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
POST A COMMENT

62 Comments

View All Comments

  • meatless - Saturday, November 20, 2004 - link

    I agree with #31, mostly; after playing both I don't think that HL2 is any better than Doom3, just different in how they look f'ing awesome.

    And saying that DX looks better than OpenGL "just because" is about the stupidest f'ing thing I've ever heard.

    [sarcasm] Oh, and have fun running those DX games on other platforms without emulation. [/sarcasm]
    Reply
  • TheRealSkywolf - Saturday, November 20, 2004 - link

    Hl2 can be easier on the eyes due to art, and the animations are also very cool. But i think doom3 is more intense in technology, doom3 just uses more in very ways, and in the long run the doom3 engine will power the best games. hl2 looks amazing, but doom3 is a better estimate to how games in the future will run in your card.
    Reply
  • Filibuster - Saturday, November 20, 2004 - link

    This article was a fun read.
    I particularly liked the part about the fallbacks that are in place for older cards and the screenshot comparisons.
    Thanks.
    Reply
  • Filibuster - Saturday, November 20, 2004 - link

    >I can't believe how much better DirectX looks compared to OpenGL. Seems like Id made the wrong choice...

    What a rediculous generalization.

    I do think that Halflife2 looks far better than Doom3 but the API has nothing to do with how things look. (I imagine HL2 will be much more fun too but I'm replaying HL1 w/source to get back into it)

    Carmack will never use Direct3D. He said so years ago and I doubt he will change his mind (even if it is just to make a point). He is sort of the champion of Opengl for games. Besides, all of the features of the video cards can be exposed in Opengl just like Direct3D (perhaps moreso through the use of extentions). Carmack just targeted a different set of features with Doom3 (mostly it was designed around the Geforce3/4 featureset, and the 6 series was designed for Doom, not the other way around like so many people like to claim)
    Reply
  • GonzoDaGr8 - Saturday, November 20, 2004 - link

    Thanx kevin and ksherman.. Reply
  • Jeff7181 - Saturday, November 20, 2004 - link

    I agree with #1... I'm well into City 17 and I have all my stuff... because of the first review saying I didn't have a flashlight, I was expecting to be thumped on the head again and have all my stuff taken away and end up in a prison cell or something. Reply
  • MrGarrison - Saturday, November 20, 2004 - link

    #3
    That's pathetic.
    nForce4 is around the corner and there are lots of good alternatives like MSI K8N Neo4 Platinum.

    I have "pals" at home who are the same way. Only Intel and only ABIT... I'm missing words to how pathetic that is.
    Reply
  • unclesam - Saturday, November 20, 2004 - link

    What is the difference between DX 8.0 and 8.1? I am playing the game on a 1.6 GHz Pentium M ThinkPad T41 with a DX 8.1 ATI Mobility Radeon 9000, 32 MB. I too have everything turned on to high, including 1400 x 1050 resolution, and I have experienced no serious hiccups. I had to reduce reflections to the minimum setting, but I just went back to that scene with reflect everything, and the water looks exactly like the DX 9.0 output. The only time the game stutters is just after loading a level. The performance limiter does not seem to be the CPU/GPU, but rather the limited throughput of my FSB. I assume that your CPU test will use "equivalent new patforms" and then compare the fastest "gaming" CPU. Since you have gone through the trouble of benchmarking older graphics cards, I think you should also benchmark the older paltforms and CPUs that go with them, or rather the other way around. Please compare platform performance rather than just CPUs.

    By the way, I am extremely envious of anyone with a halfway decent desktop setup (P4HT800fsb, >ATI 9600). For a small section I turned on reflect all and 6x AA and 16x AF. Got .25 fps, but damn, it's like you are there.

    Happy computing.
    Reply
  • Saist - Saturday, November 20, 2004 - link

    same setup Revrnd.

    The benchs I want to see though are Geforce4 MX on a 1.2ghz P4 or Athlon XP 1500. Ya know. Something that AVERAGE people have.
    Reply
  • GoodRevrnd - Saturday, November 20, 2004 - link

    Am I blind or did Anand not post what system these benches was ran on? Or was it the same setup from the first article? Reply

Log in

Don't have an account? Sign up now