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<?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 V1.78.1" /></head><body><div class="refentry"><a id="glLogicOp"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glLogicOp — specify a logical pixel operation</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <strong class="fsfunc">glLogicOp</strong>(</code></td><td>GLenum <var class="pdparam">opcode</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term">
                    <em class="parameter"><code>opcode</code></em>
                </span></dt><dd><p>Specifies a symbolic constant that selects a
                    logical operation. The following symbols are accepted:
                    <code class="constant">GL_CLEAR</code>,
                    <code class="constant">GL_SET</code>,
                    <code class="constant">GL_COPY</code>,
                    <code class="constant">GL_COPY_INVERTED</code>,
                    <code class="constant">GL_NOOP</code>,
                    <code class="constant">GL_INVERT</code>,
                    <code class="constant">GL_AND</code>,
                    <code class="constant">GL_NAND</code>,
                    <code class="constant">GL_OR</code>,
                    <code class="constant">GL_NOR</code>,
                    <code class="constant">GL_XOR</code>,
                    <code class="constant">GL_EQUIV</code>,
                    <code class="constant">GL_AND_REVERSE</code>,
                    <code class="constant">GL_AND_INVERTED</code>,
                    <code class="constant">GL_OR_REVERSE</code>, and
                    <code class="constant">GL_OR_INVERTED</code>.  The initial value is
                    <code class="constant">GL_COPY</code>.</p></dd></dl></div></div><div class="refsect1"><a id="description"></a><h2>Description</h2><p><code class="function">glLogicOp</code>
        specifies a logical operation that, when enabled, is applied
        between the incoming color and the color at the corresponding
        location in the frame buffer.
        To enable or disable the logical operation, call
        <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>
        with argument <code class="constant">GL_COLOR_LOGIC_OP</code>.
        Logical operation is initially disabled.
        </p><div class="informaltable"><table border="0"><colgroup><col align="left" /><col align="center" /></colgroup><thead><tr><th align="left">Opcode</th><th align="center">Resulting Operation</th></tr></thead><tbody><tr><td align="left"><code class="constant">GL_CLEAR</code></td><td align="center">0</td></tr><tr><td align="left"><code class="constant">GL_SET</code></td><td align="center">1</td></tr><tr><td align="left"><code class="constant">GL_COPY</code></td><td align="center"><em class="replaceable"><code>s</code></em></td></tr><tr><td align="left"><code class="constant">GL_COPY_INVERTED</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mi>s</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_NOOP</code></td><td align="center"><em class="replaceable"><code>d</code></em></td></tr><tr><td align="left"><code class="constant">GL_INVERT</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_AND</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mi>s</mml:mi><mml:mo>&amp;</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_NAND</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mfenced><mml:mrow><mml:mi>s</mml:mi><mml:mo>&amp;</mml:mo><mml:mi>d</mml:mi></mml:mrow></mml:mfenced>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_OR</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mi>s</mml:mi><mml:mo>|</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_NOR</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mfenced><mml:mrow><mml:mi>s</mml:mi><mml:mo>|</mml:mo><mml:mi>d</mml:mi></mml:mrow></mml:mfenced>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_XOR</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mi>s</mml:mi><mml:mo>^</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_EQUIV</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mfenced><mml:mrow><mml:mi>s</mml:mi><mml:mo>^</mml:mo><mml:mi>d</mml:mi></mml:mrow></mml:mfenced>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_AND_REVERSE</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mi>s</mml:mi><mml:mo>&amp;</mml:mo><mml:mo>~</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_AND_INVERTED</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mi>s</mml:mi><mml:mo>&amp;</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_OR_REVERSE</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mi>s</mml:mi><mml:mo>|</mml:mo><mml:mo>~</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr><tr><td align="left"><code class="constant">GL_OR_INVERTED</code></td><td align="center">
                            <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
                                <mml:mo>~</mml:mo><mml:mi>s</mml:mi><mml:mo>|</mml:mo><mml:mi>d</mml:mi>
                            </mml:math>
                        </td></tr></tbody></table></div><p>
        <em class="parameter"><code>opcode</code></em>
        is a symbolic constant chosen from the list above. In the
        explanation of the logical operations, <em class="parameter"><code>s</code></em>
        represents the incoming color and <em class="parameter"><code>d</code></em>
        represents the color in the frame buffer. Standard C-language
        operators are used. As these bitwise operators suggest, the
        logical operation is applied independently to each bit pair of
        the source and destination indices or colors.</p></div><div class="refsect1"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_ENUM</code> is generated if
        <em class="parameter"><code>opcode</code></em> is not an accepted value.</p></div><div class="refsect1"><a id="seealso"></a><h2>See Also</h2><p>
        <a class="citerefentry" href="glAlphaFunc.xml"><span class="citerefentry"><span class="refentrytitle">glAlphaFunc</span></span></a>,
        <a class="citerefentry" href="glBlendFunc.xml"><span class="citerefentry"><span class="refentrytitle">glBlendFunc</span></span></a>,
        <a class="citerefentry" href="glEnable.xml"><span class="citerefentry"><span class="refentrytitle">glEnable</span></span></a>,
        <a class="citerefentry" href="glStencilOp.xml"><span class="citerefentry"><span class="refentrytitle">glStencilOp</span></span></a>
        </p></div><div class="refsect1"><a id="copyright"></a><h2>Copyright</h2><p>
            Copyright <span class="trademark"></span>© 2003-2004
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></body></html>