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4 Reference Pages
</title><meta name=
"generator" content=
"DocBook XSL Stylesheets V1.69.1" /></head><body><div class=
"refentry" lang=
"en" xml:
lang=
"en"><a id=
"glClear"></a><div class=
"titlepage"></div><div class=
"refnamediv"><h2>Name
</h2><p>glClear — clear buffers to preset values
</p></div><div class=
"refsynopsisdiv"><h2>C Specification
</h2><div class=
"funcsynopsis"><p><code class=
"funcdef">void
<b class=
"fsfunc">glClear
</b>(
</code>GLbitfield
<var class=
"pdparam">mask
</var><code>)
</code>;
</p></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"parameters"></a><h2>Parameters
</h2><div class=
"variablelist"><dl><dt><span class=
"term"><em class=
"parameter"><code>mask
</code></em></span></dt><dd><p>
5 Bitwise OR of masks that indicate the buffers to be cleared.
7 <code class=
"constant">GL_COLOR_BUFFER_BIT
</code>,
8 <code class=
"constant">GL_DEPTH_BUFFER_BIT
</code>, and
9 <code class=
"constant">GL_STENCIL_BUFFER_BIT
</code>.
10 </p></dd></dl></div></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"description"></a><h2>Description
</h2><p>
11 <code class=
"function">glClear
</code> sets the bitplane area of the window to values previously selected
12 by
<code class=
"function">glClearColor
</code>,
<code class=
"function">glClearDepth
</code>, and
13 <code class=
"function">glClearStencil
</code>.
14 Multiple color buffers can be cleared simultaneously by selecting
15 more than one buffer at a time using
<a href=
"glDrawBuffer.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glDrawBuffer
</span></span></a>.
17 The pixel ownership test,
19 dithering, and the buffer writemasks affect the operation of
<code class=
"function">glClear
</code>.
20 The scissor box bounds the cleared region.
26 and depth-buffering are ignored by
<code class=
"function">glClear
</code>.
28 <code class=
"function">glClear
</code> takes a single argument that is the bitwise OR of several
29 values indicating which buffer is to be cleared.
31 The values are as follows:
32 </p><div class=
"variablelist"><dl><dt><span class=
"term"><code class=
"constant">GL_COLOR_BUFFER_BIT
</code></span></dt><dd><p>
33 Indicates the buffers currently enabled for color
35 </p></dd><dt><span class=
"term"><code class=
"constant">GL_DEPTH_BUFFER_BIT
</code></span></dt><dd><p>
36 Indicates the depth buffer.
37 </p></dd><dt><span class=
"term"><code class=
"constant">GL_STENCIL_BUFFER_BIT
</code></span></dt><dd><p>
38 Indicates the stencil buffer.
39 </p></dd></dl></div><p>
40 The value to which each buffer is cleared depends on the setting of the
41 clear value for that buffer.
42 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"notes"></a><h2>Notes
</h2><p>
43 If a buffer is not present,
44 then a
<code class=
"function">glClear
</code> directed at that buffer has no effect.
45 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"errors"></a><h2>Errors
</h2><p>
46 <code class=
"constant">GL_INVALID_VALUE
</code> is generated if any bit other than the three defined
47 bits is set in
<em class=
"parameter"><code>mask
</code></em>.
48 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"associatedgets"></a><h2>Associated Gets
</h2><p>
49 <a href=
"glGet.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGet
</span></span></a> with argument
<code class=
"constant">GL_DEPTH_CLEAR_VALUE
</code>
51 <a href=
"glGet.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGet
</span></span></a> with argument
<code class=
"constant">GL_COLOR_CLEAR_VALUE
</code>
53 <a href=
"glGet.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glGet
</span></span></a> with argument
<code class=
"constant">GL_STENCIL_CLEAR_VALUE
</code>
54 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"seealso"></a><h2>See Also
</h2><p>
55 <code class=
"function">glClearColor
</code>,
56 <code class=
"function">glClearDepth
</code>,
57 <code class=
"function">glClearStencil
</code>,
58 <a href=
"glColorMask.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glColorMask
</span></span></a>,
59 <a href=
"glDepthMask.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glDepthMask
</span></span></a>,
60 <a href=
"glDrawBuffer.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glDrawBuffer
</span></span></a>,
61 <a href=
"glScissor.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glScissor
</span></span></a>,
62 <a href=
"glStencilMask.xml"><span class=
"citerefentry"><span class=
"refentrytitle">glStencilMask
</span></span></a>
63 </p></div><div class=
"refsect1" lang=
"en" xml:
lang=
"en"><a id=
"Copyright"></a><h2>Copyright
</h2><p>
64 Copyright
<span class=
"trademark"></span>©
1991-
2006
65 Silicon Graphics, Inc. This document is licensed under the SGI
66 Free Software B License. For details, see
67 <a href=
"http://oss.sgi.com/projects/FreeB/" target=
"_top">http://oss.sgi.com/projects/FreeB/
</a>.
68 </p></div></div></body></html>