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1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "xhtml1-transitional.dtd"> |
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3 | <?xml-stylesheet type="text/xsl" href="mathml.xsl"?><html xmlns="http://www.w3.org/1999/xhtml" xmlns:pref="http://www.w3.org/2002/Math/preference" pref:renderer="mathplayer-dl"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>glLogicOp</title><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /></head><body><div class="refentry" lang="en" xml:lang="en"><a id="glLogicOp"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glLogicOp — specify a logical pixel operation for color index rendering</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0"><tr><td><code class="funcdef">void <b class="fsfunc">glLogicOp</b>(</code></td><td>GLenum </td><td><var class="pdparam">opcode</var><code>)</code>;</td></tr></table></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>opcode</code></em></span></dt><dd><p> | |
4 | Specifies a symbolic constant that selects a logical operation. | |
5 | The following symbols are accepted: | |
6 | <code class="constant">GL_CLEAR</code>, | |
7 | <code class="constant">GL_SET</code>, | |
8 | <code class="constant">GL_COPY</code>, | |
9 | <code class="constant">GL_COPY_INVERTED</code>, | |
10 | <code class="constant">GL_NOOP</code>, | |
11 | <code class="constant">GL_INVERT</code>, | |
12 | <code class="constant">GL_AND</code>, | |
13 | <code class="constant">GL_NAND</code>, | |
14 | <code class="constant">GL_OR</code>, | |
15 | <code class="constant">GL_NOR</code>, | |
16 | <code class="constant">GL_XOR</code>, | |
17 | <code class="constant">GL_EQUIV</code>, | |
18 | <code class="constant">GL_AND_REVERSE</code>, | |
19 | <code class="constant">GL_AND_INVERTED</code>, | |
20 | <code class="constant">GL_OR_REVERSE</code>, and | |
21 | <code class="constant">GL_OR_INVERTED</code>. The initial value is <code class="constant">GL_COPY</code>. | |
22 | </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p> | |
23 | <code class="function">glLogicOp</code> specifies a logical operation that, | |
24 | when enabled, | |
25 | is applied between the incoming color index or RGBA color | |
26 | and the color index or RGBA color at the corresponding location in the | |
27 | frame buffer. | |
28 | To enable or disable the logical operation, call | |
29 | <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a> and <a class="citerefentry" href="glDisable.xml"><span class="citerefentry"><span class="refentrytitle">glDisable</span></span></a> | |
30 | using the symbolic constant <code class="constant">GL_COLOR_LOGIC_OP</code> for RGBA mode or | |
31 | <code class="constant">GL_INDEX_LOGIC_OP</code> for color index mode. The initial value is | |
32 | disabled for both operations. | |
33 | </p><p> | |
34 | </p><div class="informaltable"><table border="1"><colgroup><col align="left" /><col align="left" /></colgroup><thead><tr><th align="left"><span class="bold"><strong> | |
35 | Opcode | |
36 | </strong></span></th><th align="left"><span class="bold"><strong> | |
37 | Resulting Operation | |
38 | </strong></span></th></tr></thead><tbody><tr><td align="left"> | |
39 | <code class="constant">GL_CLEAR</code> | |
40 | </td><td align="center"> | |
41 | 0 | |
42 | </td></tr><tr><td align="left"> | |
43 | <code class="constant">GL_SET</code> | |
44 | </td><td align="center"> | |
45 | 1 | |
46 | </td></tr><tr><td align="left"> | |
47 | <code class="constant">GL_COPY</code> | |
48 | </td><td align="center"> | |
49 | s | |
50 | </td></tr><tr><td align="left"> | |
51 | <code class="constant">GL_COPY_INVERTED</code> | |
52 | </td><td align="center"> | |
53 | ~s | |
54 | </td></tr><tr><td align="left"> | |
55 | <code class="constant">GL_NOOP</code> | |
56 | </td><td align="center"> | |
57 | d | |
58 | </td></tr><tr><td align="left"> | |
59 | <code class="constant">GL_INVERT</code> | |
60 | </td><td align="center"> | |
61 | ~d | |
62 | </td></tr><tr><td align="left"> | |
63 | <code class="constant">GL_AND</code> | |
64 | </td><td align="center"> | |
65 | s & d | |
66 | </td></tr><tr><td align="left"> | |
67 | <code class="constant">GL_NAND</code> | |
68 | </td><td align="center"> | |
69 | ~(s & d) | |
70 | </td></tr><tr><td align="left"> | |
71 | <code class="constant">GL_OR</code> | |
72 | </td><td align="center"> | |
73 | s | d | |
74 | </td></tr><tr><td align="left"> | |
75 | <code class="constant">GL_NOR</code> | |
76 | </td><td align="center"> | |
77 | ~(s | d) | |
78 | </td></tr><tr><td align="left"> | |
79 | <code class="constant">GL_XOR</code> | |
80 | </td><td align="center"> | |
81 | s ^ d | |
82 | </td></tr><tr><td align="left"> | |
83 | <code class="constant">GL_EQUIV</code> | |
84 | </td><td align="center"> | |
85 | ~(s ^ d) | |
86 | </td></tr><tr><td align="left"> | |
87 | <code class="constant">GL_AND_REVERSE</code> | |
88 | </td><td align="center"> | |
89 | s & ~d | |
90 | </td></tr><tr><td align="left"> | |
91 | <code class="constant">GL_AND_INVERTED</code> | |
92 | </td><td align="center"> | |
93 | ~s & d | |
94 | </td></tr><tr><td align="left"> | |
95 | <code class="constant">GL_OR_REVERSE</code> | |
96 | </td><td align="center"> | |
97 | s | ~d | |
98 | </td></tr><tr><td align="left"> | |
99 | <code class="constant">GL_OR_INVERTED</code> | |
100 | </td><td align="center"> | |
101 | ~s | d | |
102 | </td></tr></tbody></table></div><p> | |
103 | <em class="parameter"><code>opcode</code></em> is a symbolic constant chosen from the list above. | |
104 | In the explanation of the logical operations, | |
105 | <span class="emphasis"><em>s</em></span> represents the incoming color index and | |
106 | <span class="emphasis"><em>d</em></span> represents the index in the frame buffer. | |
107 | Standard C-language operators are used. | |
108 | As these bitwise operators suggest, | |
109 | the logical operation is applied independently to each bit pair of the | |
110 | source and destination indices or colors. | |
111 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p> | |
112 | Color index logical operations are always supported. RGBA logical | |
113 | operations are supported only if the GL version is 1.1 or greater. | |
114 | </p><p> | |
115 | When more than one RGBA color or index buffer is enabled for drawing, | |
116 | logical operations are performed separately for each enabled buffer, | |
117 | using for the destination value the contents of that buffer | |
118 | (see <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>). | |
119 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p> | |
120 | <code class="constant">GL_INVALID_ENUM</code> is generated if <em class="parameter"><code>opcode</code></em> is not an accepted value. | |
121 | </p><p> | |
122 | <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glLogicOp</code> | |
123 | is executed between the execution of <a class="citerefentry" href="glBegin.xml"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a> | |
124 | and the corresponding execution of <a class="citerefentry" href="glEnd.xml"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>. | |
125 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p> | |
126 | <a class="citerefentry" href="glGet.xml"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_LOGIC_OP_MODE</code>. | |
127 | </p><p> | |
128 | <a class="citerefentry" href="glIsEnabled.xml"><span class="citerefentry"><span class="refentrytitle">glIsEnabled</span></span></a> with argument <code class="constant">GL_COLOR_LOGIC_OP</code> or <code class="constant">GL_INDEX_LOGIC_OP</code>. | |
129 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p> | |
130 | <a class="citerefentry" href="glAlphaFunc.xml"><span class="citerefentry"><span class="refentrytitle">glAlphaFunc</span></span></a>, | |
131 | <a class="citerefentry" href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>, | |
132 | <a class="citerefentry" href="glDrawBuffer.xml"><span class="citerefentry"><span class="refentrytitle">glDrawBuffer</span></span></a>, | |
133 | <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>, | |
134 | <a class="citerefentry" href="glStencilOp.xml"><span class="citerefentry"><span class="refentrytitle">glStencilOp</span></span></a> | |
135 | </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="Copyright"></a><h2>Copyright</h2><p> | |
136 | Copyright <span class="trademark"></span>© 1991-2006 | |
137 | Silicon Graphics, Inc. This document is licensed under the SGI | |
138 | Free Software B License. For details, see | |
139 | <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>. | |
140 | </p></div></div></body></html> |