upstream-man-pages/man3/glGetError.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="glGetError">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>1991-2006</year>
   9                 <holder>Silicon Graphics, Inc.</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>glGetError</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>glGetError</refname>
  17         <refpurpose>return error information</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>C Specification</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>GLenum <function>glGetError</function></funcdef>
  23                 <paramdef> <parameter>void</parameter></paramdef>
  24             </funcprototype>
  25         </funcsynopsis>
  26     </refsynopsisdiv>
  27     <refsect1 id="description"><title>Description</title>
  28         <para>
  29             <function>glGetError</function> returns the value of the error flag.
  30             Each detectable error is assigned a numeric code and symbolic name.
  31             When an error occurs,
  32             the error flag is set to the appropriate error code value.
  33             No other errors are recorded until <function>glGetError</function> is called,
  34             the error code is returned,
  35             and the flag is reset to <constant>GL_NO_ERROR</constant>.
  36             If a call to <function>glGetError</function> returns <constant>GL_NO_ERROR</constant>,
  37             there has been no detectable error since the last call to <function>glGetError</function>,
  38             or since the GL was initialized.
  39         </para>
  40         <para>
  41             To allow for distributed implementations,
  42             there may be several error flags.
  43             If any single error flag has recorded an error,
  44             the value of that flag is returned
  45             and that flag is reset to <constant>GL_NO_ERROR</constant>
  46             when <function>glGetError</function> is called.
  47             If more than one flag has recorded an error,
  48             <function>glGetError</function> returns and clears an arbitrary error flag value.
  49             Thus, <function>glGetError</function> should always be called in a loop,
  50             until it returns <constant>GL_NO_ERROR</constant>,
  51             if all error flags are to be reset.
  52         </para>
  53         <para>
  54             Initially, all error flags are set to <constant>GL_NO_ERROR</constant>.
  55         </para>
  56         <para>
  57             The following errors are currently defined:
  58         </para>
  59         <variablelist>
  60             <varlistentry>
  61                 <term><constant>GL_NO_ERROR</constant></term>
  62                 <listitem>
  63                     <para>
  64                         No error has been recorded.
  65                         The value of this symbolic constant is guaranteed to be 0.
  66                     </para>
  67                 </listitem>
  68             </varlistentry>
  69             <varlistentry>
  70                 <term><constant>GL_INVALID_ENUM</constant></term>
  71                 <listitem>
  72                     <para>
  73                         An unacceptable value is specified for an enumerated argument.
  74                         The offending command is ignored
  75                         and has no other side effect than to set the error flag.
  76                     </para>
  77                 </listitem>
  78             </varlistentry>
  79             <varlistentry>
  80                 <term><constant>GL_INVALID_VALUE</constant></term>
  81                 <listitem>
  82                     <para>
  83                         A numeric argument is out of range.
  84                         The offending command is ignored
  85                         and has no other side effect than to set the error flag.
  86                     </para>
  87                 </listitem>
  88             </varlistentry>
  89             <varlistentry>
  90                 <term><constant>GL_INVALID_OPERATION</constant></term>
  91                 <listitem>
  92                     <para>
  93                         The specified operation is not allowed in the current state.
  94                         The offending command is ignored
  95                         and has no other side effect than to set the error flag.
  96                     </para>
  97                 </listitem>
  98             </varlistentry>
  99             <varlistentry>
 100                 <term><constant>GL_INVALID_FRAMEBUFFER_OPERATION</constant></term>
 101                 <listitem>
 102                     <para>
 103                         The framebuffer object is not complete. The offending command
 104                         is ignored and has no other side effect than to set the error flag.
 105                     </para>
 106                 </listitem>
 107             </varlistentry>
 108             <varlistentry>
 109                 <term><constant>GL_OUT_OF_MEMORY</constant></term>
 110                 <listitem>
 111                     <para>
 112                         There is not enough memory left to execute the command.
 113                         The state of the GL is undefined,
 114                         except for the state of the error flags,
 115                         after this error is recorded.
 116                     </para>
 117                 </listitem>
 118             </varlistentry>
 119         </variablelist>
 120         <para>
 121             When an error flag is set,
 122             results of a GL operation are undefined only if <constant>GL_OUT_OF_MEMORY</constant>
 123             has occurred.
 124             In all other cases,
 125             the command generating the error is ignored and has no effect on the GL state
 126             or frame buffer contents.
 127             If the generating command returns a value, it returns 0.
 128             If <function>glGetError</function> itself generates an error, it returns 0.
 129         </para>
 130     </refsect1>
 131     <refsect1 id="Copyright"><title>Copyright</title>
 132         <para>
 133             Copyright <trademark class="copyright"></trademark> 1991-2006
 134             Silicon Graphics, Inc. This document is licensed under the SGI
 135             Free Software B License. For details, see
 136             <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
 137         </para>
 138     </refsect1>
 139 </refentry>