[clinton/guile-figl.git] / upstream-doc / man3 / glClear.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="glClear">
    <refmeta>
        <refmetainfo>
            <copyright>
                <year>1991-2006</year>
                <holder>Silicon Graphics, Inc.</holder>
            </copyright>
        </refmetainfo>
        <refentrytitle>glClear</refentrytitle>
        <manvolnum>3G</manvolnum>
    </refmeta>
    <refnamediv>
        <refname>glClear</refname>
        <refpurpose>clear buffers to preset values</refpurpose>
    </refnamediv>
    <refsynopsisdiv><title>C Specification</title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>void <function>glClear</function></funcdef>
                <paramdef>GLbitfield <parameter>mask</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>
    <refsect1 id="parameters"><title>Parameters</title>
        <variablelist>
        <varlistentry>
            <term><parameter>mask</parameter></term>
            <listitem>
                <para>
                    Bitwise OR of masks that indicate the buffers to be cleared.
                    The three masks are
                    <constant>GL_COLOR_BUFFER_BIT</constant>,
                    <constant>GL_DEPTH_BUFFER_BIT</constant>, and
                    <constant>GL_STENCIL_BUFFER_BIT</constant>.
                </para>
            </listitem>
        </varlistentry>
        </variablelist>
    </refsect1>
    <refsect1 id="description"><title>Description</title>
        <para>
            <function>glClear</function> sets the bitplane area of the window to values previously selected
            by <function>glClearColor</function>, <function>glClearDepth</function>, and
            <function>glClearStencil</function>.
            Multiple color buffers can be cleared simultaneously by selecting
            more than one buffer at a time using <citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>.
        </para>
        <para>
            The pixel ownership test,
            the scissor test,
            dithering, and the buffer writemasks affect the operation of <function>glClear</function>.
            The scissor box bounds the cleared region.
            Alpha function,
            blend function,
            logical operation,
            stenciling,
            texture mapping,
            and depth-buffering are ignored by <function>glClear</function>.
        </para>
        <para>
            <function>glClear</function> takes a single argument that is the bitwise OR of several
            values indicating which buffer is to be cleared.
        </para>
        <para>
            The values are as follows:
        </para>
        <variablelist>
            <varlistentry>
                <term><constant>GL_COLOR_BUFFER_BIT</constant></term>
                <listitem>
                    <para>
                        Indicates the buffers currently enabled for color
                        writing.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_DEPTH_BUFFER_BIT</constant></term>
                <listitem>
                    <para>
                        Indicates the depth buffer.
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term><constant>GL_STENCIL_BUFFER_BIT</constant></term>
                <listitem>
                    <para>
                        Indicates the stencil buffer.
                    </para>
                </listitem>
            </varlistentry>
        </variablelist>
        <para>
            The value to which each buffer is cleared depends on the setting of the
            clear value for that buffer.
        </para>
    </refsect1>
    <refsect1 id="notes"><title>Notes</title>
        <para>
            If a buffer is not present,
            then a <function>glClear</function> directed at that buffer has no effect.
        </para>
    </refsect1>
    <refsect1 id="errors"><title>Errors</title>
        <para>
            <constant>GL_INVALID_VALUE</constant> is generated if any bit other than the three defined
            bits is set in <parameter>mask</parameter>.
        </para>
    </refsect1>
    <refsect1 id="associatedgets"><title>Associated Gets</title>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DEPTH_CLEAR_VALUE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_COLOR_CLEAR_VALUE</constant>
        </para>
        <para>
            <citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_STENCIL_CLEAR_VALUE</constant>
        </para>
    </refsect1>
    <refsect1 id="seealso"><title>See Also</title>
        <para>
            <function>glClearColor</function>,
            <function>glClearDepth</function>,
            <function>glClearStencil</function>,
            <citerefentry><refentrytitle>glColorMask</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDepthMask</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glScissor</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>glStencilMask</refentrytitle></citerefentry>
        </para>
    </refsect1>
    <refsect1 id="Copyright"><title>Copyright</title>
        <para>
            Copyright <trademark class="copyright"></trademark> 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</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="glClear">
	5	<refmeta>
	6	<refmetainfo>
	7	<copyright>
	8	<year>1991-2006</year>
	9	<holder>Silicon Graphics, Inc.</holder>
	10	</copyright>
	11	</refmetainfo>
	12	<refentrytitle>glClear</refentrytitle>
	13	<manvolnum>3G</manvolnum>
	14	</refmeta>
	15	<refnamediv>
	16	<refname>glClear</refname>
	17	<refpurpose>clear buffers to preset values</refpurpose>
	18	</refnamediv>
	19	<refsynopsisdiv><title>C Specification</title>
	20	<funcsynopsis>
	21	<funcprototype>
	22	<funcdef>void <function>glClear</function></funcdef>
	23	<paramdef>GLbitfield <parameter>mask</parameter></paramdef>
	24	</funcprototype>
	25	</funcsynopsis>
	26	</refsynopsisdiv>
	27	<refsect1 id="parameters"><title>Parameters</title>
	28	<variablelist>
	29	<varlistentry>
	30	<term><parameter>mask</parameter></term>
	31	<listitem>
	32	<para>
	33	Bitwise OR of masks that indicate the buffers to be cleared.
	34	The three masks are
	35	<constant>GL_COLOR_BUFFER_BIT</constant>,
	36	<constant>GL_DEPTH_BUFFER_BIT</constant>, and
	37	<constant>GL_STENCIL_BUFFER_BIT</constant>.
	38	</para>
	39	</listitem>
	40	</varlistentry>
	41	</variablelist>
	42	</refsect1>
	43	<refsect1 id="description"><title>Description</title>
	44	<para>
	45	<function>glClear</function> sets the bitplane area of the window to values previously selected
	46	by <function>glClearColor</function>, <function>glClearDepth</function>, and
	47	<function>glClearStencil</function>.
	48	Multiple color buffers can be cleared simultaneously by selecting
	49	more than one buffer at a time using <citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>.
	50	</para>
	51	<para>
	52	The pixel ownership test,
	53	the scissor test,
	54	dithering, and the buffer writemasks affect the operation of <function>glClear</function>.
	55	The scissor box bounds the cleared region.
	56	Alpha function,
	57	blend function,
	58	logical operation,
	59	stenciling,
	60	texture mapping,
	61	and depth-buffering are ignored by <function>glClear</function>.
	62	</para>
	63	<para>
	64	<function>glClear</function> takes a single argument that is the bitwise OR of several
65	values indicating which buffer is to be cleared.
66	</para>
67	<para>
68	The values are as follows:
69	</para>
70	<variablelist>
71	<varlistentry>
72	<term><constant>GL_COLOR_BUFFER_BIT</constant></term>
73	<listitem>
74	<para>
75	Indicates the buffers currently enabled for color
76	writing.
77	</para>
78	</listitem>
79	</varlistentry>
80	<varlistentry>
81	<term><constant>GL_DEPTH_BUFFER_BIT</constant></term>
82	<listitem>
83	<para>
84	Indicates the depth buffer.
85	</para>
86	</listitem>
87	</varlistentry>
88	<varlistentry>
89	<term><constant>GL_STENCIL_BUFFER_BIT</constant></term>
90	<listitem>
91	<para>
92	Indicates the stencil buffer.
93	</para>
94	</listitem>
95	</varlistentry>
96	</variablelist>
97	<para>
98	The value to which each buffer is cleared depends on the setting of the
99	clear value for that buffer.
100	</para>
101	</refsect1>
102	<refsect1 id="notes"><title>Notes</title>
103	<para>
104	If a buffer is not present,
105	then a <function>glClear</function> directed at that buffer has no effect.
106	</para>
107	</refsect1>
108	<refsect1 id="errors"><title>Errors</title>
109	<para>
110	<constant>GL_INVALID_VALUE</constant> is generated if any bit other than the three defined
111	bits is set in <parameter>mask</parameter>.
112	</para>
113	</refsect1>
114	<refsect1 id="associatedgets"><title>Associated Gets</title>
115	<para>
116	<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_DEPTH_CLEAR_VALUE</constant>
117	</para>
118	<para>
119	<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_COLOR_CLEAR_VALUE</constant>
120	</para>
121	<para>
122	<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_STENCIL_CLEAR_VALUE</constant>
123	</para>
124	</refsect1>
125	<refsect1 id="seealso"><title>See Also</title>
126	<para>
127	<function>glClearColor</function>,
128	<function>glClearDepth</function>,
129	<function>glClearStencil</function>,
130	<citerefentry><refentrytitle>glColorMask</refentrytitle></citerefentry>,
131	<citerefentry><refentrytitle>glDepthMask</refentrytitle></citerefentry>,
132	<citerefentry><refentrytitle>glDrawBuffer</refentrytitle></citerefentry>,
133	<citerefentry><refentrytitle>glScissor</refentrytitle></citerefentry>,
134	<citerefentry><refentrytitle>glStencilMask</refentrytitle></citerefentry>
135	</para>
136	</refsect1>
137	<refsect1 id="Copyright"><title>Copyright</title>
138	<para>
139	Copyright <trademark class="copyright"></trademark> 1991-2006
140	Silicon Graphics, Inc. This document is licensed under the SGI
141	Free Software B License. For details, see
142	<ulink url="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</ulink>.
143	</para>
144	</refsect1>
145	</refentry>