With Mafia 2 coming closer to it’s release, hype atmosphere is getting hotter, and apart from other materials you can find on the web, PC Games Hardware has published decent interview with Denby Grace from 2K Czech on several Mafia’s engine features, and PhysX part specifically:

PC Games Hardware: Are there any differences between the Console and the PC Version of Mafia 2 as far as technical as well as visual aspects are concerned, for example GPU accelerated PhysX effects?

Denby Grace: You hit the nail on the head. The biggest difference is the GPU enabled physics effects. While on a system without GPU (consoles and ATI cards), the game will have a great PhysX simulation with particles and cloth, however, if you have the extra hardware we are able to push things to a whole new level which has not yet been seen in open world game before.

Our destructible environments feature thousands of physical particles which in turn can be affected by individual explosion force fields to make them move. It’s all very impressive and it’s these kinds of improvements that high end PC gamers can expect.

PC Games Hardware: We know you are using Nvidia’s PhysX API and also APEX moduls (“Clothing”). Besides PhysX support why did you decide to use Nvidia’s physics middleware instead of other physics libraries like Havok or ODE? What makes Nvidia’s SDK so suitable for your title?

Denby Grace: PhysX is a really scalable system, which is something that appealed to us. We get to integrate a base system that can be dialed up and down, dependant on what system specs the users have. We have a minimum benchmark frame rate that we want to see, then the PhysX simulation level will adjust itself based upon the type of hardware you have.

CPU vs GPU quite simply means that we can really push the boat out with that much dedicated horsepower without being concerned that it’s going to affect the performance of other areas, separating this out is certainly preferable. Going a step further is separating out the gfx from the physics with separate GPU’s (SLI configuration).

People without a GPU PhysX card will still have these effects but it won’t be quite as advanced. We were very careful in ensuring that this would not affect the game play experience, no matter what system you have. , Mafia II I think looks absolutely amazing even without the full PhysX.

PC Games Hardware: Does regular by CPU calculated physics affect visuals only or is it used for gameplay terms like enemies getting hit by shattered bits of blown-away walls and the like?

Denby Grace: No we don’t do this. We didn’t want to alienate a part of our user base with that sort of selective functionality.

Also, don’t forget to check several comparison PhysX screenshots, located at this technical review.

Besides, Gametrailers.com has uploaded an interview with Eric Liu, Nvidia content manager, covering PC version specific features, like 3DVision and GPU PhysX and APEX support.

Richard Huddy, AMD’s Worldwide Developer Relations Manager, Ashu Rege, Nvidia’s Senior Director of Content and Technology, and Nadeem Mohammad, Nvidia’s Director of Product Management and PhysX, are speaking out against physics engines support strategies of their rival companies. During discussion, Bullet physics SDK is opposed to PhysX SDK.

Apart from slight pro-AMD tone and some factial mistakes in engines descriptions, it’s interesting read. Conclusion we are complitely agreed with:

Whether or not Bullet takes off remains to be seen, but the next few years will certainly be an interesting challenge for both companies.

However, as we’ve already took a view at AMD and PhysX relationship history, future of that AMD-promoted GPU Bullet and it’s implementation in games (not Bullet SDK itself) isn’t looking so bright and clear for us.

Recent articles about Metro 2033 have revealed so much technical details (about engine itself, and PhysX components specifically) so, one would think, nothing new can be added. However, recent interview with Chief Technical Officer Oles Shishkovstov by PCGamesHardware.com has something to offer:

PCGH: It could be read that your game offers an advanced physics simulation as well as a support for Nvidia’s PhysX (GPU calculated physics) can you tell us more details here? Does regular by CPU calculated physics affect visuals only or is it used for gameplay terms like enemies getting hit by shattered bits of blown-away walls and the like?

Oles Shishkovstov: Yes, the physics is tightly integrated into game-play. And your example applies as well.

PCGH: Besides PhysX support why did you decide to use Nvidia’s physics middleware instead of other physics libraries like Havok or ODE? What makes Nvidia’s SDK so suitable for your title?

Oles Shishkovstov: We’ve chosen the SDK back when it was Novodex SDK (that’s even before they became AGEIA). It was high performance and feature reach solution. Some of the reasons why we did this – they had a complete and customizable content pipeline back then, and it was important when you are writing a new engine by a relatively small team.

PCGH: What are the visual differences between physics calculated by CPU and GPU (via PhysX, OpenCL or even DX Compute)? Are there any features that players without an Nvidia card will miss? What technical features cannot be realized with the CPU as “physics calculator”?

Oles Shishkovstov: There are no visible differences as they both operate on ordinary IEEE floating point. The GPU only allows more compute heavy stuff to be simulated because they are an order of magnitude faster in data-parallel algorithms.

As for Metro2033 – the game always calculates rigid-body physics on CPU, but cloth physics, soft-body physics, fluid physics and particle physics on whatever the users have (multiple CPU cores or GPU). Users will be able to enable more compute-intensive stuff via in-game option regardless of what hardware they have.

Pay attention to last paragraph – Metro 2033 will feature true multi-core implementation of GPU PhysX content – feature that most PhysX titles are lacking currently ? We are curious to see if this will really work, and since game has already gone gold, we’ll learn that very soon.

Eurogamer.net website has published some very interesting materials, related to upcoming Metro 2033 title.  Firstly, they revealed full specifications of proprietary technology behing Metro 2033, known as 4A Engine, which is called even by its developers “one of the most advanced engines on the planet”.

You can read full specs here, and we’ll quote only part related to engine physics system:

Physics System
Powered by nVidia PhysX technology, can utilise multiple CPU cores, AGEIA PhysX hardware, or nVidia GPU hardware.

* Tightly integrated into the content pipeline and the game itself, including physical materials on all surfaces, physically driven sound, physically driven animations
* Rigid body and multi-jointed constructions. Breakable fences, walls , sheds and other objects. Thousands of different physical entities simulated per frame.
* Cloth simulation, water physics (including cross-interactions)
* Destruction and fracturing, physically based puzzles
* Soft body physics on selected special game entities
* On hardware-accelerated PhysX platforms engine implements full physically correct behaviour of particles such as smoke, debris, etc.

For dessert – Metrospective, interview with 4A Games chief technical officer Oles Shishkovtsov about game engine optimizations and platform specific features.

Metro 2033 is coming out March 16 on PC and Xbox 360, PC version will include 3D Vision, DX 11 and GPU PhysX support.

Update: second part of interview with Oles Shishkovtsov was published on Eurogamer. Provides more in-depth details on PhysX SDK integration, and engine’s genesis in general.

Digital Foundry: The 4A engine integrates NVIDIA PhysX. What are the core advantages of the hardware acceleration, what sort of hardware do you require for the best experience?

Oles Shishkovstov: The core advantage is simply the performance. The CPUs just aren’t there to enable large-scale physical effects (although they are very competitive when processing traditional rigid-body things). However, when you offload costly PhysX processing to GPU, we’ve got less GPU time for rendering.

It’s a difficult question when choosing what hardware will provide the best experience. I’d say that dedicating another (maybe less powerful) GPU specifically for PhysX is the right thing to do!

Digital Foundry: Over and above the tech demo-style elements that make PhysX cool, can you explain to us how the physics add to the gameplay experience?

Oles Shishkovstov: We do not add PhysX effects if they aren’t integral to the gameplay experience. We don’t add an effect for the sake of an effect. Human eyes and brain are trained to see the inconsistencies. We are only trying to remove those inconsistencies in order to not distract from gameplay and not to lose that immersion we were heavily building brick by brick.

Digital Foundry: How did you integrate PhysX into your many-core engine assuming you don’t have hardware acceleration? Are the same principles in use in the Xbox 360 code?

Oles Shishkovstov: That’s easy. PhysX SDK has the similar notion of the “task” as we use. The SDK spawns them for every operation which can be safely parallelised, for example each rigid-body shape-shape collision detection, each cloth or fluid update, even the solver(s) is heavily sub-divided into the tasks.

We forward those tasks to our task-scheduler and they are processed in the same manner as everything else. The only “conceptual” difference is between their and our task-model – we “spawn-and-forget” tasks and PhysX uses a “spawn-and-wait” model.

First part give a glimpse on human survival in Moscow after nuclear strikes.

In second part Luis describes new proprietary engine used to produce highly detailed post-apocalyptic world plus new innovative weapons.

In addition to excellent graphics with DX11 support and intensive storyline, Metro 2033 will include GPU accelerated PhysX content. If you are interested in details about GPU PhysX support, please refer to our  inteview with 4A Games, focused on in-game physics.

Or first, pilot article, is dedicated to RayFire Tool – awesome destruction plug-in for 3ds Max. Mir Vadim, RayFire Tool sole developer, has answered some of our questions about  RayFire history and PhysX SDK role in plug-in development.

Read The Article - PhysX From Inside Out: RayFire Tool

P.S. I’ve counted on small interview firstly, but Mir Vadim has sended a huge post-mortem like material – must read for every RayFire user and admirer.

Thanks Mir !

Yuriy Saschuk, 4A Games engine programmer, has joined us today to answer some questions about Metro 2033 in-game physics in general, and PhysX specifically.

PhysXInfo.com: How much physics is involved in gameplay ? Do players have ability to carry physical objects or drag corpses ?

Yuriy: Physics in Metro 2033 has more demonstrative, than gameplay affecting, nature. It’s supposed to enhance game, make it more diverse, realistic and exciting. But actual gameplay isn’t focused on physics.

You can’t carry or throw objects – we’ve decided that there is no need for this, but enemies (and player too) can receive damage as result of certain physical interactions.

PhysXInfo.com: Will Metro 2033 contain destructible objects, and in what quantity ?

Yuriy: Our engine supports destructible environments, and this component is used in the game.

PhysXInfo.com: Tell us a bit about hardware PhysX support in the game. Presence of appropriate Nvidia GPU will simply increase the fps numbers or add some exclusive effects ? Will GPU PhysX content have influence on gameplay ? Which advanced physics effects will be included ?

Yuriy: PhysX hardware acceleration capability of Nvidia GPUs will add performance in the first place. There are two physics modes in Metro 2033 – basic and so-called, “Advanced PhysX”, which will include both enhanced, more detailed effects from basic mode and some additional physics features. Advanced PhysX mode requires appropriate Nvidia GPU to run properly, meanwhile, it will not affect gameplay, just add some immersion.

Or engine support cloth and fluid simulation. By “fluid simulation” we imply various particles system, like lighter- and heavier-than-air gases, smoke, dust, debris from bullet hits, not only liquids.

PhysXInfo.com: Will players have ability to customize level and/or quality of physics effects?

Yuriy: Only by switching between basic and advanced physics simulation modes.

PhysXInfo.com: As it was said previously, your game supports multi-core CPUs. Does physics simulation take advantage of additional cores ?

Yuriy: Yes.

PhysXInfo.com: Why PhysX SDK was choosen as physics middleware for Metro 2033 ?

Yuriy: Main criteria – cross-platformity, functionality and price.

PhysXInfo.com: Have you encountered any issues during development ? Features that were planned, but weren’t implemented because of PhysX SDK limitations ?

Yuriy: Main problem – inherent variability of physics simulation. As a result – there are always the so-called “bad cases” when visual result of the simulation does not look good enough. Attempts to solve such problems weren’t always successful – sometimes solution was too resource intensive, and we had to compromise in “performance / quality” matter.

PhysXInfo.com: Are you using new PhysX toolset – APEX ?

Yuriy: In fact – no. But we are looking closely at APEX.

PhysXInfo.com: Do you cooperate with Nvidia at PhysX hardware area and how closely?

Yuriy: We have constant contact with engineers at nVidia’s Moscow office and with those that are “overseas”. Their representatives are visiting our office. I believe this cooperation is definitely useful and productive.

Earlier this month, AMD critized Nvidia again, this time on crippling PhysX multi-threaded capabilities.

“When they bought Ageia, they had a fairly respectable multicore implementation of PhysX. If you look at it now it basically runs predominantly on one, or at most, two cores. That’s pretty shabby! I wonder why Nvidia has done that?” said Richard Huddy, AMD worldwide developer relations manager, in an interview with Bit-tech.com

“It’s the same thing as Intel’s old compiler tricks that it used to do; Nvidia simply takes out all the multicore optimisations in PhysX. In fact, if coded well, the CPU can tackle most of the physics situations presented to it.”

Tomshardware asked Nvidia for its responce for such allegations, and here is an answer by Nadeem Mohammad, PhysX director of product management:

I have been a member of the PhysX team, first with AEGIA, and then with NVIDIA, and I can honestly say that since the merger with NVIDIA there have been no changes to the SDK code which purposely reduces the software performance of PhysX or its use of CPU multi-cores.

Our PhysX SDK API is designed such that thread control is done explicitly by the application developer, not by the SDK functions themselves. One of the best examples is 3DMarkVantage which can use 12 threads while running in software-only PhysX. This can easily be tested by anyone with a multi-core CPU system and a PhysX-capable GeForce GPU. This level of multi-core support and programming methodology has not changed since day one. And to anticipate another ridiculous claim, it would be nonsense to say we “tuned” PhysX multi-core support for this case.

PhysX is a cross platform solution. Our SDKs and tools are available for the Wii, PS3, Xbox 360, the PC and even the iPhone through one of our partners. We continue to invest substantial resources into improving PhysX support on ALL platforms–not just for those supporting GPU acceleration.

As is par for the course, this is yet another completely unsubstantiated accusation made by an employee of one of our competitors. I am writing here to address it directly and call it for what it is, completely false. NVIDIA PhysX fully supports multi-core CPUs and multithreaded applications, period. Our developer tools allow developers to design their use of PhysX in PC games to take full advantage of multi-core CPUs and to fully use the multithreaded capabilities.

Source: nTersect Blog

Live stream is available at WJPF website (click “listen live” button at the right)

After the interview, Hi Tech Legion will provide more in-deph view into the PhysX technology.

Live stream will be accessible via WJPF website

Additionally, recorded interview will be available for HTL readers, along with some extra materials.

Source: Hi Tech Legion