<s>
The	O
4A	B-Application
Engine	I-Application
is	O
a	O
graphics	O
middleware	O
engine	O
developed	O
by	O
4A	O
Games	O
for	O
use	O
in	O
their	O
video	O
game	O
Metro	B-Application
2033	I-Application
,	O
published	O
by	O
THQ	O
.	O
</s>
<s>
It	O
supports	O
Direct3D	B-Application
APIs	O
9	O
,	O
10	O
,	O
11	O
,	O
and	O
recently	O
12	O
,	O
OpenGL	B-Application
3.2	O
,	O
along	O
with	O
NVidia	O
's	O
PhysX	B-Operating_System
,	O
and	O
also	O
NVidia	O
's	O
3D	O
Vision	O
.	O
</s>
<s>
:	O
Shadow	B-Application
of	I-Application
Chernobyl	I-Application
,	O
notably	O
Oles	O
Shishkovtsov	O
and	O
Oleksandr	O
Maksimchuk	O
,	O
the	O
programmers	O
who	O
worked	O
on	O
the	O
development	O
of	O
the	O
X-Ray	B-Application
engine	I-Application
used	O
in	O
the	O
S.T.A.L.K.E.R.	O
</s>
<s>
The	O
engine	O
itself	O
is	O
capable	O
of	O
running	O
on	O
PC	O
,	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
,	O
and	O
the	O
PlayStation	B-Operating_System
3	I-Operating_System
.	O
</s>
<s>
The	O
game	O
is	O
multi-threaded	O
such	O
that	O
only	O
PhysX	B-Operating_System
had	O
a	O
dedicated	O
thread	O
and	O
uses	O
a	O
task-model	O
without	O
any	O
pre-conditioning	O
or	O
pre/post	O
-synchronising	O
,	O
allowing	O
tasks	O
to	O
be	O
done	O
in	O
parallel	O
.	O
</s>
<s>
When	O
the	B-Operating_System
Xbox	I-Operating_System
360	I-Operating_System
iteration	O
had	O
been	O
measured	O
during	O
development	O
,	O
they	O
were	O
running	O
it	O
at	O
"	O
approximately	O
3,000	O
tasks	O
per	O
30ms	O
frame	O
on	O
Xbox	B-Operating_System
360	I-Operating_System
on	O
CPU-intensive	O
scenes	O
with	O
all	O
hardware	O
threads	O
at	O
100	O
percent	O
load	O
"	O
.	O
</s>
<s>
Shishkovtsov	O
also	O
said	O
that	O
the	O
GeForce	O
6	O
series	O
architecture	O
of	O
the	O
RSX	B-Device
Reality	I-Device
Synthesizer	I-Device
in	O
the	O
PlayStation	B-Operating_System
3	I-Operating_System
proved	O
to	O
be	O
very	O
useful	O
during	O
development	O
noted	O
that	O
there	O
were	O
many	O
"	O
wasted	O
cycles	O
"	O
.	O
</s>
<s>
The	O
engine	O
can	O
utilise	O
a	O
deferred	O
shading	O
pipeline	O
,	O
and	O
uses	O
tesselation	O
for	O
greater	O
performance	O
,	O
and	O
also	O
has	O
HDR	B-General_Concept
(	O
complete	O
with	O
blue	O
shift	O
)	O
,	O
real-time	O
reflections	O
,	O
colour	O
correction	O
,	O
film	O
grain	O
and	O
noise	O
,	O
and	O
the	O
engine	O
also	O
supports	O
multi-core	O
rendering	O
.	O
</s>
<s>
The	O
4A	B-Application
Engine	I-Application
implementation	O
of	O
Metro	B-Application
2033	I-Application
features	O
volumetric	O
fog	O
,	O
double	O
PhysX	B-Operating_System
precision	O
,	O
object	O
blur	O
,	O
sub-surface	B-Algorithm
scattering	I-Algorithm
for	O
skin	O
shaders	O
,	O
parallax	O
mapping	O
on	O
all	O
surfaces	O
and	O
greater	O
geometric	O
detail	O
with	O
a	O
less	O
aggressive	O
LOD(s )	O
.	O
</s>
<s>
Using	O
PhysX	B-Operating_System
,	O
the	O
engine	O
uses	O
many	O
features	O
such	O
as	O
destructible	O
environments	O
,	O
and	O
cloth	O
and	O
water	O
simulations	O
,	O
and	O
particles	O
that	O
can	O
be	O
fully	O
affected	O
by	O
environmental	O
factors	O
.	O
</s>
<s>
The	O
audio	O
in	O
the	O
engine	O
features	O
3D	B-Application
sound	I-Application
positioning	I-Application
,	O
spatialisation	O
and	O
attenuation	O
.	O
</s>
<s>
There	O
have	O
been	O
accusations	O
that	O
the	O
4A	B-Application
Engine	I-Application
is	O
a	O
modified	O
version	O
of	O
the	O
X-Ray	B-Application
engine	I-Application
used	O
in	O
the	O
S.T.A.L.K.E.R	O
series	O
,	O
instead	O
of	O
an	O
original	O
development	O
.	O
</s>
