221 lines
11 KiB
XML
221 lines
11 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="glBufferData">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>2005</year>
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<holder>Sams Publishing</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glBufferData</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glBufferData</refname>
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<refpurpose>creates and initializes a buffer object's data store</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>glBufferData</function></funcdef>
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<paramdef>GLenum <parameter>target</parameter></paramdef>
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<paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
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<paramdef>const GLvoid * <parameter>data</parameter></paramdef>
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<paramdef>GLenum <parameter>usage</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>target</parameter></term>
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<listitem>
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<para>
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Specifies the target buffer object.
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The symbolic constant must be <constant>GL_ARRAY_BUFFER</constant>,
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<constant>GL_ELEMENT_ARRAY_BUFFER</constant>,
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<constant>GL_PIXEL_PACK_BUFFER</constant>, or
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<constant>GL_PIXEL_UNPACK_BUFFER</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>size</parameter></term>
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<listitem>
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<para>
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Specifies the size in bytes of the buffer object's new data store.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>data</parameter></term>
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<listitem>
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<para>
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Specifies a pointer to data that will be copied into the data store for initialization,
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or <constant>NULL</constant> if no data is to be copied.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>usage</parameter></term>
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<listitem>
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<para>
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Specifies the expected usage pattern of the data store. The symbolic constant must be
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<constant>GL_STREAM_DRAW</constant>, <constant>GL_STREAM_READ</constant>, <constant>GL_STREAM_COPY</constant>,
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<constant>GL_STATIC_DRAW</constant>, <constant>GL_STATIC_READ</constant>, <constant>GL_STATIC_COPY</constant>,
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<constant>GL_DYNAMIC_DRAW</constant>, <constant>GL_DYNAMIC_READ</constant>, or <constant>GL_DYNAMIC_COPY</constant>.
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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>glBufferData</function> creates a new data store for the buffer object currently bound to
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<parameter>target</parameter>. Any pre-existing data store is deleted. The new data store is created with the
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specified <parameter>size</parameter> in bytes and <parameter>usage</parameter>. If <parameter>data</parameter>
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is not <constant>NULL</constant>, the data store is initialized with data from this pointer. In its initial
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state, the new data store is not mapped, it has a <constant>NULL</constant> mapped pointer, and its mapped access
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is <constant>GL_READ_WRITE</constant>.
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</para>
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<para>
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<parameter>usage</parameter> is a hint to the GL implementation as to how a buffer object's data store will be
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accessed. This enables the GL implementation to make more intelligent decisions that may significantly
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impact buffer object performance. It does not, however, constrain the actual usage of the data store.
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<parameter>usage</parameter> can be broken down into two parts: first, the frequency of access (modification
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and usage), and second, the nature of that access. The frequency of access may be one of these:
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</para>
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<variablelist>
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<varlistentry>
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<term>STREAM</term>
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<listitem>
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<para>
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The data store contents will be modified once and used at most a few times.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>STATIC</term>
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<listitem>
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<para>
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The data store contents will be modified once and used many times.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>DYNAMIC</term>
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<listitem>
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<para>
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The data store contents will be modified repeatedly and used many times.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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The nature of access may be one of these:
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</para>
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<variablelist>
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<varlistentry>
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<term>DRAW</term>
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<listitem>
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<para>
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The data store contents are modified by the application, and used as the source for GL drawing and
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image specification commands.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>READ</term>
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<listitem>
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<para>
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The data store contents are modified by reading data from the GL, and used to return that data
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when queried by the application.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term>COPY</term>
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<listitem>
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<para>
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The data store contents are modified by reading data from the GL, and used as the source for GL
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drawing and image specification commands.
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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="notes"><title>Notes</title>
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<para>
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<function>glBufferData</function> is available only if the GL version is 1.5 or greater.
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</para>
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<para>
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Targets <constant>GL_PIXEL_PACK_BUFFER</constant> and <constant>GL_PIXEL_UNPACK_BUFFER</constant> are available
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only if the GL version is 2.1 or greater.
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</para>
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<para>
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If <parameter>data</parameter> is <constant>NULL</constant>, a data store of the specified size is still created,
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but its contents remain uninitialized and thus undefined.
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</para>
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<para>
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Clients must align data elements consistent with the requirements of the client
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platform, with an additional base-level requirement that an offset within a buffer to
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a datum comprising <inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi> bytes be a
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multiple of <mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation>.
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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_ENUM</constant> is generated if <parameter>target</parameter> is not
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<constant>GL_ARRAY_BUFFER</constant>, <constant>GL_ELEMENT_ARRAY_BUFFER</constant>,
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<constant>GL_PIXEL_PACK_BUFFER</constant>, or <constant>GL_PIXEL_UNPACK_BUFFER</constant>.
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</para>
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<para>
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<constant>GL_INVALID_ENUM</constant> is generated if <parameter>usage</parameter> is not
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<constant>GL_STREAM_DRAW</constant>, <constant>GL_STREAM_READ</constant>, <constant>GL_STREAM_COPY</constant>,
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<constant>GL_STATIC_DRAW</constant>, <constant>GL_STATIC_READ</constant>, <constant>GL_STATIC_COPY</constant>,
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<constant>GL_DYNAMIC_DRAW</constant>, <constant>GL_DYNAMIC_READ</constant>, or <constant>GL_DYNAMIC_COPY</constant>.
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</para>
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<para>
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<constant>GL_INVALID_VALUE</constant> is generated if <parameter>size</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 the reserved buffer object name 0 is bound to <parameter>target</parameter>.
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</para>
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<para>
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<constant>GL_OUT_OF_MEMORY</constant> is generated if the GL is unable to create a data store with the specified <parameter>size</parameter>.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glBufferData</function>
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is executed between the execution of
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<citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding execution of
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<citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
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</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para>
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<citerefentry><refentrytitle>glGetBufferSubData</refentrytitle></citerefentry>
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</para>
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<para>
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<citerefentry><refentrytitle>glGetBufferParameteriv</refentrytitle></citerefentry> with argument <constant>GL_BUFFER_SIZE</constant> or <constant>GL_BUFFER_USAGE</constant>
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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>glBindBuffer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glBufferSubData</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glUnmapBuffer</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> 2005 Addison-Wesley.
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This material may be distributed subject to the terms and conditions set forth in
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the Open Publication License, v 1.0, 8 June 1999.
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<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
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</para>
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</refsect1>
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</refentry>
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