Does Oblivion implement backface culling?

This is a discussion on Does Oblivion implement backface culling? within the A Brief History of Cprogramming.com forums, part of the Community Boards category; It wouldn't surprise me if the answer is "No.". The game runs so damn slow compared to every other game ...

  1. #1
    Supermassive black hole cboard_member's Avatar
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    Does Oblivion implement backface culling?

    It wouldn't surprise me if the answer is "No.". The game runs so damn slow compared to every other game I own (at least one of which is more demanding, apparently).

    I put it in wireframe mode and wasn't particularly surprised to see this:

    http://www.mknetworks.co.uk/~ahluka/ScreenShot4.jpg

    (Sorry about the image loading times - slow server)

    I'm not sure whether or not this means it doesn't use backface culling (it's probably just drawing every line in the map for the purpose of wireframe mode) but I only gain ~8 FPS by turning switching back to textured mode.

    Discuss.

    EDIT: Oh and I get no more than 20 FPS with it off, even if I turn all the settings (an I mean all) down to their lowest. I could turn the resolution down but then I'd be eye-raped by jaggies (AA doesn't work with HDR).

    Sure, I could turn off HDR, but who does that? Oblivion is one of the few games out there that makes good use of it (I.E. It doesn't blind you).

    In that particular scene I get 16 FPS in textured mode.
    Last edited by cboard_member; 07-13-2006 at 11:30 AM.
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

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  2. #2
    The superhaterodyne twomers's Avatar
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    I didn't have a clue what you were on about, so I read this article. From the screen shot (very slow!! ), it certainly seems like they don't use it. I don't see why. Also, your FPS also seems to suggest that. Weird eh.

  3. #3
    Crazy Fool Perspective's Avatar
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    Well, for starters, it sounds like your confusing back face culling with occlusion culling. Back face culling is something you simply "turn on" in your graphics API so it doesn't render the front and back of every poly.

    As for occlusion culling, it could be ignored for the sake of wireframe mode (so you can see objects through the frame of others) or it may just be too computationaly expensive with all those little trees and bushes.

    Does your PC meet the minimum requirements of the game?

  4. #4
    Supermassive black hole cboard_member's Avatar
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    Indeed it does, and yes, I got them confused. Actually, I'd never heard of occlusion culling until I read that

    P4 3GHz (Ugh)
    1GB DDR400 PC3200 RAMMY-RAM-RAM-RAM
    Geforce 6600GT 128MB VRAM (the APG aperture is set to 256MB), no overclocking otherwise (if that's classed as O/C'ing).
    7200RPM HDD Defragged once a week or more if I install something.

    Bethesda programmers are a curse. I don't exactly get top-notch performance out of Morrowind either.
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

    - Mike McShaffry

  5. #5
    (?<!re)tired Mario F.'s Avatar
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    Quote Originally Posted by ahluka
    P4 3GHz (Ugh)
    You are a funny guy

    ... P3 1Ghz ( pow(Ugh, 2) )
    The programmer’s wife tells him: “Run to the store and pick up a loaf of bread. If they have eggs, get a dozen.”
    The programmer comes home with 12 loaves of bread.


    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  6. #6
    Registered User divineleft's Avatar
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    I have a 2.8 intel p4, 516 ram and a crappy $50 vid card and i can run morrowind on the highest settings with absolutly no lag

    maybe it's just your system?

  7. #7
    The superhaterodyne twomers's Avatar
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    I have a 1.7 ghz mobile processor on my lappy, gig ram, 128 mb graphics (which never gets used. In fact it could be 64 megs. I can't remember), 60 gig hd (or it could be 40. I think it's 60 though). I don't actually have any games on my lappy, except of course for those brilliant, and graphically demanding console games which I wrote ages ago

  8. #8
    Devil's Advocate SlyMaelstrom's Avatar
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    I keep Fallout 1 and 2 on my laptop in case I feel the need to do a quick run at any given time. Suffice it to say, I get no lag on those titles. I also get no lag on my desktop PC with Marrowind, which is weaker than Ahluka. You still want that thing, by the way, man?
    Last edited by SlyMaelstrom; 07-13-2006 at 05:17 PM.
    Sent from my iPad®

  9. #9
    Supermassive black hole cboard_member's Avatar
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    Oh yeah, hell I forgot about that.
    Anyhow it sounds like, once again, my machine has issues. I spend all that money on a nice cool case and this is how she repays me?!?!
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

    - Mike McShaffry

  10. #10
    Devil's Advocate SlyMaelstrom's Avatar
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    Cool looking or cool working? Often, those two don't coincide.
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  11. #11
    Supermassive black hole cboard_member's Avatar
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    Both as it happens. I would take picture of her but my camera, it's *over there*.
    Maybe later.

    (I think it looks cool anyway. Pretty colours!)
    So many fans. (4)
    Good class architecture is not like a Swiss Army Knife; it should be more like a well balanced throwing knife.

    - Mike McShaffry

  12. #12
    Super Moderator VirtualAce's Avatar
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    The wireframe screenshot is so slow because the Z buffer test passes for every pixel on the screen that either does not lie on a line, or does not intersect another line. In essence, since there is no solid fill or texturing in polies, Z buffer does not work correctly. This means that everything is drawn. Wireframe mode is not an accurate representation of any engine's capabilities.

    I'm nearly positive that Oblivion would implement backface culling, occlusion culling, batched rendering, BSP tree rendering (which would include the two previous methods mentioned), possibly quad-tree or oct-tree rendering, shaders - which would cut down the CPU lighting algorithms a lot as well as anything else they might do in the shader.

    Also it looks as though that shot has a water plane in it which means you are attempting to draw 2 wireframe images per frame all the while having the z buffer pass every test. This would bring the game to a complete crawl. Not only is this true, but you are forcing the engine to do environment mapping which means it is drawing a wireframe version of the reflected environment (out to a certain z distance) onto a texture and then using that texture for the water plane.

    Note also that if per-pixel shaders are on as well as per-pixel environment and/or specular bump mapping, these shaders are doing next to nothing which means that you may as well disable them for wireframe screenies.
    Last edited by VirtualAce; 07-14-2006 at 03:05 AM.

  13. #13
    The superhaterodyne twomers's Avatar
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    >> I would take picture of her but my camera, it's *over there*.

    Please, for the sake of bandwidth, and everyone's happiness, if you ever find your camera, turn down the resolution


    >> ... the z buffer ...

    Interesting. I must say this thread is teaching me a lot about things I never knew, and which are good pieces of pointless trivia! Knowledge is bliss ... or something to that effect anyways Wikepedia, as always, has good info on it, if anyone, like me, is completely ignorant of the niceities behind 3D computer things. Interesting read methinks.


    EDIT:
    >> I keep Fallout 1 and 2 on my laptop in case I feel the need to do a quick run at any given time.

    Sly, you are my hero! But I don't see how you could only have a 'quick' run through either of those games - too damn addictive! In Fallout 2 there was a glitch/bug when I was playing it where my car's boot followed me around, so if I found anything cool, I'd only have to go about one screen away to my boot, deposit useless stuff, and then get the new cool toy, which were mainly bozars! It was even there when I faced the final boss! I took great pleasure in 'jibbing' Marcas in FO2! Crazy man! He kept on killing me, and then not talking to me!
    Last edited by twomers; 07-14-2006 at 01:23 PM.

  14. #14
    Super Moderator VirtualAce's Avatar
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    ...and which are good pieces of pointless trivia!
    It's only pointless if you don't use it. These topics in the field of computer graphics are far from pointless trivia.

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