[Unity] Compute Shader Indices

SV_DispatchThread ID (uint3)

Indices for which combined thread and thread group a compute shader is executing in. SV_DispatchThreadID is the sum of SV_GroupID * numthreads and GroupThreadID. It varies across the range specified in Dispatch and numthreads. For example, if Dispatch(2,2,2) is called on a compute shader with numthreads(3,3,3) SV_DispatchThreadID will have a range of 0..5 for each dimension.

SV_GroupID (uint3)

Indices for which thread group a compute shader is executing in. The indices are to the whole group and not an individual thread. Possible values vary across the range passed as parameters to Dispatch. For example calling Dispatch(2,1,1) results in possible values of 0,0,0 and 1,0,0.

Defines the group offset within a Dispatch call, per dimension of the dispatch call.

SV_GroupThreadID (uint3)

Indices for which an individual thread within a thread group a compute shader is executing in. SV_GroupThreadID varies across the range specified for the compute shader in the numthreads attribute. For example, if numthreads(3,2,1) was specified possible values for the SV_GroupThreadID input value have this range of values (0–2,0–1,0).

SV_GroupIndex (uint)

The “flattened” index of a compute shader thread within a thread group, which turns the multi-dimensional SV_GroupThreadID into a 1D value. SV_GroupIndex varies from 0 to (numthreadsX * numthreadsY * numThreadsZ) - 1.