FA-87353 / Collision detection broadphase / Member archive

Sweep reports pairs in active-list order · case 03

The pair cache sees (b,a) one frame and (a,b) the next, restarting contacts.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

solve(boxes): boxes [id,minx,miny,maxx,maxy] with closed intervals (touching overlaps). Sweep x endpoints sorted by (coord, begin-before-end); on each begin, test y against every active box. Return sorted [min id, max id] pairs overlapping on both axes.

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 1	`[[5, 21], [5, 25], [25, 21]]`	`[[5, 21], [5, 25], [21, 25]]`	Failed

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