113 lines
6.1 KiB
XML
113 lines
6.1 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
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"http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
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<refentry id="glArrayElement">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glArrayElement</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glArrayElement</refname>
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<refpurpose>render a vertex using the specified vertex array element</refpurpose>
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</refnamediv>
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<refsynopsisdiv><title>C Specification</title>
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<funcsynopsis>
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<funcprototype>
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<funcdef>void <function>glArrayElement</function></funcdef>
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<paramdef>GLint <parameter>i</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<!-- eqn: ignoring delim $$ -->
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>i</parameter></term>
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<listitem>
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<para>
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Specifies an index into the enabled vertex data arrays.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para>
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<function>glArrayElement</function> commands are used within <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>/<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry> pairs to
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specify vertex and attribute data for point, line, and polygon
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primitives. If <constant>GL_VERTEX_ARRAY</constant> is enabled when <function>glArrayElement</function> is called, a
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single vertex is drawn, using
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vertex and attribute data taken from location <parameter>i</parameter> of the enabled
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arrays. If <constant>GL_VERTEX_ARRAY</constant> is not enabled, no drawing occurs but
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the attributes corresponding to the enabled arrays are modified.
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</para>
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<para>
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Use <function>glArrayElement</function> to construct primitives by indexing vertex data, rather than
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by streaming through arrays of data in first-to-last order. Because
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each call specifies only a single vertex, it is possible to explicitly
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specify per-primitive attributes such as a single normal for each
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triangle.
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</para>
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<para>
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Changes made to array data between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the
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corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry> may affect calls to <function>glArrayElement</function> that are made
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within the same <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>/<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry> period in nonsequential ways.
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That is, a call to
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<function>glArrayElement</function> that precedes a change to array data may
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access the changed data, and a call that follows a change to array data
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may access original data.
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</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para>
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<function>glArrayElement</function> is available only if the GL version is 1.1 or greater.
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</para>
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<para>
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<function>glArrayElement</function> is included in display lists. If <function>glArrayElement</function> is entered into a
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display list, the necessary array data (determined by the array
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pointers and enables) is also entered into the display list. Because
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the array pointers and enables are client-side state, their values
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affect display lists when the lists are created, not when the lists
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are executed.
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</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para>
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<constant>GL_INVALID_VALUE</constant> may be generated if <parameter>i</parameter> is negative.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if a non-zero buffer object name is bound to an
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enabled array and the buffer object's data store is currently mapped.
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</para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para>
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<citerefentry><refentrytitle>glClientActiveTexture</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glColorPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDrawArrays</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glEdgeFlagPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glFogCoordPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glGetPointerv</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glIndexPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glInterleavedArrays</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glNormalPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glSecondaryColorPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glTexCoordPointer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexPointer</refentrytitle></citerefentry>
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</para>
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</refsect1>
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<refsect1 id="Copyright"><title>Copyright</title>
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<para>
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Copyright <trademark class="copyright"></trademark> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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