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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="glGetVertexAttrib">
<refmeta>
<refentrytitle>glGetVertexAttrib</refentrytitle>
<manvolnum>3G</manvolnum>
</refmeta>
<refnamediv>
<refdescriptor>glGetVertexAttrib</refdescriptor>
<refname>glGetVertexAttribdv</refname>
<refname>glGetVertexAttribfv</refname>
<refname>glGetVertexAttribiv</refname>
<refpurpose>Return a generic vertex attribute parameter</refpurpose>
</refnamediv>
<refsynopsisdiv><title>C Specification</title>
<funcsynopsis>
<funcprototype>
<funcdef>void <function>glGetVertexAttribdv</function></funcdef>
<paramdef>GLuint <parameter>index</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLdouble *<parameter>params</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>glGetVertexAttribfv</function></funcdef>
<paramdef>GLuint <parameter>index</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLfloat *<parameter>params</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>glGetVertexAttribiv</function></funcdef>
<paramdef>GLuint <parameter>index</parameter></paramdef>
<paramdef>GLenum <parameter>pname</parameter></paramdef>
<paramdef>GLint *<parameter>params</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>index</parameter></term>
<listitem>
<para>Specifies the generic vertex attribute
parameter to be queried.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>pname</parameter></term>
<listitem>
<para>Specifies the symbolic name of the vertex
attribute parameter to be queried. Accepted values are
<constant>GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING</constant>,
<constant>GL_VERTEX_ATTRIB_ARRAY_ENABLED</constant>,
<constant>GL_VERTEX_ATTRIB_ARRAY_SIZE</constant>,
<constant>GL_VERTEX_ATTRIB_ARRAY_STRIDE</constant>,
<constant>GL_VERTEX_ATTRIB_ARRAY_TYPE</constant>,
<constant>GL_VERTEX_ATTRIB_ARRAY_NORMALIZED</constant>, or
<constant>GL_CURRENT_VERTEX_ATTRIB</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>params</parameter></term>
<listitem>
<para>Returns the requested data.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id="description"><title>Description</title>
<para><function>glGetVertexAttrib</function> returns in
<parameter>params</parameter> the value of a generic vertex
attribute parameter. The generic vertex attribute to be queried
is specified by <parameter>index</parameter>, and the parameter
to be queried is specified by <parameter>pname</parameter>.</para>
<para>The accepted parameter names are as follows:</para>
<variablelist>
<varlistentry>
<term><constant>GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns a
single value, the name of the buffer object currently bound to
the binding point corresponding to generic vertex attribute array
<parameter>index</parameter>. If no buffer object is bound,
0 is returned. The initial value is 0.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_VERTEX_ATTRIB_ARRAY_ENABLED</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns a
single value that is non-zero (true) if the vertex
attribute array for <parameter>index</parameter> is
enabled and 0 (false) if it is disabled. The initial
value is <constant>GL_FALSE</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_VERTEX_ATTRIB_ARRAY_SIZE</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns a
single value, the size of the vertex attribute array
for <parameter>index</parameter>. The size is the
number of values for each element of the vertex
attribute array, and it will be 1, 2, 3, or 4. The
initial value is 4.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_VERTEX_ATTRIB_ARRAY_STRIDE</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns a
single value, the array stride for (number of bytes
between successive elements in) the vertex attribute
array for <parameter>index</parameter>. A value of 0
indicates that the array elements are stored
sequentially in memory. The initial value is 0.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_VERTEX_ATTRIB_ARRAY_TYPE</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns a
single value, a symbolic constant indicating the
array type for the vertex attribute array for
<parameter>index</parameter>. Possible values are
<constant>GL_BYTE</constant>,
<constant>GL_UNSIGNED_BYTE</constant>,
<constant>GL_SHORT</constant>,
<constant>GL_UNSIGNED_SHORT</constant>,
<constant>GL_INT</constant>,
<constant>GL_UNSIGNED_INT</constant>,
<constant>GL_FLOAT</constant>, and
<constant>GL_DOUBLE</constant>. The initial value is
<constant>GL_FLOAT</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_VERTEX_ATTRIB_ARRAY_NORMALIZED</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns a
single value that is non-zero (true) if fixed-point
data types for the vertex attribute array indicated
by <parameter>index</parameter> are normalized when
they are converted to floating point, and 0 (false)
otherwise. The initial value is
<constant>GL_FALSE</constant>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><constant>GL_CURRENT_VERTEX_ATTRIB</constant></term>
<listitem>
<para>
</para>
<para> <parameter>params</parameter> returns four
values that represent the current value for the
generic vertex attribute specified by index. Generic
vertex attribute 0 is unique in that it has no
current state, so an error will be generated if
<parameter>index</parameter> is 0. The initial value
for all other generic vertex attributes is
(0,0,0,1).</para>
</listitem>
</varlistentry>
</variablelist>
<para>All of the parameters except <constant>GL_CURRENT_VERTEX_ATTRIB</constant>
represent client-side state.</para>
</refsect1>
<refsect1 id="notes"><title>Notes</title>
<para><function>glGetVertexAttrib</function> is available only
if the GL version is 2.0 or greater.</para>
<para>If an error is generated, no change is made to the
contents of <parameter>params</parameter>.</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_ENUM</constant> is generated if
<parameter>pname</parameter> is not an accepted value.</para>
<para><constant>GL_INVALID_OPERATION</constant> is generated if
<parameter>index</parameter> is 0 and
<parameter>pname</parameter> is
<constant>GL_CURRENT_VERTEX_ATTRIB</constant>.</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>glGetVertexAttribPointerv</refentrytitle></citerefentry>
with arguments <parameter>index</parameter> and
<constant>GL_VERTEX_ATTRIB_ARRAY_POINTER</constant></para>
</refsect1>
<refsect1 id="seealso"><title>See Also</title>
<para><citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>,
<citerefentry><refentrytitle>glEnableVertexAttribArray</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>