Per-vertex variable rate shading for GPU rendering
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Solution Overview
Problem
Modern graphics applications face challenges with fragment shading being heavily processing-bound, especially as screen resolutions and desired frame rates increase, leading to issues like visual artifacts, overdraw, and increased processing overhead, which existing technologies struggle to address effectively.
Innovation Solution
The implementation of variable rate shading (VRS) techniques by a graphics processing unit (GPU), which renders different regions of an image at variable pixel densities or levels of detail, allowing for finer control over shading rates and enabling overlapping objects to be rendered at different resolutions, while maintaining high rendering quality and compatibility with other graphics hardware functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional uniform shading is used across the entire image, then processing is simpler and more consistent, but processing overhead increases and rendering performance decreases at high resolutions
Solution Approach 1:
The patent applies local quality by dividing the image into different regions (foreground, midground, background) and applying different shading rates to each region. Foreground objects receive higher shading rates for detailed rendering, while background objects use lower shading rates to reduce processing overhead. This resolves the contradiction by optimizing rendering performance locally rather than uniformly across the entire image.
Solution Approach 2:
The patent segments the rendering process into distinct stages: depth-based region classification, variable rate shading application, and selective amplification. By segmenting the image into multiple depth regions and applying different shading strategies to each segment, the system achieves higher overall productivity while managing processing complexity through structured division of labor.
2Productivity
If variable rate shading is implemented to reduce processing overhead, then rendering quality may be compromised due to inconsistent shading across regions
Solution Approach 1:
The patent implements dynamic shading rate adjustment based on depth information and object importance. The shading rate is not static but dynamically determined by the object's depth position and significance in the scene. This dynamic approach maintains rendering quality consistency by adapting the shading rate to local requirements rather than applying uniform or purely static variable rates.
Solution Approach 2:
The system uses depth information as feedback to determine appropriate shading rates for different regions. By continuously analyzing depth data and using it to adjust shading parameters, the system maintains quality consistency while optimizing processing efficiency. The feedback loop ensures that quality requirements are met in critical regions while allowing efficiency optimizations in less critical areas.
3Manufacturing precision
If high shading rates are applied to all regions, then rendering quality is maintained, but processing overhead increases significantly
Solution Approach 1:
The patent changes the shading rate parameter dynamically based on spatial position and depth information. Instead of using a single fixed shading rate for all regions, the system varies the shading rate parameter across different spatial regions and depth planes. This parameter change strategy maintains high rendering quality where needed while reducing processing overhead in regions where lower quality is acceptable.
Solution Approach 2:
The patent applies partial action by using high shading rates only for foreground and midground regions that require detailed rendering, while using lower shading rates for background regions. This selective application of high-quality shading to only the necessary portions of the image maintains overall rendering quality while significantly reducing total processing overhead and energy consumption.
4Productivity
If variable shading rates are used within a single primitive, then processing overhead is reduced, but visual artifacts may appear due to discontinuities at boundaries
Solution Approach 1:
The patent applies equipotentiality by using depth-based region classification to create smooth transitions between different shading rate zones. Objects at similar depth positions are grouped into the same shading region, creating equipotential zones where the shading rate is consistent. This approach prevents visual artifacts by ensuring that shading rate changes occur along smooth depth boundaries rather than creating discontinuities within primitives.
Data Source
AI summary
A graphics processing unit (GPU) may rasterize a primitive into a plurality of samples, wherein vertices of the primitive are associated with VRS parameters. The GPU may determine a VRS quality group that comprises one or more sub regions of the plurality of samples based at least in part on the VRS parameters. The GPU may fragment shade a VRS tile that represents the VRS quality group, wherein the VRS tile comprises fewer samples than the VRS quality group. The GPU may amplify the stored VRS tile into shaded fragments that correspond to the VRS quality group.