<s>
id	O
Tech	O
3	O
,	O
popularly	O
known	O
as	O
the	O
Quake	B-Application
III	I-Application
Arena	I-Application
engine'''	O
,	O
is	O
a	O
game	O
engine	O
developed	O
by	O
id	O
Software	O
for	O
their	O
video	O
game	O
Quake	B-Application
III	I-Application
Arena	I-Application
.	O
</s>
<s>
During	O
its	O
time	O
,	O
it	O
competed	O
with	O
the	O
Unreal	B-Operating_System
Engine	I-Operating_System
;	O
both	O
engines	O
were	O
widely	O
licensed	O
.	O
</s>
<s>
While	O
id	O
Tech	O
3	O
is	O
based	O
on	O
id	B-Application
Tech	I-Application
2	I-Application
engine	O
,	O
a	O
large	O
amount	O
of	O
the	O
code	O
was	O
rewritten	O
.	O
</s>
<s>
Successor	O
id	B-Application
Tech	I-Application
4	I-Application
was	O
derived	O
from	O
id	O
Tech	O
3	O
,	O
as	O
was	O
Infinity	O
Ward	O
's	O
IW	B-Application
engine	I-Application
used	O
in	O
Call	B-Application
of	I-Application
Duty	I-Application
2	I-Application
onwards	O
.	O
</s>
<s>
At	O
QuakeCon	O
2005	O
,	O
John	O
Carmack	O
announced	O
that	O
the	O
id	O
Tech	O
3	O
source	O
code	O
would	O
be	O
released	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
v2.0	I-License
or	I-License
later	I-License
,	O
and	O
it	O
was	O
released	O
on	O
August	O
19	O
,	O
2005	O
.	O
</s>
<s>
Originally	O
distributed	O
by	O
id	O
via	O
FTP	B-Protocol
,	O
quake3-1.32b-source.zip	O
the	O
code	O
can	O
be	O
downloaded	O
from	O
id	O
's	O
GitHub	B-Application
account	O
.	O
</s>
<s>
Unlike	O
most	O
other	O
game	O
engines	O
released	O
at	O
the	O
time	O
—	O
including	O
its	O
primary	O
competitor	O
,	O
the	O
Unreal	B-Operating_System
Engine	I-Operating_System
,	O
id	O
Tech	O
3	O
requires	O
an	O
OpenGL-compliant	O
graphics	B-Architecture
accelerator	I-Architecture
to	O
run	O
.	O
</s>
<s>
In-game	O
videos	O
all	O
use	O
a	O
proprietary	B-Application
format	O
called	O
"	O
RoQ	O
"	O
,	O
which	O
was	O
originally	O
created	O
by	O
Graeme	O
Devine	O
,	O
the	O
co-designer	O
of	O
Quake	B-Application
3	I-Application
,	O
for	O
the	O
game	O
The	B-Application
11th	I-Application
Hour	I-Application
.	O
</s>
<s>
Internally	O
RoQ	O
uses	O
vector	B-Algorithm
quantization	I-Algorithm
to	O
encode	O
video	O
and	O
DPCM	B-Algorithm
to	O
encode	O
audio	O
.	O
</s>
<s>
While	O
the	O
format	O
itself	O
is	O
proprietary	B-Application
it	O
was	O
successfully	O
reverse-engineered	O
in	O
2001	O
,	O
and	O
the	O
actual	O
RoQ	O
decoder	O
is	O
present	O
in	O
the	O
Quake	B-Application
3	I-Application
source	O
code	O
release	O
.	O
</s>
<s>
RoQ	O
has	O
seen	O
little	O
use	O
outside	O
games	O
based	O
on	O
the	O
id	O
Tech	O
3	O
or	O
id	B-Application
Tech	I-Application
4	I-Application
engines	O
,	O
but	O
is	O
supported	O
by	O
several	O
video	O
players	O
(	O
such	O
as	O
MPlayer	B-Application
)	O
and	O
a	O
handful	O
of	O
third-party	O
encoders	O
exist	O
.	O
</s>
<s>
The	O
animation	O
features	O
in	O
the	O
MD3	O
format	O
are	O
superior	O
to	O
those	O
in	O
id	B-Application
Tech	I-Application
2	I-Application
's	O
MD2	O
format	O
because	O
an	O
animator	O
is	O
able	O
to	O
have	O
a	O
variable	O
number	O
of	O
key	O
frames	O
per	O
second	O
instead	O
of	O
MD2	O
's	O
standard	O
10	O
key	O
frames	O
per	O
second	O
.	O
</s>
<s>
This	O
allows	O
for	O
more	O
complex	O
animations	O
that	O
are	O
less	O
"	O
shaky	O
"	O
than	O
the	O
models	O
found	O
in	O
Quake	B-Application
II	I-Application
.	O
</s>
<s>
The	O
character	O
models	O
are	O
lit	O
and	O
shaded	O
using	O
Gouraud	B-Algorithm
shading	I-Algorithm
while	O
the	O
levels	O
(	O
stored	O
in	O
the	O
BSP	B-Application
format	I-Application
)	O
are	O
lit	O
either	O
with	O
lightmaps	B-Data_Structure
or	O
Gouraud	B-Algorithm
shading	I-Algorithm
depending	O
on	O
the	O
user	O
's	O
preference	O
.	O
</s>
<s>
It	O
is	O
presumed	O
that	O
id	O
simply	O
never	O
finished	O
the	O
format	O
,	O
ioquake3	B-Application
md4-readme.txt	O
although	O
almost	O
all	O
licensees	O
derived	O
their	O
own	O
skeletal	O
animation	O
systems	O
from	O
what	O
was	O
present	O
.	O
</s>
<s>
Ritual	O
Entertainment	O
did	O
this	O
for	O
use	O
in	O
the	O
game	O
,	O
Heavy	B-Operating_System
Metal	I-Operating_System
:	I-Operating_System
F.A.K.K.²	I-Operating_System
,	O
the	O
SDK	B-Application
to	O
which	O
formed	O
the	O
basis	O
of	O
MD4	O
support	O
completed	O
by	O
someone	O
who	O
used	O
the	O
pseudonym	O
Gongo	O
.	O
</s>
<s>
Other	O
visual	O
features	O
include	O
volumetric	B-General_Concept
fog	I-General_Concept
,	O
mirrors	O
,	O
portals	O
,	O
decals	O
,	O
and	O
wave-form	O
vertex	O
distortion	O
.	O
</s>
<s>
This	O
problem	O
was	O
also	O
present	O
in	O
the	O
Doom	B-Application
3	I-Application
,	O
Quake	B-Application
,	O
and	O
Quake	B-Application
II	I-Application
engines	I-Application
.	O
</s>
<s>
Networkingid	O
Tech	O
3	O
uses	O
a	O
"	O
snapshot	O
"	O
system	O
to	O
relay	O
information	O
about	O
game	O
"	O
frames	O
"	O
to	O
the	O
client	O
over	O
UDP	B-Protocol
.	O
</s>
<s>
The	O
server	O
attempts	O
to	O
omit	O
as	O
much	O
information	O
as	O
possible	O
about	O
each	O
frame	O
,	O
relaying	O
only	O
differences	O
from	O
the	O
last	O
frame	O
the	O
client	O
confirmed	O
as	O
received	O
(	O
Delta	B-Algorithm
encoding	I-Algorithm
)	O
.	O
</s>
<s>
All	O
data	O
packets	O
are	O
compressed	O
by	O
Huffman	B-General_Concept
coding	I-General_Concept
with	O
static	O
pre-calculated	O
frequency	O
data	O
to	O
reduce	O
bandwidth	O
use	O
even	O
further.Quake	O
3	O
also	O
integrated	O
a	O
relatively	O
elaborate	O
cheat-protection	O
system	O
called	O
"	O
pure	O
server.	O
"	O
</s>
<s>
Later	O
versions	O
supplemented	O
pure	O
server	O
with	O
PunkBuster	B-Application
support	O
,	O
though	O
all	O
the	O
hooks	O
to	O
it	O
are	O
absent	O
from	O
the	O
source	O
code	O
release	O
because	O
PunkBuster	B-Application
is	O
closed	B-Application
source	I-Application
software	I-Application
and	O
including	O
support	O
for	O
it	O
in	O
the	O
source	O
code	O
release	O
would	O
have	O
caused	O
any	O
redistributors/reusers	O
of	O
the	O
code	O
to	O
violate	O
the	O
GPL	B-License
.	O
</s>
<s>
Virtual	O
machineid	O
Tech	O
3	O
uses	O
a	O
virtual	B-Architecture
machine	I-Architecture
to	O
control	O
object	O
behavior	O
on	O
the	O
server	O
,	O
effects	O
and	O
prediction	O
on	O
the	O
client	O
and	O
the	O
user	O
interface	O
.	O
</s>
<s>
This	O
presents	O
many	O
advantages	O
as	O
mod	O
authors	O
do	O
not	O
need	O
to	O
worry	O
about	O
crashing	O
the	O
entire	O
game	O
with	O
bad	O
code	O
,	O
clients	O
could	O
show	O
more	O
advanced	O
effects	O
and	O
game	O
menus	O
than	O
was	O
possible	O
in	O
Quake	B-Application
II	I-Application
and	O
the	O
user	O
interface	O
for	O
mods	O
was	O
entirely	O
customizable	O
.	O
</s>
<s>
Virtual	B-Architecture
machine	I-Architecture
files	O
are	O
developed	O
in	O
ANSI	O
C	B-Language
,	O
using	O
LCC	B-Language
to	O
compile	O
them	O
to	O
a	O
32-bit	O
RISC	B-Architecture
pseudo-assembly	O
format	O
.	O
</s>
<s>
Unless	O
operations	O
which	O
require	O
a	O
specific	O
endianness	O
are	O
used	O
,	O
a	O
QVM	O
file	O
will	O
run	O
the	O
same	O
on	O
any	O
platform	O
supported	O
by	O
Quake	O
3.The	O
virtual	B-Architecture
machine	I-Architecture
also	O
contained	O
bytecode	O
compilers	O
for	O
the	O
x86	B-Operating_System
and	O
PowerPC	B-Architecture
architectures	O
,	O
executing	O
QVM	O
instructions	O
via	O
an	O
interpreter	B-Application
.	O
</s>
<s>
Ioquake3	B-Application
is	O
a	O
game	O
engine	O
project	O
which	O
aims	O
to	O
build	O
upon	O
the	O
id	O
Tech	O
3	O
source	O
code	O
release	O
in	O
order	O
to	O
remove	O
bugs	B-Error_Name
,	O
clean	O
up	O
source	O
code	O
and	O
to	O
add	O
more	O
advanced	O
graphical	O
and	O
audio	O
features	O
via	O
SDL	B-Operating_System
and	O
OpenAL	B-Application
.	O
</s>
<s>
ioquake3	B-Application
is	O
also	O
intended	O
to	O
act	O
as	O
a	O
clean	O
base	O
package	O
,	O
upon	O
which	O
other	O
projects	O
may	O
be	O
built	O
.	O
</s>
<s>
The	O
game	O
engine	O
supports	O
Ogg	B-Algorithm
Vorbis	I-Algorithm
format	O
and	O
video	O
capture	O
of	O
demos	O
in	O
.avi	O
format	O
.	O
</s>
<s>
The	O
project	O
was	O
started	O
shortly	O
after	O
the	O
source	O
code	O
release	O
with	O
the	O
goal	O
of	O
creating	O
a	O
bug-free	O
,	O
enhanced	O
open	B-License
source	I-License
Quake	B-Application
III	I-Application
engine	O
source	O
code	O
distribution	O
upon	O
which	O
new	O
games	O
and	O
projects	O
can	O
be	O
based	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
project	O
aims	O
to	O
provide	O
an	O
improved	O
environment	O
in	O
which	O
Quake	B-Application
III	I-Application
:	I-Application
Arena	I-Application
,	O
the	O
Team	O
Arena	O
expansion	O
pack	O
and	O
all	O
the	O
popular	O
mods	O
can	O
be	O
played	O
.	O
</s>
<s>
Notable	O
features	O
added	O
by	O
the	O
project	O
include	O
builtin	O
VoIP	B-Application
support	O
,	O
Anaglyph	B-Algorithm
stereo	I-Algorithm
rendering	I-Algorithm
(	O
for	O
viewing	O
with	O
3D	O
glasses	O
)	O
,	O
and	O
numerous	O
security	O
fixes	O
.	O
</s>
<s>
Ioquake3	B-Application
has	O
been	O
the	O
basis	O
of	O
several	O
game	O
projects	O
based	O
on	O
the	O
id	O
Tech	O
3	O
engine	O
,	O
such	O
as	O
OpenArena	B-Application
(	O
mimicking	O
Quake	B-Application
III	I-Application
Arena	I-Application
)	O
,	O
Tremulous	B-Application
,	O
Smokin	B-Application
 '	I-Application
Guns	I-Application
,	O
Urban	B-Application
Terror	I-Application
,	O
Turtle	O
Arena	O
and	O
World	B-Application
of	I-Application
Padman	I-Application
as	O
well	O
as	O
game	O
engine	O
projects	O
such	O
as	O
efport	O
(	O
a	O
Star	B-Operating_System
Trek	I-Operating_System
:	I-Operating_System
Voyager	I-Operating_System
–	I-Operating_System
Elite	I-Operating_System
Force	I-Operating_System
Holomatch	B-Operating_System
engine	O
recreation	O
project	O
)	O
,	O
ioJedi	O
Outcast	O
,	O
ioJedi	O
Academy	O
,	O
ioDoom3	O
and	O
OpenMoHAA	B-Application
.	O
</s>
<s>
The	O
engine	O
and	O
its	O
associated	O
games	O
have	O
been	O
included	O
in	O
several	O
Linux	B-Application
and	O
BSD	B-Operating_System
distributions	O
.	O
</s>
<s>
The	O
cMod	O
engine	O
derived	O
from	O
the	O
earlier	O
Elite	O
Force	O
port	O
was	O
used	O
to	O
package	O
the	O
20th	O
anniversary	O
freeware	O
release	O
of	O
the	O
game	O
for	O
Windows	O
and	O
Linux	B-Application
.	O
</s>
<s>
The	O
source	O
code	O
for	O
the	O
Return	B-Application
to	I-Application
Castle	I-Application
Wolfenstein	I-Application
and	O
Wolfenstein	B-Application
:	I-Application
Enemy	I-Application
Territory	I-Application
engines	O
was	O
released	O
under	O
GNU	B-License
GPL-3.0-or-later	I-License
on	O
August	O
12	O
,	O
2010.ftp://ftp.idsoftware.com/idstuff/source/	O
The	O
ioquake3	B-Application
developers	O
announced	O
the	O
start	O
of	O
respective	O
engine	O
projects	O
(	O
iortcw	O
,	O
Iortcw	O
compiled	O
package	O
iowolfet	O
,	O
ET	O
:	O
Legacy	O
)	O
soon	O
after	O
.	O
</s>
<s>
The	O
ioquake3	B-Application
project	O
has	O
also	O
been	O
used	O
in	O
the	O
academic	O
arena	O
as	O
the	O
basis	O
for	O
a	O
variety	O
of	O
research	O
in	O
institutions	O
such	O
as	O
Stanford	O
University	O
's	O
Center	O
for	O
Computer	O
Research	O
in	O
Music	O
and	O
Acoustics	O
(	O
CCRMA	O
)	O
,	O
Notre	O
Dame	O
as	O
the	O
foundation	O
for	O
VR	O
research	O
,	O
and	O
Swinburne	O
University	O
of	O
Technology	O
's	O
Centre	O
for	O
Advanced	O
Internet	O
Architectures	O
.	O
</s>
<s>
There	O
are	O
even	O
collaborative	O
efforts	O
from	O
researchers	O
at	O
Carnegie	O
Mellon	O
University	O
and	O
the	O
University	O
of	O
Toronto	O
that	O
use	O
ioquake3	B-Application
as	O
a	O
platform	O
for	O
their	O
published	O
researches	O
.	O
</s>
<s>
Students	O
have	O
used	O
ioquake3	B-Application
as	O
the	O
basis	O
for	O
advanced	O
graphics	O
work	O
for	O
their	O
theses	O
,	O
as	O
well	O
,	O
such	O
as	O
Stephan	O
Reiter	O
's	O
work	O
which	O
has	O
even	O
been	O
noted	O
at	O
the	O
LLVM	O
project	O
due	O
to	O
his	O
synthesis	O
of	O
the	O
ioquake3	B-Application
engine	O
,	O
ray-tracing	O
rendering	O
technique	O
,	O
and	O
LLVM	O
.	O
</s>
<s>
Though	O
the	O
name	O
"	O
ioquake3	B-Application
"	O
is	O
based	O
on	O
Ryan	O
"	O
Icculus	O
"	O
Gordon	O
's	O
site	O
icculus.org,	O
Ryan	O
does	O
not	O
lead	O
the	O
project	O
.	O
</s>
<s>
Instead	O
,	O
he	O
maintains	O
a	O
mentor	O
role	O
and	O
provides	O
hosting	O
for	O
the	O
mailing	O
lists	O
and	O
the	O
SVN	B-Application
repository	I-Application
used	O
by	O
the	O
project	O
.	O
</s>
<s>
OpenArena	B-Application
–	O
An	O
open	B-License
source	I-License
standalone	O
game	O
based	O
heavily	O
on	O
the	O
Quake	O
III	O
Arena-style	O
deathmatch	O
.	O
</s>
<s>
The	O
gameplay	O
attempts	O
to	O
emulate	O
Quake	B-Application
III	I-Application
Arena	I-Application
in	O
that	O
the	O
player	O
scores	O
frags	O
to	O
win	O
the	O
game	O
using	O
a	O
variety	O
of	O
different	O
weapons	O
.	O
</s>
<s>
OpenArena	B-Application
is	O
also	O
capable	O
of	O
running	O
some	O
Quake	B-Application
III	I-Application
Arena	I-Application
based	O
mods	O
such	O
as	O
older	O
versions	O
of	O
Tremulous	B-Application
.	O
</s>
<s>
OpenArena	B-Application
runs	O
on	O
ioquake3	B-Application
and	O
version	O
0.8	O
has	O
been	O
successfully	O
ported	O
to	O
Android	B-Application
.	O
</s>
<s>
Space	B-Application
Trader	I-Application
–	O
An	O
action/strategy	O
game	O
from	O
HermitWorks	O
Entertainment	O
.	O
</s>
<s>
Smokin	B-Application
 '	I-Application
Guns	I-Application
–	O
An	O
open	B-License
source	I-License
first	O
person	O
game	O
that	O
intended	O
to	O
be	O
a	O
semi-realistic	O
simulation	O
of	O
the	O
"	O
Old	O
West	O
's	O
"	O
atmosphere	O
.	O
</s>
<s>
Originally	O
a	O
Quake	B-Application
III	I-Application
Arena	I-Application
modification	O
,	O
it	O
was	O
then	O
ported	O
to	O
the	O
ioquake3	B-Application
engine	O
in	O
2009	O
.	O
</s>
<s>
Urban	B-Application
Terror	I-Application
–	O
A	O
Quake	B-Application
III	I-Application
Arena	I-Application
total	O
conversion	O
mod	O
while	O
designed	O
and	O
released	O
to	O
work	O
with	O
the	O
retail	O
software	O
Quake	B-Application
III	I-Application
Arena	I-Application
,	O
it	O
is	O
also	O
compatible	O
with	O
open	B-License
source	I-License
engine	O
alternatives	O
.	O
</s>
<s>
The	O
gameplay	O
can	O
be	O
compared	O
to	O
Counter-Strike	B-Application
with	O
a	O
larger	O
focus	O
on	O
movement	O
with	O
its	O
parkour	O
features	O
.	O
</s>
<s>
Urban	B-Application
Terror	I-Application
runs	O
on	O
the	O
ioquake3	B-Application
engine	O
.	O
</s>
<s>
Tremulous	B-Application
–	O
Tremulous	B-Application
is	O
an	O
open	O
sourced	O
asymmetric	O
alien	O
vs	O
human	O
team	O
based	O
first-person	O
shooter	O
with	O
elements	O
of	O
real	O
time	O
strategy	O
.	O
</s>
<s>
Tremulous	B-Application
started	O
as	O
a	O
Quake	B-Application
III	I-Application
Arena	I-Application
mod	O
,	O
but	O
on	O
version	O
1.1	O
the	O
game	O
was	O
ported	O
over	O
to	O
the	O
ioquake3	B-Application
engine	O
.	O
</s>
<s>
It	O
has	O
spawned	O
a	O
successor	O
called	O
Unvanquished	B-Application
,	O
which	O
runs	O
on	O
the	O
Daemon	O
engine	O
.	O
</s>
<s>
The	O
current	O
version	O
runs	O
on	O
an	O
enhanced	O
version	O
of	O
the	O
ioquake3	B-Application
engine	O
.	O
</s>
