The State of DirectX 10 - Image Quality & Performance
The key features of this game are definitely its excellent plot and engrossing visuals which are achieved due in no small part to the game's steller graphics. From the sea water leaking in through cracks in the walls to the excellent use of particle effects in explosions and ominous shadows, Bioshock's graphics will impress. An interesting design decision that is important to note for our image quality comparisons is that Bioshock is designed to use 4x Anisotropic Filtering and no Anti-Aliasing. The game defaults to 0x AA and 4x AF and there are no in-game adjustments for either setting. The game also will not support anti-aliasing in DX10 mode even if you attempt to force AA through the graphics driver settings . Luckily, this does not seem to negatively effect image quality and we noticed little aliasing in the game despite the lack of AA.
While Bioshock is one of the first of many Unreal 3.0 based games that will be released this year, it is certainly not the first Unreal 3.0 based game to be released on the PC. That honor belongs to Rainbow Six: Vegas which has been available on the PC since last December. While both Bioshock and Vegas are built up from the Unreal 3.0 engine, they use significantly different versions and a lot of new features have been added since Vegas was developed, most notably the addition of DirectX 10 support. Like previous Unreal engines, Unreal 3.0 is being continuously developed and improved by Epic Games and new features slowly make their way into the engine.
While it was originally designed to take advantage of shader model 3.0, Epic has since added limited DirectX 10 shader support into newer builds of the engine. However, Epic's DX10 additions have, so far, been primarily focused on performance optimizations. Bioshock's developers had different ideas on how DX10 should be implemented and they have added their own modifications to support a variety of DX10 enhancements. The new DX10 enhancements include the use of dynamic water ripples, soft edges for particles, and crisper shadow edges. These enhancements are enabled by turning on the "DX10 Detailed Surfaces" option in the video menu.
Dynamic Water Ripples
Bioshock takes place in a dilapidating under water city on the Atlantic seabed called Rapture and as you might expect, water is everywhere. Water plays such an important role in creating the atmosphere of Rapture that the development team included a water effect specialist whose entire job was to program and tweak the water effects in Bioshock. It's therefore not surprising that Bioshock sports some of the best water effects in any game. Everywhere you look, you can see the Atlantic trying to seep in to reclaim Rapture and the diversity of water effects is astounding.
One of the DirectX 10 enhancements involves improved water effects, specifically better water ripples. In DX9, when something disturbs the water, ripples are created which quickly fade away. This same effect has been used in many other DX9 games and the result is relatively convincing. However, if you pay close attention to the ripples and really study them, you'll notice that the 'ripple' isn't really there, it just seems like it is thanks to clever usage of 2D animated sprites. However, in DX10 mode, Bioshock actually seems to render the ripple and give it a third dimension. The ripple actually rises slightly higher than the surrounding water, unlike in DX9 where the ripple is purely illusionary. While this is a nice effect, it's very subtle and you're unlikely to notice it unless you're really paying attention.
Soft Particle Edges
Soft particles is another touted DX10 feature supported by Bioshock. Soft particles refers to the way particle effects interact with geometric objects. Regular particle effects intersect with geometric objects sharply and the line of intersection can clearly be seen. This often results in particle effects appearing as if composed of several stacked 2D sprites which intersect with an object. With soft particles, the point of intersection is difficult to find and particle effects appear much more natural.
Soft particles are much more noticeable in-game than the previously mentioned ripple effects, however, they are still rather subtle. In the heat of the action, your unlikely to be bothered by a lack of softness in your particles.
Image Quality Impressions
Overall Bioshock is a great looking game. However, the difference in image quality between DirectX 9 and DirectX 10 rendering in Bioshock is very minimal. Chances are good that you are unlikely to notice the difference during normal play, unless you knew what to look for. For the most part, Bioshock looks equally good in DX9 and DX10. When your busy trying to survive in a anti-utopian society full of genetically spliced mutants, the sharpness of shadows on the wall and how particles are intersecting with geometry are probably the last things on your mind.
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