DirectX 9 vs. DirectX 8: Image Quality

Remember ATI’s Shader Day last year where Valve announced that NVIDIA’s DirectX 9 hardware should be treated as DX8 hardware and nothing more?  Well, things haven’t really changed – in our tests, NVIDIA’s GeForce 5900XT was between 50 and 72% slower in DX9 mode than in DX8 mode.  In fact, the 5900XT is so slow in DX9 mode that ATI’s $80 Radeon X300 SE actually posts significantly higher average frame rates.  So if you own a NV3x class GPU, you are pretty much excluded from running Valve’s DirectX 9 codepath.  What, then do you lose by going down to the DirectX 8.1/8.0 codepaths?

The first thing we wanted to check was the flashlight shader – how different did it look from DX9 to DX8?  The default image below is the DX9 image, mouse over the image to see the flashlight shader rendered using Valve’s DX8 path:



Hold mouse over image to see DX8 mode

There are some slight differences between the two images, but interesting enough none of them appear to have anything to do with the flashlight shader itself. 

The first difference is in the shading on the gun, the DX8 gun has a much brighter surface while the DX9 gun looks a bit more realistically lit. The same can be said about the rails on the train tracks, the DX8 rails stand out a lot more while the DX9 rails appear to be more realistically lit. 

There are many minor differences like this, however the biggest difference between DX8 and DX9 is the water:



Hold mouse over image to see DX8 mode

Using the DirectX 9 codepath, the water in Half Life 2 is so much more realistic.  You can download full uncompressed versions of these images here.

Overall, the move from DX9 down to DX8 isn’t horrible; while it does reduce some of the appeal of Half Life 2, the game still looks incredible in DX8 mode.  There are some issues with forcing NV3x GPUs to run in DX9 mode mainly involving the water, but as you will see on the coming pages, if you've got a NV3x you're not going to want to play in DX9 mode.

Index DirectX 9 Performance Impact
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  • abakshi - Sunday, November 21, 2004 - link

    Just a note - the last graph on page 7 seems to be a bit messed up -- the GeForce 6200 is shown as 82.3 FPS - higher than all of the over cards - while the data chart and line graph show it as 53.9 FPS. Reply
  • KrikU - Sunday, November 21, 2004 - link

    Why cant we see benchmarks with AA & AF enabled with mainstream graphics cards? HL2 is using a such engine that is only CPU limited, so AA & AF tests are really welcome!
    Im playing with ti4400 (o/c to ti4600 speeds) with AA 2x & AF 2x! This is first such new game where I can use these image quality enhancements with my card!
    Reply
  • T8000 - Sunday, November 21, 2004 - link

    Half life 2 seems to be designed around the Radeon 9700.

    Because Valve seems to have made certain promises to ATI, they where not allowed to optimize any Geforce for DX9.

    This also shows with the GF6200, that should be close to the R9600, but is not, due to the optimized Radeon 9700 codepath.

    Luckely, Valve was hacked, preventing this game from messing up the marketplace. Now, almost any card can play it and Nvidia may even be tempted to release a patch in their driver to undo Valves DX9 R9700 cheats and make the game do DX9 the right way for FX owners, without sacrificing any image quality. Just to prove Valve wrong.
    Reply
  • draazeejs - Sunday, November 21, 2004 - link

    Well, I like HL2 a lot, much more so than the pitch-black, ugly-fuzzy texture D3. But, honestly - to me it looks exactly like Far Cry, engine-wise. Is there any difference?
    Respect to the level-designers of HL2, none of the games comes even close nowadays to that sort of detail and scenery. Also I think the physics of the people and faces and AI is by far superior. And the Raven-yard is much more scary than the whole D3 :)))
    Reply
  • kmmatney - Sunday, November 21, 2004 - link

    [sarcasm] Oh, and have fun running those DX games on other platforms without emulation. [/sarcasm]

    Obviously, this game isn't meant for other platforms, and that's fine by me. I think the original half-life had an OpenGL option, but it sucked (at least on my old Radeon card). In general, OpenGL has always been a pain, dating back to the old miniGL driver days. In my experience, when playing games that had either a Dx or OpenGL option, the DX option has usually been more reliable. It sould be because I usually have ATI based cards...
    Reply
  • kmmatney - Sunday, November 21, 2004 - link

    I didn't mean that DX literally "looks" better than OpenGl, I meant that it seems to be more versatile. Here's a game that can be played comfortably over several generations of video cards. You have to buy a new one to play D3 at decent resolution. The HL2 engine seems to have room to spare in terms of using DX 9 features, so the engine can be further enhanced in the future. I would think this game engine would be preferred over the Doom3 engine. Reply
  • oneils - Sunday, November 21, 2004 - link

    #15, Steam's site (under "updates") indicates that the stuttering is due to a sound problem, and that they are working on a fix. Hopefully this will help you.

    Reply
  • vladik007 - Saturday, November 20, 2004 - link

    " I'm missing words to how pathetic that is. "

    1st my post was no.2 NOT no.3.
    2nd unlike many people i dont have time to work on my personal computers all the time. IF i dont upgrade this holliday season , i'll possibly have to wait until summer vacation. And you dont see nforce4 out now , do you ?
    3rd No it's not pathetic to follow something that's never failed me. Ever heard of satisfied customer ? Well Abit has always treated me very well , RMA proccess , crossshiping , bios updates , good support on official forums ... etc Why on earth should i change ?
    4th got it ?
    Reply
  • moletus - Saturday, November 20, 2004 - link

    I really would like to see some ATI 8500-9200 results too.. Reply
  • Pannenkoek - Saturday, November 20, 2004 - link

    #18: It depends on what features of the videocards are used for how a game will look like, and the art. It's not dirct3d vs opengl, the videocards are the limiting factor. Doom III is just too dark, and that's because of an optimization used in the shadowing. ;-)

    #26: Surely you mean "#2", I'm all for AMD. Not that my current computer is not pathetic compared with what's around nowadays...
    Reply

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