<s>
Direct3D	B-Application
and	O
OpenGL	B-Application
are	O
competing	O
application	B-Application
programming	I-Application
interfaces	I-Application
(	O
APIs	B-Application
)	O
which	O
can	O
be	O
used	O
in	O
applications	O
to	O
render	O
2D	O
and	O
3D	O
computer	O
graphics	O
.	O
</s>
<s>
,	O
graphics	B-Architecture
processing	I-Architecture
units	I-Architecture
(	O
GPUs	B-Architecture
)	O
almost	O
always	O
implement	O
one	O
version	O
of	O
both	O
of	O
these	O
APIs	B-Application
.	O
</s>
<s>
Examples	O
include	O
:	O
DirectX	B-Application
9	I-Application
and	O
OpenGL	B-Application
2	O
circa	O
2004	O
;	O
DirectX	B-Application
10	I-Application
and	O
OpenGL	B-Application
3	O
circa	O
2008	O
;	O
and	O
most	O
recently	O
,	O
DirectX	B-Application
11	O
and	O
OpenGL	B-Application
4	O
circa	O
2011	O
.	O
</s>
<s>
GPUs	B-Architecture
that	O
support	O
more	O
recent	O
versions	O
of	O
the	O
standards	O
are	O
backwards	B-General_Concept
compatible	I-General_Concept
with	O
applications	O
that	O
use	O
the	O
older	O
standards	O
;	O
for	O
example	O
,	O
one	O
can	O
run	O
older	O
DirectX	B-Application
9	I-Application
games	O
on	O
a	O
more	O
recent	O
DirectX	B-Application
11-certified	O
GPU	B-Architecture
.	O
</s>
<s>
Direct3D	B-Application
application	O
development	O
targets	O
the	O
Microsoft	B-Application
Windows	I-Application
platform	O
.	O
</s>
<s>
The	O
OpenGL	B-Application
API	B-Application
is	O
an	O
open	O
standard	O
,	O
which	O
means	O
that	O
various	O
hardware	O
makers	O
and	O
operating	B-General_Concept
system	I-General_Concept
developers	O
can	O
freely	O
create	O
an	O
OpenGL	B-Application
implementation	O
as	O
part	O
of	O
their	O
system	O
.	O
</s>
<s>
OpenGL	B-Application
implementations	O
exist	O
for	O
a	O
wide	O
variety	O
of	O
platforms	O
.	O
</s>
<s>
Most	O
notably	O
,	O
OpenGL	B-Application
is	O
the	O
dominating	O
graphics	O
API	B-Application
of	O
Unix-like	B-Operating_System
computer	O
systems	O
.	O
</s>
<s>
From	O
an	O
application	O
developer	O
's	O
perspective	O
,	O
Direct3D	B-Application
and	O
OpenGL	B-Application
are	O
equally	O
open	O
;	O
full	O
documentation	O
and	O
necessary	O
development	O
tools	O
are	O
available	O
with	O
no	O
restrictions	O
.	O
</s>
<s>
In	O
more	O
detail	O
,	O
the	O
two	O
computer	O
graphics	O
APIs	B-Application
are	O
the	O
following	O
:	O
</s>
<s>
Direct3D	B-Application
is	O
a	O
proprietary	B-Application
API	B-Application
by	O
Microsoft	O
that	O
provides	O
functions	O
to	O
render	O
two-dimensional	O
(	O
2D	O
)	O
and	O
three-dimensional	O
(	O
3D	O
)	O
graphics	O
,	O
and	O
uses	O
hardware	O
acceleration	O
if	O
available	O
on	O
the	O
graphics	O
card	O
.	O
</s>
<s>
It	O
was	O
designed	O
by	O
Microsoft	O
Corporation	O
for	O
use	O
on	O
the	O
Windows	B-Application
platform	O
.	O
</s>
<s>
OpenGL	B-Application
is	O
an	O
open	O
standard	O
API	B-Application
that	O
provides	O
many	O
functions	O
to	O
render	O
2D	O
and	O
3D	O
graphics	O
,	O
and	O
is	O
available	O
on	O
most	O
modern	O
operating	B-Operating_System
systems	I-Operating_System
including	O
but	O
not	O
limited	O
to	O
Windows	B-Application
,	O
macOS	B-Operating_System
,	O
and	O
Linux	B-Application
.	O
</s>
<s>
Note	O
that	O
many	O
essential	O
OpenGL	B-Application
extensions	O
and	O
methods	O
,	O
although	O
documented	O
,	O
are	O
also	O
patented	O
,	O
thus	O
imposing	O
serious	O
legal	O
troubles	O
to	O
implement	O
them	O
(	O
see	O
issues	O
with	O
Mesa	B-Application
)	O
.	O
</s>
<s>
OpenGL	B-Application
and	O
Direct3D	B-Application
are	O
both	O
implemented	O
in	O
the	O
display	O
device	B-Application
driver	I-Application
.	O
</s>
<s>
A	O
significant	O
difference	O
however	O
is	O
that	O
Direct3D	B-Application
implements	O
the	O
API	B-Application
in	O
a	O
common	O
runtime	O
(	O
supplied	O
by	O
Microsoft	O
)	O
,	O
which	O
in	O
turn	O
talks	O
to	O
a	O
low-level	O
device	B-Application
driver	I-Application
interface	I-Application
(	O
DDI	O
)	O
.	O
</s>
<s>
With	O
OpenGL	B-Application
,	O
every	O
vendor	O
implements	O
the	O
full	O
API	B-Application
in	O
the	O
driver	O
.	O
</s>
<s>
This	O
means	O
that	O
some	O
API	B-Application
functions	I-Application
may	O
have	O
slightly	O
different	O
behavior	O
from	O
one	O
vendor	O
to	O
the	O
next	O
.	O
</s>
<s>
The	O
following	O
compares	O
the	O
two	O
APIs	B-Application
,	O
structured	O
around	O
various	O
considerations	O
mostly	O
relevant	O
to	O
game	O
development	O
.	O
</s>
<s>
The	O
proprietary	B-Application
Direct3D	B-Application
is	O
officially	O
implemented	O
only	O
on	O
Microsoft	O
's	O
Windows	B-Application
family	O
of	O
operating	B-Operating_System
systems	I-Operating_System
,	O
including	O
embedded	O
versions	O
used	O
in	O
the	O
Xbox	B-Application
family	O
of	O
video	B-Device
game	I-Device
consoles	I-Device
and	O
Sega	O
's	O
Dreamcast	B-Operating_System
.	O
</s>
<s>
Several	O
mostly	O
functional	O
reimplementations	O
of	O
the	O
Direct3D	B-Application
API	B-Application
have	O
been	O
made	O
by	O
third	O
parties	O
such	O
as	O
Wine	B-Application
,	O
a	O
project	O
to	O
port	O
common	O
Windows	B-Application
APIs	B-Application
to	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
,	O
and	O
Cedega	B-General_Concept
,	O
a	O
proprietary	B-Application
fork	O
of	O
Wine	B-Application
.	O
</s>
<s>
However	O
,	O
this	O
process	O
is	O
progressively	O
impeded	O
due	O
to	O
the	O
interdependence	O
of	O
DirectX	B-Application
upon	O
many	O
other	O
proprietary	B-Application
components	O
of	O
Windows	B-Application
,	O
and	O
because	O
Direct3D	B-Application
's	O
proprietary	B-Application
nature	O
requires	O
the	O
difficult	O
process	O
of	O
reverse	O
engineering	O
.	O
</s>
<s>
OpenGL	B-Application
has	O
implementations	O
available	O
across	O
many	O
platforms	O
including	O
Microsoft	B-Application
Windows	I-Application
,	O
Unix-based	O
systems	O
such	O
as	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
Linux	B-Application
.	O
</s>
<s>
Nintendo	O
and	O
Sony	O
have	O
developed	O
their	O
own	O
libraries	O
which	O
are	O
similar	O
but	O
not	O
identical	O
to	O
OpenGL	B-Application
.	O
</s>
<s>
A	O
subset	O
of	O
OpenGL	B-Application
was	O
chosen	O
as	O
the	O
main	O
graphics	O
library	O
for	O
Android	B-Application
,	O
BlackBerry	B-Operating_System
,	O
iOS	B-Application
,	O
and	O
Symbian	B-Operating_System
in	O
the	O
OpenGL	B-Application
ES	I-Application
form	O
.	O
</s>
<s>
Microsoft	O
's	O
OpenGL	B-Application
driver	O
provides	O
hardware	O
acceleration	O
in	O
Windows	B-Application
Vista	I-Application
;	O
support	O
was	O
dropped	O
in	O
Windows	B-Application
XP	O
,	O
soon	O
after	O
they	O
failed	O
to	O
deliver	O
Fahrenheit	B-Library
graphics	I-Library
API	I-Library
low	O
level	O
support	O
for	O
an	O
OpenGL-Direct3D	O
merger	O
in	O
the	O
late	O
1990s	O
.	O
</s>
<s>
OpenGL	B-Application
hardware	O
acceleration	O
on	O
Windows	B-Application
is	O
achieved	O
by	O
users	O
first	O
installing	O
installable	O
client	O
drivers	O
(	O
ICDs	O
)	O
developed	O
by	O
GPU	B-Architecture
makers	O
.	O
</s>
<s>
These	O
ICDs	O
are	O
,	O
in	O
virtually	O
all	O
cases	O
,	O
bundled	O
with	O
the	O
standard	O
driver	O
download	O
package	O
from	O
the	O
hardware	B-Device
vendor	I-Device
(	O
IHV	O
)	O
,	O
so	O
installing	O
recent	O
graphics	O
drivers	O
is	O
sufficient	O
to	O
provide	O
hardware	O
OpenGL	B-Application
support	O
.	O
</s>
<s>
More	O
recently	O
,	O
Google	O
's	O
Almost	B-Language
Native	I-Language
Graphics	I-Language
Layer	I-Language
Engine	I-Language
(	O
ANGLE	B-Language
)	O
project	O
provides	O
a	O
means	O
to	O
convert	O
OpenGL	B-Application
ES	I-Application
2.0	O
application	O
calls	O
to	O
DirectX	B-Application
9	I-Application
.	O
</s>
<s>
This	O
is	O
done	O
so	O
that	O
WebGL	B-Library
(	O
a	O
subset	O
variant	O
of	O
OpenGL	B-Application
for	O
the	O
web	O
)	O
can	O
run	O
on	O
the	O
common	O
Direct3D	B-Application
runtime	O
,	O
which	O
means	O
there	O
will	O
be	O
less	O
variation	O
between	O
vendors	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
Direct3D	B-Application
in	O
1996	O
elicited	O
broad	O
criticism	O
because	O
even	O
simple	O
operations	O
,	O
such	O
as	O
state	O
changes	O
,	O
required	O
creating	O
and	O
submitting	O
objects	O
called	O
execute	O
buffers	O
.	O
</s>
<s>
In	O
contrast	O
,	O
in	O
OpenGL	B-Application
most	O
state	O
changes	O
can	O
be	O
performed	O
with	O
one	O
function	O
call	O
.	O
</s>
<s>
The	O
Direct3D	B-Application
model	O
frustrated	O
many	O
programmers	O
.	O
</s>
<s>
A	O
very	O
famous	O
complaint	O
was	O
made	O
by	O
high-profile	O
game	O
developer	O
John	O
D	O
.	O
Carmack	O
in	O
his	O
.plan	B-Application
file	O
in	O
which	O
he	O
urged	O
Microsoft	O
to	O
abandon	O
Direct3D	B-Application
in	O
favor	O
of	O
OpenGL	B-Application
.	O
</s>
<s>
Carmack	O
explained	O
,	O
"	O
OpenGL	B-Application
is	O
easy	O
to	O
use	O
and	O
fun	O
to	O
experiment	O
with	O
.	O
</s>
<s>
Version	O
5	O
(	O
the	O
second	O
version	O
,	O
named	O
to	O
reflect	O
its	O
release	O
as	O
part	O
of	O
DirectX	B-Application
5	O
)	O
replaced	O
execute	O
buffers	O
with	O
the	O
new	O
DrawPrimitive	O
API	B-Application
,	O
but	O
it	O
was	O
still	O
considered	O
cumbersome	O
.	O
</s>
<s>
Chris	O
Hecker	O
's	O
"	O
Open	O
Letter	O
to	O
Microsoft	O
"	O
referred	O
to	O
DrawPrimitive	O
as	O
"	O
an	O
immature	O
and	O
poorly-designed	O
clone	O
of	O
OpenGL	B-Application
that	O
's	O
missing	O
some	O
of	O
the	O
architectural	O
decisions	O
that	O
make	O
OpenGL	B-Application
fast.	O
"	O
</s>
<s>
Despite	O
the	O
controversy	O
,	O
Microsoft	O
continued	O
to	O
evolve	O
the	O
API	B-Application
.	O
</s>
<s>
A	O
detailed	O
history	O
of	O
releases	O
and	O
added	O
features	O
is	O
given	O
on	O
the	O
Microsoft	B-Application
Direct3D	I-Application
web	O
pages	O
.	O
</s>
<s>
Some	O
former	O
critics	O
of	O
Direct3D	B-Application
acknowledge	O
that	O
now	O
Direct3D	B-Application
is	O
as	O
good	O
if	O
not	O
better	O
than	O
OpenGL	B-Application
in	O
abilities	O
and	O
ease	O
of	O
use	O
.	O
</s>
<s>
In	O
January	O
2007	O
,	O
John	O
Carmack	O
said	O
that	O
"	O
…	O
DX9	B-Application
is	O
really	O
quite	O
a	O
good	O
API	B-Application
level	O
.	O
</s>
<s>
Even	O
with	O
the	O
Direct3D	B-Application
side	O
of	O
things	O
,	O
where	O
I	O
know	O
I	O
have	O
a	O
long	O
history	O
of	O
people	O
thinking	O
I	O
'm	O
antagonistic	O
against	O
it	O
.	O
</s>
<s>
Microsoft	O
has	O
done	O
a	O
very	O
,	O
very	O
good	O
job	O
of	O
sensibly	O
evolving	O
it	O
at	O
each	O
they	O
're	O
not	O
worried	O
about	O
breaking	O
backwards	B-General_Concept
compatibility	I-General_Concept
—	O
and	O
it	O
's	O
a	O
pretty	O
clean	O
API	B-Application
.	O
</s>
<s>
I	O
especially	O
like	O
the	O
work	O
I	O
'm	O
doing	O
on	O
the	O
360	O
,	O
and	O
it	O
's	O
probably	O
the	O
best	O
graphics	O
API	B-Application
as	O
far	O
as	O
a	O
sensibly	O
designed	O
thing	O
that	O
I	O
've	O
worked	O
with.	O
"	O
</s>
<s>
Some	O
design	O
features	O
of	O
Direct3D	B-Application
have	O
remained	O
unchanged	O
since	O
version	O
one	O
,	O
most	O
notably	O
its	O
reliance	O
on	O
Microsoft	O
's	O
Component	B-Application
Object	I-Application
Model	I-Application
(	O
COM	O
)	O
.	O
</s>
<s>
One	O
advantage	O
of	O
using	O
COM	O
is	O
that	O
the	O
API	B-Application
can	O
be	O
used	O
in	O
any	O
COM-aware	O
language	O
,	O
notably	O
Object	B-Language
Pascal	I-Language
(	O
Delphi	B-Language
)	O
,	O
and	O
Microsoft	B-Application
Visual	I-Application
C++	I-Application
,	O
C#	B-Application
,	O
and	O
Visual	B-Language
Basic	I-Language
.NET	I-Language
.	O
</s>
<s>
OpenGL	B-Application
is	O
a	O
specification	O
implemented	O
in	O
the	O
programming	B-Language
language	I-Language
C	I-Language
,	O
though	O
it	O
can	O
be	O
used	O
in	O
other	O
languages	O
,	O
including	O
Java	B-Language
,	O
Python	B-Language
and	O
C++	B-Language
.	O
</s>
<s>
It	O
is	O
built	O
on	O
the	O
concept	O
of	O
a	O
state	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
As	O
an	O
API	B-Application
,	O
OpenGL	B-Application
depends	O
on	O
no	O
one	O
programming	O
language	O
feature	O
,	O
and	O
can	O
be	O
made	O
callable	O
from	O
almost	O
any	O
language	O
with	O
the	O
proper	O
bindings	O
.	O
</s>
<s>
In	O
general	O
,	O
Direct3D	B-Application
is	O
designed	O
to	O
virtualize	O
3D	O
hardware	O
interfaces	O
.	O
</s>
<s>
Direct3D	B-Application
frees	O
the	O
game	O
programmer	O
from	O
accommodating	O
the	O
graphics	O
hardware	O
.	O
</s>
<s>
OpenGL	B-Application
,	O
on	O
the	O
other	O
hand	O
,	O
is	O
designed	O
to	O
be	O
a	O
3D	O
hardware-accelerated	O
rendering	O
system	O
that	O
may	O
be	O
emulated	O
in	O
software	O
.	O
</s>
<s>
These	O
two	O
APIs	B-Application
are	O
fundamentally	O
designed	O
under	O
two	O
separate	O
modes	O
of	O
thought	O
.	O
</s>
<s>
As	O
such	O
,	O
there	O
are	O
functional	O
differences	O
in	O
how	O
the	O
two	O
APIs	B-Application
work	O
.	O
</s>
<s>
One	O
functional	O
difference	O
between	O
the	O
APIs	B-Application
is	O
in	O
how	O
they	O
manage	O
hardware	O
resources	O
.	O
</s>
<s>
Direct3D	B-Application
expects	O
the	O
application	O
to	O
do	O
it	O
,	O
OpenGL	B-Application
makes	O
the	O
implementation	O
do	O
it	O
.	O
</s>
<s>
This	O
tradeoff	O
for	O
OpenGL	B-Application
decreases	O
difficulty	O
in	O
developing	O
for	O
the	O
API	B-Application
,	O
while	O
at	O
the	O
same	O
time	O
increasing	O
the	O
complexity	O
of	O
creating	O
an	O
implementation	O
(	O
or	O
driver	O
)	O
that	O
performs	O
well	O
.	O
</s>
<s>
With	O
Direct3D	B-Application
,	O
the	O
developer	O
must	O
manage	O
hardware	O
resources	O
independently	O
;	O
however	O
,	O
the	O
implementation	O
is	O
simpler	O
,	O
and	O
developers	O
have	O
the	O
flexibility	O
to	O
allocate	O
resources	O
in	O
the	O
most	O
efficient	O
way	O
possible	O
for	O
their	O
application	O
.	O
</s>
<s>
Until	O
about	O
2005	O
,	O
another	O
functional	O
difference	O
between	O
the	O
APIs	B-Application
was	O
the	O
way	O
they	O
handled	O
rendering	O
to	O
textures	O
.	O
</s>
<s>
The	O
Direct3D	B-Application
method	O
(SetRenderTarget( )	O
)	O
is	O
convenient	O
,	O
while	O
prior	O
versions	O
of	O
OpenGL	B-Application
required	O
manipulating	O
pixel	O
buffers	O
(	O
P-buffers	O
)	O
.	O
</s>
<s>
However	O
,	O
broad	O
support	O
for	O
the	O
frame	O
buffer	O
objects	O
extension	O
,	O
which	O
provided	O
an	O
OpenGL	B-Application
equivalent	O
of	O
the	O
Direct3D	B-Application
method	O
,	O
successfully	O
addressed	O
this	O
shortcoming	O
,	O
and	O
the	O
render	O
target	O
feature	O
of	O
OpenGL	B-Application
brought	O
it	O
up	O
to	O
par	O
with	O
Direct3D	B-Application
in	O
this	O
aspect	O
.	O
</s>
<s>
Outside	O
of	O
a	O
few	O
minor	O
functional	O
differences	O
which	O
have	O
mostly	O
been	O
addressed	O
over	O
the	O
years	O
,	O
the	O
two	O
APIs	B-Application
provide	O
nearly	O
the	O
same	O
level	O
of	O
function	O
.	O
</s>
<s>
Hardware	O
and	O
software	O
makers	O
generally	O
respond	O
rapidly	O
to	O
changes	O
in	O
DirectX	B-Application
,	O
e.g.	O
,	O
pixel	O
processor	O
and	O
shader	O
requirements	O
in	O
DirectX	B-Application
9	I-Application
to	O
stream	B-Application
processors	I-Application
in	O
DirectX	B-Application
10	I-Application
,	O
to	O
tessellation	B-Algorithm
in	O
DirectX	B-Application
11	O
.	O
</s>
<s>
In	O
contrast	O
,	O
new	O
features	O
in	O
OpenGL	B-Application
are	O
usually	O
implemented	O
first	O
by	O
vendors	O
and	O
then	O
retroactively	O
applied	O
to	O
the	O
standard	O
.	O
</s>
<s>
Shortly	O
after	O
the	O
establishment	O
of	O
both	O
Direct3D	B-Application
and	O
OpenGL	B-Application
as	O
viable	O
graphics	O
libraries	O
(	O
circa	O
1995	O
)	O
,	O
Microsoft	O
and	O
SGI	O
engaged	O
in	O
what	O
has	O
been	O
called	O
the	O
"	O
API	B-Application
Wars	O
"	O
.	O
</s>
<s>
Much	O
of	O
the	O
argument	O
revolved	O
around	O
which	O
API	B-Application
offered	O
superior	O
performance	O
.	O
</s>
<s>
This	O
question	O
was	O
relevant	O
due	O
to	O
the	O
very	O
high	O
cost	O
of	O
dedicated	B-Architecture
graphics	I-Architecture
processors	I-Architecture
during	O
this	O
time	O
,	O
which	O
meant	O
the	O
consumer	O
market	O
was	O
using	O
software	O
renderers	O
implemented	O
by	O
Microsoft	O
for	O
both	O
Direct3D	B-Application
and	O
OpenGL	B-Application
.	O
</s>
<s>
DOS	B-Device
business	O
software	O
such	O
as	O
AutoCAD	B-Algorithm
and	O
DOS	B-Device
games	O
such	O
as	O
id	O
Software	O
's	O
Quake	B-Application
originally	O
had	O
to	O
be	O
optimized	O
to	O
run	O
on	O
many	O
different	O
graphics	O
chipsets	O
.	O
</s>
<s>
When	O
hardware	O
makers	O
such	O
as	O
3Dlabs	O
(	O
member	O
of	O
the	O
OpenGL	B-Application
Architecture	O
Review	O
Board	O
)	O
made	O
OpenGL	B-Application
compatible	O
graphics	B-Architecture
accelerators	I-Architecture
(	O
e.g.	O
,	O
GLint	O
chip	O
)	O
,	O
developers	O
such	O
as	O
John	O
Carmack	O
of	O
id	O
Software	O
optimized	O
their	O
products	O
for	O
OpenGL	B-Application
.	O
</s>
<s>
As	O
multitasking	O
user	O
environments	O
such	O
as	O
Windows	B-Application
and	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
(	O
X11	B-Operating_System
)	O
on	O
Unix-like	B-Operating_System
systems	I-Operating_System
became	O
prevalent	O
,	O
the	O
relevance	O
of	O
this	O
hardware	O
faded	O
.	O
</s>
<s>
Microsoft	O
had	O
marketed	O
Direct3D	B-Application
as	O
faster	O
based	O
on	O
in-house	O
performance	O
comparisons	O
of	O
these	O
two	O
software	O
libraries	O
.	O
</s>
<s>
The	O
performance	O
deficit	O
was	O
blamed	O
on	O
the	O
rigorous	O
specification	O
and	O
conformance	O
required	O
of	O
OpenGL	B-Application
.	O
</s>
<s>
At	O
that	O
time	O
,	O
Silicon	O
Graphics	O
(	O
SGI	O
)	O
challenged	O
Microsoft	O
with	O
their	O
own	O
optimized	O
Windows	B-Application
software	O
implementation	O
of	O
OpenGL	B-Application
called	O
CosmoGL	O
which	O
in	O
various	O
demos	O
matched	O
or	O
exceeded	O
the	O
performance	O
of	O
Direct3D	B-Application
.	O
</s>
<s>
For	O
SGI	O
,	O
this	O
was	O
a	O
critical	O
milestone	O
as	O
it	O
showed	O
that	O
OpenGL	B-Application
's	O
poor	O
software	O
rendering	O
performance	O
was	O
due	O
to	O
Microsoft	O
's	O
reference	O
OpenGL	B-Application
implementation	O
,	O
and	O
not	O
due	O
to	O
alleged	O
design	O
flaws	O
in	O
OpenGL	B-Application
.	O
</s>
<s>
In	O
contrast	O
,	O
software	O
rendering	O
by	O
the	O
3D	O
API	B-Application
was	O
largely	O
irrelevant	O
for	O
both	O
Direct3D	B-Application
and	O
OpenGL	B-Application
applications	O
.	O
</s>
<s>
Not	O
many	O
DirectX	B-Application
applications	O
used	O
Direct3D	B-Application
's	O
software	O
rendering	O
,	O
preferring	O
to	O
perform	O
their	O
own	O
software	O
rendering	O
using	O
DirectDraw	B-Device
's	O
facilities	O
to	O
access	O
the	O
display	O
hardware	O
.	O
</s>
<s>
As	O
for	O
OpenGL	B-Application
applications	O
,	O
hardware	O
support	O
was	O
expected	O
,	O
and	O
the	O
hardware	O
was	O
so	O
much	O
faster	O
that	O
software	O
fallback	O
by	O
the	O
OpenGL	B-Application
application	O
constituted	O
a	O
rude	O
surprise	O
to	O
the	O
OpenGL	B-Application
developer	O
.	O
</s>
<s>
In	O
any	O
case	O
,	O
by	O
the	O
time	O
SGI	O
had	O
demonstrated	O
that	O
OpenGL	B-Application
software	O
rendering	O
performance	O
could	O
be	O
competitive	O
with	O
that	O
of	O
Direct3D	B-Application
,	O
software	O
rendering	O
was	O
fast	O
becoming	O
irrelevant	O
due	O
to	O
the	O
wide	O
availability	O
of	O
low	O
cost	O
3D	O
graphics	O
hardware	O
.	O
</s>
<s>
By	O
1998	O
,	O
even	O
the	O
S3	B-Device
ViRGE	I-Device
graphics	B-Architecture
accelerator	I-Architecture
was	O
substantially	O
faster	O
than	O
the	O
fastest	O
Pentium	B-General_Concept
II	I-General_Concept
running	O
Direct3D	B-Application
's	O
MMX	B-Architecture
rasterizer	B-Algorithm
.	O
</s>
<s>
A	O
more	O
substantive	O
and	O
modern	O
performance	O
difference	O
arises	O
because	O
of	O
the	O
structure	O
of	O
the	O
hardware	B-Application
drivers	I-Application
provided	O
by	O
hardware	O
developers	O
.	O
</s>
<s>
Under	O
DirectX	B-Application
,	O
independent	B-Device
hardware	I-Device
vendor	I-Device
(	O
IHV	O
)	O
drivers	O
are	O
kernel-mode	O
drivers	O
installed	O
into	O
the	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
user-mode	O
part	O
of	O
the	O
API	B-Application
is	O
handled	O
by	O
the	O
DirectX	B-Application
runtime	O
provided	O
by	O
Microsoft	O
.	O
</s>
<s>
Under	O
OpenGL	B-Application
however	O
,	O
the	O
IHV	O
driver	O
is	O
divided	O
in	O
two	O
parts	O
:	O
a	O
user-mode	O
part	O
that	O
implements	O
the	O
OpenGL	B-Application
API	B-Application
,	O
and	O
a	O
kernel-mode	O
driver	O
that	O
is	O
called	O
by	O
the	O
user-mode	O
part	O
.	O
</s>
<s>
This	O
is	O
an	O
issue	O
because	O
calling	O
kernel-mode	O
operations	O
from	O
user-mode	O
requires	O
performing	O
a	O
system	B-Operating_System
call	I-Operating_System
(	O
i.e.	O
,	O
making	O
the	O
CPU	O
switch	O
to	O
kernel	O
mode	O
)	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
the	O
GPU	B-Architecture
's	O
command	O
buffer	O
is	O
full	O
of	O
rendering	O
data	O
,	O
the	O
API	B-Application
could	O
simply	O
store	O
the	O
requested	O
rendering	O
call	O
in	O
a	O
temporary	O
buffer	O
and	O
,	O
when	O
the	O
command	O
buffer	O
is	O
nearly	O
empty	O
,	O
it	O
can	O
perform	O
a	O
switch	O
to	O
kernel-mode	O
and	O
add	O
a	O
set	O
of	O
stored	O
commands	O
in	O
a	O
batch	O
.	O
</s>
<s>
This	O
is	O
termed	O
marshalling	B-Application
.	O
</s>
<s>
Because	O
Direct3D	B-Application
IHV	O
drivers	O
are	O
kernel-mode	O
,	O
and	O
the	O
user-mode	O
code	O
is	O
out	O
of	O
the	O
IHV	O
's	O
hand	O
,	O
there	O
is	O
no	O
chance	O
for	O
such	O
optimizations	O
to	O
occur	O
.	O
</s>
<s>
Because	O
the	O
Direct3D	B-Application
runtime	O
,	O
the	O
user-mode	O
part	O
that	O
implements	O
the	O
API	B-Application
,	O
cannot	O
have	O
explicit	O
knowledge	O
of	O
the	O
driver	O
's	O
inner	O
workings	O
,	O
it	O
cannot	O
effectively	O
support	O
marshalling	B-Application
.	O
</s>
<s>
This	O
means	O
that	O
every	O
Direct3D	B-Application
call	O
that	O
sends	O
commands	O
to	O
the	O
hardware	O
must	O
perform	O
a	O
kernel-mode	O
switch	O
,	O
which	O
again	O
,	O
takes	O
time	O
in	O
the	O
order	O
of	O
microseconds	O
to	O
complete	O
.	O
</s>
<s>
This	O
has	O
led	O
to	O
several	O
behaviors	O
regarding	O
use	O
of	O
Direct3D	B-Application
,	O
the	O
most	O
important	O
being	O
the	O
need	O
for	O
submitting	O
large	O
batches	O
of	O
triangles	O
in	O
one	O
function	O
call	O
.	O
</s>
<s>
Since	O
OpenGL	B-Application
's	O
IHV	O
drivers	O
have	O
a	O
user-mode	O
component	O
to	O
them	O
,	O
IHVs	O
have	O
the	O
ability	O
to	O
implement	O
marshalling	B-Application
,	O
thus	O
improving	O
performance	O
.	O
</s>
<s>
There	O
is	O
still	O
kernel-mode	O
switching	O
,	O
but	O
the	O
theoretical	O
maximum	O
number	O
of	O
switches	O
under	O
OpenGL	B-Application
implementations	O
is	O
simply	O
equal	O
to	O
the	O
Direct3D	B-Application
standard	O
behavior	O
.	O
</s>
<s>
Direct3D	B-Application
10	O
,	O
the	O
release	O
included	O
with	O
Windows	B-Application
Vista	I-Application
,	O
allows	O
parts	O
of	O
drivers	O
to	O
run	O
in	O
user-mode	O
,	O
making	O
it	O
possible	O
for	O
IHVs	O
to	O
implement	O
marshalling	B-Application
,	O
thus	O
bringing	O
the	O
two	O
back	O
into	O
relative	O
performance	O
parity	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
's	O
OpenGL	B-Application
system	O
is	O
very	O
similar	O
,	O
where	O
IHVs	O
implement	O
a	O
simpler	O
version	O
of	O
the	O
OpenGL	B-Application
API	B-Application
(	O
with	O
both	O
user	O
and	O
kernel	O
mode	O
components	O
)	O
,	O
and	O
Apple	O
's	O
additions	O
to	O
the	O
runtime	O
provide	O
the	O
direct	O
interface	O
to	O
the	O
user	O
code	O
,	O
and	O
some	O
basic	O
work	O
to	O
make	O
IHVs	O
 '	O
jobs	O
easier	O
.	O
</s>
<s>
The	O
introduction	O
of	O
Mantle	B-Application
by	O
AMD	O
led	O
to	O
increased	O
discussion	O
about	O
modernizing	O
APIs	B-Application
,	O
and	O
updating	O
abstraction	O
concepts	O
used	O
by	O
all	O
APIs	B-Application
to	O
reflect	O
graphics	B-Architecture
processing	I-Architecture
unit	I-Architecture
(	O
GPU	B-Architecture
)	O
operations	O
.	O
</s>
<s>
Both	O
Microsoft	O
and	O
OpenGL	B-Application
vendors	O
began	O
to	O
showcase	O
their	O
visions	O
for	O
limiting	O
or	O
removing	O
altogether	O
driver	O
overhead	O
(	O
the	O
amount	O
of	O
work	O
the	O
CPU	O
needs	O
to	O
do	O
to	O
prepare	O
GPU	B-Architecture
commands	O
)	O
.	O
</s>
<s>
OpenGL	B-Application
vendors	O
took	O
a	O
different	O
approach	O
,	O
and	O
during	O
GDC	O
2014	O
presented	O
a	O
mix	O
of	O
features	O
mandatory	O
in	O
OpenGL	B-Application
4.3	O
&	O
OpenGL	B-Application
4.4	O
or	O
already	O
ARB	O
extensions	O
,	O
to	O
show	O
fast	O
paths	O
already	O
present	O
in	O
implementations	O
from	O
Nvidia	O
,	O
AMD	O
,	O
and	O
Intel	O
.	O
</s>
<s>
Later	O
AMD	O
donated	O
Mantle	B-Application
to	O
Khronos	B-Library
Group	I-Library
,	O
the	O
API	B-Application
was	O
renamed	O
Vulkan	B-Application
and	O
now	O
this	O
is	O
the	O
current	O
cross-platform	O
API	B-Application
dedicated	O
to	O
reduce	O
driver	O
overhead	O
,	O
while	O
better	O
distributing	O
work	O
among	O
multiple	O
CPU	O
and	O
GPU	B-Architecture
cores	O
,	O
using	O
a	O
unified	O
management	O
of	O
compute	O
kernels	O
and	O
graphical	O
shaders	O
.	O
</s>
<s>
It	O
is	O
a	O
new	O
tool	O
for	O
microbenchmarking	O
specific	O
solutions	O
for	O
given	O
problems	O
emphasizing	O
exploration	O
of	O
fast	O
paths	O
in	O
current	O
APIs	B-Application
.	O
</s>
<s>
Both	O
OpenGL	B-Application
4.x	O
and	O
Direct3D	B-Application
11	O
are	O
supported	O
.	O
</s>
<s>
Gathered	O
results	O
showed	O
that	O
modern	O
OpenGL	B-Application
can	O
be	O
many	O
times	O
faster	O
than	O
Direct3D	B-Application
11	O
.	O
</s>
<s>
OpenGL	B-Application
,	O
originally	O
designed	O
for	O
then-powerful	O
SGI	O
workstations	O
,	O
includes	O
many	O
features	O
,	O
like	O
stereo	B-Algorithm
rendering	O
and	O
the	O
imaging	O
subset	O
,	O
that	O
were	O
generally	O
considered	O
of	O
limited	O
use	O
for	O
games	O
,	O
although	O
stereoscopic	B-Algorithm
gaming	O
has	O
drawn	O
more	O
interest	O
with	O
the	O
development	O
of	O
consumer-level	O
3D	O
displays	O
.	O
</s>
<s>
The	O
API	B-Application
as	O
a	O
whole	O
contains	O
about	O
250	O
calls	O
,	O
but	O
only	O
a	O
subset	O
of	O
perhaps	O
100	O
are	O
useful	O
for	O
game	O
development	O
.	O
</s>
<s>
MiniGL	B-Library
,	O
released	O
by	O
3Dfx	O
as	O
a	O
stopgap	O
measure	O
to	O
support	O
GLQuake	O
,	O
might	O
have	O
served	O
as	O
a	O
starting	O
point	O
,	O
but	O
additional	O
features	O
like	O
stencil	O
were	O
soon	O
adopted	O
by	O
games	O
,	O
and	O
support	O
for	O
the	O
full	O
OpenGL	B-Application
standard	O
continued	O
.	O
</s>
<s>
Today	O
,	O
workstations	O
and	O
consumer	O
machines	O
use	O
the	O
same	O
architectures	O
and	O
operating	B-Operating_System
systems	I-Operating_System
,	O
and	O
so	O
modern	O
versions	O
of	O
the	O
OpenGL	B-Application
standard	O
still	O
include	O
these	O
features	O
,	O
although	O
only	O
special	O
workstation-class	O
video	O
cards	O
accelerate	O
them	O
.	O
</s>
<s>
The	O
OpenGL	B-Application
extension	O
mechanism	O
is	O
probably	O
the	O
most	O
heavily	O
disputed	O
difference	O
between	O
the	O
two	O
APIs	B-Application
.	O
</s>
<s>
OpenGL	B-Application
includes	O
a	O
mechanism	O
where	O
any	O
driver	O
can	O
advertise	O
its	O
own	O
extensions	O
to	O
the	O
API	B-Application
,	O
thus	O
introducing	O
new	O
functions	O
such	O
as	O
blend	O
modes	O
,	O
new	O
ways	O
to	O
transfer	O
data	O
to	O
GPUs	B-Architecture
,	O
or	O
different	O
texture	O
wrapping	O
parameters	O
.	O
</s>
<s>
This	O
allows	O
new	O
functions	O
to	O
be	O
exposed	O
quickly	O
,	O
but	O
can	O
lead	O
to	O
confusion	O
if	O
different	O
vendors	O
implement	O
similar	O
extensions	O
with	O
different	O
APIs	B-Application
.	O
</s>
<s>
Many	O
of	O
these	O
extensions	O
are	O
periodically	O
standardized	O
by	O
the	O
OpenGL	B-Application
Architecture	O
Review	O
Board	O
(	O
ARB	O
)	O
,	O
and	O
some	O
are	O
made	O
a	O
core	O
part	O
of	O
future	O
OpenGL	B-Application
revisions	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
Direct3D	B-Application
is	O
specified	O
by	O
one	O
vendor	O
only	O
(	O
Microsoft	O
)	O
,	O
leading	O
to	O
a	O
more	O
consistent	O
API	B-Application
,	O
but	O
denying	O
access	O
to	O
vendor-specific	O
features	O
.	O
</s>
<s>
NVIDIA	O
's	O
UltraShadow	O
technology	O
,	O
for	O
instance	O
,	O
is	O
not	O
available	O
in	O
the	O
stock	O
Direct3D	B-Application
APIs	B-Application
at	O
the	O
time	O
of	O
writing	O
.	O
</s>
<s>
Direct3D	B-Application
does	O
support	O
texture	O
format	O
extensions	O
(	O
via	O
FourCC	B-Application
)	O
.	O
</s>
<s>
When	O
graphics	O
cards	O
added	O
support	O
for	O
pixel	O
shaders	O
(	O
known	O
on	O
OpenGL	B-Application
as	O
"	O
fragment	O
shaders	O
"	O
)	O
,	O
Direct3D	B-Application
provided	O
one	O
"	O
Pixel	O
Shader	O
1.1	O
"	O
(	O
PS1.1	O
)	O
standard	O
with	O
which	O
the	O
GeForce	B-Application
3	O
and	O
up	O
,	O
and	O
Radeon	B-Device
8500	O
and	O
up	O
,	O
advertised	O
compatibility	O
.	O
</s>
<s>
Under	O
OpenGL	B-Application
the	O
same	O
functions	O
were	O
accessed	O
through	O
a	O
variety	O
of	O
custom	O
extensions	O
.	O
</s>
<s>
In	O
theory	O
,	O
the	O
Microsoft	O
approach	O
allows	O
one	O
code	O
path	O
to	O
support	O
both	O
brands	O
of	O
card	O
,	O
whereas	O
under	O
OpenGL	B-Application
,	O
programmers	O
must	O
write	O
two	O
separate	O
systems	O
.	O
</s>
<s>
In	O
reality	O
,	O
though	O
,	O
because	O
of	O
the	O
limits	O
on	O
pixel	O
processing	O
of	O
those	O
early	O
cards	O
,	O
Pixel	O
Shader	O
1.1	O
was	O
nothing	O
more	O
than	O
a	O
pseudo-assembly	O
language	O
version	O
of	O
the	O
NVIDIA-specific	O
OpenGL	B-Application
extensions	O
.	O
</s>
<s>
When	O
the	O
Radeon	B-Device
8500	O
was	O
released	O
,	O
Microsoft	O
released	O
an	O
update	O
to	O
Direct3D	B-Application
that	O
included	O
Pixel	O
Shader	O
1.4	O
,	O
which	O
was	O
nothing	O
more	O
than	O
a	O
pseudo-assembly	O
language	O
version	O
of	O
the	O
ATI-specific	O
OpenGL	B-Application
extensions	O
.	O
</s>
<s>
This	O
situation	O
existed	O
only	O
for	O
a	O
short	O
time	O
under	O
both	O
APIs	B-Application
.	O
</s>
<s>
As	O
such	O
,	O
Pixel	O
Shader	O
2.0	O
allowed	O
a	O
unified	O
code	O
path	O
under	O
Direct3D	B-Application
.	O
</s>
<s>
Around	O
the	O
same	O
time	O
OpenGL	B-Application
introduced	O
its	O
own	O
ARB-approved	O
vertex	O
and	O
pixel	O
shader	O
extensions	O
(	O
GL_ARB_vertex_program	O
and	O
GL_ARB_fragment_program	O
)	O
,	O
and	O
both	O
sets	O
of	O
cards	O
supported	O
this	O
standard	O
also	O
.	O
</s>
<s>
OpenGL	B-Application
has	O
always	O
seen	O
more	O
use	O
in	O
the	O
professional	O
graphics	O
market	O
than	O
DirectX	B-Application
,	O
while	O
DirectX	B-Application
is	O
used	O
mostly	O
for	O
computer	O
games	O
.	O
</s>
<s>
Currently	O
both	O
OpenGL	B-Application
and	O
DirectX	B-Application
have	O
a	O
large	O
enough	O
overlap	O
in	O
functionality	O
that	O
either	O
could	O
be	O
used	O
for	O
most	O
common	O
purposes	O
,	O
with	O
the	O
operating	B-General_Concept
system	I-General_Concept
often	O
being	O
the	O
main	O
criterion	O
dictating	O
which	O
is	O
used	O
;	O
DirectX	B-Application
is	O
the	O
common	O
choice	O
for	O
Windows	B-Application
,	O
and	O
OpenGL	B-Application
for	O
nearly	O
everything	O
else	O
.	O
</s>
<s>
Some	O
esoteric	O
applications	O
still	O
divide	O
the	O
applicability	O
of	O
the	O
two	O
APIs	B-Application
:	O
doing	O
accelerated	O
3D	O
across	O
a	O
network	O
connection	O
is	O
only	O
directly	O
supported	O
by	O
OpenGL	B-Application
with	O
OpenGL	B-Application
Extension	O
to	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
(	O
GLX	B-Device
)	O
,	O
for	O
example	O
.	O
</s>
<s>
In	O
the	O
past	O
,	O
many	O
professional	O
graphics	O
cards	O
supported	O
only	O
OpenGL	B-Application
.	O
</s>
<s>
As	O
of	O
2010	O
,	O
virtually	O
all	O
professional	O
cards	O
which	O
work	O
on	O
the	O
Windows	B-Application
platform	O
will	O
also	O
support	O
Direct3D	B-Application
.	O
</s>
<s>
Part	O
of	O
this	O
has	O
been	O
a	O
change	O
in	O
the	O
professional	O
graphics	O
market	O
from	O
largely	O
Unix-based	O
hardware	O
like	O
SGIs	O
and	O
Suns	O
to	O
lower	O
cost	O
PC-based	O
systems	O
,	O
leading	O
to	O
the	O
growth	O
of	O
Windows	B-Application
in	O
this	O
market	O
segment	O
,	O
while	O
at	O
the	O
same	O
time	O
providing	O
a	O
new	O
market	O
for	O
OpenGL	B-Application
software	O
in	O
Unix-based	O
consumer	O
systems	O
running	O
Linux	B-Application
or	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
.	O
</s>
<s>
The	O
principal	O
historical	O
reason	O
for	O
OpenGL	B-Application
's	O
dominance	O
in	O
the	O
professional	O
market	O
was	O
performance	O
.	O
</s>
<s>
Many	O
professional	O
graphics	O
applications	O
(	O
for	O
example	O
,	O
Softimage|3D	O
,	O
Alias	B-Device
PowerAnimator	I-Device
)	O
were	O
originally	O
written	O
in	O
IRIS	B-Library
GL	I-Library
for	O
high-end	O
SGI	O
workstations	O
,	O
which	O
were	O
far	O
more	O
capable	O
,	O
both	O
graphically	O
and	O
in	O
raw	O
CPU	O
power	O
,	O
than	O
the	O
PCs	O
of	O
the	O
time	O
.	O
</s>
<s>
Later	O
,	O
many	O
of	O
these	O
were	O
ported	O
to	O
OpenGL	B-Application
,	O
even	O
as	O
the	O
personal	O
computer	O
was	O
evolving	O
into	O
a	O
system	O
powerful	O
enough	O
to	O
run	O
some	O
professional	O
graphics	O
applications	O
.	O
</s>
<s>
Users	O
were	O
able	O
to	O
run	O
Maya	B-Language
,	O
for	O
example	O
,	O
the	O
successor	O
to	O
Alias	B-Device
PowerAnimator	I-Device
on	O
either	O
SGIs	O
or	O
Windows-based	O
personal	O
computers	O
(	O
and	O
today	O
on	O
Linux	B-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
and	O
Windows	B-Application
)	O
.	O
</s>
<s>
Price	O
competition	O
eventually	O
broke	O
SGI	O
's	O
dominance	O
in	O
the	O
market	O
,	O
but	O
the	O
established	O
base	O
of	O
OpenGL	B-Application
software	O
engineers	O
and	O
the	O
broadening	O
user	O
base	O
for	O
OpenGL	B-Application
in	O
Apple	O
,	O
Linux	B-Application
,	O
and	O
other	O
operating	B-Operating_System
systems	I-Operating_System
,	O
has	O
resulted	O
in	O
a	O
market	O
where	O
both	O
DirectX	B-Application
and	O
OpenGL	B-Application
are	O
viable	O
,	O
widespread	O
APIs	B-Application
.	O
</s>
<s>
The	O
other	O
reason	O
for	O
OpenGL	B-Application
's	O
historic	O
advantage	O
was	O
marketing	O
and	O
design	O
.	O
</s>
<s>
DirectX	B-Application
is	O
a	O
set	O
of	O
APIs	B-Application
that	O
were	O
not	O
marketed	O
for	O
professional	O
graphics	O
applications	O
.	O
</s>
<s>
DirectX	B-Application
was	O
an	O
API	B-Application
designed	O
for	O
low-level	O
,	O
high-performance	O
access	O
to	O
broadly	O
available	O
,	O
lower-performance	O
,	O
consumer-priced	O
graphics	O
hardware	O
for	O
the	O
purpose	O
of	O
game	O
development	O
.	O
</s>
<s>
OpenGL	B-Application
is	O
a	O
much	O
more	O
general	O
purpose	O
3D	O
API	B-Application
,	O
targeting	O
a	O
full	O
range	O
of	O
graphics	O
hardware	O
from	O
low-end	O
commodity	O
graphics	O
cards	O
up	O
to	O
professional	O
and	O
scientific	O
graphics	O
visualization	O
well	O
out	O
of	O
the	O
range	O
of	O
the	O
average	O
consumer	O
,	O
and	O
providing	O
features	O
that	O
are	O
not	O
necessarily	O
exclusive	O
for	O
a	O
specific	O
kind	O
of	O
user	O
.	O
</s>
<s>
Gaming	O
developers	O
typically	O
have	O
n't	O
demanded	O
as	O
wide	O
an	O
API	B-Application
as	O
professional	O
graphics	O
system	O
developers	O
.	O
</s>
<s>
Specifically	O
,	O
game	O
designers	O
are	O
rarely	O
interested	O
in	O
the	O
pixel	O
invariance	O
demanded	O
in	O
certain	O
parts	O
of	O
the	O
OpenGL	B-Application
standards	O
,	O
which	O
are	O
conversely	O
highly	O
useful	O
to	O
film	O
and	O
computer-aided	O
modeling	O
.	O
</s>
<s>
An	O
attempt	O
was	O
once	O
made	O
to	O
merge	O
OpenGL	B-Application
and	O
DirectX	B-Application
by	O
SGI	O
and	O
Microsoft	O
.	O
</s>
<s>
The	O
Fahrenheit	B-Library
graphics	I-Library
API	I-Library
was	O
intended	O
to	O
bring	O
together	O
both	O
the	O
high	O
end	O
ability	O
of	O
OpenGL	B-Application
with	O
the	O
broad	O
low-level	O
support	O
of	O
DirectX	B-Application
.	O
</s>
<s>
The	O
move	O
was	O
widely	O
held	O
to	O
be	O
purposed	O
to	O
ensure	O
lock-in	O
of	O
developers	O
to	O
the	O
Windows-DirectX	O
platform	O
,	O
which	O
would	O
be	O
lost	O
if	O
the	O
Fahrenheit	B-Library
API	B-Application
became	O
the	O
world	O
de	O
facto	O
standard	O
graphics	O
API	B-Application
.	O
</s>
<s>
However	O
,	O
Fahrenheit	B-Library
led	O
to	O
many	O
improvements	O
in	O
DirectX	B-Application
,	O
with	O
the	O
main	O
architect	O
of	O
Fahrenheit	B-Library
even	O
joining	O
Microsoft	O
to	O
assist	O
in	O
the	O
development	O
of	O
DirectX	B-Application
in	O
2003	O
.	O
</s>
<s>
In	O
the	O
earliest	O
days	O
of	O
3D	O
accelerated	O
gaming	O
,	O
performance	O
and	O
reliability	O
were	O
key	O
benchmarks	O
and	O
several	O
3D	B-Architecture
accelerator	I-Architecture
cards	I-Architecture
competed	O
against	O
each	O
other	O
for	O
dominance	O
.	O
</s>
<s>
However	O
,	O
over	O
the	O
years	O
,	O
OpenGL	B-Application
and	O
Direct3D	B-Application
emerged	O
as	O
software	O
layers	O
above	O
the	O
hardware	O
,	O
mainly	O
because	O
of	O
industry	O
support	O
for	O
a	O
cross-hardware	O
graphics	O
library	O
.	O
</s>
<s>
In	O
the	O
early	O
days	O
of	O
3D	O
accelerated	O
gaming	O
,	O
most	O
vendors	O
did	O
not	O
supply	O
a	O
full	O
OpenGL	B-Application
driver	O
.	O
</s>
<s>
Firstly	O
,	O
most	O
of	O
the	O
consumer-oriented	O
accelerators	O
did	O
not	O
implement	O
enough	O
functionality	O
to	O
properly	O
accelerate	O
OpenGL	B-Application
.	O
</s>
<s>
Secondly	O
,	O
many	O
vendors	O
struggled	O
to	O
implement	O
a	O
full	O
OpenGL	B-Application
driver	O
with	O
good	O
performance	O
and	O
compatibility	O
.	O
</s>
<s>
Instead	O
,	O
they	O
wrote	O
MiniGL	B-Library
drivers	O
,	O
which	O
only	O
implemented	O
a	O
subset	O
of	O
OpenGL	B-Application
,	O
enough	O
to	O
run	O
GLQuake	O
(	O
and	O
later	O
other	O
OpenGL	B-Application
games	O
,	O
mostly	O
based	O
on	O
the	O
Quake	B-Application
engine	O
)	O
.	O
</s>
<s>
Proper	O
OpenGL	B-Application
drivers	O
became	O
more	O
prevalent	O
as	O
hardware	O
evolved	O
,	O
and	O
consumer-oriented	O
accelerators	O
caught	O
up	O
with	O
the	O
SGI	O
systems	O
for	O
which	O
OpenGL	B-Application
was	O
originally	O
designed	O
.	O
</s>
<s>
This	O
would	O
be	O
around	O
the	O
time	O
of	O
DirectX	B-Application
6	O
or	O
DirectX	B-Application
7	I-Application
.	O
</s>
<s>
In	O
the	O
console	O
world	O
proprietary	B-Application
native	O
APIs	B-Application
are	O
dominant	O
,	O
with	O
some	O
consoles	O
(	O
e.g.	O
,	O
the	O
PS3	O
)	O
providing	O
an	O
OpenGL	B-Application
wrapper	O
around	O
its	O
native	O
API	B-Application
.	O
</s>
<s>
The	B-Application
original	I-Application
Xbox	I-Application
supported	O
Direct3D	B-Application
8.1	O
as	O
its	O
native	O
API	B-Application
while	O
the	O
Xbox	B-Application
360	O
supports	O
DirectX9	B-Application
as	O
its	O
native	O
API	B-Application
.	O
</s>
<s>
Most	O
console	O
developers	O
prefer	O
to	O
use	O
the	O
native	O
APIs	B-Application
for	O
each	O
console	O
to	O
maximize	O
performance	O
,	O
making	O
OpenGL	B-Application
and	O
Direct3D	B-Application
comparisons	O
relevant	O
for	O
mostly	O
PC	O
platforms	O
.	O
</s>
<s>
OpenGL	B-Application
for	I-Application
Embedded	I-Application
Systems	I-Application
,	O
called	O
OpenGL	B-Application
ES	I-Application
,	O
is	O
a	O
subset	O
of	O
the	O
OpenGL	B-Application
3D	O
graphics	O
API	B-Application
designed	O
for	O
embedded	B-Architecture
devices	I-Architecture
.	O
</s>
<s>
Various	O
versions	O
of	O
smartphone	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
support	O
OpenGL	B-Application
ES	I-Application
,	O
such	O
as	O
Android	B-Application
,	O
iOS	B-Application
(	O
iPad	B-Device
,	O
iPhone	B-Device
,	O
iPod	B-Device
Touch	I-Device
)	O
,	O
Maemo	B-Operating_System
(	O
Nokia	B-Application
N900	I-Application
)	O
,	O
and	O
Symbian	B-Operating_System
.	O
</s>
<s>
OpenGL	B-Application
ES	I-Application
is	O
available	O
in	O
6	O
variants	O
,	O
OpenGL	B-Application
ES	I-Application
1.0	O
,	O
1.1	O
,	O
2.0	O
,	O
3.0	O
,	O
3.1	O
,	O
3.2	O
.	O
</s>
<s>
The	O
release	O
of	O
2.0	O
removed	O
backward	B-General_Concept
compatibility	I-General_Concept
with	O
older	O
variants	O
,	O
due	O
to	O
the	O
extensive	O
programmable	O
pipeline	O
functions	O
available	O
in	O
GL	O
ES	O
2.0	O
,	O
over	O
the	O
fixed-pipeline	O
functions	O
of	O
GL	O
ES	O
1.0	O
and	O
1.1	O
.	O
</s>
<s>
OpenGL	B-Application
ES	I-Application
3.0	O
needed	O
new	O
hardware	O
over	O
OpenGL	B-Application
ES	I-Application
2.0	O
,	O
while	O
OpenGL	B-Application
ES	I-Application
3.1	O
is	O
meant	O
as	O
a	O
software	O
update	O
,	O
needing	O
only	O
new	O
drivers	O
.	O
</s>
<s>
Direct3D	B-Application
Mobile	O
,	O
a	O
Direct3D	B-Application
derivative	O
,	O
is	O
supported	O
by	O
Windows	B-Operating_System
CE	I-Operating_System
.	O
</s>
<s>
Currently	O
all	O
Windows	B-Application
Phone	O
7	O
devices	O
use	O
a	O
.NET	B-Application
Framework	I-Application
UI	O
accelerated	O
by	O
Direct3D	B-Application
Mobile	O
9	O
on	O
Adreno	O
200/205	O
integrated	O
GPUs	B-Architecture
by	O
Qualcomm	O
.	O
</s>
<s>
Windows	B-Application
Phone	O
8	O
implements	O
Direct3D	B-Application
11	O
(	O
limited	O
to	O
feature	O
level	O
9_3	O
)	O
.	O
</s>
