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Old 03-16-13, 08:10 AM   #1
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Post GPU PhysX in Hawken

GPU PhysX integration in Hawken, free-to-play mech shooter from Adhesive Games, has a long and yet ongoing story ' preliminary PhysX effects have emerged in Alpha and Closed Beta versions, then they have undergone a significant overhaul in Open Beta release.

And now, recent 'Raider' update has added a set of new, APEX Turbulence based particles effects, and we think that GPU PhysX support in Hawken has grown up enough to be reviewed.

QUANTITY7/10At current state, Hawken can offer us two types of particle effects ' physically simulated debris and APEX Turbulence driven particle simulation.

Debris particles are the most common effect, that can be found almost in every single GPU PhysX title ' in Hawken, such debris (pieces of concrete, strips of metal, rubble) are generated upon weapon impacts on various surfaces, rocket explosions, and are also produced as mechs are walking or jumping.

Impact debris can be found almost in any GPU PhysX game

Additionally, explosions and mech movement are also binded to forcefields, than can repel nearby particles in a certain radius.

In comparison, APEX Turbulence module was utilized only in one, fairly old game ' Dark Void ' but now is making a comeback with titles like PlanetSide 2, Warframe and now Hawken. Turbulence particles are controlled by volumetric velocity fields, that give them nice fluid-like and swirly behavior.

Shield creates magnetic sphere of defensive particles

Turbulence effects are applied only to four object in the game world ' energy collecting machines, deployable shields, consisting of magnetic particles, energy health orbs, dropped by fallen mechs and embers, that are emitted from mech's wreckages.

Now the negative. Hawken is not only using two types of PhysX effects in all, but even those are not utilized to their full potential. Something like environmental or area specific particles (smoke, dust, ash), would be the great addition to the particles effects. Or maybe a generation or manipulation of debris particles in a new, yet unseen way?

In turn, only a few of many potential objects are enhanced with Turbulence effects. For example, there are particles, swirling around energy collectors, but what about a process, when collected energy is extracted from mechs? It is a perfect case, especially since the player can see his mech from 3rd person perspective, but ' no. Missed opportunity.

QUALITY7/10It is natural to expect a certain quality level from GPU PhysX support after years of evolution and Hawken is not the exception. All effects are done nicely and accurately, apart from some rare problems with incorrect behavior of particles.

One can even spot a several pleasant artictic details, for example, one minigun burst can produce mesh particles of various sizes and forms from a single surface, and impact debris looks differentely on sand dunes of Bazaar and stone jungles of Prosk.

Despite of that, particle debris are still lacking large portion of visual diversity. From a distant look, you can devide particles into two categories ' crumpled metal strips, emitted mostly during explosions, and anything else.

And, to our taste, particle effects are largely missing physical sparks. Sparks, sparks, do you like sparks? They are non-intrusive and performance friendly. Sparks are something that you would expect while shooting giant metal robots in the world, half consisting of metal structures. Instead, all we can see are pieces of steel and concrete slabs.

Current look and idea of Turbulence effects can also raise several complaints. Energy collectors are looking great. Perfect match, can not be done better. Magnetic shields have some interesting particle motion too.

Collector feeds friendly mech with energy

And embers, emitted by death mech, are looking too simplistic with their random, noisy behaviour. Something like mushroom cloud, that mimic the explosion in real life, would certanly fit better.

IMMERSION8/10Now the tricky part. In Hawken, like in some other GPU PhysX games though, extra physics effects are a matter of taste. If you find them excessive and redundant, if you think that particles, flying all over the screen, do nothing but obscure your vision ' you will turn them off.

And if you like when missile, exploding near your mech, pulls out the dirt and pices of concrete from the ground, which are jumping off the windshield of your ****pit while you are trying to avoid enemy fire ' you will enable the PhysX effects and ask for more. The factor of staginess.

In any case, GPU PhysX support changes the visual look of Hawken, and quite dramatically.

PERFORMANCE8/10It is worth mentioning now, that Hawken contains three levels of PhysX interactions:

  • PhysX Particles ' 'Off' leaves only basic physics, calculated on CPU, such as ragdolls and some rigid body objects on levels (vehicles, containers and so on). CPU physics is calculated through PhysX SDK and, obviously, can not be turned off.
  • PhysX Particles ' 'On' (should be called Medium) enables first set of PhysX effects ' physical particles, such as impact and explosion debris.
  • PhysX Particles ' 'High (NVIDIA Only)' option additionally adds Turbulence effects, using latest APEX Turbulence 1.2.3 module.
'NVIDIA Only' remark applies to CPU execution of GPU PhysX effects. While particle debris can be calculated on CPU at the expense of performance loss (more on that later), we highly not recommend to enable 'High' PhysX option without a NVIDIA card in the system.

By their nature, Turbulence effects can not be calculated normally on CPU ' the velocity field, that controlls particle motion, runs only on GPU ' this means, you will see the particles, but they will simply float in the air, without any of that swirly movement.

Difference between GPU and CPU execution of Turbulence effects

In addition, performance will crawl, since Turbulence effects can contain up to 100 000 particles ' a little to much for a CPU to handle.

In short, no real particle motion and bad performance. Don't enable Turbulence effects on CPU.

Now, when we are done with specific details, let's try to extract some performance metrics. A session based MMO game like Hawken is a bad candidate for PhysX testing, since it is almost impossible to reproduce the benchmark conditions with same number and types of physics effects. However, we will try our best to give you at least the rough idea on how the GPU PhysX effects are affecting the actual game performance.

Testing system: i7 2600K CPU, GTX 580 GPU, 8 GB RAM, Win 7 64-bit.

In-game settings: 1680?1024, Ultra settings.

Conditions: framerate is measured as average of three 30 sec fragments - close quarter firefight with at least two enemy mechs. Team Deathmatch on "Prosk" level.

As you may see, a single GPU is more than enough to handle basic PhysX particles with comfortable average fps of 50-60 frames per second. At the same time, Turbulence effects are putting more stress on the system, slowing down the performance up to 35-45 frames per second (in an intensive scene, of course).

In this case, one may consider the performance drop too big for a competitive gameplay, and either disable APEX Turbulence effects or add a dedicated PhysX GPU to the system.

By the way, GPU PhysX performance has increased with a patch, released just a day ago. Before that, we have encountered framerate drops up to 20-25 fps.

As for CPU execution of PhysX effects, CPU can operate particle debris with surprisingly decent performance (40-50 fps), while enabling Turbulence effects on CPU makes the game complitely unplayble (every time such effect occur on the screen, game becomes a slideshow), just as we mentioned earlier.

And final note ' Hawken is not compatible with Hybrid PhysX. Latest methods to get Hybrids working, since as engine .dll replacements, are not working in case of Hawken, since the game is checking its files for consistency every launch, due to its MMO nature.

TOTAL7.5/10Hawken is strong project in a line of games with GPU PhysX support, but is not of anything extraordinary. We recommend to give it a try.

However, the story of Hawken does not end just here. As we heard, the game may be enhanced with even more PhysX effects in the future. In this case, we will be pleased to re-visit Hawken and update our score.

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