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<?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= "glBlendEquation" >
<refmeta >
<refmetainfo >
<copyright >
<year > 1991-2006</year>
<holder > Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle > glBlendEquation</refentrytitle>
<manvolnum > 3G</manvolnum>
</refmeta>
<refnamediv >
<refname > glBlendEquation</refname>
<refpurpose > specify the equation used for both the RGB blend equation and the Alpha blend equation</refpurpose>
</refnamediv>
<refsynopsisdiv > <title > C Specification</title>
<funcsynopsis >
<funcprototype >
<funcdef > void <function > glBlendEquation</function> </funcdef>
<paramdef > GLenum <parameter > mode</parameter> </paramdef>
</funcprototype>
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<funcprototype >
<funcdef > void <function > glBlendEquationi</function> </funcdef>
<paramdef > GLuint <parameter > buf</parameter> </paramdef>
<paramdef > GLenum <parameter > mode</parameter> </paramdef>
</funcprototype>
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</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id= "parameters" > <title > Parameters</title>
<variablelist >
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<varlistentry >
<term > <parameter > buf</parameter> </term>
<listitem >
<para >
for <function > glBlendEquationi</function> , specifies the index of the draw buffer
for which to set the blend equation.
</para>
</listitem>
</varlistentry>
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<varlistentry >
<term > <parameter > mode</parameter> </term>
<listitem >
<para >
specifies how source and destination colors are combined.
It must be <constant > GL_FUNC_ADD</constant> , <constant > GL_FUNC_SUBTRACT</constant> ,
<constant > GL_FUNC_REVERSE_SUBTRACT</constant> , <constant > GL_MIN</constant> , <constant > GL_MAX</constant> .
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id= "description" > <title > Description</title>
<para >
The blend equations determine how a new pixel (the ''source'' color)
is combined with a pixel already in the framebuffer (the ''destination''
color). This function sets both the RGB blend equation and the alpha
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blend equation to a single equation. <function > glBlendEquationi</function>
specifies the blend equation for a single draw buffer whereas <function > glBlendEquation</function>
sets the blend equation for all draw buffers.
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</para>
<para >
These equations use the source and destination blend factors
specified by either <citerefentry > <refentrytitle > glBlendFunc</refentrytitle> </citerefentry> or
<citerefentry > <refentrytitle > glBlendFuncSeparate</refentrytitle> </citerefentry> .
See <citerefentry > <refentrytitle > glBlendFunc</refentrytitle> </citerefentry> or <citerefentry > <refentrytitle > glBlendFuncSeparate</refentrytitle> </citerefentry>
for a description of the various blend factors.
</para>
<para >
In the equations that follow, source and destination
color components are referred to as
<inlineequation > <mml:math >
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<!-- eqn: ( R sub s, G sub s, B sub s, A sub s ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation>
and
<inlineequation > <mml:math >
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<!-- eqn: ( R sub d, G sub d, B sub d, A sub d ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> ,
respectively.
The result color is referred to as
<inlineequation > <mml:math >
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<!-- eqn: ( R sub r, G sub r, B sub r, A sub r ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > r</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > r</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > r</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > r</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> .
The source and destination blend factors are denoted
<inlineequation > <mml:math >
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<!-- eqn: ( s sub R, s sub G, s sub B, s sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation>
and
<inlineequation > <mml:math >
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<!-- eqn: ( d sub R, d sub G, d sub B, d sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> ,
respectively.
For these equations all color components are understood to have values
in the range
<inlineequation > <mml:math >
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<!-- eqn: [0,1]: -->
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<mml:mfenced open= "[" close= "]" >
<mml:mn > 0</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
</mml:math> </inlineequation> .
<informaltable frame= "topbot" >
<tgroup cols= "3" align= "left" >
<colspec colwidth= "1.1*" />
<colspec colwidth= "1*" />
<colspec colwidth= "1*" />
<thead >
<row >
<entry rowsep= "1" align= "left" > <emphasis role= "bold" >
Mode
</emphasis> </entry>
<entry rowsep= "1" align= "left" > <emphasis role= "bold" >
RGB Components
</emphasis> </entry>
<entry rowsep= "1" align= "left" > <emphasis role= "bold" >
Alpha Component
</emphasis> </entry>
</row>
</thead>
<tbody >
<row >
<entry align= "left" >
<constant > GL_FUNC_ADD</constant>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Rr = R sub s s sub R + R sub d d sub R : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Rr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:mo > +</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Gr = G sub s s sub G + G sub d d sub G : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Gr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:mo > +</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Br = B sub s s sub B + B sub d d sub B : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Br</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:mo > +</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Ar = A sub s s sub A + A sub d d sub A : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Ar</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
<mml:mo > +</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_FUNC_SUBTRACT</constant>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Rr = R sub s s sub R - R sub d d sub R : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Rr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Gr = G sub s s sub G - G sub d d sub G : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Gr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Br = B sub s s sub B - B sub d d sub B : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Br</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Ar = A sub s s sub A - A sub d d sub A : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Ar</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_FUNC_REVERSE_SUBTRACT</constant>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Rr = R sub d d sub R - R sub s s sub R : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Rr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Gr = G sub d d sub G - G sub s s sub G : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Gr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Br = B sub d d sub B - B sub s s sub B : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Br</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Ar = A sub d d sub A - A sub s s sub A : -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Ar</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
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<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > d</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
<mml:mo > -</mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mo > ⁢ </mml:mo>
<mml:msub > <mml:mi mathvariant= "italic" > s</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
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</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_MIN</constant>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Rr = min ( R sub s, R sub d): -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Rr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Gr = min ( G sub s, G sub d): -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Gr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Br = min ( B sub s, B sub d): -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Br</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Ar = min ( A sub s, A sub d): -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > Ar</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_MAX</constant>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
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<!-- eqn: Rr = max ( R sub s, R sub d): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > Rr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > max</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Gr = max ( G sub s, G sub d): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > Gr</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > max</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
<informalequation > <mml:math >
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<!-- eqn: Br = max ( B sub s, B sub d): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > Br</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > max</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
<entry align= "left" >
<informalequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: Ar = max ( A sub s, A sub d): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mi mathvariant= "italic" > Ar</mml:mi>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > max</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </informalequation>
</entry>
</row>
</tbody>
</tgroup>
</informaltable>
</para>
<para >
The results of these equations are clamped to the range
<inlineequation > <mml:math >
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<!-- eqn: [0,1]: -->
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<mml:mfenced open= "[" close= "]" >
<mml:mn > 0</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
</mml:math> </inlineequation> .
</para>
<para >
The <constant > GL_MIN</constant> and <constant > GL_MAX</constant> equations are useful for applications
that analyze image data (image thresholding against a constant color,
for example).
The <constant > GL_FUNC_ADD</constant> equation is useful
for antialiasing and transparency, among other things.
</para>
<para >
Initially, both the RGB blend equation and the alpha blend equation are set to <constant > GL_FUNC_ADD</constant> .
</para>
<para >
</para>
</refsect1>
<refsect1 id= "notes" > <title > Notes</title>
<para >
The <constant > GL_MIN</constant> , and <constant > GL_MAX</constant> equations do not use
the source or destination factors, only the source and destination colors.
</para>
</refsect1>
<refsect1 id= "errors" > <title > Errors</title>
<para >
<constant > GL_INVALID_ENUM</constant> is generated if <parameter > mode</parameter> is not one of
<constant > GL_FUNC_ADD</constant> , <constant > GL_FUNC_SUBTRACT</constant> , <constant > GL_FUNC_REVERSE_SUBTRACT</constant> ,
<constant > GL_MAX</constant> , or <constant > GL_MIN</constant> .
</para>
2013-10-23 18:17:08 +00:00
<para >
<constant > GL_INVALID_VALUE</constant> is generated by <function > glBlendEquationi</function> if <parameter > buf</parameter> is greater
than or equal to the value of <constant > GL_MAX_DRAW_BUFFERS</constant> .
</para>
2009-03-08 00:46:58 +00:00
</refsect1>
<refsect1 id= "associatedgets" > <title > Associated Gets</title>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with an argument of <constant > GL_BLEND_EQUATION_RGB</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with an argument of <constant > GL_BLEND_EQUATION_ALPHA</constant>
</para>
</refsect1>
<refsect1 id= "seealso" > <title > See Also</title>
<para >
<citerefentry > <refentrytitle > glBlendColor</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glBlendFunc</refentrytitle> </citerefentry>
<citerefentry > <refentrytitle > glBlendFuncSeparate</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>
