Anti-aliasing

Discussion in 'Half-Life' started by Gabe Newell, Jul 23, 2003.

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  1. Gabe Newell

    Gabe Newell Newbie

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    Since people seem to be hyperventilating over the anti-aliasing issue, I thought I'd update everyone.

    1) How bad is the problem?

    With current multi-sample implementations of anti-aliasing, you may sample texels outside of the polygon boundary, which may result in sampling light maps from other polygons.

    This has always been a problem. This is a problem with Quake 1, Quake 2, Quake 3, Daikatana, Sin, Elite Force, Half-Life, Counter-Strike on the X-Box, or any game that uses packed lightmaps with multi-sample anti-aliasing.

    You would see these artifacts on polygon boundaries where the wrong lightmap is being sampled. It will look like a bright or dark line on the edge of a polygon.

    Gary McTaggart brought this up in an email because he is being pretty hardcore about graphics quality right now. This is not a new problem. If you've run a game that uses lightmaps with anti-aliasing turned on, then you've been seeing these artifacts the whole time.

    Artifacts may show up more frequently in Half-Life 2 simply because we've eliminated lots of other artifacts, and because we have a lot of variation in scene lighting due to our art direction.

    To put this in perspective, not doing tri-linear filtering on mipmaps is a lot worse.

    2) What are potential solutions?
    • Support Centroid Sampling
    • Use Pixel Shaders to Clamp Texture Coordinates
    Centroid sampling doesn't have the problem that center sampling does in multi-sample antil-aliasing. ATI has supported this form of anti-aliasing for the 9000 series. The tricky part is enabling this when DirectX doesn't easily expose this.

    There's a different trick you can use with hardware, such as NVIDIA's, that doesn't support centroid sampling. Basically you trade off some pixel shader bandwidth to clamp the texture coordinates so that you don't sample texels outside of that polygon's lightmap sub-rect.

    Between these two approaches, multi-sample anti-aliasing artifacts should be a non-issue for any DX9-level hardware running Pixel Shader 2.0.

    3) How will this look?

    We'll release one of the demo movies with the anti-aliasing artifacts in and one with the anti-aliasing changes.
     
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  2. Axyon

    Axyon Newbie

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    If this is legit, I thank you very much for keeping us informed on the situation. It's most certainly an honour to have you here!

    [/asskiss]

    ;)
     
  3. Chris D

    Chris D Administrator.
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    :D Hey Gabe, thanks for clearing that up...
     
  4. PSX

    PSX Newbie

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    wow, thanks for the update Gabe, I never would have thought...

    man, I'm glad we got that cleared up, all these threads over fsaa concerns...
     
  5. qckbeam

    qckbeam Guest

    wow, thanks, that should clear up the whole issue
     
  6. Guest

    Guest Guest

    Thanks man, but doe that mean it is safe tp buy Nvidia FX5900 cards;;;:cool:
     
  7. Mr.Reak

    Mr.Reak Newbie

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    Looks legit to me :)
    Thank you.
     
  8. King Buzzo

    King Buzzo Guest

    You live in Kirkland? ewwww
     
  9. Lifthz

    Lifthz Newbie

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    Cool, Gabe. :p :p
     
  10. Axyon

    Axyon Newbie

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    Gabe's been registered on this forum for 5 days now, which coincides with the whole fiasco starting. It does indeed seem legit.
     
  11. Ahnteis

    Ahnteis Newbie

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    geez - with support like this I want to buy *2* copies. Or a t-shirt or something.

    Even takes the time to explain things in terms simple enough for all of us.

    pwnz0r3d!!!!!!111111
     
  12. Lifthz

    Lifthz Newbie

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    Gabe's a "headcrab". :cheese:
     
  13. marksmanHL2 :)

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    Wow, he was been watching our forums :cool:

    Thanks Mr gabe sir. :p

    I think you should try to answer the next question a newbie asks in the email valve thread if possible, and tell them yourself that their suppost to email you :p
     
  14. The Mullinator

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    Thanks for clearing that up Gabe. You really are the greatest. :thumbs:

    EDIT: hey Munro, this would make a very good sticky post. Kinda like a sacred thread that should be up for all to see. :cheese:
     
  15. SnowBall

    SnowBall Newbie

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    n00b: | Will my computar run HL2??
    ___________|____________________
    |
    Gabe Newell: |Your supposed to e-mail me.
    |
    ___________|____________________
     
  16. reever2

    reever2 Newbie

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    Ouch. If Nvidia is going to use pixel shader 2.0 to fix this problem that are in big trouble
     
  17. Skull

    Skull Newbie

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    Gabe: you made my day !
    :bounce:
     
  18. Direwolf

    Direwolf Newbie

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    Absolutely awesome to hear. :afro:
     
  19. urseus

    urseus Newbie

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    What a champ. Id always read about how helpfull valve was to day of defeat and how they could always email them about coding issues or any problems they had, but the email responses and interviews from the team are just phenominal. Ill have stearn words with anyone who bad mouths valve.
     
  20. Lifthz

    Lifthz Newbie

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    You referring to the recent reports about Fx cards not support all 2.0 features?

    We'll see if that has any effect on THIS situation.
     
  21. Axyon

    Axyon Newbie

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    Newspost made [​IMG]
     
  22. marksmanHL2 :)

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    :p exactly :D


    grrrr. I have to go sleep now. At this time. How annoying. ;)

    cheers again gabe. (video soon?) j/k j/k
     
  23. Prince of China

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    I wonder where that guy who's been making fun of Gabe has been. His name was "FatBoy Gabe", and his joke's weren't funny! Gabe should kick his @$s:cheers:
     
  24. Marauder

    Marauder Newbie

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    Cool the big man came by! Thanks for explaining it, though some of the technologically challenged (aka casual gamers) will have some problems understanding some of those words ;)

    I got the picture though, thanks for clearing up the tech side of it instead of having all these noobie idiots trying to make themselves sound smart by answering in dumb ways.
     
  25. Jagermeister

    Jagermeister Newbie

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    Welcome to the boards, Gabe :cheers:

    Will you be hanging out here more often?
     
  26. reever2

    reever2 Newbie

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    Support isnt the problem, speed is. Without Nvidia changing or having full control of what shader code is going to go into Hl2, its not going to be very fast or fast at all. I would guess nvidias drivers will balloon up a couple more mb worth of shader code once the fix is out
     
  27. Farrowlesparrow

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    Wow. I feel so privileged to be in the presence of the creator of Half-Life.

    (Yes i realise I'm not actually in his presence OK. Lets just let me have my fun)

    I hope that what you are saying is legit (by that i mean that it is in fact you saying it). Also seeing these videos would be nice. Ive been sat at my computer all the time waiting to see steam update (nice work with that by the way. I like it).:dork:
     
  28. SpuD

    SpuD Newbie

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    Im ranked higher than gabe!
    Seriously, I hope this is legit, because if it isnt its not a funny joke...
     
  29. droper

    droper Guest

    I'm just posting to be part of gabes thread :bounce:
     
  30. Lifthz

    Lifthz Newbie

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    Lol. You aren't in his presence.

    Well I dunno, we haven't seen any game that actually uses much of DX9 man. Heheh. We'll see.
     
  31. Kamakiri

    Kamakiri Spy

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    Gabe is a noob headcrab. :cheese:

    Noob noob. Let the flaming begin. noob. :eek:

    No but seriously thanks for clearing things up.
     
  32. Jagermeister

    Jagermeister Newbie

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    Gabe gets to play HL2, you don't :p



    I don't either ;(
     
  33. Torsion

    Torsion Guest

    Very professionaly done Gabe. I have never seem a company so dedicated to their fans. I think its so awsome and wish you and your team all the success in the world.

    As for me, I probably will not be using AA with my nvidea ti4200 anyways.
     
  34. ValVed RaY

    ValVed RaY Newbie

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    ahh don't thank me it's ok :D
     
  35. Lifthz

    Lifthz Newbie

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    Yeah, it's good. Bungie does similar. More through their website though. Valve has nothing at their site.
     
  36. Boogaleeboo

    Boogaleeboo Guest

    Bungie also butchers it's original idea to get it to fit on a underselling console and cuts major portions of the game for the PC release.

    Lets stick to Valve.
     
  37. mannyfresh027

    mannyfresh027 Newbie

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    yay gabe

    a spokesman who knows what hes talking about. glad we got a good technical explanation and how it could be fixed :D
     
  38. Direwolf

    Direwolf Newbie

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    You're confusing Microsoft an Bungie again.
    And the PC version of Halo actual has more stuff than the Xbox version, albeit much later.
     
  39. CommieX

    CommieX Newbie

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    Yeah, Bungie sold out. Then again, Bungie probably needed money.
     
  40. mannyfresh027

    mannyfresh027 Newbie

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    halo rocked as an xbox game :D

    it will suck for PC
     
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