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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="glLinkProgram"> | |
5 | <refmeta> | |
6 | <refentrytitle>glLinkProgram</refentrytitle> | |
7 | <manvolnum>3G</manvolnum> | |
8 | </refmeta> | |
9 | <refnamediv> | |
10 | <refname>glLinkProgram</refname> | |
11 | <refpurpose>Links a program object</refpurpose> | |
12 | </refnamediv> | |
13 | <refsynopsisdiv><title>C Specification</title> | |
14 | <funcsynopsis> | |
15 | <funcprototype> | |
16 | <funcdef>void <function>glLinkProgram</function></funcdef> | |
17 | <paramdef>GLuint <parameter>program</parameter></paramdef> | |
18 | </funcprototype> | |
19 | </funcsynopsis> | |
20 | </refsynopsisdiv> | |
21 | <refsect1 id="parameters"><title>Parameters</title> | |
22 | <variablelist> | |
23 | <varlistentry> | |
24 | <term><parameter>program</parameter></term> | |
25 | <listitem> | |
26 | <para>Specifies the handle of the program object to be linked.</para> | |
27 | ||
28 | </listitem> | |
29 | </varlistentry> | |
30 | </variablelist> | |
31 | </refsect1> | |
32 | <refsect1 id="description"><title>Description</title> | |
33 | <para><function>glLinkProgram</function> links the program | |
34 | object specified by <parameter>program</parameter>. If any | |
35 | shader objects of type <constant>GL_VERTEX_SHADER</constant> are | |
36 | attached to <parameter>program</parameter>, they will be used to | |
37 | create an executable that will run on the programmable vertex | |
38 | processor. If any shader objects of type | |
39 | <constant>GL_FRAGMENT_SHADER</constant> are attached to | |
40 | <parameter>program</parameter>, they will be used to create an | |
41 | executable that will run on the programmable fragment | |
42 | processor.</para> | |
43 | ||
44 | <para>The status of the link operation will be stored as part of | |
45 | the program object's state. This value will be set to | |
46 | <constant>GL_TRUE</constant> if the program object was linked | |
47 | without errors and is ready for use, and | |
48 | <constant>GL_FALSE</constant> otherwise. It can be queried by | |
49 | calling | |
50 | <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry> | |
51 | with arguments <parameter>program</parameter> and | |
52 | <constant>GL_LINK_STATUS</constant>.</para> | |
53 | ||
54 | <para>As a result of a successful link operation, all active | |
55 | user-defined uniform variables belonging to | |
56 | <parameter>program</parameter> will be initialized to 0, and | |
57 | each of the program object's active uniform variables will be | |
58 | assigned a location that can be queried by calling | |
59 | <citerefentry><refentrytitle>glGetUniformLocation</refentrytitle></citerefentry>. | |
60 | Also, any active user-defined attribute variables that have not | |
61 | been bound to a generic vertex attribute index will be bound to | |
62 | one at this time.</para> | |
63 | ||
64 | <para>Linking of a program object can fail for a number of | |
65 | reasons as specified in the <emphasis>OpenGL Shading Language | |
66 | Specification</emphasis>. The following lists some of the | |
67 | conditions that will cause a link error.</para> | |
68 | ||
69 | <itemizedlist> | |
70 | <listitem> | |
71 | <para>The number of active attribute variables supported | |
72 | by the implementation has been exceeded.</para> | |
73 | </listitem> | |
74 | <listitem> | |
75 | <para>The storage limit for uniform variables has been | |
76 | exceeded.</para> | |
77 | </listitem> | |
78 | <listitem> | |
79 | <para>The number of active uniform variables supported | |
80 | by the implementation has been exceeded.</para> | |
81 | </listitem> | |
82 | <listitem> | |
83 | <para>The <function>main</function> function is missing | |
84 | for the vertex shader or the fragment shader.</para> | |
85 | </listitem> | |
86 | <listitem> | |
87 | <para>A varying variable actually used in the fragment | |
88 | shader is not declared in the same way (or is not | |
89 | declared at all) in the vertex shader.</para> | |
90 | </listitem> | |
91 | <listitem> | |
92 | <para>A reference to a function or variable name is | |
93 | unresolved.</para> | |
94 | </listitem> | |
95 | <listitem> | |
96 | <para>A shared global is declared with two different | |
97 | types or two different initial values.</para> | |
98 | </listitem> | |
99 | <listitem> | |
100 | <para>One or more of the attached shader objects has not | |
101 | been successfully compiled.</para> | |
102 | </listitem> | |
103 | <listitem> | |
104 | <para>Binding a generic attribute matrix caused some | |
105 | rows of the matrix to fall outside the allowed maximum | |
106 | of <constant>GL_MAX_VERTEX_ATTRIBS</constant>.</para> | |
107 | </listitem> | |
108 | <listitem> | |
109 | <para>Not enough contiguous vertex attribute slots could | |
110 | be found to bind attribute matrices.</para> | |
111 | </listitem> | |
112 | </itemizedlist> | |
113 | ||
114 | <para>When a program object has been successfully linked, the | |
115 | program object can be made part of current state by calling | |
116 | <citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>. | |
117 | Whether or not the link operation was successful, the program | |
118 | object's information log will be overwritten. The information | |
119 | log can be retrieved by calling | |
120 | <citerefentry><refentrytitle>glGetProgramInfoLog</refentrytitle></citerefentry>.</para> | |
121 | ||
122 | <para><function>glLinkProgram</function> will also install the | |
123 | generated executables as part of the current rendering state if | |
124 | the link operation was successful and the specified program | |
125 | object is already currently in use as a result of a previous | |
126 | call to | |
127 | <citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>. | |
128 | If the program object currently in use is relinked | |
129 | unsuccessfully, its link status will be set to | |
130 | <constant>GL_FALSE</constant> , but the executables and | |
131 | associated state will remain part of the current state until a | |
132 | subsequent call to <function>glUseProgram</function> removes it | |
133 | from use. After it is removed from use, it cannot be made part | |
134 | of current state until it has been successfully relinked.</para> | |
135 | ||
136 | <para>If <parameter>program</parameter> contains shader objects | |
137 | of type <constant>GL_VERTEX_SHADER</constant> but does not | |
138 | contain shader objects of type | |
139 | <constant>GL_FRAGMENT_SHADER</constant>, the vertex shader will | |
140 | be linked against the implicit interface for fixed functionality | |
141 | fragment processing. Similarly, if | |
142 | <parameter>program</parameter> contains shader objects of type | |
143 | <constant>GL_FRAGMENT_SHADER</constant> but it does not contain | |
144 | shader objects of type <constant>GL_VERTEX_SHADER</constant>, | |
145 | the fragment shader will be linked against the implicit | |
146 | interface for fixed functionality vertex processing.</para> | |
147 | ||
148 | <para>The program object's information log is updated and the | |
149 | program is generated at the time of the link operation. After | |
150 | the link operation, applications are free to modify attached | |
151 | shader objects, compile attached shader objects, detach shader | |
152 | objects, delete shader objects, and attach additional shader | |
153 | objects. None of these operations affects the information log or | |
154 | the program that is part of the program object.</para> | |
155 | </refsect1> | |
156 | <refsect1 id="notes"><title>Notes</title> | |
157 | <para><function>glLinkProgram</function> | |
158 | is available only if the GL version is 2.0 or greater.</para> | |
159 | <para>If the link operation is unsuccessful, any information about a previous link operation on <parameter>program</parameter> | |
160 | is lost (i.e., a failed link does not restore the old state of <parameter>program</parameter> | |
161 | ). Certain information can still be retrieved from <parameter>program</parameter> | |
162 | even after an unsuccessful link operation. See for instance <citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry> | |
163 | and <citerefentry><refentrytitle>glGetActiveUniform</refentrytitle></citerefentry>.</para> | |
164 | </refsect1> | |
165 | <refsect1 id="errors"><title>Errors</title> | |
166 | <para><constant>GL_INVALID_VALUE</constant> | |
167 | is generated if <parameter>program</parameter> | |
168 | is not a value generated by OpenGL.</para> | |
169 | <para><constant>GL_INVALID_OPERATION</constant> | |
170 | is generated if <parameter>program</parameter> | |
171 | is not a program object.</para> | |
172 | <para><constant>GL_INVALID_OPERATION</constant> | |
173 | is generated if <function>glLinkProgram</function> | |
174 | is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry> | |
175 | and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.</para> | |
176 | </refsect1> | |
177 | <refsect1 id="associatedgets"><title>Associated Gets</title> | |
178 | <para><citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> | |
179 | with the argument <constant>GL_CURRENT_PROGRAM</constant></para> | |
180 | <para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry> | |
181 | with argument <parameter>program</parameter> | |
182 | and the index of an active attribute variable</para> | |
183 | <para><citerefentry><refentrytitle>glGetActiveUniform</refentrytitle></citerefentry> | |
184 | with argument <parameter>program</parameter> | |
185 | and the index of an active uniform variable<parameter></parameter></para> | |
186 | <para><citerefentry><refentrytitle>glGetAttachedShaders</refentrytitle></citerefentry> | |
187 | with argument <parameter>program</parameter></para> | |
188 | <para><citerefentry><refentrytitle>glGetAttribLocation</refentrytitle></citerefentry> | |
189 | with argument <parameter>program</parameter> | |
190 | and an attribute variable name</para> | |
191 | <para><citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry> | |
192 | with arguments <parameter>program</parameter> | |
193 | and <constant>GL_LINK_STATUS</constant></para> | |
194 | <para><citerefentry><refentrytitle>glGetProgramInfoLog</refentrytitle></citerefentry> | |
195 | with argument <parameter>program</parameter></para> | |
196 | <para><citerefentry><refentrytitle>glGetUniform</refentrytitle></citerefentry> | |
197 | with argument <parameter>program</parameter> | |
198 | and a uniform variable location</para> | |
199 | <para><citerefentry><refentrytitle>glGetUniformLocation</refentrytitle></citerefentry> | |
200 | with argument <parameter>program</parameter> | |
201 | and a uniform variable name</para> | |
202 | <para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry></para> | |
203 | </refsect1> | |
204 | <refsect1 id="seealso"><title>See Also</title> | |
205 | <para><citerefentry><refentrytitle>glAttachShader</refentrytitle></citerefentry>, | |
206 | <citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>, | |
207 | <citerefentry><refentrytitle>glCompileShader</refentrytitle></citerefentry>, | |
208 | <citerefentry><refentrytitle>glCreateProgram</refentrytitle></citerefentry>, | |
209 | <citerefentry><refentrytitle>glDeleteProgram</refentrytitle></citerefentry>, | |
210 | <citerefentry><refentrytitle>glDetachShader</refentrytitle></citerefentry>, | |
211 | <citerefentry><refentrytitle>glUniform</refentrytitle></citerefentry>, | |
212 | <citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>, | |
213 | <citerefentry><refentrytitle>glValidateProgram</refentrytitle></citerefentry></para> | |
214 | </refsect1> | |
215 | <refsect1 id="Copyright"><title>Copyright</title> | |
216 | <para> | |
217 | Copyright <trademark class="copyright"></trademark> 2003-2005 3Dlabs Inc. Ltd. | |
218 | This material may be distributed subject to the terms and conditions set forth in | |
219 | the Open Publication License, v 1.0, 8 June 1999. | |
220 | <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>. | |
221 | </para> | |
222 | </refsect1> | |
223 | </refentry> |