295 lines
13 KiB
XML
295 lines
13 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="glGetVertexAttrib">
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<refmeta>
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<refentrytitle>glGetVertexAttrib</refentrytitle>
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<manvolnum>3G</manvolnum>
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</refmeta>
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<refnamediv>
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<refdescriptor>glGetVertexAttrib</refdescriptor>
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<refname>glGetVertexAttribdv</refname>
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<refname>glGetVertexAttribfv</refname>
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<refname>glGetVertexAttribiv</refname>
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<refname>glGetVertexAttribIiv</refname>
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<refname>glGetVertexAttribIuiv</refname>
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<refname>glGetVertexAttribLdv</refname>
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<refpurpose>Return a generic vertex attribute parameter</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>glGetVertexAttribdv</function></funcdef>
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<paramdef>GLuint <parameter>index</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLdouble *<parameter>params</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>glGetVertexAttribfv</function></funcdef>
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<paramdef>GLuint <parameter>index</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLfloat *<parameter>params</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>glGetVertexAttribiv</function></funcdef>
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<paramdef>GLuint <parameter>index</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLint *<parameter>params</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>glGetVertexAttribIiv</function></funcdef>
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<paramdef>GLuint <parameter>index</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLint *<parameter>params</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>glGetVertexAttribIuiv</function></funcdef>
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<paramdef>GLuint <parameter>index</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLuint *<parameter>params</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>glGetVertexAttribLdv</function></funcdef>
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<paramdef>GLuint <parameter>index</parameter></paramdef>
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<paramdef>GLenum <parameter>pname</parameter></paramdef>
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<paramdef>GLdouble *<parameter>params</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>index</parameter></term>
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<listitem>
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<para>Specifies the generic vertex attribute
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parameter to be queried.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>pname</parameter></term>
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<listitem>
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<para>Specifies the symbolic name of the vertex
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attribute parameter to be queried. Accepted values are
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<constant>GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_ENABLED</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_SIZE</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_STRIDE</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_TYPE</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_NORMALIZED</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_INTEGER</constant>,
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<constant>GL_VERTEX_ATTRIB_ARRAY_DIVISOR</constant>, or
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<constant>GL_CURRENT_VERTEX_ATTRIB</constant>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>params</parameter></term>
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<listitem>
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<para>Returns the requested data.</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>glGetVertexAttrib</function> returns in
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<parameter>params</parameter> the value of a generic vertex
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attribute parameter. The generic vertex attribute to be queried
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is specified by <parameter>index</parameter>, and the parameter
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to be queried is specified by <parameter>pname</parameter>.</para>
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<para>The accepted parameter names are as follows:</para>
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<variablelist>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value, the name of the buffer object currently bound to
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the binding point corresponding to generic vertex attribute array
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<parameter>index</parameter>. If no buffer object is bound,
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0 is returned. The initial value is 0.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_ENABLED</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value that is non-zero (true) if the vertex
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attribute array for <parameter>index</parameter> is
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enabled and 0 (false) if it is disabled. The initial
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value is <constant>GL_FALSE</constant>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_SIZE</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value, the size of the vertex attribute array
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for <parameter>index</parameter>. The size is the
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number of values for each element of the vertex
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attribute array, and it will be 1, 2, 3, or 4. The
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initial value is 4.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_STRIDE</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value, the array stride for (number of bytes
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between successive elements in) the vertex attribute
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array for <parameter>index</parameter>. A value of 0
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indicates that the array elements are stored
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sequentially in memory. The initial value is 0.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_TYPE</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value, a symbolic constant indicating the
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array type for the vertex attribute array for
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<parameter>index</parameter>. Possible values are
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<constant>GL_BYTE</constant>,
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<constant>GL_UNSIGNED_BYTE</constant>,
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<constant>GL_SHORT</constant>,
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<constant>GL_UNSIGNED_SHORT</constant>,
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<constant>GL_INT</constant>,
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<constant>GL_UNSIGNED_INT</constant>,
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<constant>GL_FLOAT</constant>, and
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<constant>GL_DOUBLE</constant>. The initial value is
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<constant>GL_FLOAT</constant>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_NORMALIZED</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value that is non-zero (true) if fixed-point
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data types for the vertex attribute array indicated
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by <parameter>index</parameter> are normalized when
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they are converted to floating point, and 0 (false)
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otherwise. The initial value is
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<constant>GL_FALSE</constant>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_INTEGER</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value that is non-zero (true) if fixed-point
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data types for the vertex attribute array indicated
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by <parameter>index</parameter> have integer data types, and 0 (false)
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otherwise. The initial value is
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0 (<constant>GL_FALSE</constant>).</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_VERTEX_ATTRIB_ARRAY_DIVISOR</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns a
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single value that is the frequency divisor used for instanced
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rendering. See <citerefentry><refentrytitle>glVertexAttribDivisor</refentrytitle></citerefentry>.
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The initial value is 0.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>GL_CURRENT_VERTEX_ATTRIB</constant></term>
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<listitem>
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<para>
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</para>
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<para> <parameter>params</parameter> returns four
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values that represent the current value for the
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generic vertex attribute specified by index. Generic
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vertex attribute 0 is unique in that it has no
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current state, so an error will be generated if
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<parameter>index</parameter> is 0. The initial value
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for all other generic vertex attributes is
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(0,0,0,1).</para>
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<para>
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<function>glGetVertexAttribdv</function> and <function>glGetVertexAttribfv</function>
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return the current attribute values as four single-precision floating-point values;
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<function>glGetVertexAttribiv</function> reads them as floating-point values and
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converts them to four integer values; <function>glGetVertexAttribIiv</function> and
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<function>glGetVertexAttribIuiv</function> read and return them as signed or unsigned
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integer values, respectively; <function>glGetVertexAttribLdv</function> reads and returns
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them as four double-precision floating-point values.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>All of the parameters except <constant>GL_CURRENT_VERTEX_ATTRIB</constant>
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represent state stored in the currently bound vertex array object.</para>
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</refsect1>
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<refsect1 id="notes"><title>Notes</title>
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<para>If an error is generated, no change is made to the
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contents of <parameter>params</parameter>.</para>
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</refsect1>
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<refsect1 id="errors"><title>Errors</title>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if <parameter>pname</parameter>
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is not <constant>GL_CURRENT_VERTEX_ATTRIB</constant> and there is no
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currently bound vertex array object.</para>
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<para><constant>GL_INVALID_VALUE</constant> is generated if
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<parameter>index</parameter> is greater than or equal to
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<constant>GL_MAX_VERTEX_ATTRIBS</constant>.</para>
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<para><constant>GL_INVALID_ENUM</constant> is generated if
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<parameter>pname</parameter> is not an accepted value.</para>
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<para><constant>GL_INVALID_OPERATION</constant> is generated if
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<parameter>index</parameter> is 0 and
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<parameter>pname</parameter> is
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<constant>GL_CURRENT_VERTEX_ATTRIB</constant>.</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 argument <constant>GL_MAX_VERTEX_ATTRIBS</constant></para>
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<para><citerefentry><refentrytitle>glGetVertexAttribPointerv</refentrytitle></citerefentry>
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with arguments <parameter>index</parameter> and
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<constant>GL_VERTEX_ATTRIB_ARRAY_POINTER</constant></para>
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</refsect1>
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<refsect1 id="seealso"><title>See Also</title>
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<para><citerefentry><refentrytitle>glBindAttribLocation</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glBindBuffer</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glDisableVertexAttribArray</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glEnableVertexAttribArray</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexAttrib</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexAttribDivisor</refentrytitle></citerefentry>,
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<citerefentry><refentrytitle>glVertexAttribPointer</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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Copyright <trademark class="copyright"></trademark> 2010 Khronos Group.
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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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