Batman Arkham City: Technical advantages of the PC version - DX11 tessellation and more
The PC version of Batman Arkham City will arrive later than the console versions. Is the delay worth the wait? PCGH had the chance to chat with Ben Wyatt, Technical Director at Rocksteady Studios. He gives us details on the PC advantages of Batman Arkham City.
As you might know, the PC version of Batman Arkham City from Warner/Rocksteady comes a little bit later than the console parts. Word is that Rocksteady needs "several weeks" overtime for optimizing the PC part. Is it worth the wait? We allready know that Arkham City uses GPU-powered Physx, DX11 (tessellation, HDAO, soft shadows), high res textures, Nvidia's CSAA-technique and more detailed models. Ben Wyatt, Technical Director at Rocksteady Studios, gives us some more details on the technical part of Arkham City.
PCGH: Will the PC version of Batman: Arkham City like Batman: Arkham Asylum utilize Nvidia's PhysX API including support for Physics calculated on the GPU?
Ben Wyatt: Yes. Like Batman: Arkham Asylum, the PC version of Batman: Arkham City will feature realistic smoke, debris, leaves, and paper using GPU PhysX. There will also be features not seen in Batman: Arkham Asylum including clothing on characters.
PCGH: Which of the different APEX modules do you use (Apex Clothing/Particles (Destruction/Turbulence for fluids)? Can you give a short description where in the game APEX will be applied?
Ben Wyatt: APEX destructibles are used in the PC version for breakable elements in the game including breakable walls and objects that get thrown during fights. APEX clothing is used in the PC version for several of the characters you'll encounter in the game and for simulating effects like paper and leaves. APEX clothing was also used for many of the cutscenes which can be seen on all platforms.
PCGH: What are the visual differences between physics calculated by CPU and GPU (via PhysX/APEX)?
Ben Wyatt: The extra PhysX effects in the PC version of the game add another dimension of realism to the game. When fighting as Batman or Catwoman, you will see walls break into splinters, paper and debris get kicked up, smoke respond realistically, and clothes on the thugs you fight.
PCGH: Are there any features that players without an Nvidia card will miss? What technical features cannot be realized with the CPU as "physics calculator"?
Ben Wyatt: All PhysX and APEX features can be run on the CPU or an NVIDIA GPU, but you can expect the game to run much slower without NVIDIA GPU acceleration when the additional PhysX effects are enabled. An NVIDIA GPU is recommended for all the additional PhysX features.
PCGH: Do you plan to use the latest PhysX SDK 3? Which advantages do you see compared to previous versions?
Ben Wyatt: Batman: Arkham City uses PhysX 2.8.4.
PCGH: Will the PC version of Batman Arkham City be shipped with support for DX11?
Ben Wyatt: Yes. It will also be shipped with support for NVIDIA 3D Vision, including full-HD 3D Vision cut-scenes on both DX9 and DX11.
PCGH: What do you think are the deciding advantages of DX11/Shader Model 5?
Ben Wyatt: DX11 brings quite significant improvements to the game visuals and performance:
1. DX11 tessellation. Smoothing and/or displacement mapping have been manually added by artists to a number of game assets throughout the game. This provides higher visual quality and richer environments to the game.
2. Texture arrays (available since DX10) are used to simplify and accelerate the rendering of the Multi-View Soft Shadows cast by the player-controlled character (Batman or Catwoman). This algorithm could have been implemented using DX9 with a texture atlas, but that would have been complicated and slower.
3. DX11 Compute shaders. The original built-in SSAO algorithm has been enhanced in DX11 by performing some additional rendering work. DX11 compute shaders are used to accelerate the AO-generation and blur passes by caching the samples in group-shared memory to reduce the number of texture fetches, significantly improving the speed and final quality.
PCGH: Do you focus on using DX11 for speeding up the rendering or will there be special visual improvements resulting in applying DX11 rendering techniques (Tessellation, HQSSAO, better performance post processing effects)? If there are special DX11 features what visuals will gamers with older DX9 video cards miss?
Ben Wyatt: Batman Arkham City uses Shader Model 5 to improve the looks while maintaining high performance. Gamers will see significant visual differences compared to DX9 and consoles. These differences are centered around tessellated environments and objects, higher quality shadows and better ambient occlusion.
PCGH: Will there be visual differences even between the DX10 and DX11?
Ben Wyatt: Yes. There will be multiple visual differences when playing the game in DX11 mode (only supported on DX11 GPUs) vs. DX9. The game does not support DX10.
Compared to the DX9 mode, the DX11 mode will have:
1. More geometric detail on tessellated objects, such as architectural details, vines and other organic shapes. The main difference will be no visible triangles and additional displacement-mapping detail. The difference will be mostly noticeable at to object's silhouettes, as well as playing the game with 3D Vision (which makes the displacement-mapping detail much more obvious).
2. A more pronounced contact occlusion due to the DX11 SSAO (especially noticeable on the PhysX debris, leaves, and paper), which makes certain objects look more in contact with the ground (as opposed to floating above the ground).
3. Contact-hardening soft shadows for the dynamic shadows cast by the player-controlled character (either Batman or Catwoman). On DX9, this dynamic shadow does not harden on contact, which looks less realistic.
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