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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="glDrawRangeElements">
<refmeta>
<refmetainfo>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle>glDrawRangeElements</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refname>glDrawRangeElements</refname>
<refpurpose>render primitives from array data</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glDrawRangeElements</function></funcdef>
<paramdef>GLenum <parameter>mode</parameter></paramdef>
<paramdef>GLuint <parameter>start</parameter></paramdef>
<paramdef>GLuint <parameter>end</parameter></paramdef>
<paramdef>GLsizei <parameter>count</parameter></paramdef>
<paramdef>GLenum <parameter>type</parameter></paramdef>
<paramdef>const GLvoid * <parameter>indices</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_TRIANGLE_STRIP</constant>,
<constant>GL_TRIANGLE_FAN</constant>,
<constant>GL_TRIANGLES</constant>,
<constant>GL_QUAD_STRIP</constant>,
<constant>GL_QUADS</constant>,
and <constant>GL_POLYGON</constant> are accepted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>start</parameter></term>
<listitem>
<para>
Specifies the minimum array index contained in <parameter>indices</parameter>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>end</parameter></term>
<listitem>
<para>
Specifies the maximum array index contained in <parameter>indices</parameter>.
</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>glDrawRangeElements</function> is a restricted form of <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>. <parameter>mode</parameter>, <parameter>start</parameter>, <parameter>end</parameter>,
and <parameter>count</parameter> match the corresponding arguments to <citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>, with
the additional constraint that all values in the arrays <parameter>count</parameter> must lie
between <parameter>start</parameter> and <parameter>end</parameter>, inclusive.
</para>
<para>
Implementations denote recommended maximum amounts of vertex and
index data,
which may be queried by calling <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument
<constant>GL_MAX_ELEMENTS_VERTICES</constant> and <constant>GL_MAX_ELEMENTS_INDICES</constant>.
If
<inlineequation><mml:math>
<!-- eqn: end - start + 1:-->
<mml:mrow>
<mml:mi mathvariant="italic">end</mml:mi>
<mml:mo>-</mml:mo>
<mml:mi mathvariant="italic">start</mml:mi>
<mml:mo>+</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:math></inlineequation>
is greater than the value of
<constant>GL_MAX_ELEMENTS_VERTICES</constant>, or if <parameter>count</parameter> is greater than the value of
<constant>GL_MAX_ELEMENTS_INDICES</constant>, then the call may operate at reduced
performance. There is no requirement that all vertices in the range
<inlineequation><mml:math>
<!-- eqn: [start, end]:-->
<mml:mfenced open="[" close="]">
<mml:mi mathvariant="italic">start</mml:mi>
<mml:mi mathvariant="italic">end</mml:mi>
</mml:mfenced>
</mml:math></inlineequation>
be referenced. However, the implementation may
partially process unused vertices, reducing performance from what could
be achieved with an optimal index set.
</para>
<para>
When <function>glDrawRangeElements</function> is called, it uses <parameter>count</parameter> sequential elements from an
enabled array, starting at <parameter>start</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. If
<constant>GL_VERTEX_ARRAY</constant> is not enabled, no geometric primitives are
constructed.
</para>
<para>
Vertex attributes that are modified by <function>glDrawRangeElements</function> have an
unspecified value after <function>glDrawRangeElements</function> returns. For example, if
<constant>GL_COLOR_ARRAY</constant> is enabled, the value of the current color is
undefined after <function>glDrawRangeElements</function> executes. Attributes that aren't
modified maintain their previous values.
</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para>
<function>glDrawRangeElements</function> is available only if the GL version is 1.2 or greater.
</para>
<para>
<function>glDrawRangeElements</function> is included in display lists. If <function>glDrawRangeElements</function> is entered into a
display list,
the necessary array data (determined by the array pointers and
enables) is also
entered into the display list. Because the array pointers and
enables are client-side state, their values affect display lists
when the lists are created, not when the lists are executed.
</para>
</refsect1>
<refsect1 id="errors"><title>Errors</title>
<para>
It is an error for indices to lie outside the range
<inlineequation><mml:math>
<!-- eqn: [start, end]:-->
<mml:mfenced open="[" close="]">
<mml:mi mathvariant="italic">start</mml:mi>
<mml:mi mathvariant="italic">end</mml:mi>
</mml:mfenced>
</mml:math></inlineequation>,
but implementations may not check for this situation. Such indices
cause implementation-dependent behavior.
</para>
<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_VALUE</constant> is generated if
<inlineequation><mml:math>
<!-- eqn: end < start:-->
<mml:mrow>
<mml:mi mathvariant="italic">end</mml:mi>
<mml:mo><</mml:mo>
<mml:mi mathvariant="italic">start</mml:mi>
</mml:mrow>
</mml:math></inlineequation>.
</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>
<para>
<constant>GL_INVALID_OPERATION</constant> is generated if <function>glDrawRangeElements</function> is executed between
the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
</para>
</refsect1>
<refsect1 id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_ELEMENTS_VERTICES</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_MAX_ELEMENTS_INDICES</constant>
</para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para>
<citerefentry><refentrytitle>glArrayElement</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glColorPointer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDrawElements</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glEdgeFlagPointer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glGetPointerv</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glIndexPointer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glInterleavedArrays</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glNormalPointer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glSecondaryColorPointer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glTexCoordPointer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glVertexPointer</refentrytitle></citerefentry>
</para>
</refsect1>
<refsect1 id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"></trademark> 1991-2006
Silicon Graphics, Inc. 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>