Reuse one line intersector for all obstacle candidates of a profile - #1008
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sachabaclet wants to merge 1 commit into
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Reuse one line intersector for all obstacle candidates of a profile#1008sachabaclet wants to merge 1 commit into
sachabaclet wants to merge 1 commit into
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For every candidate wall or ground border of a cut profile, addGroundBuildingCutPts called LineSegment.intersection, which creates a new RobustLineIntersector and its internal arrays on each call. A JFR recording of an urban run with reflections showed this single call site producing 29% of the allocation pressure of the whole computation. The intersector is now created once per profile and reused for every candidate. The returned coordinate was already copied right after the test, so the reuse is safe. The list of new cut points also becomes an ArrayList instead of a LinkedList. The computed intersections are exactly the ones LineSegment.intersection returns, so the results are unchanged. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
pierromond
approved these changes
Jul 27, 2026
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The problem
For every candidate wall or ground border of a cut profile,
addGroundBuildingCutPtscalledLineSegment.intersection, which creates a newRobustLineIntersectorand its internal arrays on each call. A JFR recording of an urban run with order-2 reflections showed this single call site producing 29% of the allocation pressure of the whole computation.The change (+6/−2 lines)
RobustLineIntersectoris created per profile and reused for every candidate. The intersection test is exactly whatLineSegment.intersectiondoes internally, so the computed coordinates are identical. The returned coordinate was already copied right after the test, which makes the reuse safe.ArrayListinstead of aLinkedList.