Shader Model 5.0

DirectX 10 brought you Shader Model 4.0, which included full support for integers and bitwise operators among other features. Direct3D 10.1 added Shader Model 4.1, with support for direct MSAA sample access. DirectX 11 brings Shader Model 5, which utilizes object-oriented concepts to help reduce the pain of shader development and brings optional support for double precision. This update to HLSL enables you to bring the full power of the HLSL compiler to bear on the problem of shader specialization using interfaces, objects, and polymorphism. With dynamic shader linkage, developers can more easily author larger, flexible shaders and permute out specialized, optimized versions for use at run time during specific rendering.

Compute Shader

Anyone already familiar with general purpose use of GPUs will be excited to hear about the new compute shader, which brings cross-hardware vendor support for programming the GPU in general purpose ways (GPGPU). There have already been many advances made in applying the huge amount of numerical crunch power GPUs have to large scale computing problems in previously niche markets. With the addition of the compute shader in DirectX 11, Microsoft makes these algorithms possible on the client across a broad range of hardware. Look for exciting new ways that games and other application developers can take advantage of GPUs for tasks other than just rendering.

Key features include communication of data between threads, and a rich set of primitives for random access and streaming I/O operations. These features enable faster and simpler implementations of techniques already in use, such as imaging and post-processing effects, and also open up new techniques that become feasible on Direct3D 11-class hardware.

Additional Features

Even more exciting features are in store for DirectX 11 than can be covered in this basic introduction, but here are two last-minute things we simply couldn't finish this article without mentioning.

Conservative oDepth
Traditionally, IHVs have had to disable Z acceleration structures and algorithms when shaders write to the depth buffer via the oDepth register. The conservative oDepth feature in DirectX 11 enables shaders to write to the depth buffer within a specified region guarantee. This enables the hardware to avoid the full loss in performance by enabling acceleration outside of the guaranteed region.

16K Texture Limits and Texture Clamps
DirectX 11 raises the maximum texture size from 4K to 16K and also provides MIP-LOD control clamps to limit the number of mipmap levels loaded to the GPU.

Summary

We're excited to bring you this newest release of the DirectX API set. This version runs on Windows Vista as well as future versions of Windows, and it will work on your Direct3D 10-class and 10.1-class hardware, while exposing the new features of DirectX 11-class hardware. Many of the features are intended to make developer's lives easier while enabling opportunities for new functionality and performance gains. Look forward to a community tech preview in the November 2008 release of the DirectX SDK and start working with this next step in the evolution of graphics technology.

References

For more information about sub-division surface approximations, see the Sub-Division Surface sample in the DirectX SDK. Also look for the forthcoming Gamefest 2008 talks "Multithreaded Rendering for Games" and "DirectX 11 Tessellation," coming soon at http://msdn.microsoft.com/directx/presentations. Finally, also see Graphics APIs in Windows Vista on MSDN.