upstream-doc/man4/glDrawArraysInstanced.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="glDrawArraysInstanced">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2010</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glDrawArraysInstanced</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glDrawArraysInstanced</refname>
  17         <refpurpose>draw multiple instances of a range of elements</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glDrawArraysInstanced</function></funcdef>
  23                 <paramdef>GLenum <parameter>mode</parameter></paramdef>
  24                 <paramdef>GLint <parameter>first</parameter></paramdef>
  25                 <paramdef>GLsizei <parameter>count</parameter></paramdef>
  26                 <paramdef>GLsizei <parameter>primcount</parameter></paramdef>
  27             </funcprototype>
  28         </funcsynopsis>
  29     </refsynopsisdiv>
  30     <refsect1 id="parameters"><title>Parameters</title>
  31         <variablelist>
  32         <varlistentry>
  33             <term><parameter>mode</parameter></term>
  34             <listitem>
  35                 <para>
  36                     Specifies what kind of primitives to render. Symbolic constants <constant>GL_POINTS</constant>,
  37                     <constant>GL_LINE_STRIP</constant>, <constant>GL_LINE_LOOP</constant>, <constant>GL_LINES</constant>,
  38                     <constant>GL_TRIANGLE_STRIP</constant>, <constant>GL_TRIANGLE_FAN</constant>, <constant>GL_TRIANGLES</constant>
  39                     <constant>GL_LINES_ADJACENCY</constant>, <constant>GL_LINE_STRIP_ADJACENCY</constant>,
  40                     <constant>GL_TRIANGLES_ADJACENCY</constant>, <constant>GL_TRIANGLE_STRIP_ADJACENCY</constant> and <constant>GL_PATCHES</constant>
  41                     are accepted.
  42                 </para>
  43             </listitem>
  44         </varlistentry>
  45         <varlistentry>
  46             <term><parameter>first</parameter></term>
  47             <listitem>
  48                 <para>
  49                     Specifies the starting index in the enabled arrays.
  50                 </para>
  51             </listitem>
  52         </varlistentry>
  53         <varlistentry>
  54             <term><parameter>count</parameter></term>
  55             <listitem>
  56                 <para>
  57                     Specifies the number of indices to be rendered.
  58                 </para>
  59             </listitem>
  60         </varlistentry>
  61         <varlistentry>
  62             <term><parameter>primcount</parameter></term>
  63             <listitem>
  64                 <para>
  65                     Specifies the number of instances of the specified range of indices to be rendered.
  66                 </para>
  67             </listitem>
  68         </varlistentry>
  69         </variablelist>
  70     </refsect1>
  71     <refsect1 id="description"><title>Description</title>
  72         <para>
  73             <function>glDrawArraysInstanced</function> behaves identically to <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>
  74             except that <parameter>primcount</parameter> instances of the range of elements are executed and the value of the internal counter
  75             <parameter>instanceID</parameter> advances for each iteration. <parameter>instanceID</parameter> is an internal 32-bit integer counter
  76             that may be read by a vertex shader as <constant>gl_InstanceID</constant>.
  77         </para>
  78         <para>
  79             <function>glDrawArraysInstanced</function> has the same effect as:
  80             <programlisting><![CDATA[    if ( mode or count is invalid )
  81         generate appropriate error
  82     else {
  83         for (int i = 0; i < primcount ; i++) {
  84             instanceID = i;
  85             glDrawArrays(mode, first, count);
  86         }
  87         instanceID = 0;
  88     }]]></programlisting>
  89         </para>
  90     </refsect1>
  91     <refsect1 id="errors"><title>Errors</title>
  92         <para>
  93             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of
  94             the accepted values.
  95         </para>
  96         <para>
  97             <constant>GL_INVALID_OPERATION</constant> is generated if a geometry shader is active and <parameter>mode</parameter>
  98             is incompatible with the input primitive type of the geometry shader in the currently installed program object.
  99         </para>
 100         <para>
 101             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> or <parameter>primcount</parameter> are negative.
 102         </para>
 103         <para>
 104             <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
 105             enabled array and the buffer object's data store is currently mapped.
 106         </para>
 107     </refsect1>
 108     <refsect1 id="seealso"><title>See Also</title>
 109         <para>
 110             <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
 111             <citerefentry><refentrytitle>glDrawElementsInstanced</refentrytitle></citerefentry>
 112         </para>
 113     </refsect1>
 114     <refsect1 id="Copyright"><title>Copyright</title>
 115         <para>
 116             Copyright <trademark class="copyright"></trademark> 2010 Khronos Group.
 117             This material may be distributed subject to the terms and conditions set forth in
 118             the Open Publication License, v 1.0, 8 June 1999.
 119             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 120         </para>
 121     </refsect1>
 122 </refentry>