Hierarchical Primitive Patch Testing in Tile-Based Graphics
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Solution Overview
Problem
Current graphics processing systems face inefficiencies in rasterization operations, particularly when dealing with varying rendering tile sizes, which can lead to increased storage requirements and resource limitations in devices like mobile phones and tablets.
Innovation Solution
A tile-based graphics processor that selectively uses different rendering tile sizes and performs hierarchical rasterization, starting from a patch size corresponding to the actual rendering tile size, thereby reducing unnecessary patch tests and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hierarchical rasterization is performed starting from the largest patch size, then complete coverage testing is achieved, but the number of patch tests increases and processing efficiency decreases
Solution Approach 1:
The method performs a preliminary bounding box test before hierarchical patch testing to determine if the primitive can potentially cover the rendering tile. This preliminary action filters out primitives that cannot possibly contribute to the output, avoiding unnecessary hierarchical patch tests and improving overall rasterization efficiency while maintaining complete coverage testing for primitives that do intersect the tile.
2Device complexity
If fixed largest rendering tile size is used, then processing is simplified, but storage capacity is wasted and resource utilization decreases in resource-constrained devices
Solution Approach 1:
The method dynamically adjusts the rendering tile size based on the actual geometry of the primitive being rasterized. Instead of using a fixed largest tile size, the system determines the appropriate tile size by calculating the bounding box of the primitive and selecting a tile size that fits the primitive's dimensions. This dynamic adaptation maximizes storage utilization and reduces memory bandwidth requirements while maintaining processing efficiency.
3Quantity of substance
If rendering tile size is reduced to fit storage capacity, then storage constraints are satisfied, but the number of tiles increases and processing overhead increases
Solution Approach 1:
The method changes the parameter of tile size dynamically based on the primitive's bounding box dimensions. By calculating the appropriate tile size that maximizes storage utilization without exceeding device capacity, the system reduces the number of tiles needed compared to using fixed smaller tiles, thereby reducing processing overhead while satisfying storage constraints.
4Measurement precision
If primitives are tested against all patch sizes hierarchically, then accurate coverage determination is achieved, but processing time increases
Solution Approach 1:
The method segments the hierarchical patch testing process by introducing a bounding box test that divides primitives into two categories: those that can potentially cover the rendering tile and those that cannot. This segmentation allows the system to skip detailed hierarchical patch testing for primitives that fail the bounding box test, significantly reducing processing time while maintaining accurate coverage determination for primitives that do intersect the tile.
Data Source
AI summary
A method of operating a tile-based graphics processor that can use one of plural different rendering tile sizes is disclosed. The tile-based graphics processor includes a rasteriser that can rasterise primitives in a hierarchical manner. A patch size at which to begin the hierarchical testing of primitives in the rasteriser is selected based on the rendering tile size that is to be used. This can reduce the overall number of tests performed to rasterise primitives without impacting the correct functioning of the hierarchical rasterisation process.