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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="glDrawElements">
<refentryinfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
<copyright>
<year>2010-2013</year>
<holder>Khronos Group</holder>
</copyright>
</refentryinfo>
<refmeta>
<refentrytitle>glDrawElements</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glDrawElements</refname>
<refpurpose>render primitives from array data</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glDrawElements</function></funcdef>
<paramdef>GLenum <parameter>mode</parameter></paramdef>
<paramdef>GLsizei <parameter>count</parameter></paramdef>
<paramdef>GLenum <parameter>type</parameter></paramdef>
<paramdef>const GLvoid * <parameter>indices</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>mode</parameter></term>
<listitem>
<para>
Specifies what kind of primitives to render.
Symbolic constants
<constant>GL_POINTS</constant>,
<constant>GL_LINE_STRIP</constant>,
<constant>GL_LINE_LOOP</constant>,
<constant>GL_LINES</constant>,
<constant>GL_LINE_STRIP_ADJACENCY</constant>,
<constant>GL_LINES_ADJACENCY</constant>,
<constant>GL_TRIANGLE_STRIP</constant>,
<constant>GL_TRIANGLE_FAN</constant>,
<constant>GL_TRIANGLES</constant>,
<constant>GL_TRIANGLE_STRIP_ADJACENCY</constant>,
<constant>GL_TRIANGLES_ADJACENCY</constant> and <constant>GL_PATCHES</constant>
are accepted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>count</parameter></term>
<listitem>
<para>
Specifies the number of elements to be rendered.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>type</parameter></term>
<listitem>
<para>
Specifies the type of the values in <parameter>indices</parameter>. Must be one of
<constant>GL_UNSIGNED_BYTE</constant>, <constant>GL_UNSIGNED_SHORT</constant>, or
<constant>GL_UNSIGNED_INT</constant>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>indices</parameter></term>
<listitem>
<para>
Specifies a pointer to the location where the indices are stored.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para>
<function>glDrawElements</function> specifies multiple geometric primitives
with very few subroutine calls. Instead of calling a GL function
to pass each individual vertex, normal, texture coordinate, edge
flag, or color, you can prespecify
separate arrays of vertices, normals, and so on, and use them to
construct a sequence of primitives with a single
call to <function>glDrawElements</function>.
</para>
<para>
When <function>glDrawElements</function> is called, it uses <parameter>count</parameter> sequential elements from an
enabled array, starting at <parameter>indices</parameter> to construct a sequence of
geometric primitives. <parameter>mode</parameter> specifies what kind of primitives are
constructed and how the array elements construct these primitives. If
more than one array is enabled, each is used.
</para>
<para>
Vertex attributes that are modified by <function>glDrawElements</function> have an
unspecified value after <function>glDrawElements</function> returns. Attributes that aren't
modified maintain their previous values.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
<constant>GL_LINE_STRIP_ADJACENCY</constant>,
<constant>GL_LINES_ADJACENCY</constant>,
<constant>GL_TRIANGLE_STRIP_ADJACENCY</constant> and
<constant>GL_TRIANGLES_ADJACENCY</constant>
are available only if the GL version is 3.2 or greater.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not an accepted value.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> is negative.
</para>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if a geometry shader is active and <parameter>mode</parameter>
is incompatible with the input primitive type of the geometry shader in the currently installed program object.
</para>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
enabled array or the element array and the buffer object's data store is currently mapped.
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawElementsInstanced</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawElementsBaseVertex</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 1991-2006 Silicon Graphics, Inc.
Copyright <trademark class="copyright"></trademark> 2010-2013 Khronos Group.
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>
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