Playing Demos on PhysX
Even though we can't benchmark CellFactor or Hangar of Doom in any useful way, they can't be left out when talking about the usefulness of PhysX hardware. It is very clear that using the AGEIA PhysX technology in a game can yield some impressive results. It is just as clear that current production games, while adding compelling visual effects, suffer a performance penalty that is difficult to justify.What we don't know is just how much more physics a PhysX card and do than the CPU or GPU already in every computer. We just haven't found a real world scenario in which to test the same large physics load on both the CPU and the PPU. None of the games that support PhysX include the ability to enable advanced physics features in the absence of hardware. The one small demo we do have that can run in either hardware or software mode does show a good improvement with hardware, but this test diagnostic app isn't designed as a performance analysis tool (nor is it a real world example of anything).
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Now that the CellFactor demo is downloadable, there is a little more value in picking up the hardware. Even though there is only one level to play with, the CellFactor demo is quite enjoyable in a multiplayer situation. It's not $300 USD worth of goodness, but it is a step in the right direction. It is rather impressive on a technical level, but with the full version of the game nowhere near release, the success of PhysX can't rely on CellFactor. We have a short video (3.7MB) available, although you might prefer the 400 MB video available on the CellFactor web site.
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Hangar of Doom is a demo based on Epic's UnrealEngine 3. This engine will power Unreal Tournament 2007, as well as a whole host of other games. Currently, UT2007 won't be requiring the PhysX hardware, but that shouldn't stop licensees from being able to take full advantage of it. While this demo isn't as complex as CellFactor, it demonstrates some neat ideas about the destructibility of objects in a game (planes fall apart when shot down). Again, we have a short video (2.1MB) available for download.
If you would like to try grabbing all six videos (13MB including the two from the original PhysX article) using a BitTorrent client, you may find that to be a faster solution (depending on how many people are seeding the files). Just download the torrent file if you're interested.
Unfortunately, even though these demos are very interesting and compelling, developers are not targeting levels of interactivity on this scale for the near future. With the current multiplayer trend, it doesn't make sense for developers to allow gameplay to rely on hardware that many users won't have. It isn't possible to have different gameplay in multiplayer environments. Effects are a different story, and thus the first games to support PhysX do have a tacked on feel to them.
Truly innovative uses of the AGEIA's technology are out there, but we are stuck with a chicken and egg problem. Publishers don't want to require the hardware until a large install base exists, and end users won't buy the hardware until a good number of titles support it.
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yanyorga - Monday, May 22, 2006 - link
Firstly, I think it's very likely that there is a slowdown due to the increased number of objects that need to be rendered, giving credence to the apples/oranges arguement.However, I think it is possible to test where there are bottlenecks. As someone already suggested, testing in SLI would show whether there is an increased GPU load (to some extent). Also, if you test using a board with a 2nd GPU slot which is only 8x and put only 1 GPU in that slot, you will be left with at least 8x left on the pci bus. You could also experiment with various overclocking options, focusing on the multipliers and bus.
Is there any info anywhere in how to use the PPU for physics or development software that makes use of it?
Chadder007 - Friday, May 26, 2006 - link
That makes wonder why City of Villans was tested with PPU at 1500 Debris objects comparing it to software at 422 Debris objects. Anandtech needs to go back and test WITH a PPU at 422 Debris objects to compare it to the software only mode to see if there is any difference.rADo2 - Saturday, May 20, 2006 - link
Well, people have now pretty hard time justifying spending $300 on a decelerator.I am afraid, however, that Ageia will be more than willing to "slow down a bit" their future software drivers, to show some real-world "benefits" of their decelerator. By adding more features to their SW (by CPU) emulation, they may very well slow it down, so that new reviews will finally bring their HW to the first place.
But these review will still mean nothing, as they compare Ageia SW drivers, made intentionally bad performing, with their HW.
Ageia PhysX is a totally wrong concept, Havok FX can do the same via SSE/SSE2/SSE3, and/or SM 3.0 shaders, it can also use dualcore CPUs. This is the future and the right approach, not additional slow card making big noise.
Ageia approach is just a piece of nonsense and stupid marketing..
Nighteye2 - Saturday, May 20, 2006 - link
Do not take your fears to be facts. I think Ageia's approach is the right one, but it'll need to mature - and to really get used. The concept is good, but execution so far is still a bit lacking.rADo2 - Sunday, May 21, 2006 - link
Well, I think Ageia approach is the worst possible one. If game developers are able to distribute threads between singlecore CPU and PhysX decelerator, they should be able to use dualcore CPUs for just the same, and/or SM3.0 shaders. This is the right approach. With quadcore CPUs, they will be able to use 4 core, within 5-6 yers about 8 cores, etc. PhysX decelerator is a wrong direction, it is useful only for very limited portfolio of calculations, while CPU can do them as well (probably even faster).I definitely do NOT want to see Ageix succeed..
Nighteye2 - Sunday, May 21, 2006 - link
That's wrong. I tested it myself running Cellfactor without PPU on my dual-core PC. Even without the liquid and cloth physics, large explosions with a lot of debree still caused large slowdowns, after which it stayed slow until most of the flying debree stopped moving.On videos I saw of people playing with a PPU, slowdowns also occurred but lasted only a fraction of a second.
Also, the CPU is also needed for AI, and does not have enough memory bandwidth to do proper physics. If you want to get it really detailed, hardware physics on a dedicated PPU is the best way to go.
DigitalFreak - Thursday, May 18, 2006 - link
Don't know how accurate this is, but it might give the AT guys some ideas...http://www.hardforum.com/showthread.php?t=1056037">HardForum
Nighteye2 - Saturday, May 20, 2006 - link
I tried it without the PPU - and there's very notable slowdowns when things explode and lots of crates are moving around. And that's from running 25 FPS without moving objects. I imagine performance hits at higher framerates will be even bigger. At least without PPU.Clauzii - Thursday, May 18, 2006 - link
The German site Hartware.de showed this in their test:Processor Type: AGEIA PhysX
Bus Techonology: 32-bit PCI 3.0 Interface
Memory Interface: 128-bit GDDR3 memory architecture
Memory Capacity: 128 MByte
Memory Bandwidth: 12 GBytes/sec.
Effective Memory Data Rate: 733 MHz
Peak Instruction Bandwidth: 20 Billion Instructions/sec
Sphere-Sphere collision/sec: 530 Million max
Convex-Convex(Complex) collisions/sec.: 533,000 max
If graphics are moved to the card, a 12GB/s memory will be limiting, I think :)
Would be nice to see the PhysiX RAM @ the specced 500MHz, just to see if it has anything to do with that issue..
Clauzii - Thursday, May 18, 2006 - link
Not test - preview, sorry.