<s>
The	O
Weiler	B-Algorithm
–	I-Algorithm
Atherton	I-Algorithm
is	O
a	O
polygon-clipping	O
algorithm	O
.	O
</s>
<s>
It	O
is	O
used	O
in	O
areas	O
like	O
computer	O
graphics	O
and	O
games	O
development	O
where	O
clipping	B-Algorithm
of	O
polygons	O
is	O
needed	O
.	O
</s>
<s>
It	O
allows	O
clipping	B-Algorithm
of	O
a	O
subject	O
or	O
candidate	O
polygon	O
by	O
an	O
arbitrarily	O
shaped	O
clipping	B-Algorithm
polygon/area/region	O
.	O
</s>
<s>
Given	O
polygon	O
A	O
as	O
the	O
clipping	B-Algorithm
region	O
and	O
polygon	O
B	O
as	O
the	O
subject	O
polygon	O
to	O
be	O
clipped	O
,	O
the	O
algorithm	O
consists	O
of	O
the	O
following	O
steps	O
:	O
</s>
<s>
List	O
the	O
vertices	O
of	O
the	O
clipping-region	O
polygon	O
A	O
and	O
those	O
of	O
the	O
subject	O
polygon	O
B	O
.	O
</s>
<s>
Label	O
the	O
listed	O
vertices	O
of	O
subject	O
polygon	O
B	O
as	O
either	O
inside	O
or	O
outside	O
of	O
clipping	B-Algorithm
region	O
A	O
.	O
</s>
<s>
Generate	O
a	O
list	O
of	O
"	O
inbound	O
"	O
intersections	O
–	O
the	O
intersections	O
where	O
the	O
vector	O
from	O
the	O
intersection	O
to	O
the	O
subsequent	O
vertex	O
of	O
subject	O
polygon	O
B	O
begins	O
inside	O
the	O
clipping	B-Algorithm
region	O
.	O
</s>
<s>
A	O
is	O
inside	O
B	O
–	O
return	O
A	O
for	O
clipping	B-Algorithm
,	O
B	O
for	O
merging	O
.	O
</s>
<s>
B	O
is	O
inside	O
A	O
–	O
return	O
B	O
for	O
clipping	B-Algorithm
,	O
A	O
for	O
merging	O
.	O
</s>
<s>
A	O
and	O
B	O
do	O
not	O
overlap	O
–	O
return	O
None	O
for	O
clipping	B-Algorithm
or	O
A	O
&	O
B	O
for	O
merging	O
.	O
</s>
