Tile Fragment Lists for Variable Rate Shading Order Control
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Solution Overview
Problem
Managing and enforcing ordering dependencies of fragment processing operations in graphics processing, particularly in the context of variable rate shading, is challenging due to varying shading rates and overlapping primitives, which complicates the processing order of fragments.
Innovation Solution
The method involves subdividing the render output into tiles and maintaining lists for each sub-region of the tiles, where each entry in the list represents a group of fragments with associated information on their coverage and processing eligibility, allowing efficient identification and enforcement of dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fragments are processed concurrently to improve throughput, then processing speed increases, but ordering dependencies between fragments from different primitives must be maintained
Solution Approach 1:
The render output is divided into multiple tiles, and each tile is further subdivided into sub-regions. Fragment lists are maintained separately for each sub-region, allowing concurrent processing of fragments from different sub-regions while maintaining ordering within each sub-region. This segmentation enables parallelism while preserving necessary dependencies.
Solution Approach 2:
Fragment lists serve as intermediary data structures that mediate between fragment generation and fragment processing. These lists track fragment dependencies and control the ordering of fragment processing operations, enabling concurrent processing while maintaining correctness through the intermediary listing mechanism.
2Productivity
If variable rate shading is implemented to optimize rendering performance, then processing efficiency improves, but fragment ordering dependencies become more complex to manage
Solution Approach 1:
Different sub-regions of tiles can have different fragment processing characteristics based on local requirements. The fragment list mechanism allows each sub-region to independently manage its fragments with appropriate ordering, enabling variable rate shading optimization while maintaining local ordering dependencies through the distributed list structure.
Data Source
AI summary
When performing tile-based rendering in a graphics processing system, lists indicative of fragments to be processed are maintained for respective sub-regions of tiles to be rendered, with each list entry including, inter alia, at least an indication of the coverage within the tile sub-region of the group of fragments that the list entry represents, and an indication of whether the group of fragments that the list entry represents is eligible to undergo particular processing operations. The coverage information and eligibility information for the list entries is then used to control the processing of fragments for sub-regions of a tile, in such a way as to ensure that processing order dependencies are enforced and met.