It is time to summarize what PhysX Technology has achieved in year 2011, recall the most memorable events and releases.

. GAMES

GPU physics acceleration still can not gain enough momentum – only two games with support for GPU PhysX effects were released this year, this is the lowest result since Ageia was aquired.

One may call this an agony, but NVIDIA has told us that it was “conscious decision” – time was taken to develop and improve underlaying technology (PhysX SDK, APEX, DCC tools), thus sacrificing ability to create content and  integrate it into many games.

It was promised that we will see “more GPU PhysX games next year than you did this year” and even “a lot more in 2013″.

Meanwhile, both GPU PhysX titles released this year were pretty interesting by themselves:

• Batman: Arkham City, one of the best games with hardware PhysX support.
• Alice: Madness Returns, which is a decent game too and is certanly worth more than two Darkest of Days.

PhysX SDK as physics engine is still widely adopted by developers – over 45 PC console and games were released this year, according to our database.

. PHYSX SDK & TOOLS

Looking on the SDK Development you can say where all resources were spent – brand new PhysX SDK 3.0, rewritten from scratch, optimized and enhanced with new features, was released in Q2 2011, followed by SDK 3.1 and SDK 3.2 Beta. 6-months release schedule was introduced and so far is impeccably fulfilled.

PhysX 3 is a strong technological foundation, that will ensure further expansion, evolution and success of PhysX as physics engine.

NVIDIA APEX 1.0, high-level scalable framework build on top of PhysX SDK, was also revealed for public along with UDK integration, however it can not boast with same release dynamics – new APEX 1.1, promised to be delivered this autumn is now postponed till 2012. APEX 1.2, fully based on PhysX SDK 3, is also supposed to be released next year.

DCC PhysX plug-ins went throught three versions – 2.6, 2.61 and 2.7 – but during this period several compatibility problems and significant delays of releases were faced.

. MISCELLANEOUS

MassFX – new physics simulation solution, using PhysX SDK engine, was introduced in Autodesk 3ds Max 2012, thus replacing Reactor system, which was based on Havok physics. Rigid Body simulation functionality of MassFX was pretty strong along with better performance, however many users were unhappy with reduced functionality set in comparison to Reactor.

According to yearly survey by Game Developer Magazine, PhysX SDK is preferred physics middleware solution for traditional (big-budget) developers.

PhysX Research Team has showcased some new interesting technologies and prototypes. Some of them will appear in future versions of PhysX engine.

After a long break, new 1.05 version of Hybrid PhysX mod was released to support recent drivers and GPU PhysX games in AMD + NVIDIA configurations.

. . .

Well, that is all for now.

Happy New Year to everybody !

Time to update PhysX performance metrics of NVIDIA GPUs with newest title with Hardware PhysX support – Batman: Arkham City.

In following article we’ve tried to gather all the benchmarks and tests, published on the web.

[25.11.2011] Batman Arkham City im Technik-Test: Grafikkarten-, DirectX-11- und Physx-Benchmarks by PCGamesHardware.de

German article with graphics benchmarks, overview of DX 11 and PhysX features, and a superficial PhysX tests.

[25.11.2011] Batman Arkham City GPU Test by GameGPU.ru

Includes PhysX benchmarks with over 20 GPUs tested, however, only on “High” PhysX settings without Hybrid PhysX or dedicated GPU tests.

[27.11.2011] Preview: Batman Arkham City – výkon grafik pod DX11/DX9 a PhysX by DDWorld.cz

Czech preview article with very basic PhysX benchmarking part (only one GPU tested).

[28.11.2011] Want to play Batman: Arkham City with PhysX enabled? Get ready for some abysmal framerates by DSOGaming.com

Despite of provoking title, measured performance is not that bad. Also, this is the first article with benchmarks of dedicated PhysX GPUs.

[30.11.2011] Waiting for the patch: Batman: Arkham Asylum in DX9 mode by 3DNews.ru

Russian article with some PhysX/DX11 effects overview and decent PhysX testing.

[02.12.2011] Technik-Check: Batman: Arkham City im Benchmark-Test by GameStar.de

Includes some benchmarks with different PhysX settings. Results are interesting – GPU PhysX effects on CPU (AMD card) are faster that GPU PhysX on middle-end NVIDIA cards (in this case, minimum fps would be more meaning than average).

[02.12.2011] Batman Arkham City, DirectX 9 e DirectX 11 a confronto by HardwareUpgrade.it

Technology overview and minor PhysX testing.

[05.12.2011] Batman: Arkham City Gameplay Performance and IQ Review by HardOCP

Once again, disputable benchmarking methodology from HardOCP – NVIDIA cards are tested with GPU PhysX effects enabled and compared to AMD cards with PhysX disabled. Thus, it is shown what GPU PhysX takes – performance, but it is not revealed what it brings – additional effects.

[17.12.2011] Batman: Arkham City Performance Review by Playwares.com

Detailed article from a Korean website, however, PhysX part is most interesting for us.

[17.12.2011] Batman: Arkham City Graphics Breakdown & Performance Guide by GeForce.com

Performance and features overview from NVIDIA itself. Graphs are interesting, for example this one shows ineffectiveness of dedicated PhysX card usage in pair with GTX 560 Ti GPU.

[10.01.2012] Batman: Arkham City — podívejte se na PhysX a DX11 v akci by PCTuning.cz

Good technical review (in Czech) with strong benchmarking part (includes CPU tests, for example). For some reason, PhysX effects were tested only on “Medium” settings though.

– We’ll update this post as more articles emerge –

Batman: Arkham City tests the patience of PC gamers with several release delays, but will try to wheedle them with DX 11 Graphics and PhysX Technology.

Update: GPU PhysX in Batman: Arkham City - review and comparison video.

Recent comparison trailer gave us a glimpse of extra physics effects, and now we want to provide you with some additional details on what to expect from GPU PhysX content. In addition, new comparison PhysX video was released as well.

As usually, it will be possible to adjust level of in-game physics via “Hardware Accelerated PhysX” option in game’s launcher. There will be three settings:

PhysX Off: all GPU accelerated effects are disabled, only standart CPU physics (like ragdolls) is used.

PhysX Normal: enables additional particles effects (debris, volumetric smoke and steam, etc) and destructible environments.

PhysX High: includes all effects enabled withing “Normal” settings as well as realtime cloth and clothing simulation.

PhysX particle effects, most widely used type of content in GPU PhysX titles, will find their place in new Batman game. Scattered across Arkham City, they will consist of:

• Interactive SPH-smoke from fire extinguishers and smoke pellets, dynamic steam and fog.
• Ice particles for Freeze Gun and Freeze Grenade.
• Interactive debris from destructible thrown objects, like stools and vases.
• Environmental specific particles: molten and electrical sparks, coal debris, chunks, etc.
• Extra particles jutting from destructible objects like breakable glass, tiles and walls.
• Forcefields for explosions that will push particles away.

Interactive smoke and debris from Batman’s explosive gel

In addition, PhysX cloth effects are emulating the behaviour of fabric and clothing to make Batman and his enemies more realistic, as well as lend realism to environments. They will include:

• Simulated clothing on characters: coats and hoodies for Penguin, Two Face, and Joker’s thugs; Bruce Wayne’s jacket, pants, and tie.
• Dynamic paper: eviction and office papers, posters, x-ray sheets, museum tickets, etc.
• Money littering the floor of the vault (Sewer level).
• Leaves on the ground.
• Various interactive cloth objects throughout the game: rugs, banners, curtains, flags, ropes, bunting.

Banknotes are simulated as invidial cloth pieces, affected by character and weapon movement

But beauty comes with a burden, performance wise – GPU PhysX effects, especially coupled with DX 11 features like tesselation or HBAO, can bring frame rate to its knees if your GPU is not fast enough.

Various tesselation settings

Following table (based on NVIDIA testing) provides recommended baseline settings for specific GPUs to ensure the comfortable combination of playability and features (average frame rate of 40-55 frames per second and minimum 35 fps).

Batman: Arkham City is set for launch on November 22 in US and November 25 in EU.

Don’t forget to visit PhysXInfo.com soon after game’s release for comparison PhysX video, screenshots and detailed overview.

Earlier this year, Matthias Müller-Fischer, PhysX SDK Research Lead in NVIDIA, has presented new universal solver that can be used simulate almost any kind of objects – rigid, plastic, cloth or soft body.

You can familiarize with this work via previously published research papers: Solid Simulation with Oriented Particles and Adding Physics to Animated Characters with Oriented Particles.

Today, interesting video was revealed – it is showcasing impressive 20x performance improvement for this type of simulation running on GPU through CUDA, in comparison to CPU execution (5 “Lionfish” objects on CPU vs 100 on GPU – in real-time).

Sometimes findings of PhysX Research team are incorporated in PhysX/APEX products, and sometimes, for various reasons, they just become a research paper or presentation. We hope that in case with solver there will be only one option – first one.

Metro: Last Light, sequel to Metro 2033 title, is aiming technology throne with DX 11, tesselation and support for GPU accelerated PhysX effects. PCGamesHardware.com had the chance to talk with Oles Shishkovtsov, Chief Technology Officer at 4A Games, about improvements that are planned for PC version of the game.

PC Games Hardware: You keep the support for GPU PhysX in Metro Last Light. If so can we expect some improvements or enhancements compared to Metro 2033 (e.g. soft bodies, debris, and destructible environments)? What graphics card do you recommend for maxed details in Full HD with Antialiasing? An upcoming Nvidia Kepler-based Geforce for example?

Oles Shishkovtsov: Yes, you can expect a lot of improvements, especially in destruction and debris. The upcoming Geforce cards will be fully supported.

PC Games Hardware: When benchmarking Metro 2033 we found out that the engine utilized more than four cores of multicore CPUs if we were using the advanced PhysX effects on CPU, so you are utilizing Nvidias PhysX SDK 3.x? Will all the advanced PhysX effects only be available in PC version?

Oles Shishkovtsov: That’s the common misconception that PhysX 2.X cannot be multithreaded. Actually it is internally designed to be multithreaded! The only thing – it takes some programmer time to enable that multi-threading (actually task generation), mostly to integrate with engine task-model and ensure proper load-balancing. So, 2033 used PhysX 2.8.3, and Last Light uses similar, a slightly modified version at the time of writing. And yes, advanced PhysX effects will be available only on PC.

Read the full interview

Sounds good.

However, we are hoping that this time Metro will be able to surprise us with more than two minor particle effects (as in Metro 2033 – while “debris, smoke and dust” were promised) and it won’t require “upcoming GeForce card” to run those GPU PhysX effects with playble framerate.

Almost four years has passed since NVIDIA aquired Ageia and presented their version of hardware accelerated PhysX Technology. However, anyone who is watching GPU PhysX progress closely can say, that so far it has not shown any significant advancement – but is the fight already lost or is it just taking time to harness up, but will ride fast?

We got a chance to chat with Tony Tamasi, Senior Vice President of Content & Technology in NVIDIA, Ashu Rege, Vice President of Content & Technology, and Rev Lebaredian, Director of Engineering, to clear up these questions, and recieve some insider information on future development plans for PhysX SDK and NVIDIA APEX toolset.

PhysXInfo.com: Over last years, amount of GPU PhysX games is actually decreasing. There were five games in 2009, three in 2010 and so far only one in 2011. How can you explain that?

Tony Tamasi: It was a choice on our part. We had a large amount of resources we could otherwise dedicate to content, but we needed to advance the core technology. We needed to get PhysX 3 done, and we needed to get APEX done to the degree where it is usable by game developers. We had to put a lot of resources there, which meant that some of those resources weren’t directly working on games.

But in the long term, game developers can actually use PhysX and APEX, and make use of the GPU without significant amounts of effort, so that a year or two years from now more games will come out using GPU physics.

Alice: Madness Returns - most recent GPU PhysX title

Rev Lebaredian: When we initially acquired Ageia, we made a big effort to move many games over to GPU PhysX. We learned a lot in that period of time: getting GPU physics into games, what are the problems, what works and what doesn’t. That gave us the opportunity to regroup, refocus, and figure out how to do it correctly.

We made a conscious decision. After we did a bunch of PhysX and APEX games in 2009 and early 2010, we said “Ok, we have learned enough, we need to sit down and focus on finishing APEX and changing it based on what we just learned, as well as PhysX 3”. Doing as many titles as we were doing before was just going to slow us down.

It made more sense to slow down the content pipeline but get the tools right, but that puts us in the position when once those are complete, it is actually less work for us to get PhysX in games.

This slowdown has not been because of any problems. It is something that we have decided to do.

PhysXInfo.com: So NVIDIA APEX is supposed to give developers the tools for easy creation on physical content in games, and you will receive GPU PhysX support as a byproduct. Is this idea working already?

Rev Lebaredian: It won’t be 100% free. Anytime you’re going to change the quality of something, you’re going to have the artists and level designers do a little bit of work to tweak it so it will look right.

Sure, let’s say if you have clothing you can just increase the number of vertices or increase the number of bodies for something with destruction, but most likely they going to want to tune it at different levels.

What we are trying to do with APEX is minimize that work. If you spend 10 hours putting together a set of assets for consoles, it shouldn’t take you another 10 hours to do the GPU stuff, maybe an additional half hour—depending on the developers and game in question obviously.

Tony Tamasi: And  I can actually tell you for sure, when we first started on the GPU PhysX effort, it often took more time to do the GPU physics work than core physics work, which is not the right balance. So we have to get the balance to make it incremental effort.

Ashu Rege: If you compare some games with APEX and GPU PhysX from one or two years ago, with some other games we are working on today, we have improved by 4-5 times in terms of less man-hours of work to get GPU PhysX done.

PhysXInfo.com: So how many GPU PhysX games are we going to see in upcoming years?

Rev Lebaredian: I think you’ll see more GPU PhysX games next year than you did this year, and I would expect to see a lot more in 2013. PhysX 3 and APEX are now just getting integrated–that’s why you see that kind of lag.

Tony Tamasi: We’ve also taken steps to integrate it [APEX/GPU PhysX] in major engines, like UE3—that enables a lot more developers to be able to use it out of the box now. When we did the GPU titles in 2009, essentially we have to do that integration each time. So there should be a large increase in GPU physics content just because it’s easier.

PhysXInfo.com: And for how long are you planning to further develop and use PhysX Technology?

Tony Tamasi: As long as we can see!

Ashu Rege: The interesting thing is that we haven’t even touched, frankly, the surface of the cool new things that can be done in many directions; things like heightfield fluid simulation, better cloth–I mean, there are so many different improvements, for both algorithms and technology as well as improvement for the tools so developers can integrate these features much faster.

So yes, we keep working.

PhysXInfo.com: Is the fact that GPU PhysX is exclusive to NVIDIA some kind of barrier for GPU PhysX adoption?

Rev Lebaredian: It is not a secret that most of game developers are concerned about consoles. PC for them is a smaller SKU usually, so PhysX not running on competitor GPUs  does not really matter that much to them.

Tony Tamasi: For every title we have worked on; for every one that I’m aware, that was never a reason for someone to use or not to use GPU PhysX.

PhysXInfo.com: Do you have any plans to port GPU PhysX to DX11 (Direct Compute) or OpenCL?

Rev Lebaredian: No plans to do it. Maybe if there will be a good reason for that in the future, but there is no current plan.

PhysXInfo.com: So developers are not asking you to port GPU PhysX to OpenCL?

Tony Tamasi: Nope.

Rev Lebaredian: No.

PhysXInfo.com: Are GPU PhysX effects going to be friendlier to multi-core CPUs in the future?

Tony Tamasi: You can use multi-core CPUs in PhysX 2.8, but it requires a lot of extra work to do that.  In PhysX 3 most solvers are parallelized across as many threads as are available.

Rev Lebaredian: It is usually not possible to get linear scaling with increasing numbers of CPU cores automatically. It is not reasonable to expect that if you’ll throw 8 cores at it, it will be 8 times faster.  However, we’ve done a lot of work in PhysX 3 to maximize usage of multiple CPU cores whenever possible.

PhysXInfo.com: What do you think about Hybrid PhysX? Isn’t it for good?

Rev Lebaredian: Good at what cost?

Supporting it would be a huge amount of QA for us, and it would be weird too – if we’ll find a bug in AMD’s drivers, what will we do?

Ashu Rege: For the foreseeable future we will not supporting it officially. If it works- it works, if some guys can figure out how to make it work – great for them.

After discussion of common topics, we have moved to more specific questions regarding PhysX SDK and NVIDIA APEX toolset.

PhysXInfo.com: New PhysX SDK 3. Has it already equals the hopes or was it waste of time, which has created more problems that it has solved?

Tony Tamasi: As far as I can tell, every developer we talked to is happy with it.

Rev Lebaredian: We have had developers demand to use it over 2.8, and that’s actually accelerated our plans for getting APEX working with it.

PhyXInfo.com: So developers now prefer PhysX 3 over 2.8?

Rev Lebaredian: Yes.

Ashu Rege: We build it to satisfy all their needs, so it would be really strange if they won’t use it. And we will be continuing to improve it to meet what developers are asking for.

PhysXInfo.com: Will PhysX SDK support next-generation consoles in the future?

Rev Lebaredian: Here is what we can say: we will always support all platforms that are relevant to our developers, so when the next generation consoles will become a reality, we will be on it.

PhysXInfo.com: Will PhysX SDK remain focused on games/game development area only?

Tony Tamasi: The focus is games. People can use it for visual effects or for manufacturing–that is awesome. And if we can do some incremental work to enable them, we’ll do that when we can, but the focus is games.

PhysXInfo.com: Are you thinking about enhancing PhysX/APEX product line with additional middleware packages, for animation or AI simulation, for example?

Ashu Rege: We work closely with our partners, with Natural Motion, with Autodesk, with game engine guys, but we are not interested in participating in that market; making money selling software. So it is not our goal to enter all of these areas.

PhysXInfo.com: What is the current development course for NVIDIA APEX?

Rev Lebaredian: We have decided to currently focus on two modules that have the highest priority for game developers – Clothing and Destruction.

EvE Online: APEX Clothing will make your hair long and silky

PhysXInfo.com: When we are going to see APEX with PhysX SDK 3 support? What are going to be the benefits, in comparison to current APEX with SDK 2.8?

Rev Lebaredian: Internally we already have version that works with PhysX 3. That’s one of the things on the roadmap. APEX 1.2 is going to be the first version of APEX we’ll release that will support PhysX 3.

Essentially, the benefits will be all the benefits that you get from PhysX 3 – better performance, and we’ll have all new features, new solvers, and all that kind of stuff.

PhysXInfo.com: Are you planning to port APEX to mobile platforms?

Rev Lebaredian: Yes.

Ashu Rege: Internally, we already have all of those working.

Tony Tamasi: And as soon as mobile devices will support CUDA, we’ll have GPU computation on mobile devices too.

PhysXInfo.com: APEX Destruction 1.1 will include fully functional GPU Rigid body solver (you were able to see in Art Gallery demo at GDC 11) – can you provide more details about it? Is this already finished technology or first iteration with many improvements to come?

Rev Lebaredian: We’ve done a lot of work on it since the Art Gallery demo last GDC.  It is more robust now, and behavior is better.  It is essentially the same, or maybe in some cases even better quality than the rigid body behavior in PhysX 2.8

Ashu Rege: We are at the point right now where we have three baseline things working–behavior, robustness and performance. We are continuing to enhance and improve it, especially on the performance front. It is using the exact same API [as CPU RB], except some pieces of the API are not implemented yet, so things like joints are not done.

Art Gallery demo was featuring GPU Rigid Body physics with up to 10 000 individual objects

PhysXInfo.com: What other features are planned for future versions of APEX Destruction?

Rev Lebaredian: There are lots of things we want to do with Destruction, real-time fracturing instead of pre-fracturing, all kinds of stuff. There are a lot of things in the plan and we have ideas on how to implement a lot of them, but what ends up driving features is the content. We work with game developers, see what it is they want, and we will change the priority based on demand.

PhysXInfo.com: New clothing solver was introduced in PhysX SDK 3.1. How does it compare to the previous one?

Tony Tamasi: It is faster and more stable, but it is not complete in terms of the feature set that is in PhysX 2.8, but we are adding those in the future.

PhysXInfo.com: Are you going to expand this new solver with all the missing functionality, or add additional specialized solvers in the future?

Rev Lebaredian: For collision geometry and similar features, we’ll expand the same solver. We haven’t decided yet, if we’ll want to introduce tearing for example.  That is a likely candidate for a different solver, because it never quite solved this problem correctly anyway. Sometimes it is better to have different solvers that solve different problems.

PhysXInfo.com: Will it support multi-core CPUs to the full extent?

Tony Tamasi: Yes

PhysXInfo.com: Are you planning to add this new clothing solver to 2.8 PhysX SDK?

Rev Lebaredian: The plan is if the developers are using PhysX 3.1, they can just use the new solver. If the developers are using 2.8 and they can’t switch to 3.1 for whatever reason, we can take the solver and make it build with APEX, so that they can continue to use PhysX 2.8 for all of their normal physics stuff and also use the 3.1 cloth solver with APEX Clothing.

PhysXInfo.com: Is authoring pipeline going to be different for new solver?

Rev Lebaredian: There are some modifications we’ve made. The parameter space is different and there are some new features, like tapered capsules for collision geometry–we obviously had to change DCC plug-in to support that.

PhysXInfo.com: When are we going to see new clothing solver in action?

Tony Tamasi: In games shipping next year.

As for us, all of the above sounds trustworthy enough and yet promising.

And what do you think ? Tell us in comments.

Another interesting research paper was published by Dr. Matthias Müller-Fischer, PhysX SDK Research Lead in NVIDIA.

Update: Oriented Particles solver through CUDA

It is called Adding Physics to Animated Characters with Oriented Particles and it further expands oriented particles approach with techniques for simulation of clothing on animated characters.

Abstract:

We present a method to enhance the realism of animated characters by adding physically based secondary motion to deformable parts such as cloth, skin or hair. To this end, we extend the oriented particles approach to incorporate animation information. In addition, we introduce techniques to increase the stability of the original method in order to make it suitable for the fast and sudden motions that typically occur in computer games. We also propose a method for the semi-automatic creation of particle representations from arbitrary visual meshes. This way, our technique allows us to simulate complex geometry such as hair, thick cloth with ornaments and multi-layered clothing, all interacting with each other and the animated character.

NVIDIA has published a technical article, related to Smoothed Particle Hydrodynamics (SPH) fluid simulation method, used in as part of GPU PhysX effects in recently released Alice: Madness Return title.

As we said before, overall level of PhysX particle effects is impressive, but fluid dynamics itself can only be called – decent. We already saw more detailed SPH-fluids in Cryostasis (up to 30 000 particles), gameplay affecting fluids in Crazy Machines 2 and even SPH based smoke in Batman: Arkham Asylum and Mafia II.

What we are really expecting from upcoming PhysX games, are next-gen fluid solvers like those showcased in this PhysX research video or in Raging Rapids Ride demo, for example.

However, if you are interested in SPH-fluid simulation technique and particles rendering, we recommend you to familiarize with following materials (in addition to the article this post is related to – which is an interesting read anyway):

• CUDA Fluid Simulation in NVIDIA PhysX
• Screen Space Fluid Rendering for Games

Alice: Madness Returns – first game with GPU PhysX support this year and title with most impressive PhysX particle effects.

To determine hardware PhysX performance patterns and GPU requirements we tried to gather all PhysX focused articles and benchmarks, available so far.

[18.06.2011] Alice: Madness Returns GPU test by GameGpu.ru

One of the first articles with proper GPU PhysX benchmarks.

According to their test, only top level NVIDIA GPUs can ensure decent framerate, while used for both graphics and PhysX calculations (however, from our experience, only most intensive PhysX scenes are affecting performance so negative).

Benchmarks of dedicated PhysX cards are also included:

As you may see, dependance is non-linear – from certain point using more powerfull GPU is not resulting in framerate increase.

[13.07.2011] Alice: Madness Returns Review by Bjorn3D.com

Standart game review with small benchmarking part

Second of all, Alice has some fantastic PhysX features, though we’ve noticed a big performance decrease when PhysX is set to High. Medium keeps most of the PhysX effects, and users can get better FPS while gaming without sacrificing too much from the effects

[18.08.2011] Alice: Madness Returns — GPU fyzika v akci by PCtuning

Checz article, includes good set of GPU and CPU benchmarks, with various PhysX settings.

– We’ll update this post as more articles emerge –

Two new research papers have landed on a homepage of Dr. Matthias Müller-Fischer, PhysX SDK Research Lead in NVIDIA and NovodeX co-founder.

Fisrst one, called “Real-Time Eulerian Water Simulation Using a Restricted Tall Cell Grid“, presents further impovements to the real-time hybrid fluid solver, that we were able to see in recent demos like Lighhouse and Raging Rapids Ride.

Abstract:

We present a new Eulerian fluid simulation method, which allows real-time simulations of large scale three dimensional liquids. Such scenarios have hither to been restricted to the domain of off-line computation. To reduce computation time we use a hybrid grid representation composed of regular cubic cells on top of a layer of tall cells. With this layout water above an arbitrary terrain can be represented without consuming an excessive amount of memory and compute power, while focusing effort on the area near the surface where it most matters. Additionally, we optimized the grid representation for a GPU implementation of the fluid solver.

To further accelerate the simulation, we introduce a specialized multigrid algorithm for solving the Poisson equation and propose solver modifications to keep the simulation stable for large time steps. We demonstrate the efficiency of our approach in several real-world scenarios, all running above 30 frames per second on a modern GPU. Some scenes include additional features such as two-way rigid body coupling as well as particle representations of sub-grid detail.

We badly want to see this one in further releases of PhysX SDK 3 or APEX.

Second paper – Solid Simulation with Oriented Particles – describes universal solver, based on Position Based Dynamics and Shape Matching approach, that can be used to simulate rigid, plastic, cloth or soft body objects.

Update: Oriented Particles solver through CUDA

Abstract:

We propose a new fast and robust method to simulate various types of solid including rigid, plastic and soft bodies as well as one, two and three dimensional structures such as ropes, cloth and volumetric objects. The underlying idea is to use oriented particles that store rotation and spin, along with the usual linear attributes, i.e. position and velocity. This additional information adds substantially to traditional particle methods. First, particles can be represented by anisotropic shapes such as ellipsoids, which approximate surfaces more accurately than spheres.

Second, shape matching becomes robust for sparse structures such as chains of particles or even single particles because the undefined degrees of freedom are captured in the rotational states of the particles. Third, the full transformation stored in the particles, including translation and rotation, can be used for robust skinning of graphical meshes and for transforming plastic deformations back into the rest state.

Another interesting idea, that is welcomed in future PhysX SDK versions.

Thanks for AquaGeneral for a hint