<s>
The	O
even	B-Algorithm
–	I-Algorithm
odd	I-Algorithm
rule	I-Algorithm
is	O
an	O
algorithm	O
implemented	O
in	O
vector-based	O
graphic	O
software	O
,	O
like	O
the	O
PostScript	B-Language
language	I-Language
and	O
Scalable	B-Application
Vector	I-Application
Graphics	I-Application
(	O
SVG	B-Application
)	O
,	O
which	O
determines	O
how	O
a	O
graphical	O
shape	O
with	O
more	O
than	O
one	O
closed	O
outline	O
will	O
be	O
filled	O
.	O
</s>
<s>
Unlike	O
the	O
nonzero-rule	B-Algorithm
algorithm	O
,	O
this	O
algorithm	O
will	O
alternatively	O
color	O
and	O
leave	O
uncolored	O
shapes	O
defined	O
by	O
nested	O
closed	O
paths	O
irrespective	O
of	O
their	O
winding	O
.	O
</s>
<s>
The	O
SVG	B-Application
defines	O
the	O
even	B-Algorithm
–	I-Algorithm
odd	I-Algorithm
rule	I-Algorithm
by	O
saying	O
:	O
</s>
<s>
The	O
rule	O
can	O
be	O
seen	O
in	O
effect	O
in	O
many	O
vector	O
graphic	O
programs	O
(	O
such	O
as	O
Freehand	B-Application
or	O
Illustrator	B-Language
)	O
,	O
where	O
a	O
crossing	O
of	O
an	O
outline	O
with	O
itself	O
causes	O
shapes	O
to	O
fill	O
in	O
strange	O
ways	O
.	O
</s>
<s>
On	O
a	O
simple	O
curve	O
,	O
the	O
even	B-Algorithm
–	I-Algorithm
odd	I-Algorithm
rule	I-Algorithm
reduces	O
to	O
a	O
decision	O
algorithm	O
for	O
the	O
point	O
in	O
polygon	O
problem	O
.	O
</s>
<s>
The	O
SVG	B-Application
computer	O
graphics	O
vector	O
standard	O
may	O
be	O
configured	O
to	O
use	O
the	O
even	B-Algorithm
–	I-Algorithm
odd	I-Algorithm
rule	I-Algorithm
when	O
drawing	O
polygons	O
,	O
though	O
it	O
uses	O
the	O
non-zero	B-Algorithm
rule	I-Algorithm
by	O
default	O
.	O
</s>
<s>
Below	O
is	O
an	O
example	O
implementation	O
in	O
Python	B-Language
:	O
</s>
