upstream-man-pages/man3/glDrawElementsInstanced.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="glDrawElementsInstanced">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2010</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glDrawElementsInstanced</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glDrawElementsInstanced</refname>
  17         <refpurpose>draw multiple instances of a set of elements</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glDrawElementsInstanced</function></funcdef>
  23                 <paramdef>GLenum <parameter>mode</parameter></paramdef>
  24                 <paramdef>GLsizei <parameter>count</parameter></paramdef>
  25                 <paramdef>GLenum <parameter>type</parameter></paramdef>
  26                 <paramdef>const void * <parameter>indices</parameter></paramdef>
  27                 <paramdef>GLsizei <parameter>primcount</parameter></paramdef>
  28             </funcprototype>
  29         </funcsynopsis>
  30     </refsynopsisdiv>
  31     <refsect1 id="parameters"><title>Parameters</title>
  32         <variablelist>
  33         <varlistentry>
  34             <term><parameter>mode</parameter></term>
  35             <listitem>
  36                 <para>
  37                     Specifies what kind of primitives to render.
  38                     Symbolic constants
  39                     <constant>GL_POINTS</constant>,
  40                     <constant>GL_LINE_STRIP</constant>,
  41                     <constant>GL_LINE_LOOP</constant>,
  42                     <constant>GL_LINES</constant>,
  43                     <constant>GL_LINE_STRIP_ADJACENCY</constant>,
  44                     <constant>GL_LINES_ADJACENCY</constant>,
  45                     <constant>GL_TRIANGLE_STRIP</constant>,
  46                     <constant>GL_TRIANGLE_FAN</constant>,
  47                     <constant>GL_TRIANGLES</constant>,
  48                     <constant>GL_TRIANGLE_STRIP_ADJACENCY</constant> and
  49                     <constant>GL_TRIANGLES_ADJACENCY</constant>
  50                     are accepted.
  51                 </para>
  52             </listitem>
  53         </varlistentry>
  54         <varlistentry>
  55             <term><parameter>count</parameter></term>
  56             <listitem>
  57                 <para>
  58                     Specifies the number of elements to be rendered.
  59                 </para>
  60             </listitem>
  61         </varlistentry>
  62         <varlistentry>
  63             <term><parameter>type</parameter></term>
  64             <listitem>
  65                 <para>
  66                     Specifies the type of the values in <parameter>indices</parameter>. Must be one of <constant>GL_UNSIGNED_BYTE</constant>,
  67                     <constant>GL_UNSIGNED_SHORT</constant>, or <constant>GL_UNSIGNED_INT</constant>.
  68                 </para>
  69             </listitem>
  70         </varlistentry>
  71         <varlistentry>
  72             <term><parameter>indices</parameter></term>
  73             <listitem>
  74                 <para>
  75                     Specifies a pointer to the location where the indices are stored.
  76                 </para>
  77             </listitem>
  78         </varlistentry>
  79         <varlistentry>
  80             <term><parameter>primcount</parameter></term>
  81             <listitem>
  82                 <para>
  83                     Specifies the number of instances of the specified range of indices to be rendered.
  84                 </para>
  85             </listitem>
  86         </varlistentry>
  87         </variablelist>
  88     </refsect1>
  89     <refsect1 id="description"><title>Description</title>
  90         <para>
  91             <function>glDrawElementsInstanced</function> behaves identically to <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>
  92             except that <parameter>primcount</parameter> instances of the set of elements are executed and the value of the internal counter
  93             <parameter>instanceID</parameter> advances for each iteration. <parameter>instanceID</parameter> is an internal 32-bit integer counter
  94             that may be read by a vertex shader as <constant>gl_InstanceID</constant>.
  95         </para>
  96         <para>
  97             <function>glDrawElementsInstanced</function> has the same effect as:
  98             <programlisting><![CDATA[    if (mode, count, or type is invalid )
  99         generate appropriate error
 100     else {
 101         for (int i = 0; i < primcount ; i++) {
 102             instanceID = i;
 103             glDrawElements(mode, count, type, indices);
 104         }
 105         instanceID = 0;
 106     }]]></programlisting>
 107         </para>
 108     </refsect1>
 109     <refsect1 id="notes"><title>Notes</title>
 110         <para>
 111             <function>glDrawElementsInstanced</function> is available only if the GL version is 3.1 or greater.
 112         </para>
 113         <para>
 114             <constant>GL_LINE_STRIP_ADJACENCY</constant>,
 115             <constant>GL_LINES_ADJACENCY</constant>,
 116             <constant>GL_TRIANGLE_STRIP_ADJACENCY</constant> and
 117             <constant>GL_TRIANGLES_ADJACENCY</constant>
 118             are available only if the GL version is 3.2 or greater.
 119         </para>
 120     </refsect1>
 121     <refsect1 id="errors"><title>Errors</title>
 122         <para>
 123             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of <constant>GL_POINTS</constant>,
 124             <constant>GL_LINE_STRIP</constant>, <constant>GL_LINE_LOOP</constant>, <constant>GL_LINES</constant>,
 125             <constant>GL_TRIANGLE_STRIP</constant>, <constant>GL_TRIANGLE_FAN</constant>, or <constant>GL_TRIANGLES</constant>.
 126         </para>
 127         <para>
 128             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> or <parameter>primcount</parameter> are negative.
 129         </para>
 130         <para>
 131             <constant>GL_INVALID_OPERATION</constant> is generated if a geometry shader is active and <parameter>mode</parameter>
 132             is incompatible with the input primitive type of the geometry shader in the currently installed program object.
 133         </para>
 134         <para>
 135             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
 136             enabled array and the buffer object's data store is currently mapped.
 137         </para>
 138     </refsect1>
 139     <refsect1 id="seealso"><title>See Also</title>
 140         <para>
 141             <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
 142             <citerefentry><refentrytitle>glDrawArraysInstanced</refentrytitle></citerefentry>
 143         </para>
 144     </refsect1>
 145     <refsect1 id="Copyright"><title>Copyright</title>
 146         <para>
 147             Copyright <trademark class="copyright"></trademark> 2010 Khronos Group.
 148             This material may be distributed subject to the terms and conditions set forth in
 149             the Open Publication License, v 1.0, 8 June 1999.
 150             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 151         </para>
 152     </refsect1>
 153 </refentry>