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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 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>,
<constant>GL_ONE_MINUS_CONSTANT_ALPHA</constant>, and
<constant>GL_SRC_ALPHA_SATURATE</constant>.
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>
In RGBA mode, 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 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.
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, source and destination
color components are referred to as
<inlineequation><mml:math>
<!-- eqn: ( R sub s , G sub s , B sub s , A sub s ):-->
<mml:mfenced open="(" close=")">
<mml:msub><mml:mi mathvariant="italic">R</mml:mi>
<mml:mi mathvariant="italic">s</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">G</mml:mi>
<mml:mi mathvariant="italic">s</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">B</mml:mi>
<mml:mi mathvariant="italic">s</mml:mi>
</mml:msub>
<mml:msub><mml:mi mathvariant="italic">A</mml:mi>
<mml:mi mathvariant="italic">s</mml:mi>
</mml:msub>
</mml:mfenced>
</mml:math></inlineequation>
and
<inlineequation><mml:math>
<!-- 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>.
The color specified by <citerefentry><refentrytitle>glBlendColor</refentrytitle></citerefentry> is referred to as
<inlineequation><mml:math>
<!-- 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>
<!-- 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>
<para>
<inlineequation><mml:math>
<!-- 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>
<para>
and
<inlineequation><mml:math>
<!-- 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>
<!-- 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>
<!-- 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>
<!-- 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>
<!-- 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 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>
<!-- 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>
</emphasis></entry>
</row>
</thead>
<tbody>
<row>
<entry align="left">
<constant>GL_ZERO</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_ONE</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_SRC_COLOR</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- eqn: ( R sub s / k sub R , G sub s / k sub G , B sub s / k sub B , A sub s / k sub A ):-->
<mml:mfenced open="(" close=")">
<mml:mfrac>
<mml:msub><mml:mi mathvariant="italic">R</mml:mi>
<mml:mi mathvariant="italic">s</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">s</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">s</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">s</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_SRC_COLOR</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- eqn: ( 1, 1, 1, 1 ) - (R sub s / k sub R , G sub s / k sub G , B sub s / k sub B , A sub s / 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">s</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">s</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">s</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">s</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_DST_COLOR</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_ONE_MINUS_DST_COLOR</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_SRC_ALPHA</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- eqn: ( A sub s / k sub A , A sub s / k sub A , A sub s / k sub A , A sub s / k sub A ):-->
<mml:mfenced open="(" close=")">
<mml:mfrac>
<mml:msub><mml:mi mathvariant="italic">A</mml:mi>
<mml:mi mathvariant="italic">s</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">s</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">s</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">s</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_SRC_ALPHA</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- eqn: ( 1, 1, 1, 1 ) - (A sub s / k sub A , A sub s / k sub A , A sub s / k sub A , A sub s / 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">s</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">s</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">s</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">s</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_DST_ALPHA</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_ONE_MINUS_DST_ALPHA</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_CONSTANT_COLOR</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_ONE_MINUS_CONSTANT_COLOR</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_CONSTANT_ALPHA</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_ONE_MINUS_CONSTANT_ALPHA</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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 align="left">
<constant>GL_SRC_ALPHA_SATURATE</constant>
</entry>
<entry align="left">
<inlineequation><mml:math>
<!-- 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>
</tbody>
</tgroup>
</informaltable>
<para>
In the table,
</para>
<para>
<para>
<inlineequation><mml:math>
<!-- 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>⁡</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>
To determine the blended RGBA values of a pixel when drawing in RGBA mode,
the system uses the following equations:
</para>
<para>
<para>
<inlineequation><mml:math>
<!-- 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>⁡</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>
<!-- 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>⁡</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>
<!-- 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>⁡</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>
<!-- 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>⁡</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>
<!-- 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>
<!-- 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>
<para>
<inlineequation><mml:math>
<!-- 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>
<!-- 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>
<!-- 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>
<!-- 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>
</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>
<!-- 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>
Blending affects only RGBA rendering.
It is ignored by color index renderers.
</para>
<para>
<constant>GL_CONSTANT_COLOR</constant>, <constant>GL_ONE_MINUS_CONSTANT_COLOR</constant>,
<constant>GL_CONSTANT_ALPHA</constant>, <constant>GL_ONE_MINUS_CONSTANT_ALPHA</constant> are available only
if the GL version is 1.4 or greater or if the <code>ARB_imaging</code> is
supported by your implementation.
</para>
<para>
<constant>GL_SRC_COLOR</constant> and <constant>GL_ONE_MINUS_SRC_COLOR</constant> are valid only for
<parameter>sfactor</parameter> if the GL version is 1.4 or greater.
</para>
<para>
<constant>GL_DST_COLOR</constant> and <constant>GL_ONE_MINUS_DST_COLOR</constant> are valid only for
<parameter>dfactor</parameter> if the GL version is 1.4 or greater.
</para>
</refsect1>
<refsect1 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_OPERATION</constant> is generated if <function>glBlendFunc</function>
is executed between the execution of <citerefentry><refentrytitle>glBegin</refentrytitle></citerefentry>
and the corresponding execution of <citerefentry><refentrytitle>glEnd</refentrytitle></citerefentry>.
</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>glAlphaFunc</refentrytitle></citerefentry>,
<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>