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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="glDrawElementsIndirect">
+ <refmeta>
+ <refmetainfo>
+ <copyright>
+ <year>2010</year>
+ <holder>Khronos Group.</holder>
+ </copyright>
+ </refmetainfo>
+ <refentrytitle>glDrawElementsIndirect</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>glDrawElementsIndirect</refname>
+ <refpurpose>render indexed primitives from array data, taking parameters from memory</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>glDrawElementsIndirect</function></funcdef>
+ <paramdef>GLenum <parameter>mode</parameter></paramdef>
+ <paramdef>GLenum <parameter>type</parameter></paramdef>
+ <paramdef>const void *<parameter>indirect</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <!-- eqn: ignoring delim $$ -->
+ <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>type</parameter></term>
+ <listitem>
+ <para>
+ Specifies the type of data in the buffer bound to the <constant>GL_ELEMENT_ARRAY_BUFFER</constant> binding.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>indirect</parameter></term>
+ <listitem>
+ <para>
+ Specifies the address of a structure containing the draw parameters.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para>
+ <function>glDrawElementsIndirect</function> specifies multiple indexed geometric primitives
+ with very few subroutine calls. <function>glDrawElementsIndirect</function> behaves
+ similarly to <citerefentry><refentrytitle>glDrawElementsInstancedBaseVertexBaseInstance</refentrytitle></citerefentry>,
+ execpt that the parameters to <citerefentry><refentrytitle>glDrawElementsInstancedBaseVertexBaseInstance</refentrytitle></citerefentry>
+ are stored in memory at the address given by <parameter>indirect</parameter>.
+ </para>
+ <para>
+ The parameters addressed by <parameter>indirect</parameter> are packed into a structure
+ that takes the form (in C):
+ <programlisting><![CDATA[ typedef struct {
+ uint count;
+ uint primCount;
+ uint firstIndex;
+ uint baseVertex;
+ uint baseInstance;
+ } DrawElementsIndirectCommand;]]></programlisting>
+ <para>
+ <function>glDrawElementsIndirect</function> is equivalent to:
+ </para>
+<programlisting><![CDATA[ void glDrawElementsIndirect(GLenum mode, GLenum type, const void * indirect)
+ {
+ const DrawElementsIndirectCommand *cmd = (const DrawElementsIndirectCommand *)indirect;
+ glDrawElementsInstancedBaseVertexBaseInstance(mode,
+ cmd->count,
+ type,
+ cmd->firstIndex + size-of-type,
+ cmd->primCount,
+ cmd->baseVertex,
+ cmd->baseInstance);
+ }]]></programlisting>
+ </para>
+ <para>
+ If a buffer is bound to the <constant>GL_DRAW_INDIRECT_BUFFER</constant> binding at the time
+ of a call to <function>glDrawElementsIndirect</function>, <parameter>indirect</parameter>
+ is interpreted as an offset, in basic machine units, into that buffer and the parameter
+ data is read from the buffer rather than from client memory.
+ </para>
+ <para>
+ Note that indices stored in client memory are not supported. If no buffer is bound to the
+ <constant>GL_ELEMENT_ARRAY_BUFFER</constant> binding, an error will be generated.
+ </para>
+ <para>
+ The results of the operation are undefined if the <code>reservedMustBeZero</code> member
+ of the parameter structure is non-zero. However, no error is generated in this case.
+ </para>
+ <para>
+ Vertex attributes that are modified by <function>glDrawElementsIndirect</function> have an
+ unspecified value after <function>glDrawElementsIndirect</function> returns. Attributes that aren't
+ modified remain well defined.
+ </para>
+ </refsect1>
+ <refsect1 id="notes"><title>Notes</title>
+ <para>
+ The <parameter>baseInstance</parameter> member of the <parameter>DrawElementsIndirectCommand</parameter>
+ structure is defined only if the GL version is 4.2 or greater. For versions of the GL less than 4.2,
+ this parameter is present but is reserved and should be set to zero. On earlier versions of the GL,
+ behavior is undefined if it is non-zero.
+ </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_OPERATION</constant> is generated if no buffer is bound to the <constant>GL_ELEMENT_ARRAY_BUFFER</constant>
+ binding, or if such a buffer's data store is currently mapped.
+ </para>
+ <para>
+ <constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
+ enabled array or to the <constant>GL_DRAW_INDIRECT_BUFFER</constant> binding and the buffer object's data store is currently mapped.
+ </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 <parameter>mode</parameter> is <constant>GL_PATCHES</constant>
+ and no tessellation control shader is active.
+ </para>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glDrawArraysInstanced</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glDrawArraysIndirect</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glDrawRangeElements</refentrytitle></citerefentry>,
+ </para>
+ </refsect1>
+ <refsect1 id="Copyright"><title>Copyright</title>
+ <para>
+ Copyright <trademark class="copyright"></trademark> 2010 Khronos Group.
+ This material may be distributed subject to the terms and conditions set forth in
+ the Open Publication License, v 1.0, 8 June 1999.
+ <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
+ </para>
+ </refsect1>
+</refentry>
HCoop / clinton / guile-figl.git / blobdiff