> ../.. From a 3D engine design POV, it's much
> better to abstract shaders into a higher-level
> interface that allows artists specify a "material"
> for an object rather than directly specify shader-code.
Yes, that's exactly my design choice, actualy.
> ../.. The engineers would then be free to implement
> the material in the most optimized way for each
> platform. In that sense, you might actually end
> up mixing Cg and HLSL and GLSL or even a company-proprietary
> language for a single project. And personally I wouldn't
> consider that a bad design...
Yep, I think it is currently inevitable, anyway.
--
guy rabiller | 3d technical director (at) LaMaison
Wessam Bahnassi a écrit :
Honestly, all this multi-platform thing is totally dependent on the
company's policy. I think casual games have more tendency to support
multiple platforms because their problems are usually easily-manageable. But
larger titles concentrate on the market with the biggest numbers, and they
ship to other platforms as well if the title becomes a top-seller.
Realistically, even if a title is to be launched on targets that use D3D and
OGL, it's hard to share shaders across platforms mainly because of the huge
hardware differences. Advanced features vary a lot between platforms, and it
would be a shame to lose all that for a common-denominator solution that
allows you to write a shader once and reuse on multiple platforms. From a 3D
engine design POV, it's much better to abstract shaders into a higher-level
interface that allows artists specify a "material" for an object rather than
directly specify shader-code. The engineers would then be free to implement
the material in the most optimized way for each platform. In that sense, you
might actually end up mixing Cg and HLSL and GLSL or even a
company-proprietary language for a single project. And personally I wouldn't
consider that a bad design...
Does this answer your question? :)
Wessam Bahnassi
Microsoft DirectX MVP,
Programmer
Electronic Arts
--
In|Structurez Arabic Gamedev Community
www.instructurez.com
-----Original Message-----
From: owner-3dgames(at)Softimage.COM [mailto:owner-3dgames(at)Softimage.COM] On
Behalf Of Guy Rabiller
Sent: Friday, October 20, 2006 9:36 AM
To: 3DGames(at)Softimage.COM
Subject: Re: High Level Shading & Gaming Industry
Thanks for your input Wessam.
> ../.. Cross-platform support? For what? Linux? FreeBSD?
> These are not OSs that gamers use ../..
What about the Mac ?
But, lets say that both support for DirectX and OpenGL is needed.
From your <personal>opinion</personal> would it be preferable to only
support Cg or only HLSL/GLSL ?
--
guy rabiller | 3d technical director (at) LaMaison
Wessam Bahnassi a écrit :
HLSL is well-integrated within the DirectX SDK and is very easy to use
and
integrate out of the box. If the game (or even the whole company) is not
going to use OpenGL, then why bother with Cg? And thanks to the Xbox,
your
HLSL code can be easily ported to Xbox and 360, whereas Cg doesn't
compile
for these targets...
<personal opinion>
Well, asking about whether to choose Cg or HLSL is similar to asking
whether
to use OpenGL or Direct3D. As you know, most PC game titles today use
Direct3D as a 3D API.
Now, from a 3D Engine developer point-of-view, it's a big waste of time
to
support both D3D and OGL. Cross-platform support? For what? Linux?
FreeBSD?
These are not OSs that gamers use. But Xbox, and Xbox360 (which are D3D-
only
based) are widely distributed. PS2 and PS3 do not use OGL as their
graphics
API so the engine will still have to support these in a different code
path
anyways whether it supports OGL or not...
</personal opinion>
Performance-wise, one might argue that Cg delivers better performance on
nVidia hardware because the compiler knows exactly what's running
beneath
it. This fact will mostly change with D3D10 now as the compilation of
HLSL
will be moved to the driver itself, which means nVidia ca provide the
same
optimization capabilities as they do with the Cg compiler (unless if
they
intentionally don't want to :)
Wessam Bahnassi
Microsoft DirectX MVP,
Programmer
Electronic Arts
--
In|Structurez Arabic Gamedev Community
www.instructurez.com
-----Original Message-----
From: owner-3dgames(at)Softimage.COM [mailto:owner-3dgames(at)Softimage.COM]
On
Behalf Of Guy Rabiller
Sent: Friday, October 20, 2006 3:22 AM
To: 3DGames(at)Softimage.COM
Subject: High Level Shading & Gaming Industry
Hi,
I'm trying to gather usefull informations about high level shading
habits and usages in the gaming industry.
So far, and afaik, there are HLSL, GLSL & Cg among the most used high
level shading languages available.
I've seen that most engines are trying to support all of these, some
only support one.
The kind of questions I have in mind is for instance:
What the point of supporting HLSL & GLSL if Cg is able to handle both
OpenGL and DirectX ?
Do you think it would be reasonable to only support Cg ? Are there any
strong reasons why an engine should support Cg and HLSL for instance ?
I'm thinking about one: Gaming Console ( especialy XBox for instance
where HLSL is mandatory, afaik ).
But outside the gaming console world, would there be any reason at all
?
Performance may be ?
What are your thoughts/informations about this matter ?
Thanks in advance for any hint.
--
guy rabiller | 3d technical director (at) LaMaison
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