Batch Clip State Generation for Graphics Pipeline Optimization
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Solution Overview
Problem
Conventional graphics processing pipelines waste memory bandwidth and processing resources by performing operations on graphics primitives and vertices that are eventually clipped or culled downstream, as these operations are executed regardless of visibility.
Innovation Solution
A method is introduced to generate a clip state for a set of vertices relative to multiple clip planes, determining whether each vertex is inside, outside, or in a mixed state with respect to each plane, and updating a clip state machine to decide whether to process the vertices further in the pipeline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If operations are performed on all graphics primitives in conventional pipeline stages, then processing completeness is maintained, but memory bandwidth and processing resources are wasted on primitives that are eventually clipped or culled
Solution Approach 1:
The patent applies preliminary action by performing clip state generation early in the graphics pipeline, before vertex shading and geometry shader stages. The clip state machine determines which vertices will be clipped or culled in advance, allowing the system to skip processing operations on vertices that will ultimately be discarded, thus conserving processing resources while maintaining correctness for visible geometry
Solution Approach 2:
The patent extracts the clip state determination logic from later pipeline stages and places it in an early clip state machine. This separate extraction of clipping information allows the main processing pipeline to be optimized by skipping operations on culled vertices, reducing wasted processing on invisible geometry while preserving complete processing for visible elements
2Productivity
If clip state generation is performed early in the pipeline for all vertices, then processing bandwidth is conserved, but computational load on the clip state machine increases
Solution Approach 1:
The patent applies local quality by generating clip states at the vertex level rather than processing entire primitives uniformly. Each vertex receives individual clip state evaluation against the view frustum, allowing fine-grained control over which vertices require full processing. This localized approach optimizes the balance between early clip state generation benefits and the computational complexity of the clip state machine
Data Source
AI summary
One embodiment of the present invention sets forth a technique for generating a batch clip state stored in clip state machine (CSM) associated with a batch of vertices. Per-vertex clip state is generated for each vertex in the batch of vertices based on the position of each vertex relative to each clip plane. For a given vertex, per-vertex clip state indicates whether the vertex is inside or outside each of the one or more clip planes. The per-vertex clip states of all the vertices in the batch of vertices are coalesced into a batch clip state by determining whether each vertex in the batch of vertices is inside every clip plane, each vertex is outside at least one clip plane or neither. The batch clip state is stored in the CSM associated with the thread group that processes the batch of vertices that can be accessed by further stages of the graphics pipeline.