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Lars-Erik Østerud
January 15th 07, 05:45 PM
If you exchange a videocard that emulates DX9 in software (like old
cards when playing "Source" games) with a new one with hardware DX9,
will this move some of the load from the PCs CPU to the video GPU?
(CPU cycles that can be used for other thing in the game that is :-)
--
Lars-Erik - http://www.osterud.name - ICQ 7297605
XP, Asus P4PE, 2.53 GHz, Asus V8420 (Ti4200), SB-Live

Benjamin Gawert
January 15th 07, 08:34 PM
* Lars-Erik Østerud:

> If you exchange a videocard that emulates DX9 in software (like old
> cards when playing "Source" games) with a new one with hardware DX9,
> will this move some of the load from the PCs CPU to the video GPU?
> (CPU cycles that can be used for other thing in the game that is :-)

No video card emulates DX9 in software. DX9 games that run on non-DX9
cards simply fall back to a DirectX 8 render path which is in these
games. To use the DirectX 9 render path you need DirectX 9 compliant gfx
hardware...

Benjamin

Lars-Erik Østerud
January 15th 07, 09:10 PM
Benjamin Gawert wrote:

> No video card emulates DX9 in software. DX9 games that run on non-DX9
> cards simply fall back to a DirectX 8 render path which is in these
> games. To use the DirectX 9 render path you need DirectX 9 compliant gfx

Why does the Source engine then state "DX9 support though software"
(or somthing like that). I interpreted that as it emulated something.

Will upgrade from a DX8 to DX9 card offload the CPU a lot in games
like HL2 then as DX9 would push more computation to the GPU instead?
--
Lars-Erik - http://www.osterud.name - ICQ 7297605
XP, Asus P4PE, 2.53 GHz, Asus V8420 (Ti4200), SB-Live

deimos
January 16th 07, 03:10 AM
Lars-Erik Østerud wrote:
> Benjamin Gawert wrote:
>
>> No video card emulates DX9 in software. DX9 games that run on non-DX9
>> cards simply fall back to a DirectX 8 render path which is in these
>> games. To use the DirectX 9 render path you need DirectX 9 compliant gfx
>
> Why does the Source engine then state "DX9 support though software"
> (or somthing like that). I interpreted that as it emulated something.
>
> Will upgrade from a DX8 to DX9 card offload the CPU a lot in games
> like HL2 then as DX9 would push more computation to the GPU instead?

You can run DX9 on a Geforce FX class part, but for older cards like the
GF4, a game like HL2 requires hardware features to implement the pixel
shaders and effects. For example, normal mapping can be implemented
through software, but it's not a part of the DX9 API, only hardware
features are supported. Emulating these features exactly through
software would be fairly slow, so most games drop back their "rendering
path" to equivalent DX8.1 features that mimick the effect.

Another example; with a GF3 or 4, you don't get HDR, but you can mimick
it with overbright calculations (a multitexture trick) or fake bloom.
Other games simply use the more efficient DX9 API for regular rendering;
not always for pixel shaders and advanced features.