139 lines
6.2 KiB
XML
139 lines
6.2 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="glGetError">
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<refmeta>
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<refmetainfo>
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<copyright>
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<year>1991-2006</year>
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<holder>Silicon Graphics, Inc.</holder>
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</copyright>
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</refmetainfo>
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<refentrytitle>glGetError</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glGetError</refname>
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<refpurpose>return error information</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>GLenum <function>glGetError</function></funcdef>
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<paramdef> <parameter>void</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 id="description"><title>Description</title>
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<para>
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<function>glGetError</function> returns the value of the error flag.
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Each detectable error is assigned a numeric code and symbolic name.
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When an error occurs,
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the error flag is set to the appropriate error code value.
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No other errors are recorded until <function>glGetError</function> is called,
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the error code is returned,
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and the flag is reset to <constant>GL_NO_ERROR</constant>.
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If a call to <function>glGetError</function> returns <constant>GL_NO_ERROR</constant>,
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there has been no detectable error since the last call to <function>glGetError</function>,
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or since the GL was initialized.
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</para>
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<para>
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To allow for distributed implementations,
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there may be several error flags.
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If any single error flag has recorded an error,
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the value of that flag is returned
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and that flag is reset to <constant>GL_NO_ERROR</constant>
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when <function>glGetError</function> is called.
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If more than one flag has recorded an error,
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<function>glGetError</function> returns and clears an arbitrary error flag value.
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Thus, <function>glGetError</function> should always be called in a loop,
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until it returns <constant>GL_NO_ERROR</constant>,
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if all error flags are to be reset.
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</para>
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<para>
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Initially, all error flags are set to <constant>GL_NO_ERROR</constant>.
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</para>
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<para>
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The following errors are currently defined:
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</para>
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<variablelist>
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<varlistentry>
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<term><constant>GL_NO_ERROR</constant></term>
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<listitem>
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<para>
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No error has been recorded.
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The value of this symbolic constant is guaranteed to be 0.
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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><constant>GL_INVALID_ENUM</constant></term>
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<listitem>
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<para>
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An unacceptable value is specified for an enumerated argument.
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The offending command is ignored
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and has no other side effect than to set the error flag.
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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><constant>GL_INVALID_VALUE</constant></term>
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<listitem>
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<para>
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A numeric argument is out of range.
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The offending command is ignored
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and has no other side effect than to set the error flag.
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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><constant>GL_INVALID_OPERATION</constant></term>
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<listitem>
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<para>
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The specified operation is not allowed in the current state.
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The offending command is ignored
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and has no other side effect than to set the error flag.
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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><constant>GL_INVALID_FRAMEBUFFER_OPERATION</constant></term>
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<listitem>
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<para>
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The framebuffer object is not complete. The offending command
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is ignored and has no other side effect than to set the error flag.
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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><constant>GL_OUT_OF_MEMORY</constant></term>
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<listitem>
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<para>
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There is not enough memory left to execute the command.
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The state of the GL is undefined,
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except for the state of the error flags,
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after this error is recorded.
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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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When an error flag is set,
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results of a GL operation are undefined only if <constant>GL_OUT_OF_MEMORY</constant>
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has occurred.
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In all other cases,
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the command generating the error is ignored and has no effect on the GL state
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or frame buffer contents.
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If the generating command returns a value, it returns 0.
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If <function>glGetError</function> itself generates an error, it returns 0.
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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> 1991-2006
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Silicon Graphics, Inc. This document is licensed under the SGI
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Free Software B License. For details, see
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<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
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</para>
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</refsect1>
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</refentry>
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