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Games Entertainment

The Technology Behind ID's Games 324

orac2 writes: "The current issue of IEEE Spectrum has an article on the groundbreaking technology behind iD Software's games, from the days of Commander Keen through to Return to Castle Wolfenstein. Graphics technologies covered include the original 2-D buffer trick that made side-scrolling games on the PC feasible, as well as the more modern Raycasting and Binary Space Partition Tree techniques. Carmack is quoted extensively."
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The Technology Behind ID's Games

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  • Quake I / II (Score:3, Informative)

    by Shamanin ( 561998 ) on Tuesday August 13, 2002 @04:51PM (#4064568)
    I read this in the IEEE spectrum. They kept mixing up the advances in Quake I with Quake II. They even refer to a picture of Quake II as Quake I. But, there was some interesting history nonetheless.
    • Re: Quake I / II (Score:2, Insightful)

      by Doppler00 ( 534739 )
      I just received the issue of IEEE recently. I thought it was funny to see an article about id in a magazine like IEEE which usually discusses things like transistor band gaps and such.

      They talk about id's technology in depth, but they really don't understand the gaming culture that was behind creating the games. This was the driving force for the technology and it was far more important than just the latest advances in BSP.

      The original article even mentions that Super Mario Brothers 3 was for the Super Nintendo, which of course isn't true. It was for the original Nintendo Entertainment System.
      • There was a version of SMB3 for the SNES, included in the All Stars pack. It was much nicer graphically than the NES version.

        But the game rocked regardless :)
  • by Ted_Green ( 205549 ) on Tuesday August 13, 2002 @04:54PM (#4064590)
    "First, they decided to see if they could recreate on a PC the gaming industry's biggest hit at the time, Super Mario Brothers 3. This two-dimensional game ran on the Super Nintendo Entertainment System, which drove a regular television screen."

    If they can't even get that right, how am I to believe what they say about frame buffering, Hmmmmmmmmmm?????

    I'm going to go get some pie instead.
  • Carmack IS God! (Score:5, Interesting)

    by casings ( 257363 ) on Tuesday August 13, 2002 @04:55PM (#4064604)
    I mean, hes not only a very good programmer, he looks like a computer dork, has a phat car, and actually cares what the community thinks about his games. As was the case when there was such a backlash about fixing the bug in the engine of quake2 that produced the strafe jump, he changed it, uproar ensued, he changed it back.

    Carmack embodies what every programmer and any kind of computer company should strive to be.

    Carmack has embraced the platform-generic opengl, and even coded his engine to be compatible on every major os. I love you carmack, please have my love child.

    I MEAN C'MON hes the one responsible for such things as the infamous railgun, and the hilarious warnings about piracy on my copied version of wolf3d, which i still play on my 386 laptop.
  • Excellent diagrams (Score:4, Informative)

    by jukal ( 523582 ) on Tuesday August 13, 2002 @04:55PM (#4064606) Journal
    This one is particularly good: about binary space partition tree [ieee.org].
    • by jtdubs ( 61885 ) on Tuesday August 13, 2002 @05:14PM (#4064719)
      Binary space partitioning trees proper have fallen out of use in games.

      All BSP-based games now-a-days use Solid Leaf BSP trees, which are a variation of the original and have many more useful properties for games.

      It is these trees and the sectors that they create that are used for determining portals.

      If two sectors have the same portal then those two portals connect and can see eachother. If a portal has no pair, then it is a portal out in to infinite space and is hence a leak in your map. Assuming, of course, a map based on a single BSP tree.

      Once you have portals, PVS generation is easy. And there you go, BSP and PVS.

      A lot of modern research is shying away from BSP and PVS. They limit you to indoor spaces. Entirely different technology is required for outdoor scenes. And then special hacks and logic are needed to allow for seamless transitions between the indoor and outdoor worlds.

      Some think that octrees with a form of occlusion culling might very well be better as they can represent both indoor and outdoor geometry without making any distinction between them. They are much harder to cull though as no handy PVS information is present and only more difficult methods exist such as Z-pyramids.

      Others stick with BSP and PVS and use the one-sided portals that would normally represent leaks but instead in this case represent windows from the BSP into the terrain, and vice-versa. This combined with some extra lighting and shodow-volume information and you can have your lighting and transitioning between indoor and outdoor be seemless.

      Anyway, just the ranting of a bored man at work.

      Justin Dubs

  • Excellent. I wish I had read it when I was 12! ;)
  • Truly impressive (Score:5, Informative)

    by aengblom ( 123492 ) on Tuesday August 13, 2002 @04:56PM (#4064612) Homepage
    The truly breakthrough technology is that ID made it possible to spontaneously induce vomiting without noxious fumes! ;-)

    ARRG (offtopic)
    Editors please (as in pretty) fix this:

    User types in comment and submits it (without subject). Is told to type in subject, but then is told "you have submitted to quickly." User loses comment because it is cleared from browser cache and slashdot doesn't put it in the error page.

    ( /offtopic )

  • by Tall Rob Mc ( 579885 ) on Tuesday August 13, 2002 @05:02PM (#4064647)
    Basically, what I got out of this article was that John Carmack is almost single-handedly responsible for all of my non-productive time over the past 10 years. Thanks John!
  • by death00 ( 551487 ) on Tuesday August 13, 2002 @05:05PM (#4064665)

    "There were critical points in the evolution of this stuff," Carmack says, "getting into first person at all, then getting into arbitrary 3-D, and then getting into hardware acceleration....But the critical goals have been met. There's still infinite refinement that we can do on all these different things, but...we can build an arbitrary representational world at some level of fidelity. We can be improving our fidelity and our special effects and all that. But we have the fundamental tools necessary to be doing games that are a simulation of the world."

    This article highlights how far we have come as game developers. id has been the "poster child" of the game development community, with the majority of other game developers following their lead. Doom III will continue this trend.

    The next generation of games is going to be outstanding!

    This article [extremetech.com] gives a great view of where we can be going with new technology. How realistic will games be in 10 years? My guess is that the graphic reality will become nearly indistinguishable from real life, but the greatest innovations will be in game-play. Interfacing with a keyboard/mouse/joystick isn't realistic. Voice control and force-feedback-like technologies are the way of the future, if our computing power can support it.

    Kudos to Carmack on 10 years of FPS game design. Here's to the next 10!

  • by Junks Jerzey ( 54586 ) on Tuesday August 13, 2002 @05:05PM (#4064666)
    Good article, but the Commander Keen scrolling trick was old news by then. Lots of Apple II, Atari ST, and Amiga scrolling games did the same thing. Impressive? At the time, yes. But let's not get too carried away with giving Carmack credit for everything.
    • I can't speak for the Apple and Atari, but on the Amiga and C64, screen scrolling was quite different than the technique Carmack had to use on the PC. Both Amiga and C64 had hardware scrolling, and just by incrementing a single register the screen could be scrolled in single pixel imcrements both horizontally and vertically. The point was that Carmack found a way to achieve the same effect on hardware that was not intended to do that.

      • Both Amiga and C64 had hardware scrolling, and just by incrementing a single register the screen could be scrolled in single pixel imcrements both horizontally and vertically. The point was that Carmack found a way to achieve the same effect on hardware that was not intended to do that.

        Yes, by using double buffering, a well known technique by that point (I'd been using it for many years by then, for example, starting somewhere around 1985 or so). Although the C64 and Amiga supported hardware scrolling, that wasn't always appropriate to the task in hand, and double buffering was used extensively on both systems before 1990.

    • Good article, but the Commander Keen scrolling trick was old news by then. Lots of Apple II, Atari ST, and Amiga scrolling games did the same thing. Impressive? At the time, yes. But let's not get too carried away with giving Carmack credit for everything.

      The article doesn't say that The Carmack invented smooth scrolling full stop. It said that he figured out how to do it in EGA mode on the PC. The market for EGA cards was much larger than any of those closed (but optimized for cool graphics and sound unlike the PC) platforms.

      Kind of like how someone figured out how to [kind of] play digital sound through the standard PC beeper. Of course the Amiga, etc. could do that with dedicated hardware but that's not the point.
    • As others have pointed out, Carmack was the first to do this on the PC. I do not have much experience in coding for the EGA, but I've done my share of VGA register-level programming.

      Basically, to achieve smooth scrolling etc you have to have a screen buffer which is larger than the visible part of the screen. By using mode-x on the VGA it is possible to address 256k of videomemory using only a 64k window and setting a mask you select which pixels to address. Another thing which is mentioned in the article is to store graphics tiles in video-memory instead of system-memory. If you set up some registers, you can perform a video-video memory copy with regular CPU instructions without actually moving data from the cpu to video memory and vice-versa. A read followed by a write will just copy the data from one part of the video memory to another part.

      To achieve smooth scrolling, you just set the starting address to somewhere in the buffer + set up scroll registers (in mode-x you can only select every 4th pixel as starting address). In the EGA only bitplane-modes are available., but the same scroll registers/screen buffer start address-registers are available. This is about the same way the amiga does it, but a bit more limited. (The amiga had separate addresses for each bitplane, and two scroll-registers, one for odd planes and one for even. It also had the blitter hardware which could move chunks of data with different logical operations and shifting).

    • No, the approach of modifying the base of the graphics buffer to achieve smooth scrolling did not work on the Apple II, because the memory location of the Apple II's graphics buffer was fixed by the hardware (well, two locations actually, since it did provide for double buffering. Basically, there was no way to scroll on the Apple II without rewriting the entire graphics buffer.

      However, I do remember an Apple II maze game with a first-person perspective, long before Wolfenstein 3D. And it was lightning fast (unfortunately, I don't recall the name). I'd love to know how that was implemented. However it was a pure maze game, not a shooter.
      • the dungeons in Ultima 4 had a first person pseudo-3d perspective, too. Pretty sure that was before Wolfenstein.
  • by matastas ( 547484 ) on Tuesday August 13, 2002 @05:13PM (#4064713)
    Our Carmack, who art in Texas,
    hallowed be thy textures.
    Thy software come, thy games be done,
    on my b0xen as it is at E3.

    Give us this day, our daily FPS.
    And forgive us our camping,
    as we gun down those who camp against us.

    Lead us not into a spawn site,
    but just give me the damn BFG.
    For the gaming market, the GeForce,
    and the booth babes are yours, now and until payday.

  • you can read more about bsp trees and other graphics tricks on this wonderful online book written my Michael Abrash, an id software programmer: http://gpbb.dk.eu.org:81/ [eu.org]
    make sure you check the forewords [eu.org] by john carmack
  • I love you carmack, please have my love child

    John, this post demands a response along these [slashdot.org] lines, methinks...

    C'mon, give us geeks occasion for joy! :)

  • Softdisk (Score:5, Interesting)

    by Sean Clifford ( 322444 ) on Tuesday August 13, 2002 @05:26PM (#4064804) Journal
    For those interested:

    I joined Softdisk in 1995, a few years after the id guys left. The company was stunned by the success of Wolfenstein and Doom, and by Duke Nukem - also born of Softdisk alumni. It was basically a subscription software company, selling a package (card games, screen savers, etc.) on disk monthly. It was a good model for the 80's.

    Softdisk tried to produce a couple of games, one called Greed (later In Pursuit of Greed) which was basically a 3D Doom-clone shooter. There was some neat technology (e.g. curved surfaces), but the art was...uh, well weak. The gameplay was decent, but there were some bugs to stomp and the ship date slipped...and slipped...and slipped. It was released, but didn't live up to the hype. The game was torn to shreds in the reviews. There was a second 3D shooter - developed totally in house, though it was basically a one-man project. The lead (only) programmer left, so it was shelved.

    Softdisk finally shut down its on-disk-monthly subscription software and became an ISP/web development company. It was a necessary move, but sad since the company kicked a lot of ass in the 80's with LoadStar and Big Blue Disk.

    For those interested, I ran Softdisk's online download software stores on CompuServe, Prodigy, AOL while another dude took care of eWorld. We were selling Commander Keen, Dangerous Dave, and a host of other early games the id guys produced at Softdisk. Last I checked, they were still being sold (at $19.95 a pop, even).

    • I remember playing Greed... along with a slew of other FPS between DOOM/DOOM II and Quake. And for a change, they had vastly different engines/gameplay/objectives!

      Was it in that game that you had a camera pointing backwards, so you could see if something was happening behind your back? I'm pretty sure it was called the Asscam (no kidding).
      If it wasn't in Greed, can somebody who recalls it can point me to the right game it was in?
      • It was Greed. We got a good laugh with the ASSCam - it was an acronym (a forced one that that), but it was cool. Very useful for those behind you. You could also cloak yourself as different objects.

        A little known fact - our archivist put a build on a server for some of our testers and 'oops' - he mis-set permissions. There were loads of people continuously scanning our site for a demo and 'viola'. The game got passed around - it wasn't done, but it was getting there - and we got a LOT of unsolicited feedback. Our guys also scoured message boards for opinions, etc. The feedback was 'bad, keep working' - and we did. However, the game was a disappointment in my book - good idea, some really cool features, but...it wasn't all that.

    • Re:Softdisk (Score:5, Informative)

      by John Carmack ( 101025 ) on Wednesday August 14, 2002 @12:02AM (#4067566)
      Here is an interesting bit of history:

      Greed was built on the engine I wrote for Raven/Origin's Shadowcaster game, while the other Id guys were working on Spear of Destiny, the commercial Wolfenstein game.

      The reason softdisk got the technology was that they were still making lots of noise about suing us for doing Keen while we were working at softdisk. Our original parting deal was that we were going to continue doing the Gamer's Edge games for a while, basically for free, as penance. We weren't savvy enough to get anything binding down on paper, so even when it was all wrapped up, there was room for twisting our arm a bit. (another trivia bit -- George Broussard at Apogee arranged to have Apogee produce one of the Gamer's Edge titles for us, so we could focus more on Wolfenstein).

      We finally arranged a technology transfer of the latest engine code for free and clear severing of our ties. After they showed that just having the technology was not a guarantee of success, they had the nerve to come back and ask for more, but by then we were able to just tell them to go away.

      BTW, Duke Nukem does not have a Softdisk heritage, it was by Todd Replogle (sp?), who was strictly Apogee-grown.

      John Carmack
      • Softdisk v. Id (Score:4, Informative)

        by Sean Clifford ( 322444 ) on Wednesday August 14, 2002 @12:36AM (#4067685) Journal
        Unsubstantiated company rumor on the Duke thing, I guess. :)

        I remember Al talking about the lawsuit and the source code. One poker night (which I played badly) Dan Tobias went on a long rant (suprise) about the whole ordeal. I share his opinion that moonlight code belonged to the programmer, not the company.

        Absolutely nothing came of the source code. It sat in Jim's office unused.

        • A lot of job contracts now have the clause about any software developed in your own time still belongs to the company. Mine does, I couldn't get rid of it either. The job market the way it is, it's either sign the contract or we'll give the job to one of the next 100 people in the queue...

          • Hey, I understand where you're coming from. The job market is tight and most big companies have a huge cudgel in their contract. Most say 'take it or leave it' and most people grudgingly sign. However, I'm single with no family and am stubborn/lucky enough to hold out for a place that's geek friendly.

            I just absolutely will not sign a contract that has an intellectual property clause that claims ownership of code I develop for non-company-related projects on my own time. I've invested years learning my trade because I enjoy what I do and I won't allow that enjoyment to be crushed out of me.

            Arguably such clauses mean that you cannot participate in open source projects or hell - can't develop for fun at all without your efforts being assigned to XYZ Corp. Hell, arguably you're required to give notice of any such projects or could find yourself being sued b/c the company lost a market window...blah...blah...blah.

  • by ragnarok ( 6947 ) on Tuesday August 13, 2002 @05:31PM (#4064854)
    Carmack is only 31? Damn, I better get to work.
  • by Animats ( 122034 ) on Tuesday August 13, 2002 @05:44PM (#4064938) Homepage
    Carmack's real innovations were in ways to do something that looked like general 3D but wasn't, quite. So his games did things that are easy now, but were really tough on the hardware he did them on.

    Flight Simulator pioneered this sort of limited 3D. Bruce Artwick did the original Flight Simulator on machines that didn't have enough power to fill the whole screen with a solid color in one refresh. He wrote a book [amazon.com] about how he did it in 1985. The pain, the agony...

    Artwick seems to have dropped out of game development, but Carmack keeps pushing what's possible with available hardware.

  • "There were critical points in the evolution of this stuff," Carmack says, "getting into first person at all, then getting into arbitrary 3-D, and then getting into hardware acceleration....But the critical goals have been met. There's still infinite refinement that we can do on all these different things, but...we can build an arbitrary representational world at some level of fidelity. We can be improving our fidelity and our special effects and all that. But we have the fundamental tools necessary to be doing games that are a simulation of the world."

    So, rendering engine improvement is essentially incremental from here? It seems to be that way, coming from Id's last two or three offerings. This is a rather distressing for someone as forward looking as myself.

    Although the fundamentals have been laid into place, there must be a way or two to leap ahead of the current generation while sacrificing something from the generic style engine such as what Id has produced. For example, if you had a game where you wandered around looking for people to scrap with, you could optimize the 1 on 1 fighting with a different networking model where you are guaranteed to only have one opponent.

    Windows of advantage for things like this come and go, but they certainly do seem to exist to me.

    • Re:How depressing... (Score:2, Interesting)

      by Vulture_ ( 106594 )
      So, rendering engine improvement is essentially incremental from here?
      I believe that, eventually, games will use real-time ray tracers as their rendering engines. This is as different from Quake as Quake is from Doom. It also seems inevitable because of what can be done with it -- most notably lighting/shadow effects, but you also get true curved surfaces, as opposed to the (admittedly very good) approximations used by Quake 3's curved surface support. Ray tracing is also easily SMP-able.

      Or perhaps I'm completely off kilter and ray tracing is counterproductive and/or unnecessary. Anyone care to comment?

  • by SpryGuy ( 206254 )
    I seem to recall that "Descent" had arbitrary 3D (along with MAPPING!, which the Quake series simply doesn't have) way way before it ever came out in any id software games.

    How come the Descent series doesn't get any respect? There's some AWESOME graphics in them thar games! Smooth indoor/outdoor transitions, even rain on your windshield, not to mention a full six degrees of freedom in moving about.

    I loved those games.
    • Personally, I think the guys at Parallax/Interplay are geniuses, although if I remember correctly, Descent 1 came out after Doom 2. But then I'm biased since I own Descent 1, 2, 3 and the Mercenary add on, as well as Descent Freespace, the Silent Threat addon, and Freespace 2. Anyway, here's my promo for Descent:

      The key to Descent was the fact that you could simultaneously move in three directions with control. You couldn't do that in any of the Doom clones. There was an original way of thinking: a space shooter with constraints on where you could fly. Most shooters and doom have a map which is essentially 2D. Descent forced you to fly in corridors which could bend at any angle. The map was based on a cube instead of a square, and the cube could be modified to look like a 3D trapezoid. Descent had a 3D map which requires being able to view it in 3D at multiple angles to be able to figure out where you had to go. You had an original storyline that went from Descent 1 through 3. Descent 3 went on to allow movement between two environments (inside and out) and was much more of a thinking game than was Quake or Doom or the earlier Descent incarnations. Forsaken tried to copy the original Descent versions, but fizzled quickly.

      Creating a level is easy (anybody remember Devil?) and the newer versions shipped with mission builders. The levels you got from Interplay's Levels of the World contest were hard, but awesome (and in the case of Freespace, those levels were integrated into Silent Threat).

      Its a crying shame...Descent 4 has been shut down. But the Descent series IMHO, was groundbreaking. I'm glad to find someone who agrees with me.
    • There's some AWESOME graphics in them thar games! Smooth indoor/outdoor transitions, even rain on your windshield, not to mention a full six degrees of freedom in moving about.

      And don't forget the vertigo, and the vomit on your keyboard and the monitor after having gotten motionsickness after playing it for a while...

      But damn... it was worth it :)

  • Was DoomII really ported to an arcade machine over in the States? I remember seeing one in the Film "Grosse Point Blanke" and thought it was probably a fabrication. If it was real, it must have been a nightmare to play with a joystick and XX buttons for weapons, jump, strafe etc etc!!
  • by aztektum ( 170569 ) on Tuesday August 13, 2002 @11:40PM (#4067470)
    It's *id* Software. Not ID. Not iD. id. as in the psychology term.

    id
    Pronunciation: 'id
    Function: noun
    Etymology: New Latin, from Latin, it
    Date: 1924
    : one of the three divisions of the psyche in psychoanalytic theory that is completely unconscious and is the source of psychic energy derived from instinctual needs and drives.
  • by John Carmack ( 101025 ) on Wednesday August 14, 2002 @12:58AM (#4067767)
    I was fairly pleased with how that article turned out - when I first heard about it, I dreaded seeing a trivialized simplification of the issues, but it turned out as representative as you can be in that space.

    However, I really dislike discussions of the attribution of techniques to a particular programmer. Everything is derived from things before it, and I make no claims of originality. I would say that one of my talents is the ability to be aware of what sources are feeding into my work, and be able to backtrack to them. Also, there are always lots of other possible answers for any given problem that can be made to work. BSP vs sector list, Portals vs PVS vs scan line occlusion, tilted constant Z rasterization vs block subdivision vs background divides, etc. Looked at in the proper perspective, individual techniques just aren't all that important. Sometimes it sounds like "Dude, he INVENTED needle nose pliers!!!"

    Heck, I somewhat deride the very concept of originality. Creativity is just synthesis without the introspection. Lots of people will catch on that and start a rant about how Id games aren't original, but they are missing the point - it is possible to set out and develop something that will be received as "original" without ever having an "original" idea spring into your mind.

    The best way to get answers is to just keep working the problem, recognizing when you are stalled, and directing the search pattern. Many of the popular notions of innovation and creativity are in some ways cop-outs that keep people from being as effective as they could be. The little document I wrote about developing a part of the shadow algorithm for Doom that Nvidia has on their website was a pretty good example of my process. Don't just wait for The Right Thing to strike you - try everything you think might even be in the right direction, so you can collect clues about the nature of the problem.

    John Carmack

    • "Creativity is just synthesis without the introspection."

      I disagree with this view. You cannot completely decouple originality from creativity. Even if you only combine existing ideas together: for example packages and a kernel into a distribution; a graphics engine and art into a game; or off-the-shelf parts into a rocket you no doubt have to use an introspective process to create. It is the integration process that is the invention, not its indivdual parts, because after all: the individual parts were an integration process at an earlier time to begin with until we go back in human history to where we started to bang rocks together!

      Even if you had only managed to exactly synthesize another persons work but you had beaten them at market, it proves that you had thought of another idea to more effectively share your invention with the world...but you had to think to make this happen. Nothing in this world happens automatically * .

      However, I believe it is the mark of a genius to claim otherwise: I was reading an article on John Frusciante of the Red Hot Chili Peppers and during the interview he was asked where he got his musical ideas. He said (and I paraphrase,) "I don't come up with anything, the music simply enters me from another dimension." I would argue however, that the process becomes so deeply introspective that you are hooked up directly to yourself at such a deep level that the creative process happens nearly automatically.

      Here's a quote:

      "Great minds don't think alike, for that is why they are great." - Derek Weidl

      John, iD, thanks for the innovation...no matter how it happens I'm always entertained!

      -AP

      * : except the fundamental actions of the universe; or so it seams.

      • by Paul Komarek ( 794 ) <komarek.paul@gmail.com> on Wednesday August 14, 2002 @12:57PM (#4070897) Homepage
        To add another perspective:

        The mathematicians I have met (I'm one of them) by-and-large feel that new math ideas are *discovered* instaed of *created*. The distinction is important. Truth and algorithms already exist, we're just trying to *find* them and sort through the crap. Just because no human has previously written down some piece of truth or an algorithm before you do, doesn't mean you invented that truth or algorithm.

        We're all standing on the shoulders of reality, trying to decode what we see. John Carmack's comment about struggling with a problem in order to understand it seems very much in line with this view, and very much inline with the academic research process. Academics don't get research done just by sitting around, trying to be creative. We do research by repeatedly struggling with a problem until we figure out which defects in our brain prevented earlier understanding.

        -Paul Komarek
        • It all depends on the philosophical foundation that you use for your mathematics. Most constructive mathematicians would say that math ideas (truth and algorithms are part of math) are created.

          But yes, because of our public school system what is effectively the Platonic philosophy of math is taught as the one correct understanding. Such a philosophy states that mathematical ideas already exist... Now, in my opinion, such a foundation for mathematics seems to be very irrational and non-mathematical. Assuming that math ideas already exists is something akin to assuming that god exists. Hence it requires faith like a religion.

          This is why L.E.J. Brouwer, for example, put great effort in founding mathematics on constructive foundations as opposed to Platonic foundations. Ideas are created, created again, and again. No, ideas don't already exist... for who created them? Where do they exist? For how long have they existed?

          Finally, such a distinction isn't trivial or meaningless as the philosophy used as a foundation for mathematics greatly influences what can and cannot be proven to be true in your mathematical system. The math that you seem to subscribe to is what is sometimes referred to as "classical", while the math that I am talking about is typicaly called "constructive". Computer Science is part of constructive mathematics, for reasons that I will not go into now.
          • Heh, you've caught me. I've never studied with constructionists, and in fact have never heard many good words said about that philosophy. Philosophically, I'm definitely an Existence & Uniqueness guy.

            I think that invoking Plato isn't really necessary to justify the non-constructionist view. It's always seemed clear to me that there is something constraining mathematical thought, and that something seems *fairly* universal among humans. For instance, anyone not bothered by certain consequences of the Axiom of Choice is clearly a martian and probably not from our Universe. ;-)

            These unspoken and unspeakable constraints are what drives the notion that we're discovering something and not creating it. It's not that our ideas exist, its that our new ideas are forced to come into agreement with existing principles in order to maintain consistency in mathematics.

            Computer science is not entirely based upon constructive mathematics, as near as I can tell. The first example coming to mind is complexity theory. I believe a lot of complexity theory depends on existence proofs which do not provide a method of constructing the necessary objects. While computers are Turing machines with finite resources and useful algorithms run in finite time, computer hardware is merely a part of computer science. The humans in computer science, though, are often classically-trained mathematicians. In fact, I've never met a constructionist face-to-face, and only if you describe yourself as one have I ever encountered a constructionist.

            Any mathematical system which limited itself to constructive techniques would be less rich than modern mathematics. While the constructionist approach is a useful paradigm, I see it as only a part of mathematical practice.

            At any rate, I don't want you or anyone to take the creation vs. discovery description I wrote too literally. As you probalby noticed, I wasn't particularly careful and didn't define most of my terms. It was meant as an informal summary of a constrasting viewpoint, a viewpoint which allows that ideas may be new but reality already exists.

            -Paul Komarek
  • IIRC, ultima underworld was out just before wolf3d, and had a more realistic (albeit slower) 3d engine. The speed didn't matter as much as it was an adventure vs. a shooter.

    comments?

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