PDA

View Full Version : DX9 software vs hardware


Lars-Erik
01-15-07, 11:55 AM
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 :-)

fatal1ty
01-15-07, 12:10 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 :-)


Yup, thats why its called hardware acceleration, acclerated by hardware in this case the GPU. It will move the graphic stuff to the video card and allow the CPU to handle things like physics, audio and other calculations needed for the game.

jolle
01-15-07, 03:17 PM
older cards in Source doesnt emulate DX9, they run DX8 or DX7 (might even go as low as DX6, dont remember really)
No software renderer in any game emulates DX9, I think one of the latest software renderers (I can recall) is the Pixomatic renderer in UT2k4, which only runs geometry and textures. (um, I guess the entire game does, but anyway)
I dont think you can acctually run anything with shaders on a software renderer and get any decent performance out of it.
So software renderers have to run games very stripped down, which is why they are so rare these days, the visual difference between Direct3d (or OpenGL) and software renderered is way to big for anyone to bother anymore.

Lars-Erik
01-15-07, 03:25 PM
What is then the point of these lines in Source games "video settings":

Hardware DirectX level: DirectX v8.0
Software DirectX level: DirectX v9.0

Why mention DX9 if it isn't used for anything?

(any reason why Source games don't have OpenGL support BTW?)

jolle
01-15-07, 04:13 PM
I guess that means you have DirectX9 installed, while your hardware only supports DX8 rendering, and thats what it will be running.

Dunno why they choose D3d over OpenGL, most do these days.
And for not adding a optional OpenGL renderer, I assume they didnt feel there was any point in doing so.
HL1 had support for both, but I think that was cause the market was a bit split up, some things didnt run OGL well, some only worked on D3d etc.
The d3d6 renderer back then was pretty slow on anything I ran it on compared to OGL tho, and D3d didnt really start to take of seriously until DX7 as I recall it.