by Anton Shilov
03/17/2009 | 03:38 PM
ATI, graphics products group of Advanced Micro Devices, plans to promote DirectX 11 as well as its tessellation feature rather seriously at the forthcoming Game Developers Conference 2009. ATI has a long history of tessellation support in its hardware, but with the Direct3D 11 the feature becomes compulsory and hence will become mainstream.
During the GDC ’09, ATI/AMD will host two sessions about DirectX 11 and its influence on the forthcoming games. It is noteworthy that the arch-rival of AMD’s ATI business unit, Nvidia Corp., will not specifically cover DirectX 11 at the Game Developers Conference this year, but will concentrate on some other technologies that are also likely to be points of interest for video game creators.
The first DX11-related session to be held by ATI – Direct3D11 Tessellation Deep Dive – will exclusively cover tessellation feature of the forthcoming application programming interface developed by Microsoft Corp.
The Direct3D 11 introduces three new graphics pipeline stages designed for flexible tessellation. The session at GDC 2009 will summarize the design of the hull shader, tessellator, domain shader pipeline stages, and outline their intended usage. The second half of the talk will describe in depth and demonstrate the real-time Catmull-Clark subdivision surface approximation algorithm developed by Microsoft Research and implemented in the DirectX SDK samples.
Hardware tessellation is something that ATI has been developing for many years and it looks like the fans of curved surfaces will reach their Mecca with the introduction of DirectX 11.
The first hardware tessellation mechanism branded Truform was introduced back in 2001 along with the Radeon 8500-series (R200) graphics processing units and even provided some improvements in demos and a couple of games. However, due to limitations in programmability, the vast majority of game creators decided not to utilize the technology and later on the hardware was removed from more advanced graphics chips.
The second attempt to introduce tessellation to the masses was the implementation of the hardware tessellation block into the graphics core (R500/Xenos) of Microsoft Xbox 360 video game console in 2005, though, only one title – Viva Pinata – utilized the technology.
ATI claims that the tessellation unit of the Xbox 360 GPU was integrated into the ATI Radeon HD 2000-/3000-series graphics processors, which is why it could be programmed only using vertex shaders. Therefore, the tessellation hardware of the sixth-generation Radeon graphics processors can either be called second attempt to intro tessellation on the PC by ATI, or the company’s third attempt to make the technology popular.
With the latest ATI Radeon HD 4000-series graphics chips AMD’s graphics product group introduced a more advanced tessellation block that can be programmed using both vertex and geometry shaders.
All-in-all, after four failed attempts to make hardware tessellation an adopted feature, ATI will have this done in DirectX 11, which is due later this year. Needless to say that after so many attempts, the company should be quite capable of describing the benefits of industry-standard tessellation implementation.
In addition to a dedicated session regarding DX11’s hardware tessellation, AMD’s graphics products group will also discuss other advantages of the new API, such as compute shaders, which, besides abilities to implement certain physics effects in a more convenient way, can make post-processing faster and easier.
“You’ll need Direct3D 11 to have the best graphics, and this talk will show you how you can get started using current generation hardware,” the description of the session reads.
One of the other key API difference (besides tessellation and compute shaders) from Direct3D 10 in Direct3D 11 is the addition of deferred contexts, which enables scalable execution of Direct3D commands distributed over multiple cores. A Deferred Context captures and assembles actions like state changes and draw submissions that can be executed on the actual device at a later time. By utilizing Deferred Contexts on multiple threads, an application can distribute the CPU overhead needed in the Direct3D 11 runtime and the driver to multiple cores, enabling better use of an end-user's machine configuration. In addition, Direct3D 11 introduces a limited form of Runtime Shader Linkage that allows for near-optimal shader specialization during execution of an application.
The first DirectX 11-compatible graphics processing units are set to become available in 2009.
Game Developers Conference 2009 will be held March 23 – 27, 2009 in Moscone Center, San Francisco, California.