DirectX-Specs

HLSL Shader Model 6.8

v0.6 2024-03-11

Contents

• Introduction
• Work Graphs
• Expanded Comparison Sampling
• Extended Command Information
• Wave Size Range
• Change Log

Introduction

This document covers the new Shader Model 6.8. A brief summary of each new feature is listed below along with links to detailed specifications.

Work Graphs

Work Graphs define a system of shader nodes that feed into each other to enable tailored GPU work creation.

See the Work Graphs documentation for more details.

Expanded Comparison Sampling

Several existing operations have been expanded to support Comparison Samplers. New methods: SampleCmpBias, SampleCmpGrad. Added overloads: CalculateLevelOfDetail, CalculateLevelOfDetailUnclamped.

See the Expanded Comparison Sampling documentation for more details.

Extended Command Information

Two new system-value semantics are required to be supported in HLSL shader model 6.8:

• SV_StartVertexLocation - Reports StartVertexLocation from DrawInstanced() or BaseVertexLocation from DrawIndexedInstanced() to a vertex shader.
• SV_StartInstanceLocation - Reports StartInstanceLocation From Draw*Instanced to a vertex shader.

See the Extended Command Information documentation for more details.

Wave Size Range

A new variant of the WaveSize attribute is added: [WaveSize( min, max [, preferred] )]. This allows you to specify a range and optional preferred size.

See the Wave Size Range documentation for more details.

Change Log

Version	Date	Description
0.1	29 Jun 2021	Initial draft outline
0.2	20 Oct 2021	Update spec links
0.3	24 Aug 2022	Add WaveMMA spec link
0.4	01 May 2023	Update included elements
0.5	21 Jun 2023	Update for preview release
0.6	11 Mar 2024	Remove WaveMMA; remove experimental; add Expanded Comparison Sampling, Extended Command Information, and Wave Size Range