Distributed View Frustum Clipping in Graphics Pipeline
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Solution Overview
Problem
Current 3D computer graphics processing pipelines face bottlenecks due to the complexity and cost of performing view frustum clipping/culling, either by transforming all objects to screen space or using complex 6-plane clipping algorithms, which can increase implementation complexity and cost.
Innovation Solution
A method is introduced that distributes clipping/culling operations across multiple modules in the graphics processing pipeline, including primitive assembly, setup, and rasterization modules, performing multiple stages of clipping to efficiently handle 3D objects within the view frustum, reducing unnecessary transformations and computations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all 3D objects are transformed to screen space for clipping, then clipping accuracy is improved, but computational cost and pipeline complexity increase
Solution Approach 1:
The patent divides the clipping operation into multiple segments performed at different pipeline stages: view frustum clipping in the PA module, clipping window clipping in the SE module, and additional clipping in the RA module. Each segment handles specific clipping tasks appropriate to that stage, avoiding the need to transform all objects to screen space while maintaining clipping accuracy for visible geometry.
Solution Approach 2:
The patent performs preliminary clipping operations in the PA and SE modules before final rasterization. By conducting view frustum clipping early in the pipeline and clipping window clipping in the setup module, the system eliminates invisible geometry before it reaches the rasterization stage, reducing unnecessary computations while preserving accurate clipping boundaries.
2Reliability
If complex 6-plane clipping algorithms are used in the PA module, then view frustum clipping completeness is improved, but implementation cost and hardware complexity increase
Solution Approach 1:
The patent segments the complex 6-plane clipping operation into simpler clipping stages distributed across multiple modules. The PA module performs basic view frustum clipping, the SE module performs clipping window clipping, and the RA module performs additional clipping. This segmentation reduces hardware complexity in each individual module while maintaining overall clipping completeness.
Solution Approach 2:
The patent moves clipping operations from a single location (PA module) to multiple locations throughout the pipeline (PA, SE, and RA modules). This dimensional change in the pipeline architecture allows clipping to be performed incrementally at appropriate stages, reducing the computational burden and hardware complexity at any single point while maintaining comprehensive clipping coverage.
3Ease of manufacture
If clipping is performed in a single location in the pipeline, then implementation simplicity is improved, but processing speed and pipeline throughput deteriorate due to bottlenecks
Solution Approach 1:
The patent segments the clipping function across multiple pipeline modules (PA, SE, and RA) rather than concentrating it in a single location. This distribution eliminates the processing bottleneck that would occur at a single clipping stage, allowing parallel processing and improving overall pipeline throughput while maintaining implementation feasibility through modular design.
Solution Approach 2:
The patent creates a dynamic clipping system where different modules perform clipping operations based on their specific functions and the current processing stage. The PA module handles view frustum clipping, the SE module handles clipping window clipping, and the RA module handles additional clipping as needed. This dynamic distribution adapts to the processing requirements at each stage, optimizing pipeline throughput.
Data Source
AI summary
A distributed clipping scheme is provided, view frustum culling is distributed in several places in a graphics processing pipeline to simplify hardware implementation and improve performance. In general, many 3D objects are outside viewing frustum. In one embodiment, clipping is performed on these objects with a simple algorithm in the PA module, such as near Z clipping, trivial rejection and trivial acceptance. In one embodiment, the SE and RA modules perform the rest of clipping, such as X, Y and far Z clipping. In one embodiment, the SE module performs clipping by way of computing a initial point of rasterization. In one embodiment, the RA module performs clipping by way of conducting the rendering step of the rasterization process. This approach distributes the complexity in the graphics processing pipeline and makes the design simpler and faster, therefore design complexity, cost and performance may all be improved in hardware implementation.