152 lines
7.4 KiB
XML
152 lines
7.4 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="glBufferSubData">
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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>glBufferSubData</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glBufferSubData</refname>
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<refpurpose>updates a subset of 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>glBufferSubData</function></funcdef>
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<paramdef>GLenum <parameter>target</parameter></paramdef>
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<paramdef>GLintptr <parameter>offset</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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</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>offset</parameter></term>
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<listitem>
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<para>
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Specifies the offset into the buffer object's data store where data replacement will begin,
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measured in bytes.
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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 data store region being replaced.
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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 the new data that will be copied into the data store.
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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>glBufferSubData</function> redefines some or all of the data store for the buffer object currently
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bound to <parameter>target</parameter>. Data starting at byte offset <parameter>offset</parameter> and
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extending for <parameter>size</parameter> bytes is copied to the data store from the memory pointed to by
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<parameter>data</parameter>. An error is thrown if <parameter>offset</parameter> and <parameter>size</parameter>
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together define a range beyond the bounds of the buffer object's data store.
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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>glBufferSubData</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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When replacing the entire data store, consider using <function>glBufferSubData</function> rather
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than completely recreating the data store with <function>glBufferData</function>. This avoids the cost of
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reallocating the data store.
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</para>
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<para>
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Consider using multiple buffer objects to avoid stalling the rendering pipeline during data store updates.
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If any rendering in the pipeline makes reference to data in the buffer object being updated by
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<function>glBufferSubData</function>, especially from the specific region being updated, that rendering must
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drain from the pipeline before the data store can be updated.
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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_VALUE</constant> is generated if <parameter>offset</parameter> or
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<parameter>size</parameter> is negative, or if together they define a region of memory
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that extends beyond the buffer object's allocated data store.
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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_INVALID_OPERATION</constant> is generated if the buffer object being updated is mapped.
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</para>
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<para>
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<constant>GL_INVALID_OPERATION</constant> is generated if <function>glBufferSubData</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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</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>glBufferData</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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