<s>
AC3D	B-Language
is	O
a	O
3D	O
design	O
program	O
which	O
has	O
been	O
available	O
since	O
1994	O
.	O
</s>
<s>
The	O
software	O
is	O
used	O
by	O
designers	O
for	O
modeling	O
3D	O
graphics	O
for	O
games	O
and	O
simulations	O
-	O
most	O
notably	O
it	O
is	O
used	O
by	O
the	O
scenery	O
creators	O
at	O
Laminar	O
Research	O
on	O
the	O
X-Plane	O
(	O
simulator	O
)	O
.	O
</s>
<s>
The	O
.ac	O
format	O
has	O
also	O
been	O
used	O
in	O
FlightGear	B-Language
for	O
scenery	O
objects	O
and	O
aircraft	O
models	O
.	O
</s>
<s>
Initially	O
developed	O
on	O
the	O
Amiga	B-Device
,	O
the	O
code	O
was	O
then	O
ported	O
to	O
Silicon	O
Graphics	O
workstations	O
which	O
used	O
the	O
GL	O
graphics	O
library	O
.	O
</s>
<s>
At	O
that	O
time	O
,	O
the	O
user	O
interface	O
was	O
implemented	O
using	O
X11/Motif	O
.	O
</s>
<s>
A	O
Linux	B-Application
port	O
was	O
released	O
onto	O
the	O
internet	O
in	O
1994	O
(	O
the	O
GL	O
graphics	O
were	O
replaced	O
with	O
OpenGL	B-Application
)	O
.	O
</s>
<s>
A	O
Microsoft	B-Application
Windows	I-Application
port	O
followed	O
when	O
the	O
X11	B-Operating_System
interface	O
was	O
dropped	O
in	O
favor	O
of	O
the	O
portable	O
Tcl/Tk	B-Application
scripting	O
library	O
.	O
</s>
<s>
In	O
2002	O
,	O
Inivis	O
Limited	O
purchased	O
the	O
full	O
intellectual	O
property	O
rights	O
to	O
AC3D	B-Language
and	O
continues	O
to	O
develop	O
and	O
market	O
the	O
software	O
.	O
</s>
<s>
They	O
decided	O
to	O
keep	O
the	O
name	O
AC3D	B-Language
for	O
the	O
software	O
.	O
</s>
<s>
In	O
2005	O
,	O
a	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
version	O
of	O
AC3D	B-Language
was	O
released	O
.	O
</s>
<s>
AC3D	B-Language
's	O
modeling	O
is	O
polygon/subdivision	O
-surface	O
based	O
.	O
</s>
<s>
Unlike	O
some	O
other	O
3D	O
software	O
,	O
AC3D	B-Language
refers	O
to	O
'	O
surfaces	O
 '	O
rather	O
than	O
'	O
polygons	O
 '	O
.	O
</s>
<s>
An	O
AC3D	B-Language
surface	O
can	O
be	O
a	O
polygon	O
,	O
polygon-outline	O
or	O
line	O
.	O
</s>
<s>
An	O
AC3D	B-Language
object	O
is	O
a	O
collection	O
of	O
surfaces	O
.	O
</s>
<s>
AC3D	B-Language
can	O
load	O
and	O
save	O
a	O
wide	O
variety	O
of	O
3D	O
file	O
formats	O
but	O
primarily	O
uses	O
its	O
own	O
.ac	O
file	O
format	O
which	O
is	O
ascii	O
.	O
</s>
<s>
Inivis	O
is	O
the	O
first	O
3rd	O
party	O
vendor	O
to	O
offer	O
officially	O
sanctioned	O
support	O
for	O
the	O
Second	B-Application
Life	I-Application
sculpted	B-Application
prim	I-Application
format	O
;	O
exporters	O
for	O
other	O
3D	O
software	O
packages	O
exist	O
,	O
but	O
are	O
solely	O
user-supported	O
.	O
</s>
<s>
Extra	O
functionality	O
can	O
be	O
added	O
to	O
AC3D	B-Language
via	O
Tcl/Tk	B-Application
scripts	O
and/or	O
C/C	O
++	O
dynamic	O
libraries	O
(	O
plug-ins	B-Application
)	O
.	O
</s>
<s>
A	O
software	B-Application
development	I-Application
kit	I-Application
(	O
SDK	O
)	O
is	O
available	O
to	O
licensed	O
users	O
.	O
</s>
