upstream-doc/man4/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
  39                     <constant>GL_ARRAY_BUFFER</constant>,
  40                     <constant>GL_ATOMIC_COUNTER_BUFFER</constant>,
  41                     <constant>GL_COPY_READ_BUFFER</constant>,
  42                     <constant>GL_COPY_WRITE_BUFFER</constant>,
  43                     <constant>GL_DRAW_INDIRECT_BUFFER</constant>,
  44                     <constant>GL_DISPATCH_INDIRECT_BUFFER</constant>,
  45                     <constant>GL_ELEMENT_ARRAY_BUFFER</constant>,
  46                     <constant>GL_PIXEL_PACK_BUFFER</constant>,
  47                     <constant>GL_PIXEL_UNPACK_BUFFER</constant>,
  48                     <constant>GL_SHADER_STORAGE_BUFFER</constant>,
  49                     <constant>GL_TEXTURE_BUFFER</constant>,
  50                     <constant>GL_TRANSFORM_FEEDBACK_BUFFER</constant>, or
  51                     <constant>GL_UNIFORM_BUFFER</constant>.
  52                 </para>
  53             </listitem>
  54         </varlistentry>
  55         <varlistentry>
  56             <term><parameter>size</parameter></term>
  57             <listitem>
  58                 <para>
  59                     Specifies the size in bytes of the buffer object's new data store.
  60                 </para>
  61             </listitem>
  62         </varlistentry>
  63         <varlistentry>
  64             <term><parameter>data</parameter></term>
  65             <listitem>
  66                 <para>
  67                     Specifies a pointer to data that will be copied into the data store for initialization,
  68                     or <constant>NULL</constant> if no data is to be copied.
  69                 </para>
  70             </listitem>
  71         </varlistentry>
  72         <varlistentry>
  73             <term><parameter>usage</parameter></term>
  74             <listitem>
  75                 <para>
  76                     Specifies the expected usage pattern of the data store. The symbolic constant must be
  77                     <constant>GL_STREAM_DRAW</constant>, <constant>GL_STREAM_READ</constant>, <constant>GL_STREAM_COPY</constant>,
  78                     <constant>GL_STATIC_DRAW</constant>, <constant>GL_STATIC_READ</constant>, <constant>GL_STATIC_COPY</constant>,
  79                     <constant>GL_DYNAMIC_DRAW</constant>, <constant>GL_DYNAMIC_READ</constant>, or <constant>GL_DYNAMIC_COPY</constant>.
  80                 </para>
  81             </listitem>
  82         </varlistentry>
  83         </variablelist>
  84     </refsect1>
  85     <refsect1 id="description"><title>Description</title>
  86         <para>
  87             <function>glBufferData</function> creates a new data store for the buffer object currently bound to
  88             <parameter>target</parameter>. Any pre-existing data store is deleted. The new data store is created with the
  89             specified <parameter>size</parameter> in bytes and <parameter>usage</parameter>. If <parameter>data</parameter>
  90             is not <constant>NULL</constant>, the data store is initialized with data from this pointer. In its initial
  91             state, the new data store is not mapped, it has a <constant>NULL</constant> mapped pointer, and its mapped access
  92             is <constant>GL_READ_WRITE</constant>.
  93         </para>
  94         <para>
  95             <parameter>usage</parameter> is a hint to the GL implementation as to how a buffer object's data store will be
  96             accessed. This enables the GL implementation to make more intelligent decisions that may significantly
  97             impact buffer object performance. It does not, however, constrain the actual usage of the data store.
  98             <parameter>usage</parameter> can be broken down into two parts: first, the frequency of access (modification
  99             and usage), and second, the nature of that access. The frequency of access may be one of these:
 100         </para>
 101         <variablelist>
 102             <varlistentry>
 103                 <term>STREAM</term>
 104                 <listitem>
 105                     <para>
 106                         The data store contents will be modified once and used at most a few times.
 107                     </para>
 108                 </listitem>
 109             </varlistentry>
 110             <varlistentry>
 111                 <term>STATIC</term>
 112                 <listitem>
 113                     <para>
 114                         The data store contents will be modified once and used many times.
 115                     </para>
 116                 </listitem>
 117             </varlistentry>
 118             <varlistentry>
 119                 <term>DYNAMIC</term>
 120                 <listitem>
 121                     <para>
 122                         The data store contents will be modified repeatedly and used many times.
 123                     </para>
 124                 </listitem>
 125             </varlistentry>
 126         </variablelist>
 127         <para>
 128             The nature of access may be one of these:
 129         </para>
 130         <variablelist>
 131             <varlistentry>
 132                 <term>DRAW</term>
 133                 <listitem>
 134                     <para>
 135                         The data store contents are modified by the application, and used as the source for GL drawing and
 136                         image specification commands.
 137                     </para>
 138                 </listitem>
 139             </varlistentry>
 140             <varlistentry>
 141                 <term>READ</term>
 142                 <listitem>
 143                     <para>
 144                         The data store contents are modified by reading data from the GL, and used to return that data
 145                         when queried by the application.
 146                     </para>
 147                 </listitem>
 148             </varlistentry>
 149             <varlistentry>
 150                 <term>COPY</term>
 151                 <listitem>
 152                     <para>
 153                         The data store contents are modified by reading data from the GL, and used as the source for GL
 154                         drawing and image specification commands.
 155                     </para>
 156                 </listitem>
 157             </varlistentry>
 158         </variablelist>
 159     </refsect1>
 160     <refsect1 id="notes"><title>Notes</title>
 161         <para>
 162             If <parameter>data</parameter> is <constant>NULL</constant>, a data store of the specified size is still created,
 163             but its contents remain uninitialized and thus undefined.
 164         </para>
 165         <para>
 166             Clients must align data elements consistent with the requirements of the client
 167             platform, with an additional base-level requirement that an offset within a buffer to
 168             a datum comprising <inlineequation><mml:math><mml:mi mathvariant="italic">N</mml:mi> bytes be a
 169             multiple of <mml:mi mathvariant="italic">N</mml:mi></mml:math></inlineequation>.
 170         </para>
 171         <para>
 172             The <constant>GL_ATOMIC_COUNTER_BUFFER</constant> target is available only if the GL version
 173             is 4.2 or greater.
 174         </para>
 175         <para>
 176             The <constant>GL_DISPATCH_INDIRECT_BUFFER</constant> and <constant>GL_SHADER_STORAGE_BUFFER</constant> targets are available only if the GL version
 177             is 4.3 or greater.
 178         </para>
 179     </refsect1>
 180     <refsect1 id="errors"><title>Errors</title>
 181         <para>
 182             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>target</parameter> is not
 183             one of the accepted buffer targets.
 184         </para>
 185         <para>
 186             <constant>GL_INVALID_ENUM</constant> is generated if <parameter>usage</parameter> is not
 187             <constant>GL_STREAM_DRAW</constant>, <constant>GL_STREAM_READ</constant>, <constant>GL_STREAM_COPY</constant>,
 188             <constant>GL_STATIC_DRAW</constant>, <constant>GL_STATIC_READ</constant>, <constant>GL_STATIC_COPY</constant>,
 189             <constant>GL_DYNAMIC_DRAW</constant>, <constant>GL_DYNAMIC_READ</constant>, or <constant>GL_DYNAMIC_COPY</constant>.
 190         </para>
 191         <para>
 192             <constant>GL_INVALID_VALUE</constant> is generated if <parameter>size</parameter> is negative.
 193         </para>
 194         <para>
 195             <constant>GL_INVALID_OPERATION</constant> is generated if the reserved buffer object name 0 is bound to <parameter>target</parameter>.
 196         </para>
 197         <para>
 198             <constant>GL_OUT_OF_MEMORY</constant> is generated if the GL is unable to create a data store with the specified <parameter>size</parameter>.
 199         </para>
 200     </refsect1>
 201     <refsect1 id="associatedgets"><title>Associated Gets</title>
 202         <para>
 203             <citerefentry><refentrytitle>glGetBufferSubData</refentrytitle></citerefentry>
 204         </para>
 205         <para>
 206             <citerefentry><refentrytitle>glGetBufferParameter</refentrytitle></citerefentry> with argument <constant>GL_BUFFER_SIZE</constant> or <constant>GL_BUFFER_USAGE</constant>
 207         </para>
 208     </refsect1>
 209     <refsect1 id="seealso"><title>See Also</title>
 210         <para>
 211             <citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
 212             <citerefentry><refentrytitle>glBufferSubData</refentrytitle></citerefentry>,
 213             <citerefentry><refentrytitle>glMapBuffer</refentrytitle></citerefentry>,
 214             <citerefentry><refentrytitle>glUnmapBuffer</refentrytitle></citerefentry>
 215         </para>
 216     </refsect1>
 217     <refsect1 id="Copyright"><title>Copyright</title>
 218         <para>
 219             Copyright <trademark class="copyright"></trademark> 2005 Addison-Wesley.
 220             Copyright <trademark class="copyright"></trademark> 2011-2012 Khronos Group.
 221             This material may be distributed subject to the terms and conditions set forth in
 222             the Open Publication License, v 1.0, 8 June 1999.
 223             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 224         </para>
 225     </refsect1>
 226 </refentry>