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Nvidia Physics Engine Almost Complete

Posted by ScuttleMonkey on Mon Apr 14, 2008 11:12 AM
from the close-only-counts-in-horseshoes-and-hand-grenades dept.
Graphics Software Hardware
Nvidia has stated that their translation of Ageia's physics engine to CUDA is almost complete. To showcase the capabilities of the new tech Nvidia ran a particle demonstration similar to Intel's Nehalem demo, at ten times the speed. "While Intel's Nehalem demo had 50,000-60,000 particles and ran at 15-20 fps (without a GPU), the particle demo on a GeForce 9800 card resulted in 300 fps. In the very likely event that Nvidia's next-gen parts (G100: GT100/200) will double their shader units, this number could top 600 fps, meaning that Nehalem at 2.53 GHz is lagging 20-40x behind 2006/2007/2008 high-end GPU hardware. However, you can't ignore the fact that Nehalem in fact can run physics."
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Nvidia Physics Engine Almost Complete 50 Comments More /

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  • It's just particles (Score:3, Interesting)

    by Animats (122034) on Monday April 14 2008, @11:14AM (#23064958) Homepage

    This is just a particle system. Smoke, snow, rain, and maybe water look better, but it apparently has no influence on gameplay.

    • Re:It's just particles (Score:4, Funny)

      by Dr. Eggman (932300) on Monday April 14 2008, @11:16AM (#23065010)
      Super-soakers Online! Cloth and liquid simulations determine who got wet, how wet, and whether or not that means they're out!

      • Re:It's just particles (Score:5, Funny)

        by grahamd0 (1129971) on Monday April 14 2008, @11:22AM (#23065132)
        EA Presents: Cancun Wet T-Shirt Contest 2K9!

      • Super-soakers Online! Cloth and liquid simulations determine who got wet, how wet, and whether or not that means they're out!
        Only if everybody else is using the same brand of physics accelerator, or if some physics API specification makes some guarantees about the output given the inputs. Otherwise, simulations run on multiple machines fall out of sync. A compromise solution is to use coarse particles for game logic and finer particles for iCandy.

        • Re:Sync between machines with different cards? (Score:5, Informative)

          by Mr Z (6791) on Monday April 14 2008, @12:30PM (#23066348) Homepage Journal

          Huh? The local physics computations are only being used for presentation and local extrapolation. The server recomputes the relevant physics anyway, and can re-sync everyone periodically. That's how FPSes work to reduce lag--they do local extrapolation, and the server periodically snaps everyone back in line. It sometimes leads to what John Carmack calls "paradoxes" where locally displayed events get undone, but it works.

          So, if some portion of your local physics calculation is purely for local presentation (e.g. game outcome doesn't depend on exactly how dirt particles fly around or boobs bounce, but you want it to look realistic), the server doesn't need to reproduce any of that to model the game correctly. Your screen might look different than someone else's, but in an immaterial way. For the super-soaker example, the server will still compute actual "wetness," possibly with a simplified model that skips computing the goosebumps and most of the dripping water.

          --Joe

          • The local physics computations are only being used for presentation and local extrapolation. The server recomputes the relevant physics anyway, and can re-sync everyone periodically.

            Using how much bandwidth per particle?

            For the super-soaker example, the server will still compute actual "wetness," possibly with a simplified model that skips computing the goosebumps and most of the dripping water.

            That's kind of what I meant by "use coarse particles for game logic and finer particles for iCandy."

    • Re: (Score:2, Funny)

      by Anonymous Coward
      because if Portal taught us anything, its that modern games have no need for physics!
    • To what extend does this contain real physics as opposed to "game" physics. Cuda maps to linear algebra fairly well but most phyics is second order (either algebraically or as differential equations). Are they actually trying to implement those or are they just making things that "look right" but really don't obey physics.

      I recall that in the original Toy Story there is only one place they used "real physics". When the jump rope is thrown off the balcony (for the army men to descend), they used real phys

      • Re: (Score:3, Interesting)

        by king-manic (409855)

        I recall that in the original Toy Story there is only one place they used "real physics". When the jump rope is thrown off the balcony (for the army men to descend), they used real physics to model it's tangled fall. But thye later sent it was not a good idea to use the real physics. Not only was it harder but it didn't really look right and could not be easily tweaked. So all the rest is pretend physics.

        What people perceive a situation to look like and how it would realistically look have drifted a lot. Due partially to the real life rarity of those situations and Hollywood/Video games distortion of it. We all expect shot guns to be massive overkill at medium to short ranges when in reality they don't hit that hard. We expect all explosions to involve flames. We expect bullets to hit with far more kinetic force then they do. We expect a whole lot of things that just don't happen in real life. It doesn't h

      • Re: (Score:3, Informative)

        by CastrTroy (595695)
        You obviously don't remember what it was like when 3D cards first came out. There were many games that were Glide only. Meaning that you had to have a 3DFX graphics card to run them. Back when sound cards first came out, this also happened. You had to have a sound blaster, or Adlib, or Gravis ultrasound, and again only certain cards would work with certain games, I imagine that physics cards could probably work in the same way. Require that you use a certain physics card, or you don't get to play the g

  • Duke! (Score:5, Funny)

    by wild_quinine (998562) on Monday April 14 2008, @11:15AM (#23064992)
    The best news about this is that it implies that if hardcore kit kills with it, then at least budget hardware (that many people have already!) can do it acceptably. That means finally seeing games that REQUIRE physics acceleration.

    It'll be like 1996 all over again, only from a physics not graphics perspective. That, and there might be a new Duke Nukem game due out within the next 12 years.

  • ...provide Linux drivers, or will the F/OSS community have to reverse-engineer this one?

  • Is particle motion a fair test case? (Score:5, Informative)

    by DoofusOfDeath (636671) on Monday April 14 2008, @11:24AM (#23065158)
    Is a particle motion simulator a abnormally easy test case?

    When I was getting up to speed on IBM Cell programming, IBM had a programmer's tutorial (excellently written, btw). The example problem they used for their chapter(s?) on code tuning were a particle simulator. It was a wonderful example problem, because it showed how to vectorize a program. But then when we went to vectorize our own algorithm, it didn't fit the Cell's vector programming instructions nearly as cleanly, so in the end we didn't get nearly the performance increase due to vector instructions as did the particle simulator.

    So I'm thinking that just even though CUDA can do a good job with particle motion simulations, we shouldn't remotely assume that it's good for particular algorithms for which each of us is responsible.

    • Re: (Score:2, Interesting)

      by Anonymous Coward
      Yes, particle systems are easy (in terms of physics), because they are essentially just moving points with varying velocities and accelerations... Such a simulation is easy to vectorize (eg: update the position of all points in parallel by performing lots of additions at the same time).

      Actually useful collision detection of say, convex volumes with rotational velocities, with the volumes being stored in a 3D space partition (eg: kd-tree or BSP tree) will likely prove significantly more difficult to parallel

    • Re:Is particle motion a fair test case? (Score:5, Interesting)

      by AcidPenguin9873 (911493) on Monday April 14 2008, @11:46AM (#23065594)

      That's exactly why I'm skeptical of CUDA in general. Rendering graphics is one of those "embarrassingly parallel" operations, where for every frame rendered, each triangle, vertex, and pixel is independent of the others. I don't know much about physics processing, but I'm guessing it's the same. Simply throwing say, 4x more hardware at the problem gives you pretty much the ideal 4x speedup. Once you introduce random data dependencies into the problem, though, parallelization is much harder and you don't get the same speedups.

      There are a lot of easily-parallelizable problems out there, which is great...but then again, there are a lot of not-so-easily-parallelizable problems out there too. I don't think CUDA would do any better than a general-purpose CPU on the latter class of problems.

  • So (Score:3, Funny)

    by Snuz (1271620) on Monday April 14 2008, @11:29AM (#23065268)
    PC Gaming is dead . . . right?

  • Experts please explain something (Score:5, Interesting)

    by Handlarn (911194) on Monday April 14 2008, @11:30AM (#23065274)
    Anyone care to explain why there's such a big difference between a GPU and a CPU? I keep hearing how GPU's are this and that much faster than a CPU at calculations like graphics, physics and such, so naturally I assume there's a big difference that makes us still chose the x86 and x64 CPUs as the main processors of a PC. What are the limitations; why can't just the libraries be ported for GPUs instead of CPUs and why don't we then just run all calculations on a GPU, if they are anything from 2 to 50 times faster?

    It just seems to me that if a graphics card can calculate physics then it would also be able to do pretty much all the same types of calculations that a regular CPU can do, but I am obviously missing a big part of it.

    Experts, continue! :)
    • CPU's are general purpose processors that perform a lot of different functions. GPU's are highly specialized ASICs [wikipedia.org] designed to do one or two things very, very quickly.

      CPU = Jack of all trades, master of none; GPU = the highly trained specialist.
      • Except that GPUs aren't highly specialised anymore; the latest generation of Nvidia cards are basically just a large number of general-purpose CPU cores.

    • Re:Experts please explain something (Score:5, Informative)

      by caerwyn (38056) on Monday April 14 2008, @11:46AM (#23065592)
      Particle systems are about as perfectly a parallel problem as it's possible to get- and not only that, the calculations are generally very straightforward with few (if any) general CPU control structures (branches, loops, etc).

      As a result, the massively parallel hardware on a GPU that exists to render many triangles/pixels/shader programs/etc at once can be exploited to calculate updates for many particles at once. The CPU is at an inherent disadvantage because it is only leveraging a small subset of it's full capabilities.

      The CPU is very good at *lots* of different tasks. The GPU is phenomenally good at a very specific set of tasks. Physics just happens to fit within that set.

    • Re:Experts please explain something (Score:5, Informative)

      by cowscows (103644) on Monday April 14 2008, @11:54AM (#23065716) Journal
      In its most basic definition, a GPU is just a CPU that's been highly specialized towards graphics. It can't do anything that a CPU can't also do, it just is able to do particular things much faster. Basically, they take a lot of the common tasks that graphics require of a processor, and they put really efficient ways to do it directly into the hardware, and they put a whole lot of them.

      Think of a CPU as a big tool box. There's something in there for every task, including a screwdriver that can be used to put screws into things. Then next to it, you have a big cordless 18 volt drill (The GPU). Way easier to drive screws with that than the manual screwdriver in your toolbox. But when you need to drive a nail instead, yeah you could bash it in with your screw gun, but it's easier to go back to your toolbox and find a hammer.

      I guess that would make a physics processor the nail gun. Or something...

    • Re: (Score:3, Informative)

      by ardor (673957)
      A GPU excels at massively parallel tasks. Stuff like rendering, raytracing (yes! a GPU can raytrace!), DCTs, ... essentially, a GPU is a stream processor that maps a function (a shader) on independent entities (pixels, or vertices).
      Applying a complex formula millions of times, each time with a different set of coefficients? -> GPU.
      GPUs fail at tasks where lots of synchronization or frequent branching is necessary. Stuff like game logic, for instance, or state machines. Your typical office application is

    • Re: (Score:3, Informative)

      by Space cowboy (13680) *
      Simple reason:

      On my Mac Pro, I have 8 3GHz CPU's. Consider that the baseline.

      I have 2 8800GT cards to drive the 30" and 2x23" (rotated, one each side of the 30" :-) monitors. That gives me 224 1.5GHz stream processors in the GPU. Even harmonising GHz, thats 8 compared to 112, and its a lot easier to get a parallel algorithm running efficiently on a GPU than on multiple CPU's due to differing hardware designs...

      Now stream processors aren't quite the same as general purpose processors, but the way they're imp

      • Re:Experts please explain something (Score:5, Funny)

        by cerelib (903469) on Monday April 14 2008, @11:51AM (#23065666)
        Wow, that has to be the worst car analogy I have ever read on Slasdot. Instead of comparing on specialization of hardware (minivan vs drag-racer might have been a winner), you went down some sort of bandwidth path. I don't even know what the "re-fuel", gas vs electric thing equates to.

        • Re: (Score:3, Funny)

          by hey! (33014)
          Well, analogies are a left brain function, and left brains probably prefer to generate cdr analogies.

  • Why particle systems? (Score:5, Interesting)

    by Thanshin (1188877) on Monday April 14 2008, @11:30AM (#23065290)
    They should test physics systems with spheres on irregular ground, with uneven μ (coefficient of kinetic friction), and changing wind.

    Those are the kind of problems that force programmers to use approximations when using a physics engine.

    The next step is really abstracting the physics from the development, not having pretty water.

    • Re:Why particle systems? (Score:5, Interesting)

      by Animats (122034) on Monday April 14 2008, @11:57AM (#23065760) Homepage

      They should test physics systems with spheres on irregular ground, with uneven (coefficient of kinetic friction), and changing wind.

      I always liked to test on the hard cases (see my web site) but, in fact, what game developers and animators want is not realistic physics. The game people want "infinitely destructible environments", where you can blow up anything. And, of course, eye candy. The animation people want physics they can direct, where the starting and ending positions are specified but what happens in the middle might be automated. So most character motion in video games is spliced-together motion capture bits, hand animation, and a bit of physics now and then.

      Most game physics engines today cheat on the hard cases, but by now, they usually cheat in ways that don't do something blatantly nonphysical.

      My original goal, back in 1996 when I was working on this, was to get to a two-person fighting game with real martial arts. The physics engine we had was good enough, although in the era of 200MHz CPUs, a bit slow. But a control system that can do a judo throw against an uncooperative opponent is still out of reach. Worse, controlling a physically realistic martial arts character through a game pad is just hopeless. Play would be like a typical day at the dojo: "You lost your center. Your left foot should have been further forward when you tried that throw." "Yes, sensi". Work out three times a week for a year, and you get to be halfway decent. As a game, that sucks.

      So I created the "ragdoll falling downstairs" cliche as a demo, licensed the technology to a middleware provider, and went on to other things.

  • Oh really? (Score:5, Funny)

    by bconway (63464) on Monday April 14 2008, @11:41AM (#23065474) Homepage
    However, you can't ignore the fact that Nehalem in fact can run physics.

    In fact, I can.
  • Forgive my naivety,

    but is there such thing as netsted particles?

    Full objects, made of "bound particles" (polygons that when constrained to eachother act as an object) but that whole object can be a particle?

    Then if destroyed the resultant triagles themselves become particles?

    I ask in that I would like to know if a whole seemingly static scene can really be generated/destroyed/interacted with as if everything were particles...

    Or is this how things are already done??

    It just seems to me that super-particles is
    • I dont know much more than you about the current situation, but in the interviews of The Force Unleashed (360/PS3 versions), thats pretty much how they described their physics engine... so I'm guessing its not a new idea. Something about all of the objects being made of "molecules", and the physics engine had information about these "molecules" and how to break/bend/move them.

  • Real Physics engine goal (Score:5, Funny)

    by Anonymous Coward on Monday April 14 2008, @11:53AM (#23065696)
    I want to see 10^88 particles simulated at 10^33 frames / second.

    • Re: (Score:3, Funny)

      by Anonymous Coward
      How do you know you're not?

  • What about graphics? (Score:3, Interesting)

    by Guspaz (556486) on Monday April 14 2008, @12:22PM (#23066166) Homepage
    It's great that they can do all this physics stuff on the GPU, but they seem to be forgetting the other thing you need that for; graphics. Games like Crysis don't exactly leave room on the GPU to do anything but graphics, and throwing physics into the mix will only make things worse.
    • I don't think it will push it out any.....this is one less system that the designers / coders need to account for.....eventually, technology will catch up with DNF and we can simply click a "do it" button and have DNF be released.

      Layne

    • Re: (Score:3, Informative)

      by Z34107 (925136)

      Wow ! That's more than 4 times faster than the human brain can detect. Now if I only knew why a frame rate this high is needed. Anybody?

      It's not needed. But it's useful for comparison.

      Nehalem only got x frames per second, but nVidia Magic Goodness 9800 Large Numbers GTX got y FPS, where y > x, can show that nVidia MG9600LNGTX > CPU.

      Also, presumably this won't be used to run 50,000 particle games at 300fps, but much more complicated simulations (infinitely destructable environments, not line

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