Opentk/Source/Bind/Specifications/Docs/GL/glBlendFunc.xml

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<!DOCTYPE refentry [ <!ENTITY % mathent SYSTEM "math.ent"> %mathent; ]>
<!-- Converted by db4-upgrade version 1.1 -->
<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="glBlendFunc">
<info>
<copyright>
<year>1991-2006</year>
<holder>Silicon Graphics, Inc.</holder>
</copyright>
<copyright>
<year>2010-2013</year>
<holder>Khronos Group</holder>
</copyright>
</info>
<refmeta>
<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>
<funcprototype>
<funcdef>void <function>glBlendFunci</function></funcdef>
<paramdef>GLuint <parameter>buf</parameter></paramdef>
<paramdef>GLenum <parameter>sfactor</parameter></paramdef>
<paramdef>GLenum <parameter>dfactor</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1 xml:id="parameters"><title>Parameters</title>
<variablelist>
<varlistentry>
<term><parameter>buf</parameter></term>
<listitem>
<para>
For <function>glBlendFunci</function>, specifies the index of the draw
buffer for which to set the blend function.
</para>
</listitem>
</varlistentry>
<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 xml:id="description"><title>Description</title>
<para>
Pixels can be drawn using a function that blends
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 for all draw buffers when it is enabled.
<function>glBlendFunci</function> defines the operation of blending for a single draw buffer
specified by <parameter>buf</parameter> when enabled for that draw buffer.
<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.
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>.
The possible methods are described in the following table.
Each method defines four scale factors,
one each for red, green, blue, and alpha.
In the table and in subsequent equations, first source, second source
and destination color components are referred to as
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( R sub s0 , G sub s0 , B sub s0 , A sub s0 ): -->
<mml:mfenced open="(" close=")">
<mml:msub><mml:mi mathvariant="italic">R</mml:mi>
<mml:mi mathvariant="italic">s0</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">G</mml:mi>
<mml:mi mathvariant="italic">s0</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">B</mml:mi>
<mml:mi mathvariant="italic">s0</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">A</mml:mi>
<mml:mi mathvariant="italic">s0</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math></inlineequation>,
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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>
</mml:msub>
</mml:mfenced>
</mml:math></inlineequation>
and
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( R sub d , G sub d , B sub d , A sub d ): -->
<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 color specified by <citerefentry><refentrytitle>glBlendColor</refentrytitle></citerefentry> is referred to as
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( R sub c , G sub c , B sub c , A sub c ): -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( k sub R , k sub G , k sub B , k sub A ): -->
<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>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: k sub c = 2 sup {m sub c} - 1: -->
<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>
and
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( m sub R , m sub G , m sub B , m sub A ): -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( s sub R , s sub G , s sub B , s sub A ): -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( d sub R , d sub G , d sub B , d sub A ): -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( f sub R , f sub G , f sub B , f sub A ): -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: [0,1]: -->
<mml:mfenced open="[" close="]">
<mml:mn>0</mml:mn>
<mml:mn>1</mml:mn>
</mml:mfenced>
</mml:math></inlineequation>.
</para>
<para>
</para>
<informaltable>
<tgroup cols="2" align="left">
<colspec/>
<colspec/>
<thead>
<row>
<entry>
<emphasis role="bold"> Parameter </emphasis>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( f sub R , f sub G , f sub B , f sub A ): -->
<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>
</entry>
</row>
</thead>
<tbody>
<row>
<entry>
<constant>GL_ZERO</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( 0, 0, 0, 0 ): -->
<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>
<constant>GL_ONE</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( 1, 1, 1, 1 ): -->
<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>
<constant>GL_SRC_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<mml:mfenced open="(" close=")">
<mml:mfrac>
<mml:msub><mml:mi mathvariant="italic">R</mml:mi>
<mml:mi mathvariant="italic">s0</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">s0</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">s0</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">s0</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>
<constant>GL_ONE_MINUS_SRC_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<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">s0</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">s0</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">s0</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">s0</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>
<constant>GL_DST_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<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>
<constant>GL_ONE_MINUS_DST_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<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>
<constant>GL_SRC_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<mml:mfenced open="(" close=")">
<mml:mfrac>
<mml:msub><mml:mi mathvariant="italic">A</mml:mi>
<mml:mi mathvariant="italic">s0</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">s0</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">s0</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">s0</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>
<constant>GL_ONE_MINUS_SRC_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<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">s0</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">s0</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">s0</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">s0</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>
<constant>GL_DST_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<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>
<constant>GL_ONE_MINUS_DST_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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 ): -->
<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>
<constant>GL_CONSTANT_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( R sub c, G sub c, B sub c, A sub c ): -->
<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>
<constant>GL_ONE_MINUS_CONSTANT_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( 1, 1, 1, 1 ) - ( R sub c, G sub c, B sub c, A sub c ): -->
<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>
<constant>GL_CONSTANT_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( A sub c, A sub c, A sub c, A sub c ): -->
<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>
<constant>GL_ONE_MINUS_CONSTANT_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( 1, 1, 1, 1 ) - ( A sub c, A sub c, A sub c, A sub c ): -->
<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>
<constant>GL_SRC_ALPHA_SATURATE</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: ( i, i, i, 1 ): -->
<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>
<row>
<entry>
<constant>GL_SRC1_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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>
<constant>GL_ONE_MINUS_SRC1_COLOR</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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>
<constant>GL_SRC1_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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>
<constant>GL_ONE_MINUS_SRC1_ALPHA</constant>
</entry>
<entry>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- 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>
</tbody>
</tgroup>
</informaltable>
<para>
In the table,
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: i = min (A sub s , k sub A - A sub d ) / k sub A: -->
<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>&af;</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>
To determine the blended RGBA values of a pixel,
the system uses the following equations:
</para>
<para>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: R sub d = min ( k sub R, R sub s s sub R + R sub d d sub R ): -->
<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>&af;</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>&it;</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>&it;</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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: G sub d = min ( k sub G, G sub s s sub G + G sub d d sub G ): -->
<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>&af;</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>&it;</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>&it;</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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: B sub d = min ( k sub B, B sub s s sub B + B sub d d sub B ): -->
<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>&af;</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>&it;</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>&it;</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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: A sub d = min ( k sub A, A sub s s sub A + A sub d d sub A ): -->
<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>&af;</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>&it;</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>&it;</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>
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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: A sub s: -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: k sub A: -->
<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>
<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: R sub d = R sub s: -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: G sub d = G sub s: -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: B sub d = B sub s: -->
<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 xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: A sub d = A sub s: -->
<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>
</refsect1>
<refsect1 xml: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 xml:id="notes"><title>Notes</title>
<para>
Incoming (source) alpha is correctly thought of as a material opacity,
ranging from 1.0
(<inlineequation><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<!-- eqn: K sub A: -->
<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>
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>.
</para>
</refsect1>
<refsect1 xml:id="errors"><title>Errors</title>
<para>
<constant>GL_INVALID_ENUM</constant> is generated if either <parameter>sfactor</parameter>
or <parameter>dfactor</parameter> is not an accepted value.
</para>
<para>
<constant>GL_INVALID_VALUE</constant> is generated by <function>glBlendFunci</function> if <parameter>buf</parameter> is greater
than or equal to the value of <constant>GL_MAX_DRAW_BUFFERS</constant>.
</para>
</refsect1>
<refsect1 xml:id="associatedgets"><title>Associated Gets</title>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_BLEND_SRC_RGB</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_BLEND_SRC_ALPHA</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_BLEND_DST_RGB</constant>
</para>
<para>
<citerefentry><refentrytitle>glGet</refentrytitle></citerefentry> with argument <constant>GL_BLEND_DST_ALPHA</constant>
</para>
<para>
<citerefentry><refentrytitle>glIsEnabled</refentrytitle></citerefentry> with argument <constant>GL_BLEND</constant>
</para>
<para>
</para>
</refsect1>
<refsect1 xml: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 xml:id="Copyright"><title>Copyright</title>
<para>
Copyright <trademark class="copyright"/> 1991-2006 Silicon Graphics, Inc.
Copyright <trademark class="copyright"/> 2010-2013 Khronos Group.
This document is licensed under the SGI Free Software B License.
For details, see
<link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://oss.sgi.com/projects/FreeB/">http://oss.sgi.com/projects/FreeB/</link>.
</para>
</refsect1>
</refentry>