<s>
Cube	B-Application
2	I-Application
:	I-Application
Sauerbraten	I-Application
(	O
German	O
for	O
"	O
sour	B-Application
roast	I-Application
"	O
,	O
also	O
known	O
as	O
Sauer	O
)	O
is	O
a	O
cross-platform	B-Operating_System
,	O
Quake-like	O
first-person	O
shooter	O
that	O
runs	O
on	O
Microsoft	B-Application
Windows	I-Application
,	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
,	O
OpenBSD	B-Operating_System
,	O
and	O
Mac	B-Application
OS	I-Application
X	I-Application
using	O
OpenGL	B-Application
and	O
SDL	B-Operating_System
.	O
</s>
<s>
The	O
game	O
engine	O
is	O
free	B-License
and	I-License
open-source	I-License
software	I-License
,	O
under	O
the	O
zlib	B-License
License	I-License
,	O
with	O
commercial	O
support	O
available	O
from	O
the	O
developer	O
's	O
business	O
counterpart	O
,	O
Dot3	O
Labs	O
.	O
</s>
<s>
Cube	B-Application
2	O
features	O
singleplayer	O
and	O
multiplayer	O
,	O
the	O
latter	O
offering	O
LAN	B-General_Concept
,	O
local	O
,	O
and	O
online	O
play	O
.	O
</s>
<s>
The	O
game	O
features	O
multiple	O
modes	O
,	O
such	O
as	O
deathmatch	O
,	O
Capture	B-Application
the	I-Application
Flag	I-Application
,	O
and	O
variations	O
thereof	O
.	O
</s>
<s>
Cube	B-Application
2	I-Application
:	I-Application
Sauerbraten	I-Application
started	O
as	O
a	O
redesign	O
of	O
the	O
original	O
Cube	B-Application
game	O
engine	O
.	O
</s>
<s>
The	O
engine	O
is	O
written	O
in	O
C++	B-Language
and	O
OpenGL	B-Application
.	O
</s>
<s>
The	O
game	O
shares	O
most	O
of	O
its	O
design	O
goals	O
and	O
philosophy	O
with	O
its	O
predecessor	O
,	O
but	O
uses	O
a	O
new	O
6-directional	O
heightfield	O
(	O
or	O
octree	B-Data_Structure
)	O
world	O
model	O
.	O
</s>
<s>
The	O
game	O
was	O
ported	O
to	O
iOS	B-Application
by	O
FernLightning	O
.	O
</s>
<s>
Since	O
the	O
engine	O
code	O
is	O
open-source	O
,	O
a	O
number	O
of	O
forks	B-Application
and	O
derivatives	O
have	O
been	O
based	O
on	O
it	O
,	O
most	O
notably	O
:	O
</s>
<s>
Platinum	B-Application
Arts	I-Application
Sandbox	I-Application
forks	B-Application
the	O
Cube	B-Application
2	I-Application
engine	I-Application
to	O
create	O
a	O
standalone	O
game	B-Application
creation	I-Application
system	I-Application
.	O
</s>
<s>
Red	B-Application
Eclipse	I-Application
,	O
a	O
fork	B-Application
of	O
Cube	B-Application
2	O
with	O
improvements	O
to	O
the	O
engine	O
featuring	O
a	O
different	O
style	O
of	O
gameplay	O
.	O
</s>
<s>
Tesseract	O
,	O
which	O
features	O
an	O
improved	O
version	O
of	O
the	O
Cube	B-Application
2	O
game	O
engine	O
.	O
</s>
<s>
OctaForge	O
is	O
a	O
fork	B-Application
of	O
Tesseract	O
.	O
</s>
<s>
Tomatenquark	O
is	O
a	O
fork	B-Application
of	O
Cube	B-Application
2	O
that	O
is	O
available	O
from	O
Steam	B-Application
.	O
</s>
<s>
Cardboard	O
is	O
fork	B-Application
created	O
for	O
the	O
shooter	O
game	O
Carmine	O
Impact	O
available	O
on	O
Steam	B-Application
.	O
</s>
<s>
Syntensity	O
was	O
a	O
fork	B-Application
of	O
Cube	B-Application
2	O
focused	O
on	O
creating	O
online	O
content	O
.	O
</s>
<s>
In	O
2012	O
,	O
Mozilla	B-Operating_System
researcher	O
Alon	O
Zakai	O
created	O
a	O
browser	O
based	O
demo	O
called	O
BananaBread	O
by	O
using	O
Emscripten	B-Language
to	O
port	O
the	O
C++	B-Language
code	I-Language
to	O
JavaScript	B-Language
and	O
WebGL	B-Library
.	O
</s>
<s>
Cube	B-Application
2'''s	O
rendering	O
engine	O
is	O
designed	O
around	O
modern	O
graphics	B-Architecture
processing	I-Architecture
units	I-Architecture
,	O
which	O
perform	O
best	O
with	O
huge	O
batches	O
of	O
geometry	O
already	O
stored	O
in	O
video	O
memory	O
.	O
</s>
<s>
Lighting	O
is	O
precomputed	O
into	O
lightmaps	B-Data_Structure
—	O
image	O
files	O
that	O
correspond	O
to	O
geometry	O
as	O
textures	O
—	O
for	O
efficient	O
batching	O
,	O
with	O
an	O
additional	O
stored	O
directional	O
component	O
,	O
that	O
allows	O
for	O
efficient	O
shader-based	O
lighting	O
effects	O
.	O
</s>
<s>
The	O
original	O
Cube	B-Application
engine	I-Application
's	O
rendering	O
engine	O
assumed	O
that	O
overdraw	O
(	O
where	O
polygons	O
that	O
do	O
not	O
appear	O
in	O
the	O
final	O
scene	O
are	O
occluded	O
via	O
the	O
z-buffer	O
)	O
was	O
more	O
processor-intensive	O
than	O
sending	O
new	O
streams	O
of	O
triangles	O
to	O
the	O
graphics	O
processing	O
every	O
frame	O
,	O
which	O
vastly	O
limited	O
its	O
performance	O
on	O
more	O
modern	O
hardware	O
where	O
memory	B-General_Concept
bandwidth	I-General_Concept
is	O
a	O
greater	O
limiting	O
factor	O
.	O
</s>
<s>
thumb|140px|right|An	O
example	O
of	O
a	O
primitive	O
cube	B-Application
subdivisionCube	O
2	O
:	O
Sauerbraten	B-Application
uses	O
a	O
6-directional	O
heightfield	O
(	O
or	O
octree	B-Data_Structure
)	O
world	O
model	O
.	O
</s>
<s>
An	O
octree	B-Data_Structure
,	O
in	O
Sauerbraten	B-Application
,	O
is	O
a	O
cube	B-Application
that	O
can	O
be	O
split	O
into	O
eight	O
smaller	O
cubes	B-Application
;	O
those	O
smaller	O
cubes	B-Application
are	O
also	O
octrees	B-Data_Structure
,	O
and	O
can	O
be	O
subdivided	O
further	O
.	O
</s>
<s>
Each	O
cube-shaped	O
node	O
in	O
the	O
octree	B-Data_Structure
represents	O
a	O
renderable	O
volume	O
,	O
or	O
a	O
type	O
of	O
Marching	O
cube	B-Application
,	O
which	O
are	O
referred	O
to	O
as	O
a	O
cube	B-Application
,	O
where	O
each	O
edge	O
of	O
this	O
cube	B-Application
can	O
be	O
lengthened	O
or	O
shortened	O
to	O
deform	O
the	O
cube	B-Application
into	O
a	O
variety	O
of	O
other	O
shapes	O
.	O
</s>
<s>
Corners	O
of	O
cubes	B-Application
can	O
also	O
be	O
"	O
pushed	O
"	O
or	O
"	O
pulled	O
"	O
to	O
create	O
crude	O
curves	O
.	O
</s>
<s>
The	O
what	B-Application
you	I-Application
see	I-Application
is	I-Application
what	I-Application
you	I-Application
get	I-Application
realtime	O
editing	O
has	O
enabled	O
level	O
designers	O
to	O
add	O
a	O
lot	O
of	O
detail	O
to	O
maps	O
,	O
while	O
reducing	O
the	O
time	O
spent	O
on	O
actual	O
creation	O
.	O
</s>
<s>
This	O
is	O
in	O
contrast	O
to	O
traditional	O
modern	O
polygon	B-Data_Structure
soup	I-Data_Structure
3D	O
engines	O
which	O
take	O
a	O
model	O
generated	O
as	O
an	O
essentially	O
random	O
batch	O
of	O
triangles	O
from	O
an	O
external	O
modelling	O
program	O
and	O
attempt	O
to	O
spatially	B-Algorithm
subdivide	I-Algorithm
the	O
model	O
's	O
triangles	O
after	O
the	O
fact	O
by	O
splitting	O
them	O
to	O
fit	O
into	O
tree	O
structures	O
,	O
such	O
as	O
a	O
BSP	O
tree	O
or	O
even	O
an	O
octree	B-Data_Structure
,	O
that	O
require	O
costly	O
pre-processing	O
to	O
build	O
.	O
</s>
<s>
Cube	B-Application
2	O
's	O
novelty	O
thus	O
lies	O
in	O
that	O
the	O
world	O
representation	O
is	O
the	O
octree	B-Data_Structure
,	O
or	O
Marching	B-Algorithm
cubes	I-Algorithm
,	O
structure	O
itself	O
,	O
from	O
which	O
efficient	O
triangle	O
batches	O
are	O
generated	O
for	O
the	O
graphics	B-Architecture
processing	I-Architecture
unit	I-Architecture
to	O
render	O
,	O
without	O
need	O
for	O
expensive	O
and	O
time-consuming	O
pre-processing	O
.	O
</s>
<s>
The	O
"	O
CTF	O
Edition	O
"	O
was	O
reviewed	O
positively	O
by	O
Phoronix	O
,	O
a	O
Linux-focused	O
hardware	O
and	O
software	O
review	O
website	O
,	O
as	O
well	O
as	O
Linux.com,	O
a	O
website	O
providing	O
news	O
related	O
to	O
free	B-License
and	I-License
open-source	I-License
software	I-License
.	O
</s>
