Mirror’s Edge PhysX Performance: PPU vs CPU vs GPU
As we discussed in our Cryostasis PhysX Performance Preview article back in December, 2009 could finally be the year PhysX could begin to matter for PC gamers. With NVIDIA recently signing on game publishers EA, 2K Games, and THQ, plus PhysX being supported by the world’s number one and number two most popular gaming engines – Unreal Engine 3 and Gamebryo – the technology appears to finally be poised for liftoff.
Mirror’s Edge is the first 2009 title to support the technology. Mirror’s Edge also happens to be the first AAA title to support PhysX out-of-the-box: PhysX is an adjustable setting that can be toggled on and off from right within the game’s graphics menu, regardless if you have a GeForce GPU or not. Obviously if you don’t have GeForce 8 or better card installed, PhysX will run on your PCs CPU instead of the GPU. Or if you happen to have an AGEIA PhysX PPU card, you can run Mirror’s Edge on that as well.
PhysX enhancements in Mirror’s Edge
So what enhancements does PhysX bring to Mirror’s Edge? Quite a few. The most obvious addition to the game is persistent shattered glass.
With or without PhysX, glass shatters pretty similarly when it’s hit by bullets. Whether it’s the glass from a window, display case, etc, the effect looks very good. However with PhysX turned off, the glass shatters and literally disappears into thin air, it doesn’t even hit the floor! With PhysX enabled, the shattered glass hits the floor and rests there. It doesn’t disappear after a few moments, and you can even kick up a few shards when you walk over them.
Along the same lines, one other aspect we noticed with PhysX turned on is added objects. For instance, with PhysX enabled, curtains are placed behind many glass windows. When these windows are then shattered, the curtains flop about realistically as the glass basically explodes right in front of it. Occasionally a few of these curtains will pop off completely and fly across the room onto the ground. We’ve taken screenshots of these effects:
PhysX on. See the curtains
PhysX off. No curtains
PhysX on. Glass shatters as bullets begin flying
PhysX on. You can see the curtains swing as they are hit by glass shards and bullets
PhysX on. See the glass shards on the floor? Curtains swinging as well
PhysX on. More glass shards on the floor
PhysX off. Glass shatters
PhysX off. Glass shatters but is not persistent: note the clean floor
PhysX off. Glass shatters and then literally disappears into thin air
PhysX off. Glass explodes here...
...But literally disappears into thin air
In this second sequence of screenshots you can see the results when a team of SWAT officers takes out a glass display case and more windows in this room:
PhysX on. SWAT shoots through glass
PhysX off. SWAT shoots through glass
PhysX on. More glass shatters as I take hit
PhysX on. Glass displays shatter
PhysX on. Glass shards hitting ground.
PhysX off. Glass displays shatter...
...But the floor is still spotless.
Besides adding curtains to windows for the PhysX version of Mirror’s Edge, DICE has also added cloth tarps in select areas of levels as well. These tarps flap in the wind, and respond accordingly when shot:
PhysX on. Cloth tarps flap in the wind.
PhysX on. Taking a shot at the tarp
With PhysX disabled, these tarps aren’t even present in the game:
Phys off. Where did everything go?
The final PhysX effect we captured screenshots of is the helicopter kicking up debris in the prologue of the game. As you can see in the shots, with PhysX enabled, newspapers and other objects on the rooftop fly across the screen when the helicopter descends. With PhysX off, these objects aren’t present.
PhysX off, no debris
PhysX on. You can see what appear to be newspapers and other objects
Besides these aforementioned effects, NVIDIA and DICE also use PhysX to provide volumetric smoke and fog but unfortunately we didn’t snag any good shots of that. The best way to see these PhysX effects in action is still the updated Mirror’s Edge PhysX trailer NVIDIA provided us back in December. The video provides a side-by-side comparison showing Mirror’s Edge running with PhysX, versus without:
Mirror’s Edge PhysX Impressions
Overall, the added PhysX effects add an additional layer of polish to the game, although we wouldn’t by any means label them as game changers. Unlike PhysX games like Warmonger or Cell Factor, the added physics elements in Mirror’s Edge don’t affect gameplay – for instance there are rumors floating around that shattering glass in Mirror’s Edge with PhysX can cause damage to your character, but those rumors aren’t true. We tested this out by standing right next to a window multiple times as it was shattered and didn’t take any damage.
Basically PhysX brings an additional layer of eye candy to Mirror’s Edge. Nothing more, nothing less. It is however good-looking eye candy that gives the game world an added dose of reality. After all, it’s a bit hard to take a game seriously when an entire wall of windows explodes right in front of your eyes yet leaves no trace of any glass on the floor beneath you.
PhysX basically ensures that the PC version of Mirror’s Edge is the best-looking of all the platforms the game has been released on.
PhysX doesn’t come for free though. You will see a performance hit by turning on this feature. How much of a performance hit bring? Let’s load up some benchmarks!