upstream-doc/man2/glBufferData.xml

   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="glBufferData">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2005</year>
   9                 <holder>Sams Publishing</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glBufferData</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glBufferData</refname>
  17         <refpurpose>creates and initializes a buffer object's data store</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>void <function>glBufferData</function></funcdef>
  23                 <paramdef>GLenum <parameter>target</parameter></paramdef>
  24                 <paramdef>GLsizeiptr <parameter>size</parameter></paramdef>
  25                 <paramdef>const GLvoid * <parameter>data</parameter></paramdef>
  26                 <paramdef>GLenum <parameter>usage</parameter></paramdef>
  27             </funcprototype>
  28         </funcsynopsis>
  29     </refsynopsisdiv>
  30     <!-- eqn: ignoring delim $$ -->
  31     <refsect1 id="parameters"><title>Parameters</title>
  32         <variablelist>
  33         <varlistentry>
  34             <term><parameter>target</parameter></term>
  35             <listitem>
  36                 <para>
  37                     Specifies the target buffer object.
  38                     The symbolic constant must be <constant>GL_ARRAY_BUFFER</constant>,
  39                     <constant>GL_ELEMENT_ARRAY_BUFFER</constant>,
  40                     <constant>GL_PIXEL_PACK_BUFFER</constant>, or
  41                     <constant>GL_PIXEL_UNPACK_BUFFER</constant>.
  42                 </para>
  43             </listitem>
  44         </varlistentry>
  45         <varlistentry>
  46             <term><parameter>size</parameter></term>
  47             <listitem>
  48                 <para>
  49                     Specifies the size in bytes of the buffer object's new data store.
  50                 </para>
  51             </listitem>
  52         </varlistentry>
  53         <varlistentry>
  54             <term><parameter>data</parameter></term>
  55             <listitem>
  56                 <para>
  57                     Specifies a pointer to data that will be copied into the data store for initialization,
  58                     or <constant>NULL</constant> if no data is to be copied.
  59                 </para>
  60             </listitem>
  61         </varlistentry>
  62         <varlistentry>
  63             <term><parameter>usage</parameter></term>
  64             <listitem>
  65                 <para>
  66                     Specifies the expected usage pattern of the data store. The symbolic constant must be
  67                     <constant>GL_STREAM_DRAW</constant>, <constant>GL_STREAM_READ</constant>, <constant>GL_STREAM_COPY</constant>,
  68                     <constant>GL_STATIC_DRAW</constant>, <constant>GL_STATIC_READ</constant>, <constant>GL_STATIC_COPY</constant>,
  69                     <constant>GL_DYNAMIC_DRAW</constant>, <constant>GL_DYNAMIC_READ</constant>, or <constant>GL_DYNAMIC_COPY</constant>.
  70                 </para>
  71             </listitem>
  72         </varlistentry>
  73         </variablelist>
  74     </refsect1>
  75     <refsect1 id="description"><title>Description</title>
  76         <para>
  77             <function>glBufferData</function> creates a new data store for the buffer object currently bound to
  78             <parameter>target</parameter>. Any pre-existing data store is deleted. The new data store is created with the
  79             specified <parameter>size</parameter> in bytes and <parameter>usage</parameter>. If <parameter>data</parameter>
  80             is not <constant>NULL</constant>, the data store is initialized with data from this pointer. In its initial
  81             state, the new data store is not mapped, it has a <constant>NULL</constant> mapped pointer, and its mapped access
  82             is <constant>GL_READ_WRITE</constant>.
  83         </para>
  84         <para>
  85             <parameter>usage</parameter> is a hint to the GL implementation as to how a buffer object's data store will be
  86             accessed. This enables the GL implementation to make more intelligent decisions that may significantly
  87             impact buffer object performance. It does not, however, constrain the actual usage of the data store.
  88             <parameter>usage</parameter> can be broken down into two parts: first, the frequency of access (modification
  89             and usage), and second, the nature of that access. The frequency of access may be one of these:
  90         </para>
  91         <variablelist>
  92             <varlistentry>
  93                 <term>STREAM</term>
  94                 <listitem>
  95                     <para>
  96                         The data store contents will be modified once and used at most a few times.
  97                     </para>
  98                 </listitem>
  99             </varlistentry>
 100             <varlistentry>
 101                 <term>STATIC</term>
 102                 <listitem>
 103                     <para>
 104                         The data store contents will be modified once and used many times.
 105                     </para>
 106                 </listitem>
 107             </varlistentry>
 108             <varlistentry>
 109                 <term>DYNAMIC</term>
 110                 <listitem>
 111                     <para>
 112                         The data store contents will be modified repeatedly and used many times.
 113                     </para>
 114                 </listitem>
 115             </varlistentry>
 116         </variablelist>
 117         <para>
 118             The nature of access may be one of these:
 119         </para>
 120         <variablelist>
 121             <varlistentry>
 122                 <term>DRAW</term>
 123                 <listitem>
 124                     <para>
 125                         The data store contents are modified by the application, and used as the source for GL drawing and
 126                         image specification commands.
 127                     </para>
 128                 </listitem>
 129             </varlistentry>
 130             <varlistentry>
 131                 <term>READ</term>
 132                 <listitem>
 133                     <para>
 134                         The data store contents are modified by reading data from the GL, and used to return that data
 135                         when queried by the application.
 136                     </para>
 137                 </listitem>
 138             </varlistentry>
 139             <varlistentry>
 140                 <term>COPY</term>
 141                 <listitem>
 142                     <para>
 143                         The data store contents are modified by reading data from the GL, and used as the source for GL
 144                         drawing and image specification commands.
 145                     </para>
 146                 </listitem>
 147             </varlistentry>
 148         </variablelist>
 149     </refsect1>
 150     <refsect1 id="notes"><title>Notes</title>
 151         <para>
 152             <function>glBufferData</function> is available only if the GL version is 1.5 or greater.
 153         </para>
 154         <para>
 155             Targets <constant>GL_PIXEL_PACK_BUFFER</constant> and <constant>GL_PIXEL_UNPACK_BUFFER</constant> are available
 156             only if the GL version is 2.1 or greater.
 157         </para>
 158         <para>
 159             If <parameter>data</parameter> is <constant>NULL</constant>, a data store of the specified size is still created,
 160             but its contents remain uninitialized and thus undefined.
 161         </para>
 162         <para>
 163             Clients must align data elements consistent with the requirements of the client
 164             platform, with an additional base-level requirement that an offset within a buffer to
 165             a datum comprising <inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi> bytes be a
 166             multiple of <mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation>.
 167         </para>
 168     </refsect1>
 169     <refsect1 id="errors"><title>Errors</title>
 170         <para>
 171             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
 172             <constant>GL_ARRAY_BUFFER</constant>, <constant>GL_ELEMENT_ARRAY_BUFFER</constant>,
 173             <constant>GL_PIXEL_PACK_BUFFER</constant>, or <constant>GL_PIXEL_UNPACK_BUFFER</constant>.
 174         </para>
 175         <para>
 176             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>usage</parameter> is not
 177             <constant>GL_STREAM_DRAW</constant>, <constant>GL_STREAM_READ</constant>, <constant>GL_STREAM_COPY</constant>,
 178             <constant>GL_STATIC_DRAW</constant>, <constant>GL_STATIC_READ</constant>, <constant>GL_STATIC_COPY</constant>,
 179             <constant>GL_DYNAMIC_DRAW</constant>, <constant>GL_DYNAMIC_READ</constant>, or <constant>GL_DYNAMIC_COPY</constant>.
 180         </para>
 181         <para>
 182             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>size</parameter> is negative.
 183         </para>
 184         <para>
 185             <constant>GL_INVALID_OPERATION</constant> is generated if the reserved buffer object name 0 is bound to <parameter>target</parameter>.
 186         </para>
 187         <para>
 188             <constant>GL_OUT_OF_MEMORY</constant> is generated if the GL is unable to create a data store with the specified <parameter>size</parameter>.
 189         </para>
 190         <para>
 191             <constant>GL_INVALID_OPERATION</constant> is generated if <function>glBufferData</function>
 192             is executed between the execution of
 193             <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> and the corresponding execution of
 194             <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
 195         </para>
 196     </refsect1>
 197     <refsect1 id="associatedgets"><title>Associated Gets</title>
 198         <para>
 199             <citerefentry><refentrytitle>glGetBufferSubData</refentrytitle></citerefentry>
 200         </para>
 201         <para>
 202             <citerefentry><refentrytitle>glGetBufferParameteriv</refentrytitle></citerefentry> with argument <constant>GL_BUFFER_SIZE</constant> or <constant>GL_BUFFER_USAGE</constant>
 203         </para>
 204     </refsect1>
 205     <refsect1 id="seealso"><title>See Also</title>
 206         <para>
 207             <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
 208             <citerefentry><refentrytitle>glBufferSubData</refentrytitle></citerefentry>,
 209             <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
 210             <citerefentry><refentrytitle>glUnmapBuffer</refentrytitle></citerefentry>
 211         </para>
 212     </refsect1>
 213     <refsect1 id="Copyright"><title>Copyright</title>
 214         <para>
 215             Copyright <trademark class="copyright"></trademark> 2005 Addison-Wesley.
 216             This material may be distributed subject to the terms and conditions set forth in
 217             the Open Publication License, v 1.0, 8 June 1999.
 218             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 219         </para>
 220     </refsect1>
 221 </refentry>