<s>
Glide	B-Operating_System
is	O
a	O
3D	O
graphics	O
API	B-Application
developed	O
by	O
3dfx	O
Interactive	O
for	O
their	O
Voodoo	O
Graphics	O
3D	B-Architecture
accelerator	I-Architecture
cards	I-Architecture
.	O
</s>
<s>
Although	O
it	O
originally	O
started	O
as	O
a	O
proprietary	O
API	B-Application
,	O
it	O
was	O
later	O
open	B-License
sourced	I-License
by	O
3dfx	O
.	O
</s>
<s>
Wide	O
adoption	O
of	O
3Dfx	O
led	O
to	O
Glide	B-Operating_System
being	O
extensively	O
used	O
in	O
the	O
late	O
1990s	O
,	O
but	O
further	O
refinement	O
of	O
Microsoft	O
's	O
Direct3D	B-Application
and	O
the	O
appearance	O
of	O
full	O
OpenGL	B-Application
implementations	O
from	O
other	O
graphics	B-Device
card	I-Device
vendors	O
,	O
in	O
addition	O
to	O
growing	O
diversity	O
in	O
3D	O
hardware	O
,	O
eventually	O
caused	O
it	O
to	O
become	O
superfluous	O
.	O
</s>
<s>
Glide	B-Operating_System
emulator	O
development	O
has	O
been	O
in	O
progress	O
since	O
the	O
late	O
1990s	O
.	O
</s>
<s>
During	O
3dfx	O
's	O
lifetime	O
,	O
the	O
company	O
was	O
aggressive	O
at	O
trying	O
to	O
stop	O
these	O
attempts	O
to	O
emulate	O
their	O
proprietary	O
API	B-Application
,	O
shutting	O
down	O
early	O
emulation	O
projects	O
with	O
legal	O
threats	O
.	O
</s>
<s>
However	O
,	O
just	O
before	O
it	O
ceased	O
operations	O
and	O
had	O
its	O
assets	O
purchased	O
by	O
Nvidia	O
,	O
3dfx	O
released	O
the	O
Glide	B-Operating_System
API	I-Operating_System
,	O
along	O
with	O
the	O
Voodoo	O
2	O
and	O
Voodoo	O
3	O
specifications	O
,	O
under	O
an	O
open	B-License
source	I-License
license	O
,	O
which	O
later	O
evolved	O
into	O
an	O
open	B-License
source	I-License
project	O
.	O
</s>
