FA-87623 / Collision detection broadphase / Member archive

Grid level uses the smaller box extent · case 03

Long thin objects are placed on too fine a level and span many cells.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

solve(objs, base, levels): multi-level grid. Each [id,minx,miny,maxx,maxy] goes to the smallest level l (cell size base*2^l) whose cell size is >= the larger box extent, capped at levels-1; its home cell is floor(min corner / level cell size). Return sorted [[id, level, cx, cy]].

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	`[[1, 0, 4, -2], [15, 2, -1, 0], [18, 0, -5, -5], [19, 1, 1, 1], [31, 0, 2, 3], [33, 0, -4, 3]]`	`[[1, 2, 1, -1], [15, 3, -1, 0], [18, 2, -2, -2], [19, 1, 1, 1], [31, 2, 0, 0], [33, 2, -1, 0]]`	Failed

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