<s>
A	O
shading	B-Language
language	I-Language
is	O
a	O
graphics	O
programming	O
language	O
adapted	O
to	O
programming	O
shader	O
effects	O
(	O
characterizing	O
surfaces	O
,	O
volumes	O
,	O
and	O
objects	O
)	O
.	O
</s>
<s>
Such	O
language	O
forms	O
usually	O
consist	O
of	O
special	O
data	O
types	O
,	O
like	O
"	O
vector	O
"	O
,	O
"	O
matrix	B-Architecture
"	O
,	O
"	O
color	O
"	O
and	O
"	O
normal	O
"	O
.	O
</s>
<s>
Due	O
to	O
the	O
variety	O
of	O
target	O
markets	O
for	O
3D	O
computer	O
graphics	O
,	O
different	O
shading	B-Language
languages	I-Language
have	O
been	O
developed	O
.	O
</s>
<s>
Offline	O
rendering	O
uses	O
shading	B-Language
languages	I-Language
to	O
produce	O
high-quality	O
images	O
,	O
often	O
developed	O
by	O
artists	O
for	O
photorealistic	O
results	O
.	O
</s>
<s>
Rendering	O
these	O
shaders	O
requires	O
significant	O
computational	O
power	O
and	O
is	O
typically	O
run	O
on	O
large	O
computer	B-Architecture
clusters	I-Architecture
.	O
</s>
<s>
Some	O
common	O
shading	B-Language
languages	I-Language
include	O
RenderMan	B-Application
Shading	I-Application
Language	I-Application
(	O
RSL	O
)	O
,	O
Houdini	B-Application
VEX	O
Shading	B-Language
Language	I-Language
,	O
Gelato	B-Application
Shading	B-Language
Language	I-Language
,	O
and	O
Open	B-Language
Shading	I-Language
Language	I-Language
(	O
OSL	O
)	O
.	O
</s>
<s>
Real-time	B-General_Concept
rendering	I-General_Concept
shading	B-Language
languages	I-Language
offer	O
more	O
flexibility	O
and	O
higher	O
hardware	O
abstraction	O
than	O
previous	O
paradigms	O
,	O
allowing	O
programmers	O
to	O
control	O
the	O
rendering	O
process	O
with	O
lower	O
overhead	O
.	O
</s>
<s>
These	O
shaders	O
are	O
designed	O
for	O
direct	O
execution	O
on	O
GPUs	B-Architecture
and	O
have	O
contributed	O
to	O
the	O
development	O
of	O
compute	B-Operating_System
shaders	I-Operating_System
.	O
</s>
<s>
Some	O
notable	O
shading	B-Language
languages	I-Language
for	O
real-time	B-General_Concept
rendering	I-General_Concept
include	O
ARB	B-Language
assembly	I-Language
language	I-Language
,	O
OpenGL	B-Language
shading	I-Language
language	I-Language
(	O
GLSL	B-Language
)	O
,	O
Cg	B-Language
programming	I-Language
language	I-Language
,	O
DirectX	B-Application
Shader	O
Assembly	O
Language	O
,	O
DirectX	B-Application
High-Level	B-Language
Shader	I-Language
Language	I-Language
(	O
HLSL	B-Language
)	O
,	O
Adobe	B-General_Concept
Pixel	I-General_Concept
Bender	I-General_Concept
and	O
Adobe	B-Language
Graphics	I-Language
Assembly	I-Language
Language	I-Language
(	O
AGAL	O
)	O
,	O
PlayStation	B-Language
Shader	I-Language
Language	I-Language
(	O
PSSL	O
)	O
,	O
Metal	B-Library
Shading	I-Library
Language	I-Library
(	O
MSL	O
)	O
,	O
and	O
WebGPU	B-Operating_System
Shading	I-Operating_System
Language	I-Operating_System
(	O
WGSL	O
)	O
.	O
</s>
<s>
As	O
more	O
graphics	O
APIs	O
emerge	O
,	O
developers	O
face	O
challenges	O
in	O
porting	O
shaders	O
between	O
different	O
shading	B-Language
languages	I-Language
.	O
</s>
<s>
Common	O
approaches	O
include	O
manual	O
switching	O
using	O
C	B-Language
preprocessor	I-Language
statements	O
,	O
translating	O
one	O
language	O
to	O
another	O
,	O
or	O
defining	O
a	O
different	O
intermediate	O
language	O
like	O
SPIR-V	B-Application
.	O
</s>
<s>
Shading	B-Language
languages	I-Language
used	O
in	O
offline	O
rendering	O
produce	O
maximum	O
image	O
quality	O
.	O
</s>
<s>
Most	O
of	O
the	O
time	O
,	O
production	O
rendering	O
is	O
run	O
on	O
large	O
computer	B-Architecture
clusters	I-Architecture
.	O
</s>
<s>
The	O
RenderMan	B-Application
Shading	I-Application
Language	I-Application
(	O
often	O
referenced	O
as	O
RSL	O
or	O
SL	O
,	O
for	O
short	O
)	O
,	O
which	O
is	O
defined	O
in	O
the	O
RenderMan	B-Application
Interface	I-Application
Specification	I-Application
is	O
the	O
most	O
common	O
shading	B-Language
language	I-Language
for	O
production-quality	O
rendering	O
.	O
</s>
<s>
It	O
is	O
also	O
one	O
of	O
the	O
first	O
shading	B-Language
languages	I-Language
ever	O
implemented	O
.	O
</s>
<s>
This	O
is	O
much	O
like	O
an	O
image	B-Algorithm
filter	I-Algorithm
,	O
however	O
the	O
imager	O
shader	O
operates	O
on	O
data	O
prior	O
to	O
quantization	B-Algorithm
.	O
</s>
<s>
Houdini	B-Application
VEX	O
(	O
Vector	O
Expressions	O
)	O
shading	B-Language
language	I-Language
(	O
often	O
abbreviated	O
to	O
"	O
VEX	O
"	O
)	O
is	O
closely	O
modeled	O
after	O
RenderMan	O
.	O
</s>
<s>
Gelato	B-Application
's	O
shading	B-Language
language	I-Language
,	O
like	O
Houdini	B-Application
's	O
VEX	O
,	O
is	O
closely	O
modeled	O
after	O
RenderMan	O
.	O
</s>
<s>
The	O
differences	O
between	O
Gelato	B-Application
Shading	B-Language
Language	I-Language
and	O
RSL	O
are	O
mainly	O
syntactical	O
—	O
Gelato	B-Application
uses	O
semicolons	O
instead	O
of	O
commas	O
to	O
separate	O
arguments	O
in	O
function	O
definitions	O
and	O
a	O
few	O
shadeops	O
have	O
different	O
names	O
and	O
parameters	O
.	O
</s>
<s>
Open	B-Language
Shading	I-Language
Language	I-Language
(	O
OSL	O
)	O
was	O
developed	O
by	O
Sony	O
Pictures	O
Imageworks	O
for	O
use	O
in	O
its	O
Arnold	O
Renderer	O
.	O
</s>
<s>
It	O
is	O
also	O
used	O
by	O
Blender	B-Application
's	O
Cycles	O
render	O
engine	O
.	O
</s>
<s>
Shading	B-Language
languages	I-Language
for	O
real-time	B-General_Concept
rendering	I-General_Concept
are	O
now	O
widespread	O
.	O
</s>
<s>
Shaders	O
that	O
are	O
designed	O
to	O
be	O
executed	O
directly	O
on	O
the	O
GPU	B-Architecture
became	O
useful	O
for	O
high	O
throughput	O
general	O
processing	O
because	O
of	O
their	O
stream	B-Application
programming	I-Application
model	O
;	O
this	O
led	O
to	O
the	O
development	O
of	O
compute	B-Operating_System
shaders	I-Operating_System
running	O
on	O
similar	O
hardware	O
(	O
see	O
also	O
:	O
GPGPU	B-Architecture
)	O
.	O
</s>
<s>
The	O
OpenGL	B-Application
Architecture	O
Review	O
Board	O
established	O
the	O
ARB	B-Language
assembly	I-Language
language	I-Language
in	O
2002	O
as	O
a	O
standard	O
low-level	O
instruction	O
set	O
for	O
programmable	O
graphics	B-Architecture
processors	I-Architecture
.	O
</s>
<s>
High-level	O
OpenGL	B-Language
shading	I-Language
languages	I-Language
often	O
compile	O
to	O
ARB	B-Language
assembly	O
for	O
loading	O
and	O
execution	O
.	O
</s>
<s>
Unlike	O
high-level	B-Language
shading	I-Language
languages	I-Language
,	O
ARB	B-Language
assembly	O
does	O
not	O
support	O
control	O
flow	O
or	O
branching	O
.	O
</s>
<s>
However	O
,	O
it	O
continues	O
to	O
be	O
used	O
when	O
cross-GPU	O
portability	O
is	O
required	O
.	O
</s>
<s>
Also	O
known	O
as	O
GLSL	B-Language
or	O
glslang	B-Language
,	O
this	O
standardized	O
shading	B-Language
language	I-Language
is	O
meant	O
to	O
be	O
used	O
with	O
OpenGL	B-Application
.	O
</s>
<s>
The	O
language	O
unifies	O
vertex	O
and	O
fragment	B-General_Concept
processing	I-General_Concept
in	O
a	O
single	O
instruction	O
set	O
,	O
allowing	O
conditional	O
loops	O
and	O
(	O
more	O
generally	O
)	O
branches	B-General_Concept
.	O
</s>
<s>
Historically	O
,	O
GLSL	B-Language
was	O
preceded	O
by	O
the	O
ARB	B-Language
assembly	I-Language
language	I-Language
.	O
</s>
<s>
The	O
programming	O
language	O
Cg	B-Language
,	O
developed	O
by	O
NVIDIA	O
,	O
was	O
designed	O
for	O
easy	O
and	O
efficient	O
production	O
pipeline	O
integration	O
.	O
</s>
<s>
Development	O
of	O
Cg	B-Language
was	O
stopped	O
in	O
2012	O
and	O
the	O
language	O
is	O
now	O
deprecated	O
.	O
</s>
<s>
The	O
shader	O
assembly	O
language	O
in	O
Direct3D	O
8	O
and	O
9	O
is	O
the	O
main	O
programming	O
language	O
for	O
vertex	O
and	O
pixel	O
shaders	O
in	O
Shader	B-Language
Model	I-Language
1.0/1.1	O
,	O
2.0	O
,	O
and	O
3.0	O
.	O
</s>
<s>
The	O
shader	O
assembly	O
language	O
cannot	O
be	O
directly	O
used	O
to	O
program	O
unified	O
Shader	B-Language
Model	I-Language
4.0	I-Language
,	O
4.1	O
,	O
5.0	O
,	O
and	O
5.1	O
,	O
although	O
it	O
retains	O
its	O
function	O
as	O
a	O
representation	O
of	O
the	O
intermediate	O
bytecode	O
for	O
debug	O
purposes	O
.	O
</s>
<s>
The	O
High-Level	B-Language
Shading	I-Language
Language	I-Language
(	O
also	O
called	O
HLSL	B-Language
for	O
short	O
)	O
is	O
a	O
C-style	O
shader	B-Language
language	I-Language
for	O
DirectX	B-Application
9	I-Application
and	O
higher	O
and	O
Xbox	O
game	O
consoles	O
.	O
</s>
<s>
It	O
is	O
related	O
to	O
Nvidia	O
's	O
Cg	B-Language
but	O
is	O
only	O
supported	O
by	O
DirectX	B-Application
and	O
Xbox	O
.	O
</s>
<s>
HLSL	B-Language
programs	O
are	O
compiled	O
into	O
bytecode	O
equivalent	O
of	O
DirectX	B-Application
shader	O
assembly	O
language	O
.	O
</s>
<s>
HLSL	B-Language
was	O
introduced	O
as	O
an	O
optional	O
alternative	O
to	O
the	O
shader	O
assembly	O
language	O
in	O
Direct3D	O
9	O
,	O
but	O
became	O
a	O
requirement	O
in	O
Direct3d	O
10	O
and	O
higher	O
,	O
where	O
the	O
shader	O
assembly	O
language	O
is	O
deprecated	O
.	O
</s>
<s>
Adobe	O
Systems	O
added	O
Pixel	B-General_Concept
Bender	I-General_Concept
as	O
part	O
of	O
the	O
Adobe	B-Operating_System
Flash	I-Operating_System
10	O
API	O
.	O
</s>
<s>
Pixel	B-General_Concept
Bender	I-General_Concept
could	O
only	O
process	O
pixel	O
but	O
not	O
3D-vertex	O
data	O
.	O
</s>
<s>
Flash	O
11	O
introduced	O
an	O
entirely	O
new	O
3D	O
API	O
called	O
Stage3D	B-Operating_System
,	O
which	O
uses	O
its	O
own	O
shading	B-Language
language	I-Language
called	O
Adobe	B-Language
Graphics	I-Language
Assembly	I-Language
Language	I-Language
(	O
AGAL	O
)	O
,	O
which	O
offers	O
full	O
3D	B-Architecture
acceleration	I-Architecture
support	O
.	O
</s>
<s>
GPU	B-Architecture
acceleration	O
for	O
Pixel	B-General_Concept
Bender	I-General_Concept
was	O
removed	O
in	O
Flash	O
11.8	O
.	O
</s>
<s>
AGAL	O
is	O
a	O
low-level	O
but	O
platform-independent	O
shading	B-Language
language	I-Language
,	O
which	O
can	O
be	O
compiled	O
,	O
for	O
example	O
,	O
or	O
GLSL	B-Language
.	O
</s>
<s>
Sony	O
announced	O
PSSL	O
(	O
PlayStation	B-Language
Shader	I-Language
Language	I-Language
)	O
as	O
a	O
platform-specific	O
shading	B-Language
language	I-Language
similar	O
to	O
Cg/HLSL	O
for	O
the	B-Operating_System
PlayStation	I-Operating_System
4	I-Operating_System
.	O
</s>
<s>
It	O
is	O
said	O
to	O
be	O
largely	O
compatible	O
with	O
HLSL	B-Language
shaders	O
on	O
PC	O
,	O
but	O
with	O
additional	O
features	O
for	O
the	O
PS4	B-Operating_System
platform	O
.	O
</s>
<s>
Apple	O
has	O
created	O
a	O
low-level	O
graphics	O
API	O
called	O
Metal	B-Library
,	O
which	O
runs	O
on	O
most	O
Macs	O
made	O
since	O
2012	O
,	O
iPhones	O
since	O
the	O
5S	O
,	O
and	O
iPads	O
since	O
the	O
iPad	O
Air	O
.	O
</s>
<s>
Metal	B-Library
introduces	O
its	O
own	O
shading	B-Language
language	I-Language
called	O
Metal	B-Library
Shading	I-Library
Language	I-Library
(	O
MSL	O
)	O
,	O
which	O
is	O
based	O
on	O
C++14	B-Language
and	O
implemented	O
using	O
clang	B-Application
and	O
LLVM	B-Application
.	O
</s>
<s>
WebGPU	B-Operating_System
Shading	I-Operating_System
Language	I-Operating_System
(	O
WGSL	O
)	O
is	O
the	O
shader	B-Language
language	I-Language
for	O
WebGPU	B-Operating_System
.	O
</s>
<s>
That	O
is	O
,	O
an	O
application	O
using	O
the	O
WebGPU	B-Operating_System
API	O
uses	O
WGSL	O
to	O
express	O
the	O
programs	O
,	O
known	O
as	O
shaders	O
,	O
that	O
run	O
on	O
the	O
GPU	B-Architecture
.	O
</s>
<s>
As	O
more	O
and	O
more	O
graphics	O
APIs	O
become	O
available	O
,	O
developers	O
face	O
the	O
problem	O
of	O
porting	O
shaders	O
from	O
one	O
shading	B-Language
languages	I-Language
to	O
another	O
.	O
</s>
<s>
Manual	O
switching	O
using	O
C	B-Language
preprocessor	I-Language
(	O
CPP	O
)	O
statements	O
.	O
</s>
<s>
Cg/HLSL	O
,	O
GLSL	B-Language
,	O
and	O
MSL	O
all	O
implement	O
CPP	O
macros	O
,	O
so	O
it	O
is	O
possible	O
to	O
wrap	O
all	O
the	O
different	O
operations	O
into	O
a	O
common	O
interface	O
.	O
</s>
<s>
Valve	O
's	O
Source	O
2	O
and	O
NVIDIA	O
's	O
FXAA	B-Algorithm
3.11	O
do	O
this	O
.	O
</s>
<s>
DirectX	B-Language
bytecode	I-Language
partially	O
can	O
be	O
converted	O
to	O
GLSL	B-Language
via	O
HLSLcc	O
,	O
and	O
several	O
tools	O
for	O
converting	O
GLSL	B-Language
to	O
HLSL	B-Language
such	O
as	O
ANGLE	B-Language
and	O
HLSL2GLSL	B-Application
exist	O
.	O
</s>
<s>
SPIR-V	B-Application
is	O
designed	O
partially	O
for	O
this	O
purpose	O
.	O
</s>
<s>
It	O
can	O
be	O
generated	O
from	O
HLSL	B-Language
or	O
GLSL	B-Language
,	O
and	O
be	O
decompiled	O
into	O
HLSL	B-Language
,	O
GLSL	B-Language
,	O
or	O
MSL	O
.	O
</s>
