Getting Started with Direct3D - Direct3D Rendering - page 16

Compute Shader (CS) stage
The compute shader (also known as DirectCompute) is an optional programmable stage that
executes a shader program upon multiple threads, optionally passing in a dispatch thread
identifier ( SV_DispatchThreadID ) and up to three thread group identifier values as input
( SV_GroupIndex , SV_GroupID , and SV_GroupThreadID ). This shader supports a whole
range of uses including post processing, physics simulation, AI, and GPGPU tasks.
Compute shader support is mandatory for hardware devices from feature level 11_0 onwards,
and optionally available on hardware for feature levels 10_0 and 10_1.
The thread identifier is generally used as an index into a resource to perform an operation.
The same shader program is run upon many thousands of threads at the same time,
usually with each reading and/or writing to an element of a UAV resource.
Device context commands that control the compute shader stage are grouped in the
ComputeShader property or begin with CS in the unmanaged API.
After the compute shader is prepared, it is executed by calling the Dispatch command
on the device context, passing in the number of thread groups to use.
Introducing Direct3D 11.1 and 11.2
With the release of Windows 8 came a minor release of Direct3D, Version 11.1 and the
DXGI API, Version 1.2. A number of features that do not require Windows Display Driver
Model (WDDM) 1.2 were later made available for Windows 7 and Windows Server 2008
R2 with the Platform Update for Windows 7 SP1 and Windows Server 2008 R2 SP1.
Now with the release of Windows 8.1 in October 2013 and the arrival of the Xbox One
not long after, Microsoft has provided another minor release of Direct3D, Version 11.2
and DXGI Version 1.3. These further updates are not available on previous versions of
Windows 7 or Windows 8.
Direct3D 11.1 and DXGI 1.2 features
Direct3D 11.1 introduces a number of enhancements and additional features, including:
F Unordered Access Views (UAVs) can now be used in any shader stage, not just the
pixel and compute shaders
F A larger number of UAVs can be used when you bind resources to the output
merger stage
F Support for reducing memory bandwidth and power consumption (HLSL minimum
precision and swap chain dirty regions and scroll present parameters)