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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
+ "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
+<refentry id="glBindAttribLocation">
+ <refmeta>
+ <refentrytitle>glBindAttribLocation</refentrytitle>
+ <manvolnum>3G</manvolnum>
+ </refmeta>
+ <refnamediv>
+ <refname>glBindAttribLocation</refname>
+ <refpurpose>Associates a generic vertex attribute index with a named attribute variable</refpurpose>
+ </refnamediv>
+ <refsynopsisdiv><title>C Specification</title>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>void <function>glBindAttribLocation</function></funcdef>
+ <paramdef>GLuint <parameter>program</parameter></paramdef>
+ <paramdef>GLuint <parameter>index</parameter></paramdef>
+ <paramdef>const GLchar *<parameter>name</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+ <refsect1 id="parameters"><title>Parameters</title>
+ <variablelist>
+ <varlistentry>
+ <term><parameter>program</parameter></term>
+ <listitem>
+ <para>Specifies the handle of the program object in
+ which the association is to be made.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>index</parameter></term>
+ <listitem>
+ <para>Specifies the index of the generic vertex
+ attribute to be bound.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>name</parameter></term>
+ <listitem>
+ <para>Specifies a null terminated string containing
+ the name of the vertex shader attribute variable to
+ which <parameter>index</parameter> is to be
+ bound.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+ <refsect1 id="description"><title>Description</title>
+ <para><function>glBindAttribLocation</function> is used to
+ associate a user-defined attribute variable in the program
+ object specified by <parameter>program</parameter> with a
+ generic vertex attribute index. The name of the user-defined
+ attribute variable is passed as a null terminated string in
+ <parameter>name</parameter>. The generic vertex attribute index
+ to be bound to this variable is specified by
+ <parameter>index</parameter>. When
+ <parameter>program</parameter> is made part of current state,
+ values provided via the generic vertex attribute
+ <parameter>index</parameter> will modify the value of the
+ user-defined attribute variable specified by
+ <parameter>name</parameter>.</para>
+
+ <para>If <parameter>name</parameter> refers to a matrix
+ attribute variable, <parameter>index</parameter> refers to the
+ first column of the matrix. Other matrix columns are then
+ automatically bound to locations <parameter>index+1</parameter>
+ for a matrix of type <function>mat2</function>; <parameter>index+1</parameter> and
+ <parameter>index+2</parameter> for a matrix of type <function>mat3</function>; and
+ <parameter>index+1</parameter>, <parameter>index+2</parameter>,
+ and <parameter>index+3</parameter> for a matrix of type
+ <function>mat4</function>.</para>
+
+ <para>This command makes it possible for vertex shaders to use
+ descriptive names for attribute variables rather than generic
+ variables that are numbered from 0 to
+ <constant>GL_MAX_VERTEX_ATTRIBS</constant> -1. The values sent
+ to each generic attribute index are part of current state.
+ If a different program object is made current by calling
+ <citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>,
+ the generic vertex attributes are tracked in such a way that the
+ same values will be observed by attributes in the new program
+ object that are also bound to
+ <parameter>index</parameter>.</para> <para>Attribute variable
+ name-to-generic attribute index bindings for a program object
+ can be explicitly assigned at any time by calling
+ <function>glBindAttribLocation</function>. Attribute bindings do
+ not go into effect until
+ <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>
+ is called. After a program object has been linked successfully,
+ the index values for generic attributes remain fixed (and their
+ values can be queried) until the next link command
+ occurs.</para>
+
+ <para>Any attribute binding that occurs after the program object has been linked will not take effect
+ until the next time the program object is linked.</para>
+ </refsect1>
+ <refsect1 id="notes"><title>Notes</title>
+ <para><function>glBindAttribLocation</function> can be called
+ before any vertex shader objects are bound to the specified
+ program object. It is also permissible to bind a generic
+ attribute index to an attribute variable name that is never used
+ in a vertex shader.</para>
+
+ <para>If <parameter>name</parameter> was bound previously, that
+ information is lost. Thus you cannot bind one user-defined
+ attribute variable to multiple indices, but you can bind
+ multiple user-defined attribute variables to the same
+ index.</para>
+
+ <para>Applications are allowed to bind more than one
+ user-defined attribute variable to the same generic vertex
+ attribute index. This is called <emphasis>aliasing</emphasis>,
+ and it is allowed only if just one of the aliased attributes is
+ active in the executable program, or if no path through the
+ shader consumes more than one attribute of a set of attributes
+ aliased to the same location. The compiler and linker are
+ allowed to assume that no aliasing is done and are free to
+ employ optimizations that work only in the absence of aliasing.
+ OpenGL implementations are not required to do error checking to
+ detect aliasing.</para>
+
+ <para>Active attributes that are not explicitly bound will be
+ bound by the linker when
+ <citerefentry><refentrytitle>glLinkProgram</refentrytitle></citerefentry>
+ is called. The locations assigned can be queried by calling
+ <citerefentry><refentrytitle>glGetAttribLocation</refentrytitle></citerefentry>.</para>
+
+ <para>OpenGL copies the <parameter>name</parameter> string when
+ <function>glBindAttribLocation</function> is called, so an
+ application may free its copy of the <parameter>name</parameter>
+ string immediately after the function returns.</para>
+
+ <para>Generic attribute locations may be specified in the shader source
+ text using a <function>location</function> layout qualifier. In this case,
+ the location of the attribute specified in the shader's source takes precedence
+ and may be queried by calling <citerefentry><refentrytitle>glGetAttribLocation</refentrytitle></citerefentry>.
+ </para>
+ </refsect1>
+ <refsect1 id="errors"><title>Errors</title>
+ <para><constant>GL_INVALID_VALUE</constant> is generated if
+ <parameter>index</parameter> is greater than or equal to
+ <constant>GL_MAX_VERTEX_ATTRIBS</constant>.</para>
+
+ <para><constant>GL_INVALID_OPERATION</constant> is generated if
+ <parameter>name</parameter> starts with the reserved prefix
+ "gl_".</para>
+
+ <para><constant>GL_INVALID_VALUE</constant> is generated if
+ <parameter>program</parameter> is not a value generated by
+ OpenGL.</para>
+
+ <para><constant>GL_INVALID_OPERATION</constant> is generated if
+ <parameter>program</parameter> is not a program object.</para>
+
+ </refsect1>
+ <refsect1 id="associatedgets"><title>Associated Gets</title>
+ <para><citerefentry><refentrytitle>glGet</refentrytitle></citerefentry>
+ with argument <constant>GL_MAX_VERTEX_ATTRIBS</constant></para>
+
+ <para><citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>
+ with argument <parameter>program</parameter></para>
+
+ <para><citerefentry><refentrytitle>glGetAttribLocation</refentrytitle></citerefentry>
+ with arguments <parameter>program</parameter> and
+ <parameter>name</parameter></para>
+
+ <para><citerefentry><refentrytitle>glIsProgram</refentrytitle></citerefentry></para>
+ </refsect1>
+ <refsect1 id="seealso"><title>See Also</title>
+ <para><citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glEnableVertexAttribArray</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glUseProgram</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glVertexAttrib</refentrytitle></citerefentry>,
+ <citerefentry><refentrytitle>glVertexAttribPointer</refentrytitle></citerefentry></para>
+ </refsect1>
+ <refsect1 id="Copyright"><title>Copyright</title>
+ <para>
+ Copyright <trademark class="copyright"></trademark> 2003-2005 3Dlabs Inc. Ltd.
+ This material may be distributed subject to the terms and conditions set forth in
+ the Open Publication License, v 1.0, 8 June 1999.
+ <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
+ </para>
+ </refsect1>
+</refentry>
HCoop / clinton / guile-figl.git / blobdiff