223 lines
11 KiB
XML
223 lines
11 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="glLinkProgram">
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<refmeta>
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<refentrytitle>glLinkProgram</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>glLinkProgram</refname>
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<refpurpose>Links a program object</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>void <function>glLinkProgram</function></funcdef>
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<paramdef>GLuint <parameter>program</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1 id="parameters"><title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><parameter>program</parameter></term>
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<listitem>
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<para>Specifies the handle of the program object to be linked.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1 id="description"><title>Description</title>
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<para><function>glLinkProgram</function> links the program
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object specified by <parameter>program</parameter>. If any
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shader objects of type <constant>GL_VERTEX_SHADER</constant> are
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attached to <parameter>program</parameter>, they will be used to
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create an executable that will run on the programmable vertex
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processor. If any shader objects of type
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<constant>GL_FRAGMENT_SHADER</constant> are attached to
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<parameter>program</parameter>, they will be used to create an
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executable that will run on the programmable fragment
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processor.</para>
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<para>The status of the link operation will be stored as part of
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the program object's state. This value will be set to
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<constant>GL_TRUE</constant> if the program object was linked
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without errors and is ready for use, and
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<constant>GL_FALSE</constant> otherwise. It can be queried by
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calling
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<citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>
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with arguments <parameter>program</parameter> and
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<constant>GL_LINK_STATUS</constant>.</para>
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<para>As a result of a successful link operation, all active
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user-defined uniform variables belonging to
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<parameter>program</parameter> will be initialized to 0, and
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each of the program object's active uniform variables will be
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assigned a location that can be queried by calling
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<citerefentry><refentrytitle>glGetUniformLocation</refentrytitle></citerefentry>.
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Also, any active user-defined attribute variables that have not
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been bound to a generic vertex attribute index will be bound to
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one at this time.</para>
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<para>Linking of a program object can fail for a number of
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reasons as specified in the <emphasis>OpenGL Shading Language
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Specification</emphasis>. The following lists some of the
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conditions that will cause a link error.</para>
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<itemizedlist>
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<listitem>
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<para>The number of active attribute variables supported
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by the implementation has been exceeded.</para>
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</listitem>
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<listitem>
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<para>The storage limit for uniform variables has been
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exceeded.</para>
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</listitem>
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<listitem>
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<para>The number of active uniform variables supported
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by the implementation has been exceeded.</para>
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</listitem>
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<listitem>
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<para>The <function>main</function> function is missing
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for the vertex shader or the fragment shader.</para>
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</listitem>
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<listitem>
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<para>A varying variable actually used in the fragment
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shader is not declared in the same way (or is not
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declared at all) in the vertex shader.</para>
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</listitem>
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<listitem>
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<para>A reference to a function or variable name is
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unresolved.</para>
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</listitem>
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<listitem>
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<para>A shared global is declared with two different
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types or two different initial values.</para>
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</listitem>
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<listitem>
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<para>One or more of the attached shader objects has not
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been successfully compiled.</para>
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</listitem>
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<listitem>
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<para>Binding a generic attribute matrix caused some
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rows of the matrix to fall outside the allowed maximum
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of <constant>GL_MAX_VERTEX_ATTRIBS</constant>.</para>
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</listitem>
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<listitem>
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<para>Not enough contiguous vertex attribute slots could
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be found to bind attribute matrices.</para>
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</listitem>
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</itemizedlist>
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<para>When a program object has been successfully linked, the
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program object can be made part of current state by calling
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<citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>.
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Whether or not the link operation was successful, the program
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object's information log will be overwritten. The information
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log can be retrieved by calling
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<citerefentry><refentrytitle>glGetProgramInfoLog</refentrytitle></citerefentry>.</para>
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<para><function>glLinkProgram</function> will also install the
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generated executables as part of the current rendering state if
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the link operation was successful and the specified program
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object is already currently in use as a result of a previous
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call to
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<citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>.
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If the program object currently in use is relinked
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unsuccessfully, its link status will be set to
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<constant>GL_FALSE</constant> , but the executables and
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associated state will remain part of the current state until a
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subsequent call to <function>glUseProgram</function> removes it
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from use. After it is removed from use, it cannot be made part
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of current state until it has been successfully relinked.</para>
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<para>If <parameter>program</parameter> contains shader objects
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of type <constant>GL_VERTEX_SHADER</constant> but does not
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contain shader objects of type
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<constant>GL_FRAGMENT_SHADER</constant>, the vertex shader will
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be linked against the implicit interface for fixed functionality
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fragment processing. Similarly, if
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<parameter>program</parameter> contains shader objects of type
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<constant>GL_FRAGMENT_SHADER</constant> but it does not contain
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shader objects of type <constant>GL_VERTEX_SHADER</constant>,
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the fragment shader will be linked against the implicit
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interface for fixed functionality vertex processing.</para>
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<para>The program object's information log is updated and the
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program is generated at the time of the link operation. After
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the link operation, applications are free to modify attached
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shader objects, compile attached shader objects, detach shader
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objects, delete shader objects, and attach additional shader
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objects. None of these operations affects the information log or
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the program that is part of the program object.</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para><function>glLinkProgram</function>
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is available only if the GL version is 2.0 or greater.</para>
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<para>If the link operation is unsuccessful, any information about a previous link operation on <parameter>program</parameter>
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is lost (i.e., a failed link does not restore the old state of <parameter>program</parameter>
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). Certain information can still be retrieved from <parameter>program</parameter>
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even after an unsuccessful link operation. See for instance <citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>
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and <citerefentry><refentrytitle>glGetActiveUniform</refentrytitle></citerefentry>.</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para><constant>GL_INVALID_VALUE</constant>
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is generated if <parameter>program</parameter>
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is not a value generated by OpenGL.</para>
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<para><constant>GL_INVALID_OPERATION</constant>
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is generated if <parameter>program</parameter>
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is not a program object.</para>
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<para><constant>GL_INVALID_OPERATION</constant>
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is generated if <function>glLinkProgram</function>
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is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
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and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.</para>
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</refsect1>
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<refsect1 id="associatedgets"><title>Associated Gets</title>
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<para><citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
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with the argument <constant>GL_CURRENT_PROGRAM</constant></para>
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<para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>
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with argument <parameter>program</parameter>
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and the index of an active attribute variable</para>
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<para><citerefentry><refentrytitle>glGetActiveUniform</refentrytitle></citerefentry>
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with argument <parameter>program</parameter>
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and the index of an active uniform variable<parameter></parameter></para>
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<para><citerefentry><refentrytitle>glGetAttachedShaders</refentrytitle></citerefentry>
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with argument <parameter>program</parameter></para>
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<para><citerefentry><refentrytitle>glGetAttribLocation</refentrytitle></citerefentry>
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with argument <parameter>program</parameter>
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and an attribute variable name</para>
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<para><citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>
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with arguments <parameter>program</parameter>
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and <constant>GL_LINK_STATUS</constant></para>
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<para><citerefentry><refentrytitle>glGetProgramInfoLog</refentrytitle></citerefentry>
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with argument <parameter>program</parameter></para>
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<para><citerefentry><refentrytitle>glGetUniform</refentrytitle></citerefentry>
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with argument <parameter>program</parameter>
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and a uniform variable location</para>
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<para><citerefentry><refentrytitle>glGetUniformLocation</refentrytitle></citerefentry>
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with argument <parameter>program</parameter>
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and a uniform variable name</para>
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<para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry></para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para><citerefentry><refentrytitle>glAttachShader</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCompileShader</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glCreateProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDeleteProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDetachShader</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glUniform</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glValidateProgram</refentrytitle></citerefentry></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> 2003-2005 3Dlabs Inc. Ltd.
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This material may be distributed subject to the terms and conditions set forth in
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the Open Publication License, v 1.0, 8 June 1999.
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<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
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</para>
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</refsect1>
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</refentry>
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