[clinton/guile-figl.git] / upstream-doc / man4 / glDrawElementsInstancedBaseInstance.xml

<?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="glDrawElementsInstancedBaseInstance">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2011</year>
                <holder>Khronos Group</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glDrawElementsInstancedBaseInstance</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glDrawElementsInstancedBaseInstance</refname>
        <refpurpose>draw multiple instances of a set of elements with offset applied to instanced attributes</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glDrawElementsInstancedBaseInstance</function></funcdef>
                <paramdef>GLenum <parameter>mode</parameter></paramdef>
                <paramdef>GLsizei <parameter>count</parameter></paramdef>
                <paramdef>GLenum <parameter>type</parameter></paramdef>
                <paramdef>const void * <parameter>indices</parameter></paramdef>
                <paramdef>GLsizei <parameter>primcount</parameter></paramdef>
                <paramdef>GLuitn <parameter>baseinstance</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>
        <varlistentry>
            <term><parameter>primcount</parameter></term>
            <listitem>
                <para>
                    Specifies the number of instances of the specified range of indices to be rendered.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>baseinstance</parameter></term>
            <listitem>
                <para>
                    Specifies the base instance for use in fetching instanced vertex attributes.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glDrawElementsInstancedBaseInstance</function> behaves identically to <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>
            except that <parameter>primcount</parameter> instances of the set of elements are executed and the value of the internal counter
            <parameter>instanceID</parameter> advances for each iteration. <parameter>instanceID</parameter> is an internal 32-bit integer counter
            that may be read by a vertex shader as <constant>gl_InstanceID</constant>.
        </para>
        <para>
            <function>glDrawElementsInstancedBaseInstance</function> has the same effect as:
            <programlisting><![CDATA[    if (mode, count, or type is invalid )
        generate appropriate error
    else {
        for (int i = 0; i < primcount ; i++) {
            instanceID = i;
            glDrawElements(mode, count, type, indices);
        }
        instanceID = 0;
    }]]></programlisting>
        </para>
        <para>
            Specific vertex attributes may be classified as <emphasis>instanced</emphasis> through the use of
            <citerefentry><refentrytitle>glVertexAttribDivisor</refentrytitle></citerefentry>. Instanced vertex attributes
            supply per-instance vertex data to the vertex shader. The index of the vertex fetched from the enabled instanced vertex
            attribute arrays is calculated as
<mml:math>
  <mml:mrow>
    <mml:mfenced open = '&lfloor;' close = '&rfloor;'>
      <mml:mfrac>
        <mml:mrow>
          <mml:mi>gl</mml:mi>
          <mml:mo>_</mml:mo>
          <mml:mi>InstanceID</mml:mi>
        </mml:mrow>
        <mml:mi>divisor</mml:mi>
      </mml:mfrac>
    </mml:mfenced>
    <mml:mo lspace='2px' rspace='2px'>&plus;</mml:mo>
    <mml:mi>baseInstance</mml:mi>
  </mml:mrow>
</mml:math>. Note that <parameter>baseinstance</parameter> does not affect the shader-visible value of <constant>gl_InstanceID</constant>.
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            <function>glDrawElementsInstancedBaseInstance</function> is available only if the GL version is 4.2 or greater.
        </para>
        <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 one of <constant>GL_POINTS</constant>,
            <constant>GL_LINE_STRIP</constant>, <constant>GL_LINE_LOOP</constant>, <constant>GL_LINES</constant>,
            <constant>GL_TRIANGLE_STRIP</constant>, <constant>GL_TRIANGLE_FAN</constant>, or <constant>GL_TRIANGLES</constant>.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> or <parameter>primcount</parameter> are 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 and the buffer object's data store is currently mapped.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawArraysInstanced</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 2011 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>
Commit	Line	Data
7faf1d71 AW	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="glDrawElementsInstancedBaseInstance">
	5	<refmeta>
	6	<refmetainfo>
	7	<copyright>
	8	<year>2011</year>
	9	<holder>Khronos Group</holder>
	10	</copyright>
	11	</refmetainfo>
	12	<refentrytitle>glDrawElementsInstancedBaseInstance</refentrytitle>
	13	<manvolnum>3G</manvolnum>
	14	</refmeta>
	15	<refnamediv>
	16	<refname>glDrawElementsInstancedBaseInstance</refname>
	17	<refpurpose>draw multiple instances of a set of elements with offset applied to instanced attributes</refpurpose>
	18	</refnamediv>
	19	<refsynopsisdiv><title>C Specification</title>
	20	<funcsynopsis>
	21	<funcprototype>
	22	<funcdef>void <function>glDrawElementsInstancedBaseInstance</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	<paramdef>GLuitn <parameter>baseinstance</parameter></paramdef>
	29	</funcprototype>
	30	</funcsynopsis>
	31	</refsynopsisdiv>
	32	<refsect1 id="parameters"><title>Parameters</title>
	33	<variablelist>
	34	<varlistentry>
	35	<term><parameter>mode</parameter></term>
	36	<listitem>
	37	<para>
	38	Specifies what kind of primitives to render.
	39	Symbolic constants
	40	<constant>GL_POINTS</constant>,
	41	<constant>GL_LINE_STRIP</constant>,
	42	<constant>GL_LINE_LOOP</constant>,
	43	<constant>GL_LINES</constant>,
	44	<constant>GL_LINE_STRIP_ADJACENCY</constant>,
	45	<constant>GL_LINES_ADJACENCY</constant>,
	46	<constant>GL_TRIANGLE_STRIP</constant>,
	47	<constant>GL_TRIANGLE_FAN</constant>,
	48	<constant>GL_TRIANGLES</constant>,
	49	<constant>GL_TRIANGLE_STRIP_ADJACENCY</constant>,
	50	<constant>GL_TRIANGLES_ADJACENCY</constant> and <constant>GL_PATCHES</constant>
	51	are accepted.
	52	</para>
	53	</listitem>
	54	</varlistentry>
	55	<varlistentry>
	56	<term><parameter>count</parameter></term>
	57	<listitem>
	58	<para>
	59	Specifies the number of elements to be rendered.
	60	</para>
	61	</listitem>
	62	</varlistentry>
	63	<varlistentry>
	64	<term><parameter>type</parameter></term>
65	<listitem>
66	<para>
67	Specifies the type of the values in <parameter>indices</parameter>. Must be one of <constant>GL_UNSIGNED_BYTE</constant>,
68	<constant>GL_UNSIGNED_SHORT</constant>, or <constant>GL_UNSIGNED_INT</constant>.
69	</para>
70	</listitem>
71	</varlistentry>
72	<varlistentry>
73	<term><parameter>indices</parameter></term>
74	<listitem>
75	<para>
76	Specifies a pointer to the location where the indices are stored.
77	</para>
78	</listitem>
79	</varlistentry>
80	<varlistentry>
81	<term><parameter>primcount</parameter></term>
82	<listitem>
83	<para>
84	Specifies the number of instances of the specified range of indices to be rendered.
85	</para>
86	</listitem>
87	</varlistentry>
88	<varlistentry>
89	<term><parameter>baseinstance</parameter></term>
90	<listitem>
91	<para>
92	Specifies the base instance for use in fetching instanced vertex attributes.
93	</para>
94	</listitem>
95	</varlistentry>
96	</variablelist>
97	</refsect1>
98	<refsect1 id="description"><title>Description</title>
99	<para>
100	<function>glDrawElementsInstancedBaseInstance</function> behaves identically to <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>
101	except that <parameter>primcount</parameter> instances of the set of elements are executed and the value of the internal counter
102	<parameter>instanceID</parameter> advances for each iteration. <parameter>instanceID</parameter> is an internal 32-bit integer counter
103	that may be read by a vertex shader as <constant>gl_InstanceID</constant>.
104	</para>
105	<para>
106	<function>glDrawElementsInstancedBaseInstance</function> has the same effect as:
107	<programlisting><![CDATA[ if (mode, count, or type is invalid )
108	generate appropriate error
109	else {
110	for (int i = 0; i < primcount ; i++) {
111	instanceID = i;
112	glDrawElements(mode, count, type, indices);
113	}
114	instanceID = 0;
115	}]]></programlisting>
116	</para>
117	<para>
118	Specific vertex attributes may be classified as <emphasis>instanced</emphasis> through the use of
119	<citerefentry><refentrytitle>glVertexAttribDivisor</refentrytitle></citerefentry>. Instanced vertex attributes
120	supply per-instance vertex data to the vertex shader. The index of the vertex fetched from the enabled instanced vertex
121	attribute arrays is calculated as
122	<mml:math>
123	<mml:mrow>
124	<mml:mfenced open = '&lfloor;' close = '&rfloor;'>
125	<mml:mfrac>
126	<mml:mrow>
127	<mml:mi>gl</mml:mi>
128	<mml:mo>_</mml:mo>
129	<mml:mi>InstanceID</mml:mi>
130	</mml:mrow>
131	<mml:mi>divisor</mml:mi>
132	</mml:mfrac>
133	</mml:mfenced>
134	<mml:mo lspace='2px' rspace='2px'>+</mml:mo>
135	<mml:mi>baseInstance</mml:mi>
136	</mml:mrow>
137	</mml:math>. Note that <parameter>baseinstance</parameter> does not affect the shader-visible value of <constant>gl_InstanceID</constant>.
138	</para>
139	</refsect1>
140	<refsect1 id="notes"><title>Notes</title>
141	<para>
142	<function>glDrawElementsInstancedBaseInstance</function> is available only if the GL version is 4.2 or greater.
143	</para>
144	<para>
145	<constant>GL_LINE_STRIP_ADJACENCY</constant>,
146	<constant>GL_LINES_ADJACENCY</constant>,
147	<constant>GL_TRIANGLE_STRIP_ADJACENCY</constant> and
148	<constant>GL_TRIANGLES_ADJACENCY</constant>
149	are available only if the GL version is 3.2 or greater.
150	</para>
151	</refsect1>
152	<refsect1 id="errors"><title>Errors</title>
153	<para>
154	<constant>GL_INVALID_ENUM</constant> is generated if <parameter>mode</parameter> is not one of <constant>GL_POINTS</constant>,
155	<constant>GL_LINE_STRIP</constant>, <constant>GL_LINE_LOOP</constant>, <constant>GL_LINES</constant>,
156	<constant>GL_TRIANGLE_STRIP</constant>, <constant>GL_TRIANGLE_FAN</constant>, or <constant>GL_TRIANGLES</constant>.
157	</para>
158	<para>
159	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>count</parameter> or <parameter>primcount</parameter> are negative.
160	</para>
161	<para>
162	<constant>GL_INVALID_OPERATION</constant> is generated if a geometry shader is active and <parameter>mode</parameter>
163	is incompatible with the input primitive type of the geometry shader in the currently installed program object.
164	</para>
165	<para>
166	<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
167	enabled array and the buffer object's data store is currently mapped.
168	</para>
169	</refsect1>
170	<refsect1 id="seealso"><title>See Also</title>
171	<para>
172	<citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
173	<citerefentry><refentrytitle>glDrawArraysInstanced</refentrytitle></citerefentry>
174	</para>
175	</refsect1>
176	<refsect1 id="Copyright"><title>Copyright</title>
177	<para>
178	Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
179	This material may be distributed subject to the terms and conditions set forth in
180	the Open Publication License, v 1.0, 8 June 1999.
181	<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
182	</para>
183	</refsect1>
184	</refentry>