<s>
A	O
navigation	B-Algorithm
mesh	I-Algorithm
,	O
or	O
navmesh	B-Algorithm
,	O
is	O
an	O
abstract	O
data	O
structure	O
used	O
in	O
artificial	B-Application
intelligence	I-Application
applications	O
to	O
aid	O
agents	B-General_Concept
in	O
pathfinding	B-Algorithm
through	O
complicated	O
spaces	O
.	O
</s>
<s>
This	O
approach	O
has	O
been	O
known	O
since	O
at	O
least	O
the	O
mid-1980s	O
in	O
robotics	O
,	O
where	O
it	O
has	O
been	O
called	O
a	O
meadow	B-Algorithm
map	I-Algorithm
,	O
and	O
was	O
popularized	O
in	O
video	B-Application
game	I-Application
AI	I-Application
in	O
2000	O
.	O
</s>
<s>
A	O
navigation	B-Algorithm
mesh	I-Algorithm
is	O
a	O
collection	O
of	O
two-dimensional	O
convex	O
polygons	O
(	O
a	O
polygon	B-Algorithm
mesh	I-Algorithm
)	O
that	O
define	O
which	O
areas	O
of	O
an	O
environment	O
are	O
traversable	O
by	O
agents	B-General_Concept
.	O
</s>
<s>
Adjacent	O
polygons	O
are	O
connected	O
to	O
each	O
other	O
in	O
a	O
graph	B-Application
.	O
</s>
<s>
Pathfinding	B-Algorithm
within	O
one	O
of	O
these	O
polygons	O
can	O
be	O
done	O
trivially	O
in	O
a	O
straight	O
line	O
because	O
the	O
polygon	O
is	O
convex	O
and	O
traversable	O
.	O
</s>
<s>
Pathfinding	B-Algorithm
between	O
polygons	O
in	O
the	O
mesh	B-Algorithm
can	O
be	O
done	O
with	O
one	O
of	O
the	O
large	O
number	O
of	O
graph	B-Algorithm
search	I-Algorithm
algorithms	O
,	O
such	O
as	O
A*	B-Protocol
.	O
</s>
<s>
Agents	B-General_Concept
on	O
a	O
navmesh	B-Algorithm
can	O
thus	O
avoid	O
computationally	O
expensive	O
collision	O
detection	O
checks	O
with	O
obstacles	O
that	O
are	O
part	O
of	O
the	O
environment	O
.	O
</s>
<s>
The	O
polygons	O
of	O
various	O
sizes	O
and	O
shapes	O
in	O
navigation	B-Algorithm
meshes	I-Algorithm
can	O
represent	O
arbitrary	O
environments	O
with	O
greater	O
accuracy	O
than	O
regular	O
grids	O
can	O
.	O
</s>
<s>
Navigation	B-Algorithm
meshes	I-Algorithm
can	O
be	O
created	O
manually	O
,	O
automatically	O
,	O
or	O
by	O
some	O
combination	O
of	O
the	O
two	O
.	O
</s>
<s>
In	O
video	O
games	O
,	O
a	O
level	O
designer	O
might	O
manually	O
define	O
the	O
polygons	O
of	O
the	O
navmesh	B-Algorithm
in	O
a	O
level	O
editor	O
.	O
</s>
<s>
Alternatively	O
,	O
an	O
application	O
could	O
be	O
created	O
that	O
takes	O
the	O
level	O
geometry	O
as	O
input	O
and	O
automatically	O
outputs	O
a	O
navmesh	B-Algorithm
.	O
</s>
<s>
It	O
is	O
commonly	O
assumed	O
that	O
the	O
environment	O
represented	O
by	O
a	O
navmesh	B-Algorithm
is	O
static	O
–	O
it	O
does	O
not	O
change	O
over	O
time	O
–	O
and	O
thus	O
the	O
navmesh	B-Algorithm
can	O
be	O
created	O
offline	B-Algorithm
and	O
be	O
immutable	O
.	O
</s>
<s>
However	O
,	O
there	O
has	O
been	O
some	O
investigation	O
of	O
online	O
updating	O
of	O
navmeshes	B-Algorithm
for	O
dynamic	O
environments	O
.	O
</s>
<s>
Navigation	B-Algorithm
meshes	I-Algorithm
in	O
video	B-Application
game	I-Application
artificial	I-Application
intelligence	I-Application
are	O
usually	O
credited	O
to	O
Greg	O
Snook	O
's	O
2000	O
article	O
"	O
Simplified	O
3D	O
Movement	O
and	O
Pathfinding	B-Algorithm
Using	O
Navigation	B-Algorithm
Meshes	I-Algorithm
"	O
in	O
Game	O
Programming	O
Gems	O
.	O
</s>
<s>
van	O
Waveren	O
described	O
a	O
similar	O
structure	O
with	O
convex	O
and	O
connected	O
3D	O
polygons	O
,	O
dubbed	O
the	O
"	O
Area	O
Awareness	O
System	O
"	O
,	O
used	O
for	O
bots	O
in	O
Quake	B-Application
III	I-Application
Arena	I-Application
.	O
</s>
