Getting Physical: AMD, NVIDIA Trade Shots Over Hardware Physics

PhysX would be cool if the implementation was across the board, and could be a tool used in any game. Then the programmers could choose if they wanted to use it, and the gamers could choose whether it was important enough to buy the title because it was or is supported in it. Other than that all I see is a cat fight. As for the largest holding of specific hardware which is currently (seeing as Nvidia new devices are not yet and have not been available although talked about a lot for the last year) unavailable as it will be for the near future, there hurting themselves. If it was an open spec and ran on anything, and Nvidia did it better this would earn them business. As it currently stands it really does not do much for anyone.That is except for a few extra objects which would not really be missed flying around in the air on a game (and 10 games total at that).

I hate those dam fogs(in fps games) :P lol

When the dust does settle and they can HOPEFULLY get along, earth will become a better place (gamers world at least)

Inspector:

I hate those dam fogs(in fps games) :P lol

When the dust does settle and they can HOPEFULLY get along, earth will become a better place (gamers world at least)

And the fog will still be there. But why would you want them to get along? When they are going-at-it, lawyers duking-it-out and all, at least you know they aren't in some kind of anti-trust collusion. Competition is GOOD!

Wow. These guys make the flame wars between Windows and Mac users look like water balloon fights (with completely accurate trajectories, of course). I guess AMD is still glowing from their victory of sorts over Intel-- the language looks limilar.

I have nothing against physics, or PhysX as all th kids are calling it these days; I just wish that it'd be used in more games, and not in the traditional way. For example, an old saying in Everquest (and other MMORPGs) is "the weakest among us can carry twenty anvils; the strongest among us cannot carry twenty-one feathers." (Substitute the numbers and objects based on current stack sizes in your favorite game.) Weights and measures in games, not just MMO games, are piss-poor gosh-awful. People now expect to be able to carry a rocket launcher, two assault guns, a brace of shotguns, a Civil War-era cannon, and the odd fusion gun or two without keeling over from the weight.

Oh, I know it's a gameplay issue, that people don't want to go around picking things up and putting them down. We can presume that this is because most gamers are males, who never pick things up around the house. But I really do wish for some reality injected into my fantasy.

Something else to think about: Why would I want to tax my GPU even further, when I've got a quad core machine that isn't doing much to begin with? How about throwing two cores at physics, the other two at general game code/networking/AI, and leave the graphics for the GPU? It's a bit of a shame to be wasting all this CPU power while the GPUs continue to be pushed to the limit.

Absolutely correct Joel - on both pieces.

"Weights and measures in games, not just MMO games, are piss-poor gosh-awful. People now expect to be able to carry a rocket launcher, two assault guns, a brace of shotguns, a Civil War-era cannon, and the odd fusion gun or two without keeling over from the weight."

It's also ironic that Halo, a game that got rid of the dozen-weapons syndrome, completely defied physics in other ways: grenade jumps? Changing direction in midair? But yes, I would love to see more realistic physics and inventories in games. Unlike Doom 3, for example. Where does he keep the BFG, in his trousers? :P

"Why would I want to tax my GPU even further, when I've got a quad core machine that isn't doing much to begin with? How about throwing two cores at physics, the other two at general game code/networking/AI, and leave the graphics for the GPU?"

Excellent point Joel, especially since the LGA 1156 chips have a PCIe-controlling "northbridge" built in: this gets rid of latencies to the point where your idea is feasible. To be honest though the programmers already thought of it: RTS games with more complex AI are more CPU-intensive. And on a related note GPUs are also being used to aid the CPU in parallel processing, since that's what they're better at.

>Where does he keep the BFG, in his trousers? :P

Check out the comic book Sam & Max: Freelance Police. Every so often, Max (the clothesless rabbit, er, lagomorph) will pull out a huge firearm. Sam (a McGruff-like trenchcoated, anthropomorphic dog) will ask "Where'd you pull that gun out from, little buddy? Max will reply "None of your damn business, Sam."

Joel,

Physics calculations are a much better fit for the GPU than the CPU. Such calculations are performed independently (and simultaneously) on a huge number of widgets. If you want to run calculations on the intersection and movement of independent particles, you want the widest parallel engine you can get your hands on.

Let's look at some practical examples. Assume a GeForce card with 240 SPs running at 650MHz. When the program needs physical calculations done, it allocates between 32-64 SPs to the task. (Theoretically it may not need this many; I don't honestly know). Between 13.3 percent and 26.7 percent of the GPU's pixel-crunching power has just been re-allocated. Does your frame rate drop? Possibly--but massive explosions that send tons of particles flying around are the sorts of scenarios that *already* cause frame rate dips in modern games, so you don't notice anything out of the ordinary.

Now, let's assume that a modern, complex x86 core is capable of handling the physics work it takes 4 SPs to do. Since our hypothetical core is running at 3.2GHz, it can handle the equivalent workload of 19.7 SPs per core. Thus we can dedicate two CPUs worth of performance to hardware physics calculations and see similar performance, right?

Not so much. Remember that Windows is constantly handling a variety of background tasks and shifting which programs are running on which cores to best balance power consumption, CPU loads, and responsiveness. It also takes time to spin threads out to CPUs for physics calculations and then spin the data back into the main program. (I'm guessing the GPU avoids this problem due to a thread scheduler built into the hardware.) You also need to remember that interacting particles could end up calculated on two separate CPUs. CPU1 knows what Particle X will do, CPU2 knows what Particle Y will do, but neither CPU knows what happens when Particle X meets Particle Y until they talk to CPU0.

Is it possible to do physics on the CPU? Of course--we've been doing it for decades. The fact remains, however, that physics calculations are embarassingly parallel--and since 3D graphics are as well, it makes sense that GPUs would make for excellent physics engines. If you want optimal performance, you want a bunch of small, simple engines working in parallel with an overarching thread scheduler, not a few massive engines that rely on the OS for performance tuning and data updates.