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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_STACK_OVERFLOW</constant></term> | |
101 | <listitem> | |
102 | <para> | |
103 | This command would cause a stack overflow. | |
104 | The offending command is ignored | |
105 | and has no other side effect than to set the error flag. | |
106 | </para> | |
107 | </listitem> | |
108 | </varlistentry> | |
109 | <varlistentry> | |
110 | <term><constant>GL_STACK_UNDERFLOW</constant></term> | |
111 | <listitem> | |
112 | <para> | |
113 | This command would cause a stack underflow. | |
114 | The offending command is ignored | |
115 | and has no other side effect than to set the error flag. | |
116 | </para> | |
117 | </listitem> | |
118 | </varlistentry> | |
119 | <varlistentry> | |
120 | <term><constant>GL_OUT_OF_MEMORY</constant></term> | |
121 | <listitem> | |
122 | <para> | |
123 | There is not enough memory left to execute the command. | |
124 | The state of the GL is undefined, | |
125 | except for the state of the error flags, | |
126 | after this error is recorded. | |
127 | </para> | |
128 | </listitem> | |
129 | </varlistentry> | |
130 | <varlistentry> | |
131 | <term><constant>GL_TABLE_TOO_LARGE</constant></term> | |
132 | <listitem> | |
133 | <para> | |
134 | The specified table exceeds the implementation's maximum supported table | |
135 | size. The offending command is ignored and has no other side effect | |
136 | than to set the error flag. | |
137 | </para> | |
138 | </listitem> | |
139 | </varlistentry> | |
140 | </variablelist> | |
141 | <para> | |
142 | When an error flag is set, | |
143 | results of a GL operation are undefined only if <constant>GL_OUT_OF_MEMORY</constant> | |
144 | has occurred. | |
145 | In all other cases, | |
146 | the command generating the error is ignored and has no effect on the GL state | |
147 | or frame buffer contents. | |
148 | If the generating command returns a value, it returns 0. | |
149 | If <function>glGetError</function> itself generates an error, it returns 0. | |
150 | </para> | |
151 | </refsect1> | |
152 | <refsect1 id="notes"><title>Notes</title> | |
153 | <para> | |
154 | <constant>GL_TABLE_TOO_LARGE</constant> was introduced in GL version 1.2. | |
155 | </para> | |
156 | </refsect1> | |
157 | <refsect1 id="errors"><title>Errors</title> | |
158 | <para> | |
159 | <constant>GL_INVALID_OPERATION</constant> is generated if <function>glGetError</function> | |
160 | is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
161 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>. | |
162 | In this case, <function>glGetError</function> returns 0. | |
163 | </para> | |
164 | </refsect1> | |
165 | <refsect1 id="Copyright"><title>Copyright</title> | |
166 | <para> | |
167 | Copyright <trademark class="copyright"></trademark> 1991-2006 | |
168 | Silicon Graphics, Inc. This document is licensed under the SGI | |
169 | Free Software B License. For details, see | |
170 | <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>. | |
171 | </para> | |
172 | </refsect1> | |
173 | </refentry> |