[clinton/guile-figl.git] / upstream-doc / man4 / glGetTransformFeedbackVarying.xml

<?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="glGetTransformFeedbackVarying">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>2010</year>
                <holder>Khronos Group</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glGetTransformFeedbackVarying</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glGetTransformFeedbackVarying</refname>
        <refpurpose>retrieve information about varying variables selected for transform feedback</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glGetTransformFeedbackVarying</function></funcdef>
                <paramdef>GLuint<parameter>program</parameter></paramdef>
                <paramdef>GLuint<parameter>index</parameter></paramdef>
                <paramdef>GLsizei<parameter>bufSize</parameter></paramdef>
                <paramdef>GLsizei *<parameter>length</parameter></paramdef>
                <paramdef>GLsizei<parameter>size</parameter></paramdef>
                <paramdef>GLenum *<parameter>type</parameter></paramdef>
                <paramdef>char *<parameter>name</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>program</parameter></term>
            <listitem>
                <para>
                    The name of the target program object.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>index</parameter></term>
            <listitem>
                <para>
                    The index of the varying variable whose information to retrieve.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>bufSize</parameter></term>
            <listitem>
                <para>
                    The maximum number of characters, including the null terminator, that may be written into <parameter>name</parameter>.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>length</parameter></term>
            <listitem>
                <para>
                    The address of a variable which will receive the number of characters written into <parameter>name</parameter>,
                    excluding the null-terminator. If <parameter>length</parameter> is <constant>NULL</constant> no length is returned.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>size</parameter></term>
            <listitem>
                <para>
                    The address of a variable that will receive the size of the varying.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>type</parameter></term>
            <listitem>
                <para>
                    The address of a variable that will recieve the type of the varying.
                </para>
            </listitem>
        </varlistentry>
        <varlistentry>
            <term><parameter>name</parameter></term>
            <listitem>
                <para>
                    The address of a buffer into which will be written the name of the varying.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            Information about the set of varying variables in a linked program that will be captured
            during transform feedback may be retrieved by calling <function>glGetTransformFeedbackVarying</function>.
            <function>glGetTransformFeedbackVarying</function> provides information about the varying
            variable selected by <parameter>index</parameter>. An <parameter>index</parameter> of 0 selects
            the first varying variable specified in the <parameter>varyings</parameter> array passed
            to <citerefentry><refentrytitle>glTransformFeedbackVaryings</refentrytitle></citerefentry>, and
            an <parameter>index</parameter> of <constant>GL_TRANSFORM_FEEDBACK_VARYINGS-1</constant> selects
            the last such variable.
        </para>
        <para>
            The name of the selected varying is returned as a null-terminated string in
            <parameter>name</parameter>. The actual number of characters written into <parameter>name</parameter>,
            excluding the null terminator, is returned in <parameter>length</parameter>. If <parameter>length</parameter>
            is NULL, no length is returned. The maximum number of characters that may be written into <parameter>name</parameter>,
            including the null terminator, is specified by <parameter>bufSize</parameter>.
        </para>
        <para>
            The length of the longest varying name in program is given by <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>,
            which can be queried with <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>.
        </para>
        <para>
            For the selected varying variable, its type is returned into <parameter>type</parameter>. The size of
            the varying is returned into <parameter>size</parameter>. The value in <parameter>size</parameter> is
            in units of the type returned in <parameter>type</parameter>. The type returned can be any of the
            scalar, vector, or matrix attribute types returned by <citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>.
            If an error occurred, the return parameters <parameter>length</parameter>, <parameter>size</parameter>,
            <parameter>type</parameter> and <parameter>name</parameter> will be unmodified. This command will return as much
            information about the varying variables as possible. If no information is available, <parameter>length</parameter>
            will be set to zero and <parameter>name</parameter> will be an empty string. This situation could
            arise if <function>glGetTransformFeedbackVarying</function> is called after a failed link.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>program</parameter> is not
            the name of a program object.
        </para>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if <parameter>index</parameter> is greater or equal to
            the value of <constant>GL_TRANSFORM_FEEDBACK_VARYINGS</constant>.
        </para>
        <para>
            <constant>GL_INVALID_OPERATION</constant> is generated <parameter>program</parameter> has not been linked.
        </para>
    </refsect1>
    <refsect1 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry> with argument <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>.
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <citerefentry><refentrytitle>glBeginTransformFeedback</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glEndTransformFeedback</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glTransformFeedbackVaryings</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>
        </para>
    </refsect1>    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 2010 Khronos Group. 
            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>
Commit	Line	Data
7faf1d71 AW	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="glGetTransformFeedbackVarying">
	5	<refmeta>
	6	<refmetainfo>
	7	<copyright>
	8	<year>2010</year>
	9	<holder>Khronos Group</holder>
	10	</copyright>
	11	</refmetainfo>
	12	<refentrytitle>glGetTransformFeedbackVarying</refentrytitle>
	13	<manvolnum>3G</manvolnum>
	14	</refmeta>
	15	<refnamediv>
	16	<refname>glGetTransformFeedbackVarying</refname>
	17	<refpurpose>retrieve information about varying variables selected for transform feedback</refpurpose>
	18	</refnamediv>
	19	<refsynopsisdiv><title>C Specification</title>
	20	<funcsynopsis>
	21	<funcprototype>
	22	<funcdef>void <function>glGetTransformFeedbackVarying</function></funcdef>
	23	<paramdef>GLuint<parameter>program</parameter></paramdef>
	24	<paramdef>GLuint<parameter>index</parameter></paramdef>
	25	<paramdef>GLsizei<parameter>bufSize</parameter></paramdef>
	26	<paramdef>GLsizei *<parameter>length</parameter></paramdef>
	27	<paramdef>GLsizei<parameter>size</parameter></paramdef>
	28	<paramdef>GLenum *<parameter>type</parameter></paramdef>
	29	<paramdef>char *<parameter>name</parameter></paramdef>
	30	</funcprototype>
	31	</funcsynopsis>
	32	</refsynopsisdiv>
	33	<refsect1 id="parameters"><title>Parameters</title>
	34	<variablelist>
	35	<varlistentry>
	36	<term><parameter>program</parameter></term>
	37	<listitem>
	38	<para>
	39	The name of the target program object.
	40	</para>
	41	</listitem>
	42	</varlistentry>
	43	<varlistentry>
	44	<term><parameter>index</parameter></term>
	45	<listitem>
	46	<para>
	47	The index of the varying variable whose information to retrieve.
	48	</para>
	49	</listitem>
	50	</varlistentry>
	51	<varlistentry>
	52	<term><parameter>bufSize</parameter></term>
	53	<listitem>
	54	<para>
	55	The maximum number of characters, including the null terminator, that may be written into <parameter>name</parameter>.
	56	</para>
	57	</listitem>
	58	</varlistentry>
	59	<varlistentry>
	60	<term><parameter>length</parameter></term>
	61	<listitem>
	62	<para>
	63	The address of a variable which will receive the number of characters written into <parameter>name</parameter>,
	64	excluding the null-terminator. If <parameter>length</parameter> is <constant>NULL</constant> no length is returned.
65	</para>
66	</listitem>
67	</varlistentry>
68	<varlistentry>
69	<term><parameter>size</parameter></term>
70	<listitem>
71	<para>
72	The address of a variable that will receive the size of the varying.
73	</para>
74	</listitem>
75	</varlistentry>
76	<varlistentry>
77	<term><parameter>type</parameter></term>
78	<listitem>
79	<para>
80	The address of a variable that will recieve the type of the varying.
81	</para>
82	</listitem>
83	</varlistentry>
84	<varlistentry>
85	<term><parameter>name</parameter></term>
86	<listitem>
87	<para>
88	The address of a buffer into which will be written the name of the varying.
89	</para>
90	</listitem>
91	</varlistentry>
92	</variablelist>
93	</refsect1>
94	<refsect1 id="description"><title>Description</title>
95	<para>
96	Information about the set of varying variables in a linked program that will be captured
97	during transform feedback may be retrieved by calling <function>glGetTransformFeedbackVarying</function>.
98	<function>glGetTransformFeedbackVarying</function> provides information about the varying
99	variable selected by <parameter>index</parameter>. An <parameter>index</parameter> of 0 selects
100	the first varying variable specified in the <parameter>varyings</parameter> array passed
101	to <citerefentry><refentrytitle>glTransformFeedbackVaryings</refentrytitle></citerefentry>, and
102	an <parameter>index</parameter> of <constant>GL_TRANSFORM_FEEDBACK_VARYINGS-1</constant> selects
103	the last such variable.
104	</para>
105	<para>
106	The name of the selected varying is returned as a null-terminated string in
107	<parameter>name</parameter>. The actual number of characters written into <parameter>name</parameter>,
108	excluding the null terminator, is returned in <parameter>length</parameter>. If <parameter>length</parameter>
109	is NULL, no length is returned. The maximum number of characters that may be written into <parameter>name</parameter>,
110	including the null terminator, is specified by <parameter>bufSize</parameter>.
111	</para>
112	<para>
113	The length of the longest varying name in program is given by <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>,
114	which can be queried with <citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>.
115	</para>
116	<para>
117	For the selected varying variable, its type is returned into <parameter>type</parameter>. The size of
118	the varying is returned into <parameter>size</parameter>. The value in <parameter>size</parameter> is
119	in units of the type returned in <parameter>type</parameter>. The type returned can be any of the
120	scalar, vector, or matrix attribute types returned by <citerefentry><refentrytitle>glGetActiveAttrib</refentrytitle></citerefentry>.
121	If an error occurred, the return parameters <parameter>length</parameter>, <parameter>size</parameter>,
122	<parameter>type</parameter> and <parameter>name</parameter> will be unmodified. This command will return as much
123	information about the varying variables as possible. If no information is available, <parameter>length</parameter>
124	will be set to zero and <parameter>name</parameter> will be an empty string. This situation could
125	arise if <function>glGetTransformFeedbackVarying</function> is called after a failed link.
126	</para>
127	</refsect1>
128	<refsect1 id="errors"><title>Errors</title>
129	<para>
130	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>program</parameter> is not
131	the name of a program object.
132	</para>
133	<para>
134	<constant>GL_INVALID_VALUE</constant> is generated if <parameter>index</parameter> is greater or equal to
135	the value of <constant>GL_TRANSFORM_FEEDBACK_VARYINGS</constant>.
136	</para>
137	<para>
138	<constant>GL_INVALID_OPERATION</constant> is generated <parameter>program</parameter> has not been linked.
139	</para>
140	</refsect1>
141	<refsect1 id="associatedgets"><title>Associated Gets</title>
142	<para>
143	<citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry> with argument <constant>GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH</constant>.
144	</para>
145	</refsect1>
146	<refsect1 id="seealso"><title>See Also</title>
147	<para>
148	<citerefentry><refentrytitle>glBeginTransformFeedback</refentrytitle></citerefentry>,
149	<citerefentry><refentrytitle>glEndTransformFeedback</refentrytitle></citerefentry>,
150	<citerefentry><refentrytitle>glTransformFeedbackVaryings</refentrytitle></citerefentry>,
151	<citerefentry><refentrytitle>glGetProgram</refentrytitle></citerefentry>
152	</para>
153	</refsect1> <refsect1 id="Copyright"><title>Copyright</title>
154	<para>
155	Copyright <trademark class="copyright"></trademark> 2010 Khronos Group.
156	This material may be distributed subject to the terms and conditions set forth in
157	the Open Publication License, v 1.0, 8 June 1999.
158	<ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
159	</para>
160	</refsect1>
161	</refentry>