Per-Pixel Variable Rate Shading via Stencil Data

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Solution Overview

Problem

Current 3D graphics processing pipelines face inefficiencies in rendering performance due to the lack of effective methods for determining and implementing variable rate shading rates across different areas of the render target, leading to suboptimal resource utilization and increased computational load.

Innovation Solution

The technique involves determining per-pixel variable rate shading rates for fragments and calculating a coarse shading rate for areas based on these rates, allowing for optimized shading operations by adjusting the workload of pixel shader work-items according to the coverage and complexity of render target pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If per-pixel variable rate shading rates are determined and applied, then rendering performance is improved and computational workload is reduced, but device complexity and implementation difficulty increase

Engineering Contradiction:

Improverendering performanceVSAvoidimplementation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The render target is divided into multiple coarse variable rate shading areas, each with its own shading rate. This segmentation allows the system to apply different shading rates to different regions, optimizing rendering performance while managing complexity through hierarchical organization rather than per-pixel control

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different shading rates are applied to different coarse pixel areas based on their specific coverage and complexity characteristics. High-frequency detail areas receive finer shading rates while low-frequency areas use coarser rates, achieving local optimization without system-wide complexity

Inventive Principle:

Principle #3Local quality

2Use of energy by moving object

If coarse variable rate shading areas are determined based on per-pixel rates, then resource utilization is improved, but processing overhead increases

Engineering Contradiction:

Improveresource utilizationVSAvoidprocessing overhead

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

Per-pixel variable rate shading rates are determined in advance during the rasterization stage, before the actual shading computation. This preliminary determination allows the system to optimize resource allocation upfront, reducing processing overhead during the main rendering pipeline

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts shading rates based on real-time coverage and complexity metrics of each coarse pixel area. This dynamic adaptation allows optimal resource utilization without fixed processing overhead, as the shading rate is adjusted according to actual scene requirements

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12067649B2Per-pixel variable rate shading controls using stencil data

Publication Date: 2024.08.20 ADVANCED MICRO DEVICES INC

AI summary

A disclosed technique includes determining a plurality of per-pixel variable rate shading rates for a plurality of fragments; determining a coarse variable shading rate for a coarse variable rate shading area based on the plurality of per-pixel variable rate shading rates; and shading one or more fragments based on the plurality of fragments and based on the coarse variable shading rate.