Scene Graph Hit Testing with Viewable-Region Node Filtering
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Solution Overview
Problem
Assessing the entirety of a scene graph for hit testing is computationally expensive for devices tasked with rendering and other operations, given limited time and computational resources.
Innovation Solution
Electronic devices identify a subset of nodes in a scene graph that satisfy a relevancy criterion based on a viewable region, assessing only this subset to determine intersection with a spatial selector, thereby reducing computational expense.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entirety of the scene graph is assessed for hit testing, then complete and accurate hit testing is achieved, but computational expense increases significantly
Solution Approach 1:
The scene graph is divided into multiple subsets based on spatial regions. Instead of assessing all nodes uniformly, the system segments the scene graph into relevant and irrelevant portions, assessing only the relevant subset that corresponds to the viewable region. This segmentation maintains hit testing accuracy for visible objects while eliminating unnecessary computational expense for hidden objects.
Solution Approach 2:
Different parts of the scene graph are treated differently based on their relevance to the viewable region. Nodes within the viewable region undergo comprehensive hit testing assessment, while nodes outside the viewable region are excluded from assessment. This local quality approach ensures accurate hit testing where needed while reducing overall computational expense.
2Reliability
If the entirety of the scene graph is assessed for hit testing, then complete object selection is ensured, but processing time increases
Solution Approach 1:
The scene graph nodes are segmented into two groups: those within the viewable region and those outside it. Hit testing is performed only on the segmented subset within the viewable region, significantly reducing processing time while maintaining complete object selection for all visible objects that could potentially be selected by the user.
Solution Approach 2:
Instead of performing hit testing on all scene graph nodes (excessive action), the system performs hit testing only on the necessary subset of nodes within the viewable region (partial action). This partial assessment is sufficient to ensure complete object selection for selectable objects, eliminating wasted processing time on non-selectable hidden objects.
3Measurement precision
If hit testing is performed on all scene graph nodes, then accurate spatial selector intersection is determined, but device performance degrades
Solution Approach 1:
The system extracts and isolates only the relevant portion of the scene graph that lies within the viewable region, separating it from the rest of the scene graph. Hit testing is then performed exclusively on this extracted subset, maintaining accurate spatial selector intersection determination for visible objects while improving overall device performance by eliminating unnecessary computations.
Solution Approach 2:
Before performing hit testing, the system preliminarily identifies and filters nodes based on their spatial relationship to the viewable region. This preliminary action of pre-filtering nodes ensures that only potentially intersectable objects are assessed for spatial selector intersection, maintaining measurement precision while preventing device performance degradation from unnecessary computations.
Data Source
AI summary
A method is performed at an electronic device with one or more processors, a non-transitory memory, and a display. The method includes obtaining a scene graph that includes a plurality of nodes. Each of the plurality of nodes represents an object. The method includes identifying, within the plurality of nodes, a first subset of nodes based on each of the first subset of nodes satisfying a relevancy criterion with respect to a viewable region associated with the display. The first subset of nodes respectively represents a first subset of objects. The method includes assessing the first subset of objects in order to determine whether a spatial selector intersects with a particular object of the first subset of the objects. The method includes selecting the particular object based on determining that the spatial selector intersects with the particular object.