsect1>
 166     <refsect1 id="seealso"><title>See Also</title>
 167         <para>
 168             <citerefentry><refentrytitle>glFeedbackBuffer</refentrytitle></citerefentry>,
 169             <citerefentry><refentrytitle>glInitNames</refentrytitle></citerefentry>,
 170             <citerefentry><refentrytitle>glLoadName</refentrytitle></citerefentry>,
 171             <citerefentry><refentrytitle>glPassThrough</refentrytitle></citerefentry>,
 172             <citerefentry><refentrytitle>glPushName</refentrytitle></citerefentry>,
 173             <citerefentry><refentrytitle>glSelectBuffer</refentrytitle></citerefentry>
 174         </para>
 175     </refsect1>
 176     <refsect1 id="Copyright"><title>Copyright</title>
 177         <para>
 178             Copyright <trademark class="copyright"></trademark> 1991-2006
 179             Silicon Graphics, Inc. This document is licensed under the SGI
 180             Free Software B License. For details, see
 181             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 182         </para>
 183     </refsect1>
 184 </refentry>