FA-87815 / Collision detection broadphase / Member archive

Swap events record pairs in swap orientation · case 05

The same pair appears as both (a,b) and (b,a).

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

solve(prev, curr): incremental sweep-and-prune on x. Endpoints [x, 0=min/1=max, id] of prev are sorted, refreshed with curr coordinates and insertion-sorted by (x, kind). Each swap where a min passes left over a max begins a pair (if y overlaps in curr); a max passing left over a min ends a pair. Return [sorted begin pairs, sorted end pairs, swap count], pairs as [min,max].

Why this case matters

Broadphase stages decide which object pairs ever reach narrowphase; a wrong boundary, ordering or bookkeeping rule silently drops real contacts or floods the solver with false candidates.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
case 0	`[[], [[11, 5], [15, 2], [34, 7], [34, 20]], 15]`	`[[], [[2, 15], [5, 11], [7, 34], [20, 34]], 15]`	Failed

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