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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= "glBlendFunc" >
<refmeta >
<refmetainfo >
<copyright >
<year > 1991-2006</year>
<holder > Silicon Graphics, Inc.</holder>
</copyright>
</refmetainfo>
<refentrytitle > glBlendFunc</refentrytitle>
<manvolnum > 3G</manvolnum>
</refmeta>
<refnamediv >
<refname > glBlendFunc</refname>
<refpurpose > specify pixel arithmetic</refpurpose>
</refnamediv>
<refsynopsisdiv > <title > C Specification</title>
<funcsynopsis >
<funcprototype >
<funcdef > void <function > glBlendFunc</function> </funcdef>
<paramdef > GLenum <parameter > sfactor</parameter> </paramdef>
<paramdef > GLenum <parameter > dfactor</parameter> </paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<!-- eqn: ignoring delim $$ -->
<refsect1 id= "parameters" > <title > Parameters</title>
<variablelist >
<varlistentry >
<term > <parameter > sfactor</parameter> </term>
<listitem >
<para >
Specifies how the red, green, blue,
and alpha source blending factors are computed.
The initial value is <constant > GL_ONE</constant> .
</para>
</listitem>
</varlistentry>
<varlistentry >
<term > <parameter > dfactor</parameter> </term>
<listitem >
<para >
Specifies how the red, green, blue,
and alpha destination blending factors are computed.
The following symbolic constants are accepted:
<constant > GL_ZERO</constant> ,
<constant > GL_ONE</constant> ,
<constant > GL_SRC_COLOR</constant> ,
<constant > GL_ONE_MINUS_SRC_COLOR</constant> ,
<constant > GL_DST_COLOR</constant> ,
<constant > GL_ONE_MINUS_DST_COLOR</constant> ,
<constant > GL_SRC_ALPHA</constant> ,
<constant > GL_ONE_MINUS_SRC_ALPHA</constant> ,
<constant > GL_DST_ALPHA</constant> ,
<constant > GL_ONE_MINUS_DST_ALPHA</constant> .
<constant > GL_CONSTANT_COLOR</constant> ,
<constant > GL_ONE_MINUS_CONSTANT_COLOR</constant> ,
<constant > GL_CONSTANT_ALPHA</constant> , and
<constant > GL_ONE_MINUS_CONSTANT_ALPHA</constant> .
The initial value is <constant > GL_ZERO</constant> .
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id= "description" > <title > Description</title>
<para >
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Pixels can be drawn using a function that blends
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the incoming (source) RGBA values with the RGBA values
that are already in the frame buffer (the destination values).
Blending is initially disabled.
Use <citerefentry > <refentrytitle > glEnable</refentrytitle> </citerefentry> and <citerefentry > <refentrytitle > glDisable</refentrytitle> </citerefentry> with argument <constant > GL_BLEND</constant>
to enable and disable blending.
</para>
<para >
<function > glBlendFunc</function> defines the operation of blending when it is enabled.
<parameter > sfactor</parameter> specifies which method is used to scale the
source color components.
<parameter > dfactor</parameter> specifies which method is used to scale the
destination color components.
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Both parameters must be one of the following symbolic constants:
<constant > GL_ZERO</constant> ,
<constant > GL_ONE</constant> ,
<constant > GL_SRC_COLOR</constant> ,
<constant > GL_ONE_MINUS_SRC_COLOR</constant> ,
<constant > GL_DST_COLOR</constant> ,
<constant > GL_ONE_MINUS_DST_COLOR</constant> ,
<constant > GL_SRC_ALPHA</constant> ,
<constant > GL_ONE_MINUS_SRC_ALPHA</constant> ,
<constant > GL_DST_ALPHA</constant> ,
<constant > GL_ONE_MINUS_DST_ALPHA</constant> ,
<constant > GL_CONSTANT_COLOR</constant> ,
<constant > GL_ONE_MINUS_CONSTANT_COLOR</constant> ,
<constant > GL_CONSTANT_ALPHA</constant> ,
<constant > GL_ONE_MINUS_CONSTANT_ALPHA</constant> ,
<constant > GL_SRC_ALPHA_SATURATE</constant> ,
<constant > GL_SRC1_COLOR</constant> ,
<constant > GL_ONE_MINUS_SRC1_COLOR</constant> ,
<constant > GL_SRC1_ALPHA</constant> , and
<constant > GL_ONE_MINUS_SRC1_ALPHA</constant> .
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The possible methods are described in the following table.
Each method defines four scale factors,
one each for red, green, blue, and alpha.
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In the table and in subsequent equations, first source, second source
and destination color components are referred to as
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<inlineequation > <mml:math >
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<!-- eqn: ( R sub s0 , G sub s0 , B sub s0 , A sub s0 ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> ,
<inlineequation > <mml:math >
<!-- eqn: ( R sub s1 , G sub s1 , B sub s1 , A sub s1 ): -->
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
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</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>
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</mml:math> </inlineequation> , respectively.
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The color specified by <citerefentry > <refentrytitle > glBlendColor</refentrytitle> </citerefentry> is referred to as
<inlineequation > <mml:math >
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<!-- eqn: ( R sub c , G sub c , B sub c , A sub c ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> .
They are understood to have integer values between 0 and
<inlineequation > <mml:math >
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<!-- eqn: ( k sub R , k sub G , k sub B , k sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> ,
where
</para>
<para >
<para >
<inlineequation > <mml:math >
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<!-- eqn: k sub c = 2 sup {m sub c} - 1: -->
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<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:msup > <mml:mn > 2</mml:mn>
<mml:mfenced open= "" close= "" >
<mml:msub > <mml:mi mathvariant= "italic" > m</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:msup>
<mml:mo > -</mml:mo>
<mml:mn > 1</mml:mn>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
</para>
</para>
<para >
and
<inlineequation > <mml:math >
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<!-- eqn: ( m sub R , m sub G , m sub B , m sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > m</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > m</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > m</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > m</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation>
is the number of red,
green,
blue,
and alpha bitplanes.
</para>
<para >
Source and destination scale factors are referred to as
<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> .
The scale factors described in the table,
denoted
<inlineequation > <mml:math >
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<!-- eqn: ( f sub R , f sub G , f sub B , f sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation> ,
represent either source or destination factors.
All scale factors have 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 >
</para>
<informaltable frame= "topbot" >
<tgroup cols= "2" align= "left" >
<colspec />
<colspec />
<thead >
<row >
<entry rowsep= "1" align= "left" > <emphasis role= "bold" >
Parameter
</emphasis> </entry>
<entry rowsep= "1" align= "left" > <emphasis role= "bold" >
<inlineequation > <mml:math >
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<!-- eqn: ( f sub R , f sub G , f sub B , f sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > f</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation>
</emphasis> </entry>
</row>
</thead>
<tbody >
<row >
<entry align= "left" >
<constant > GL_ZERO</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
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<!-- eqn: ( 0, 0, 0, 0 ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:mn > 0</mml:mn>
<mml:mn > 0</mml:mn>
<mml:mn > 0</mml:mn>
<mml:mn > 0</mml:mn>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
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<!-- eqn: ( 1, 1, 1, 1 ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_SRC_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
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<!-- eqn: ( R sub s0 / k sub R , G sub s0 / k sub G , B sub s0 / k sub B , A sub s0 / k sub A ): -->
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<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_SRC_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
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<!-- eqn: ( 1, 1, 1, 1 ) - (R sub s0 / k sub R , G sub s0 / k sub G , B sub s0 / k sub B , A sub s0 / k sub A ): -->
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<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
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<mml:mi mathvariant= "italic" > s0</mml:mi>
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</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_DST_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( R sub d / k sub R , G sub d / k sub G , B sub d / k sub B , A sub d / k sub A ): -->
2009-03-08 00:46:58 +00:00
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_DST_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( 1, 1, 1, 1 ) - (R sub d / k sub R , G sub d / k sub G , B sub d / k sub B , A sub d / k sub A ): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_SRC_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( A sub s0 / k sub A , A sub s0 / k sub A , A sub s0 / k sub A , A sub s0 / k sub A ): -->
2009-03-08 00:46:58 +00:00
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_SRC_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( 1, 1, 1, 1 ) - (A sub s0 / k sub A , A sub s0 / k sub A , A sub s0 / k sub A , A sub s0 / k sub A ): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
2010-11-21 14:34:29 +00:00
<mml:mi mathvariant= "italic" > s0</mml:mi>
2009-03-08 00:46:58 +00:00
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_DST_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( A sub d / k sub A , A sub d / k sub A , A sub d / k sub A , A sub d / k sub A ): -->
2009-03-08 00:46:58 +00:00
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_DST_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( 1, 1, 1, 1 ) - ( A sub d / k sub A , A sub d / k sub A , A sub d / k sub A , A sub d / k sub A ): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_CONSTANT_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( R sub c, G sub c, B sub c, A sub c ): -->
2009-03-08 00:46:58 +00:00
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_CONSTANT_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( 1, 1, 1, 1 ) - ( R sub c, G sub c, B sub c, A sub c ): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_CONSTANT_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( A sub c, A sub c, A sub c, A sub c ): -->
2009-03-08 00:46:58 +00:00
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_CONSTANT_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( 1, 1, 1, 1 ) - ( A sub c, A sub c, A sub c, A sub c ): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > c</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_SRC_ALPHA_SATURATE</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: ( i, i, i, 1 ): -->
2009-03-08 00:46:58 +00:00
<mml:mfenced open= "(" close= ")" >
<mml:mi mathvariant= "italic" > i</mml:mi>
<mml:mi mathvariant= "italic" > i</mml:mi>
<mml:mi mathvariant= "italic" > i</mml:mi>
<mml:mn > 1</mml:mn>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
2010-11-21 14:34:29 +00:00
<row >
<entry align= "left" >
<constant > GL_SRC1_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
<!-- eqn: ( R sub s1 / k sub R , G sub s1 / k sub G , B sub s1 / k sub B , A sub s1 / k sub A ): -->
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_SRC1_COLOR</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
<!-- eqn: ( 1, 1, 1, 1 ) - (R sub s1 / k sub R , G sub s1 / k sub G , B sub s1 / k sub B , A sub s1 / k sub A ): -->
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_SRC1_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
<!-- eqn: ( A sub s1 / k sub A , A sub s1 / k sub A , A sub s1 / k sub A , A sub s1 / k sub A ): -->
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:math> </inlineequation>
</entry>
</row>
<row >
<entry align= "left" >
<constant > GL_ONE_MINUS_SRC1_ALPHA</constant>
</entry>
<entry align= "left" >
<inlineequation > <mml:math >
<!-- eqn: ( 1, 1, 1, 1 ) - (A sub s1 / k sub A , A sub s1 / k sub A , A sub s1 / k sub A , A sub s1 / k sub A ): -->
<mml:mrow >
<mml:mfenced open= "(" close= ")" >
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
<mml:mn > 1</mml:mn>
</mml:mfenced>
<mml:mo > -</mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
<mml:mfrac >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s1</mml:mi>
</mml:msub>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mfenced>
</mml:mrow>
</mml:math> </inlineequation>
</entry>
</row>
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</tbody>
</tgroup>
</informaltable>
<para >
In the table,
</para>
<para >
<para >
<inlineequation > <mml:math >
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<!-- eqn: i = min (A sub s , k sub A - A sub d ) / k sub A: -->
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<mml:mrow >
<mml:mi mathvariant= "italic" > i</mml:mi>
<mml:mo > =</mml:mo>
<mml:mfrac >
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > k</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:mrow>
</mml:mfenced>
</mml:mrow>
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:mfrac>
</mml:mrow>
</mml:math> </inlineequation>
</para>
</para>
<para >
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To determine the blended RGBA values of a pixel,
2009-03-08 00:46:58 +00:00
the system uses the following equations:
</para>
<para >
<para >
<inlineequation > <mml:math >
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<!-- eqn: R sub d = min ( k sub R, R sub s s sub R + R sub d d sub R ): -->
2009-03-08 00:46:58 +00:00
<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > R</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > R</mml:mi>
</mml:msub>
<mml:mrow >
<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>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
<inlineequation > <mml:math >
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<!-- eqn: G sub d = min ( k sub G, G sub s s sub G + G sub d d sub G ): -->
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<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > G</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > G</mml:mi>
</mml:msub>
<mml:mrow >
<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>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
<inlineequation > <mml:math >
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<!-- eqn: B sub d = min ( k sub B, B sub s s sub B + B sub d d sub B ): -->
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<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > B</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > B</mml:mi>
</mml:msub>
<mml:mrow >
<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>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
<inlineequation > <mml:math >
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<!-- eqn: A sub d = min ( k sub A, A sub s s sub A + A sub d d sub A ): -->
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<mml:mrow >
<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > d</mml:mi>
</mml:msub>
<mml:mo > =</mml:mo>
<mml:mrow >
<mml:mi mathvariant= "italic" > min</mml:mi>
<mml:mo > ⁡ </mml:mo>
<mml:mfenced open= "(" close= ")" >
<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
<mml:mrow >
<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>
</mml:mrow>
</mml:mfenced>
</mml:mrow>
</mml:mrow>
</mml:math> </inlineequation>
</para>
</para>
<para >
Despite the apparent precision of the above equations,
blending arithmetic is not exactly specified,
because blending operates with imprecise integer color values.
However,
a blend factor that should be equal to 1
is guaranteed not to modify its multiplicand,
and a blend factor equal to 0 reduces its multiplicand to 0.
For example,
when <parameter > sfactor</parameter> is <constant > GL_SRC_ALPHA</constant> ,
<parameter > dfactor</parameter> is <constant > GL_ONE_MINUS_SRC_ALPHA</constant> ,
and
<inlineequation > <mml:math >
2010-11-21 14:34:29 +00:00
<!-- eqn: A sub s: -->
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<mml:msub > <mml:mi mathvariant= "italic" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:math> </inlineequation>
is equal to
<inlineequation > <mml:math >
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<!-- eqn: k sub A: -->
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<mml:msub > <mml:mi mathvariant= "italic" > k</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:math> </inlineequation> ,
the equations reduce to simple replacement:
</para>
<para >
<para >
<inlineequation > <mml:math >
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<!-- eqn: R sub d = R sub s: -->
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<mml:mrow >
<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" > R</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
</mml:math> </inlineequation>
<inlineequation > <mml:math >
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<!-- eqn: G sub d = G sub s: -->
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<mml:mrow >
<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" > G</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
</mml:math> </inlineequation>
<inlineequation > <mml:math >
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<!-- eqn: B sub d = B sub s: -->
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<mml:mrow >
<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" > B</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
</mml:math> </inlineequation>
<inlineequation > <mml:math >
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<!-- eqn: A sub d = A sub s: -->
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<mml:mrow >
<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" > A</mml:mi>
<mml:mi mathvariant= "italic" > s</mml:mi>
</mml:msub>
</mml:mrow>
</mml:math> </inlineequation>
</para>
</para>
<para >
</para>
</refsect1>
<refsect1 id= "examples" > <title > Examples</title>
<para >
</para>
<para >
Transparency is best implemented using blend function
(<constant > GL_SRC_ALPHA</constant> , <constant > GL_ONE_MINUS_SRC_ALPHA</constant> )
with primitives sorted from farthest to nearest.
Note that this transparency calculation does not require
the presence of alpha bitplanes in the frame buffer.
</para>
<para >
Blend function
(<constant > GL_SRC_ALPHA</constant> , <constant > GL_ONE_MINUS_SRC_ALPHA</constant> )
is also useful for rendering antialiased points and lines
in arbitrary order.
</para>
<para >
Polygon antialiasing is optimized using blend function
(<constant > GL_SRC_ALPHA_SATURATE</constant> , <constant > GL_ONE</constant> )
with polygons sorted from nearest to farthest.
(See the <citerefentry > <refentrytitle > glEnable</refentrytitle> </citerefentry> , <citerefentry > <refentrytitle > glDisable</refentrytitle> </citerefentry> reference page and the
<constant > GL_POLYGON_SMOOTH</constant> argument for information on polygon antialiasing.)
Destination alpha bitplanes,
which must be present for this blend function to operate correctly,
store the accumulated coverage.
</para>
</refsect1>
<refsect1 id= "notes" > <title > Notes</title>
<para >
Incoming (source) alpha is correctly thought of as a material opacity,
ranging from 1.0
(<inlineequation > <mml:math >
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<!-- eqn: K sub A: -->
2009-03-08 00:46:58 +00:00
<mml:msub > <mml:mi mathvariant= "italic" > K</mml:mi>
<mml:mi mathvariant= "italic" > A</mml:mi>
</mml:msub>
</mml:math> </inlineequation> ),
representing complete opacity,
to 0.0 (0), representing complete
transparency.
</para>
<para >
When more than one color buffer is enabled for drawing,
the GL performs blending separately for each enabled buffer,
using the contents of that buffer for destination color.
(See <citerefentry > <refentrytitle > glDrawBuffer</refentrytitle> </citerefentry> .)
</para>
<para >
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When dual source blending is enabled (i.e., one of the blend factors requiring
the second color input is used), the maximum number of enabled draw buffers
is given by <constant > GL_MAX_DUAL_SOURCE_DRAW_BUFFERS</constant> , which may
be lower than <constant > GL_MAX_DRAW_BUFFERS</constant> .
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</para>
</refsect1>
<refsect1 id= "errors" > <title > Errors</title>
<para >
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<constant > GL_INVALID_ENUM</constant> is generated if either <parameter > sfactor</parameter>
or <parameter > dfactor</parameter> is not an accepted value.
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</para>
</refsect1>
<refsect1 id= "associatedgets" > <title > Associated Gets</title>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_BLEND_SRC</constant>
</para>
<para >
<citerefentry > <refentrytitle > glGet</refentrytitle> </citerefentry> with argument <constant > GL_BLEND_DST</constant>
</para>
<para >
<citerefentry > <refentrytitle > glIsEnabled</refentrytitle> </citerefentry> with argument <constant > GL_BLEND</constant>
</para>
<para >
</para>
</refsect1>
<refsect1 id= "seealso" > <title > See Also</title>
<para >
<citerefentry > <refentrytitle > glBlendColor</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glBlendEquation</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glBlendFuncSeparate</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glClear</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glDrawBuffer</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glEnable</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glLogicOp</refentrytitle> </citerefentry> ,
<citerefentry > <refentrytitle > glStencilFunc</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>
