New interview about Ps3 CM:Dirt

[NRP]

Some of you seem to be too easily seduced by PR and hype.

While it's probably reasonable to conclude that Cell can run a more advanced physics simulation than Xcpu, it is much less certain that it can run one in an actual game that is advanced enough to be perceptibly better. Game programming is more about fakery than rigorous simulation, so it is difficult to be certain if what you see in a game is a better simulation or just better fakery.

 

[one]

Even if the Cell is better suited for physics, it's not so much better than Xenon to actually make a visible (or meaningful) difference. And that's what is relevant.
(although this works both ways)

I'd say finding a conclusive example in a multi-platform game is preposterous, if you design a game that really exploits the physics capability of Cell it becomes impossible to port it to other platforms without altering the game design itself.

Some of you seem to be too easily seduced by PR and hype.

While it's probably reasonable to conclude that Cell can run a more advanced physics simulation than Xcpu, it is much less certain that it can run one in an actual game that is advanced enough to be perceptibly better. Game programming is more about fakery than rigorous simulation, so it is difficult to be certain if what you see in a game is a better simulation or just better fakery.

Fakery can't become interactive in a perceptibly correct manner. Hiding glitches to maintain a good illusion needs processing power to judge a correct behavior of things.

 

[Neb]

I'd say finding a conclusive example in a multi-platform game is preposterous, if you design a game that really exploits the physics capability of Cell it becomes impossible to port it to other platforms without altering the game design itself.

Are you shure about that (just asking)? :smile:

 

[one]

Are you shure about that (just asking)? :smile:

I'm pretty sure, think about a game that needs 2000 rigid body blocks on screen. Or a game wholly rendered with raycasting.

 

[Arwin]

I'm pretty sure, think about a game that needs 2000 rigid body blocks on screen. Or a game wholly rendered with raycasting.

A game like this could already get close enough, maybe, as simple as it seems originally:

http://forum.beyond3d.com/showthread.php?t=42398

We are able to get over 10,000 active objects with physics and collisions and over 75,000 particles simulated and drawn @60fps. That said, we were unable to use all the available processing power from Cell for this game, so for the next game there are still plenty of reserves left

 

[Cheezdoodles]

Even if the Cell is better suited for physics, it's not so much better than Xenon to actually make a visible (or meaningful) difference. And that's what is relevant.
(although this works both ways)

Like I said, we'll see.

I think that what ErnstH meant is that it requires an astonishing amount of raw power to get physics to be noticeable (visibly) better.

The physics guys at funcom said something that roughly you need 20x more calculations to get something that you can notice is better.

This is because you can easily achieve something that looks close enough, nobody here in this forum knows how a brick wall is supposed to blow up, thus its largely irrelevant for us if each induvidual brick movement is determined by 10,000 calculations on the PS3 or 2000 calculations on the X360. As long as they both react to the environment in a "realistic" way. We cannot simply tell the difference.

In the end, it can come down down to is one platform being able to handle a lot more objects with physics calcuations at the same time.

Physics by itself on one induvidual thing wont be different.

 

[Mintmaster]

Yes it is. You were saying that Motorstorm's physics had nothing to do with the hardware and everything with the code they had written. I'm not saying sevanig isn't being naive here. But your comment shoots off so much in the other direction that it's not much better, now is it?

How did it shoot off so far? I said two things in that post. What you see in Motorstorm has nothing to do with PS3 (e.g. Wii could do that if you bring down the graphics), and judging hardware by comparing Motorstorm and Flatout is ludicrous.

Motorstorm has impressive physics because of the breaking parts that no racing game has done before to this extent. This is not something that only Cell can do, nor is it something you can calculate automatically from any model in realtime. The artists have to decide the break points, and have to make models with pieces that look right when everything is broken apart.

There's really nothing else that's impressive in terms of physics. Open wheel racers should have far more catastrophic results when touching wheels, for example. Number of objects is low. There's no stacking of objects. Springy suspension is very easy to model.

So that's all it takes to make a nice looking physics based game huh?

At the level we see in Motorstorm? Absolutely. The physics load is very low. Show me a screenshot with 100 objects resting on top of each other, or 10,000 objects floating around, and maybe I would concede that there's are points which actually stress Cell. I haven't seen any example even close to one order of magnitude less than that.

Do you have any experience in physics coding? I've coded a physics engine, played with ODE, seen various demos from physics engines, looked at the leaked HL2 code, etc.

Don't make a habit out of this 'as far as I can see' thing. Googling for 'FlatOut and Havok' is but a small effort and saves you from making a fool out of yourself.

I did google it you condescending ass. Show me a link if it's so obvious.

There is only one comment from some random guy that thinks Havok would be nice in a racing game in a post about FlatOut, and even there he doesn't make any direct statement that FlatOut does use Havok. There is no link confirming Bugbear uses Havok, but there are lots of links saying they have their own physics engine. Look at this interview for example where nothing about Havok is mentioned when discussing physics. No PR from Havok shows BugBear is a licensee. Nothing on this list from Havok. For any other studio using Havok, it's abundantly clear from Google. Since nobody can prove the abscence of anything, "as far as I can see" is fully appropriate.

So now I put the onus on you. Prove to me that FlatOut uses Havok, or concede that you are the fool.

Havok is used in a ***load of games though, even previous-gen, so that it runs above average on Cell is certainly good news for PS3 owners and it is not that far-fetched to assume that multi-platform games may benefit from it at some point. I personally think we'll find out soon enough.

We still have no idea how much faster it is on Cell. I've searched and searched, and all I find is a PR statement that Havok 4.5 is 5-10 times faster than before on Cell. We don't know how much 360 improved, how it applies to in-game scenarios, etc.

In other words, we know nothing, yet you parade this around like an indisputable fact applicable everywhere.

 

[Cheezdoodles]

Being very non-technical. After playing most of the 360's games since launch, even the new flatout game where the collision detection is not good + floaty physics...
And then after playing the ps3, specifically motorstorm. you can see the ps3 is better at physics calculations.

Both games being exclusive to each platform, and motorstorm being a 1st generation ps3 game (i think latest version of havok was released after motorstorm shipped).

I look forward to see what more optimization can do (motorstorm 2)...

This is an ridiculous comparison. Your comparing a game thats made by a developer called Bug Bear published by a very small publisher, vs a game made by a first party developer for Sony with a budget thats probably is 10x in magnitude.

There hasn't been any titles that are trying to do what Motorstorm does (they also need to have a huge budget, that alone will not ensure it to be a good enough effort but its a helluva lot better than what your doing right here), so any random comparisons with games not trying to do the same thing is ridiculus.

And yes arwin, Havoc said that bla bla bla Havoc 4.5 or whatever runs good on the Cell. Its not like Havoc 4.5 cannot be run on the Xenon. It can and it will (its a very expensive license, so few games will use it thought). You also have no idea how havoc 4.5 runs on the X360 vs the PS3 on a theoretical level, all statements are in regards to tweaking the PS3, not a comparison of eachother.

Even if it did run better on the PS3 (which, by all means, it could) Thats not to say that physics will actually look better in PS3 games. With physics there are as many shortcuts as there are calculations.


Physics engines is all about cheating mathetmatics, if you can make a shortcut by having predefined values instead of calculating new ones. And you can make it look good, very good, even tho it has a lot of less calculations being done.

Motorstorm is not some kind of physcis show case, the cars aren't broken down in real time. They have predefined ways of braking down, some physics calculations are involved, but its not like they are bending the metal on the fly here. What else is there? Deformable terrain? Do they actually calculate every little part of how that mud is supposed to deform? No, its semi scripted, and with lots of short cuts. Just because you haven't seen a next-gen game trying to do the same thing on the same budget with the same talent, doesn't make it impossible for it to be done.

 

[Mintmaster]

I don't think your description of scripted lean and body roll in GT4 is right, Ostepop. You get those things automatically even with the simplest physics model. If you apply the friction reaction force to the car at the wheels, the body automatically moves as necessary.

There is some fudging because GT4, Forza, and some other games apparently can't let the cars flip over. BTW, does anyone know why automakers are so anal about this?

EDIT: Did you remove your GT4 comment or am I imagining things?

 

[Cheezdoodles]

Thats why i edited it out. I was going in the wrong direction

There is some fudging because GT4, Forza, and some other games apparently can't let the cars flip over. BTW, does anyone know why automakers are so anal about this?

Apparently its bad press

 

[sevanig]

http://www.gametrailers.com/player/17745.html?type=wmv

Physics tech demo from GDC 07
Quiet alot of objects, they didn't say how many though...
But i'd say in the thousands at least.

 

[Shifty Geezer]

The physics guys at funcom said something that roughly you need 20x more calculations to get something that you can notice is better.

Well, 20x is one of those progressive figures. Like all diminishing returns, the more powerful the base, the bigger the improvement with a smaller increase in results. If Platform 1 can only manage 10 physical boxes and platform 2 can handle 30, a 3x increase will be noticeable. But if Platform 1 can handle 1000, 3000 won't be an obvious improvement - it's all too many boxes. If the physics are just being applied to particles and stuff, it'll make little difference.

Still, another aspect that's overlooked is whatever 'cheats' XB360 could use, PS3 could use also. If you're targeting 1000 objects on PS3, and can only manage 200 on XB360, if you use some technique to make that a comparable experience to the PS3 version, you could apply that same technique to PS3 and free up processing power for something else. Thus being better at physics doesn't only mean doing more physics, but also spending less effort on the same physics and applying that elsewhere. And with stuff like the Rigs of Rods being different approaches to an old problem, one system may be a huge degree more powerful too (either 'coz of Cell's LS, or Xenos working on it somehow). I doubt the difference will extend much beyond being noticeable only in side-by-side comparisons - 'Oh, this explosion has a lot more sparks.' 'I see, that crowd actually has quite a few more people' - but you never know.

 

[Mintmaster]

http://www.gametrailers.com/player/17745.html?type=wmv

Physics tech demo from GDC 07
Quiet alot of objects, they didn't say how many though...
But i'd say in the thousands at least.

Now THAT is the kind of stuff that need serious horsepower. See the stacking of everything on top of one another? Very nasty to calculate and keep stable, especially if, for example, you drop a bowling ball on top of that.

One important thing to take away here: See the scene with six different piles of boxes? What if we only saw one pile? Wouldn't everyone still be clamouring about the power of PS3? Wouldn't it still be stupendously impressive to see just one pile with one eighth as many boxes in a game?

That would need a tiny fraction of either PS3's or XB360's power, but is still orders of magnitude more complex than anything we see in Motorstorm or any other game!

Physics software has come a long way, and continues to bring chop off orders of magnitude from the cost of doing various effects. Nobody can tell me that they can see they physics in a game and declare that only the PS3 could do that. Absolute assessments of processing power needed are near impossible, and relative comparisons in an apples to oranges cases are ridiculous. Unless you have multiplatform source code, a profiler, and dev kits, you know nothing about the physics capabilities.

The situations we find in games need only a fraction of the computation in that demo. It's a lot harder having artists make models that can break in a hundred places, or making a world where everything can be thrown around and broken. The easy part is doing the calculations, as only a few hundred objects will be closely interacting with each other at one time in the worst case. A 10,000 particle explosion is just as easy because the objects aren't stacked in a pile and rarely affect neighbours. What is really tough is keeping track of, say, a million objects around the city that can be moved or destroyed. For a 10km x 10km town, that's only 40 objects per acre.

For games, it's ALL about the software.

 

[Shifty Geezer]

It's a lot harder having artists make models that can break in a hundred places...

Ideally they wouldn't ahve to, and with enough processing power they won't. As LucasArts demos of Digital Molecular Matter show, destruction can be calculated and geometry created on the fly. If one of these consoles can manage physics like that, and the other can't and needs to use the conventional systems, than that will be apparent. Only with a disparity of that magnitude though really it make any difference.

 

[Terarrim]

This thread seems to be a little strange to me. As the argument is running that software and dev talent are all that matter. and that hardware is of small concern.

Now while obviously the tools (software) and an artist (dev/programmer) can make a masterpiece on the Comodore Amiga. Surely the more powerfull and efficient the hardware is the more freedom the artist (dev/programmer/graphics artist etc) gets to create his/her vision.

As somone said in this thread if you want to achieve a certain amount of physics but the hardware is more powerfull then this gives you overhead for other things.

For example I would imagine for the most part that a car racing game has smaller requirments (animation, physics, collision detection etc) than say something like heavenly sword. So the dev could get as much done as he/she wanted with the physics like car handinling, (down force, speed vs mass etc), 7.1 sound etc. Then they could use the remaining SPE's for assisting with graphical tasks (culling) or even help with gemotry (a la edge).

Obviously at the moment its still very early in the dev cycle, and I am sure that neither the Xbox 360 nor the PS3 has really been tested at present so it matters less about hardware power. However the more experiance that devs had at the hardware the more tricks, and knowledge gained regarding just how well the hardware can do, can feed into the intial design process and opening up the scope of what the devs can achieve.

In other words the more power the hardware gives you the more freedom it gives you to create your vision of "your perfect game" and the less trade offs need to be made.

So while without the software and talent the hardware is useless, so hardware is then equally a part of the triangle for pushing forward what is perceived and actually possible in next gen gaming!

 

[patsu]

That would need a tiny fraction of either PS3's or XB360's power, but is still orders of magnitude more complex than anything we see in Motorstorm or any other game!

Yeah.. it's a tech demo, so I presume they will try to build an extreme case.

Mintmaster, have you played MotorStorm ? What happens if there is a multiple/cascading car crash (with parts flying all over the place, plus smoke and flames), the drivers flailing around in the car or mid air, the gravels on the road "splashing", plus any other large obstacle on the road that get knocked around (e.g., junk yard car chassis or barrels). The player can actually pause the game and marvel at the crash scene (I like !).

While the crash is happening, the other vehicles will continue to roll forward. So the devs will only be able to use part of the resources to do physics. The other challenge is they have to fit the crash animation realistically within the time penalty.

But I enjoy the final work nonetheless.

 

[NRP]

This thread seems to be a little strange to me. As the argument is running that software and dev talent are all that matter. and that hardware is of small concern.

Now while obviously the tools (software) and an artist (dev/programmer) can make a masterpiece on the Comodore Amiga. Surely the more powerfull and efficient the hardware is the more freedom the artist (dev/programmer/graphics artist etc) gets to create his/her vision.

As somone said in this thread if you want to achieve a certain amount of physics but the hardware is more powerfull then this gives you overhead for other things.

For example I would imagine for the most part that a car racing game has smaller requirments (animation, physics, collision detection etc) than say something like heavenly sword. So the dev could get as much done as he/she wanted with the physics like car handinling, (down force, speed vs mass etc), 7.1 sound etc. Then they could use the remaining SPE's for assisting with graphical tasks (culling) or even help with gemotry (a la edge).

Obviously at the moment its still very early in the dev cycle, and I am sure that neither the Xbox 360 nor the PS3 has really been tested at present so it matters less about hardware power. However the more experiance that devs had at the hardware the more tricks, and knowledge gained regarding just how well the hardware can do, can feed into the intial design process and opening up the scope of what the devs can achieve.

In other words the more power the hardware gives you the more freedom it gives you to create your vision of "your perfect game" and the less trade offs need to be made.

So while without the software and talent the hardware is useless, so hardware is then equally a part of the triangle for pushing forward what is perceived and actually possible in next gen gaming!

I think in reality it mostly boils down to a developer's priorities. Great physics in a demo is one thing, but incorporating those physics into a real game and making it fun while not detracting from other areas of the game is the tough task. Remember, all this "creating your vision" stuff has to take place within the context of a budget and release timeline.

I don't think anyone is saying that the hardware is "useless" for physics, only that software and dev talent are much more important for achieving game play physics that are perceptible better. That seems to be the point that some people can't (or won't) accept.

 

[Mintmaster]

Now while obviously the tools (software) and an artist (dev/programmer) can make a masterpiece on the Comodore Amiga. Surely the more powerfull and efficient the hardware is the more freedom the artist (dev/programmer/graphics artist etc) gets to create his/her vision.

That's a strawman argument and you know it. Just because you can come up with some ridiculous extreme like that doesn't mean you invalidate our claim.

PS3 is probably 3 orders of magnitue more powerful than any Amiga. It is going to be generally within a factor of 2 of XB360, maybe up to a factor of 5 in specific scenarios. The two aren't even remotely comparable.

This small performance gain is completely lost in the variation of developer talent, software, approximations/tradeoffs, developer priorities, and the relevance of CPU power to gameplay even if those factors are fixed (which they aren't).

 

[Mintmaster]

Mintmaster, have you played MotorStorm ? What happens if there is a multiple/cascading car crash (with parts flying all over the place, plus smoke and flames), the drivers flailing around in the car or mid air, the gravels on the road "splashing", plus any other large obstacle on the road that get knocked around (e.g., junk yard car chassis or barrels). The player can actually pause the game and marvel at the crash scene (I like !).

While the crash is happening, the other vehicles will continue to roll forward. So the devs will only be able to use part of the resources to do physics. The other challenge is they have to fit the crash animation realistically within the time penalty.

You're not describing anything tough at all.

Parts flying in the air along with smoke/flames is the simplest thing a CPU can do, even though it has the most dramatic effect (especially when viewed in slow motion replay). You just need a handful of ops per object. Processors do billions of ops per second.

A cascading car crash is absolutely nothing compared to the box example above. In the worst case you may have a stack 3 cars cars high, not 50+ (and resolving these situations is not linear). Drop 1000 cars on top of each other, and maybe you'll start pushing the CPU.

 

[Mintmaster]

Ideally they wouldn't ahve to, and with enough processing power they won't. As LucasArts demos of Digital Molecular Matter show, destruction can be calculated and geometry created on the fly.

Nope, you still need lots of modelling. A car's damage, for example, depends on the space frame, firewall, crumple zones, material parameters, etc. An artist does not model these things ordinarily.

If you want to be even remotely realistic, you have to tune a lot of parameters by hand. Manufacturers know the weakpoints and do various things to strengthen them. Even if you don't want to be realistic you still need plenty of tuning. If you watch Baja racing videos with crashes, you can see that Motorstorm really makes many joints a lot weaker than real-life so that we can watch the breaking pieces. It's an art direction choice, and given that Sony is trying to market the PS3 as being in a whole other league as the 360 for physics, it makes perfect sense.

As for DMM, it's not as "on the fly" as it seems. In the tech demo, for example, watch a bit closer. The wood has the same break patterns each time, despite the commentator saying otherwise. What's happening is that the DMM tools generate several broken pieces and joint properties offline automatically, sparing the artist the work for continuous materials (which a car in Motorstorm is not). The in game mechanism is pretty much identical, and you still have to store all the pieces. Often this is the limiting factor as opposed to artist talent/time due to RAM budget.

Again, the problem with using these techniques all over a game world is the massive game state you generate. We have to make hacks, like regenerating terrain/buildings (or predefined intermediate states) and object position resetting in areas you haven't been to in a while.